fix(web): headroom + symmetric insets for network-timeline marker labels

A left-edge "Clock -3h 0m" label collided with the HTML legend above the
band (first live fleet session d0c5b672). Marker-label headroom grows to
48 units so long labels stay inside the SVG, and the drawing content is
now inset 64 units on BOTH sides - the left inset mirrors the existing
right one, giving edge labels room and a calmer, symmetric frame.

Verified against the live session carrying the first system_clock_changed
event (backfilled step -> marker only, no rebase, as designed).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/agent/cmtrace-time-resolution.md

@@ -0,0 +1,127 @@
+---
+type: concept
+title: CMTrace Time Resolution — Per-Line Self-Anchoring
+description: How the agent converts bias-less CMTrace local times to UTC without trusting any process's timezone belief — each provably fresh line anchors its own offset against the agent clock on the 15-minute grid; everything not provably fresh falls back uniformly and says so.
+resource: src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/Ime
+tags: [agent, ime, cmtrace, timestamps, timezone, calibration, provenance]
+timestamp: 2026-08-20
+---
+
+# Problem
+
+A CMTrace line carries local time and no offset — IME 1.104 writes `DateTime.Now.TimeOfDay`
+in both of its trace listeners. Converting such a line with the reader's own
+`TimeZoneInfo.Local` silently assumes the writing and reading processes agree on the zone.
+They do not: each caches its zone at process start and follows neither a later `tzutil` nor
+a Windows auto-timezone change. The error is `Offset_writer − Offset_reader` — zero only
+when both believe the same thing, right or wrong. Field measurement over 11,068 sessions
+found 26 sessions with a real error, from +1 h to −17 h.
+
+Two designs failed before this one:
+
+* **Fix the reader's belief** (`TimeZoneInfo.ClearCachedData`, live OS offset): makes the
+  agent isolated-correct and thereby breaks the majority of sessions, where two equally
+  stale beliefs cancel.
+* **One measured offset per file** (agent 2.0.1410, reverted in `04b1a7c6`): a single log
+  file holds lines from multiple writer *eras*. `AgentExecutor.log` is written by
+  short-lived child processes whose zone belief flips per process — interleaved in one
+  file, and flipping *back* (fixture:
+  `tests/fixtures/cmtrace-logs/agentexecutor-two-writer-eras-v1.cmtrace`). Any cross-line
+  anchor — per file, or nearest-in-write-order — applies one era's offset to the other
+  era's lines. In the field this shifted `script_started` events by −9 h against their
+  correct completions.
+
+# Schema
+
+The resolution rule, in order:
+
+1. **Writer-declared bias** (`+480` suffix): authoritative, used as-is. Never a calibration
+   anchor — it needs no measurement and must not overwrite one.
+2. **Per-line self-anchoring** — only for lines read in a *provably fresh* pass:
+
+   ```
+   offset_line = round((local − agentUtcNow) / 15 min) · 15 min
+   lineUtc     = local − offset_line
+   ```
+
+   Every real UTC offset is a whole multiple of 15 minutes, so the rounding absorbs poll
+   and flush latency. No cross-line state exists, so interleaved eras resolve line by
+   line — the property the fixture test pins. The line's own timestamp still contributes
+   sub-poll precision and ordering (two lines 6 ms apart stay 6 ms apart; a plain
+   `occurredAt = now` could not do that). Guards: grid residual ≤ 2 min, offset within
+   UTC−12 … UTC+14.
+3. **Uniform reader-zone fallback** for everything else: wrong in absolute terms whenever
+   the writer held a different belief, but *self-consistent* — both ends of a duration are
+   wrong by the same amount, so derived durations stay right. The revert's core lesson:
+   partially corrected is strictly worse than uniformly wrong.
+
+**Freshness** is what makes rule 2 sound, and it is strict:
+
+* Every poll look at a file stamps `LastCheckedUtc` (`LogFilePositionTracker.MarkChecked`),
+  including "no new data" and an empty first sight — so a file first seen empty
+  (`AgentExecutor.log` appearing mid-enrollment) anchors from its very first content.
+* A pass's lines are fresh only if the file was previously observed *in this process* and
+  the gap since the last look is ≤ `FreshLineMaxAge` (30 s — far above the 100 ms poll,
+  far below the 13-minute zone where a line's *age* could round onto the offset grid).
+* A restart-restored position bookmark deliberately carries **no** freshness: the first
+  pass after a restart reads downtime backlog and must never anchor.
+
+**Provenance** (`sourceOffsetOrigin` in event DataJson): `bias` | `line-anchored` |
+`reader-zone-fallback` (plus retired `calibrated` from 2.0.1410 events). The applied
+offset is always recorded (`sourceOffsetMinutes`), the raw local time too
+(`sourceLocalTs`), so any event can be re-derived later. The per-*file* measurement still
+runs, purely observationally (`measuredWriterOffsetMinutes`, Info log when it disagrees
+with the process zone).
+
+# Constraints
+
+* An anchored line resolves to `now ± 2 min` *by construction*. The accepted edge: a
+  freshly written line carrying a **replayed** old timestamp whose age is exactly
+  N×15 min ± 2 min anchors to ≈now instead of its replayed past — bounded error, and
+  sub-24 h replays are treated as current by the historic-replay guard anyway.
+* Snapshot readers (`StallProbeCollector`, `LogParserCollector`) cannot tail and therefore
+  cannot prove freshness — they stay on the marked fallback. This is a documented limit,
+  not an omission; sharing the per-file measurement with them would re-apply exactly what
+  the revert removed.
+* Mixed pairs remain possible across a restart (start resolved from backlog fallback,
+  completion line-anchored) and are recognizable via provenance.
+
+# Backend regression tripwire
+
+The backend watches for the failure mode this design eliminates. On every terminal ingest
+batch, the counter reconcile's existing event-partition scan additionally collects
+`Δ = ReceivedAt − OccurredUtc` per event, split by `Source == "ImeLogTracker"` versus the
+rest (`CmTraceSkewTripwire`, hooked in `EventIngestProcessor`). If
+`median(Δ_IME) − median(Δ_other)` is a clean 15-minute multiple (residual < 2 min — the
+same constants as the anchoring grid guard above) with ≥ 20 samples over ≥ 3 distinct
+upload batches per side, a `CmTraceTimeSkewRegression` ops event fires (category Agent,
+warning), carrying all numbers plus the session's `sourceOffsetOrigin` histogram.
+Bias-dominated sessions are suppressed (writer-declared offsets cannot be an anchoring
+regression); `measuredWriterOffsetMinutes` is never consulted (sticky after era
+flip-backs). Kill switch: app setting `CmTraceSkewTripwireDisabled`. Goal state: the event
+never fires — any hit is an anchoring case the per-line design misses, or a detector bug.
+
+Device-clock problems (the customer-actionable cousin) are covered separately by the
+`clock_skew` analyze condition behind `ANALYZE-DEV-008`, which excludes IME-derived events
+precisely so an anchoring regression can never surface as a customer finding.
+
+# Citations
+
+* `CmTraceOffsetCalibrator.TryMeasureOffset` — the pure grid measurement, shared by
+  anchoring and the observational per-file path.
+* `CmTraceSkewTripwire` + `CmTraceSkewTripwireTests` — the backend tripwire above.
+* `RuleEngine.ConditionEvaluators.EvaluateClockSkewCondition` + `RuleEngineClockSkewTests`
+  — the customer-facing device-clock metrics (batch-median frames, spool-spread filter,
+  plateau step detection, end-state persistence).
+* `ImeLogTracker.LogProcessing.cs` `ResolveEntryUtc` — the resolution order above.
+* `ImeLogTrackerLineAnchoringTests` — resolves-to-T across writer beliefs, interleaved
+  eras in one chunk, freshness boundaries (first sight, empty first sight, poll gap,
+  restart restore), the grid-replay edge, and the field fixture replayed at production
+  poll cadence.
+* `CmTraceCalibratorFileIsolationTests` — pins per-file isolation of the observational
+  measurement (session e9753578 logged a cross-file pairing the committed code could not
+  be shown to produce; the mechanism remains open, the resolution path is immune by
+  design, and `CalibrateFrom` logs the anchor timestamp as a tripwire).
+* `tasks/todo.md` (2026-08-20) — full evidence trail: field measurements, the revert,
+  the two-writer-era fixture, and the disproven foreign-binary hypothesis (the SHA
+  mismatch was the known release race against the 5-minute AdminConfiguration cache).

docs/agent/decision-engine.md

@@ -143,11 +143,29 @@ advisory backstop. All routes converge on `CompleteThroughFinalizingOrDefer`:
    first-deployment window 100/101 for 200/210 without 110 — the RJ ESP was aborted,
    typically by an interactive logon reclassifying the run as secondary-user; emits
    the `realmjoin_first_deployment_incomplete` Warning, session 224b2087), and
-   `Timeout` (hard 60-min deadline). The abort rule reads the *persisted*
+   `Timeout` (60-min deadline from detection). The abort rule reads the *persisted*
    `RealmJoinFacts.LastDeploymentPhase` (updated by the typed `RealmJoinPhaseChanged`
    signal), so it survives agent restarts — the `RealmJoinDetected` replay path
    evaluates it too. A first observation of 210 does **not** release (RJ may have
    completed before agent boot and deploy afterwards).
+
+   **Activity-based timeout extension** (report 55e6afd61c9d — a large RJ package
+   catalog outlived the 60-min window mid-install): when the timeout deadline fires
+   while the first deployment is demonstrably active — `LastDeploymentPhase` 100/101
+   *and* deployment activity (`RealmJoinPhaseChanged` or a package observation, tracked
+   in `RealmJoinFacts.LastActivityUtc`; the phase captured at detection deliberately
+   does not count) within the last 60 min — the handler re-arms the deadline to
+   `lastActivity + 60 min` instead of timing out, emitting an Info
+   `realmjoin_timeout_extended` event. Re-arms clamp to an absolute cap of
+   **detection + 4 h**. Package activity is only observable at package *completion*
+   (RJ writes the registry subkey when the install finishes), so a single install
+   that is registry-silent for over 60 min still times out — the eventual
+   `realmjoin_timeout` carries a `reason` payload (`hard_timeout` / `inactivity` /
+   `absolute_cap`) telling the three shapes apart. A stale fire of an older deadline
+   incarnation (armed due later than the fire time; `OccurredAtUtc = DueAtUtc` per
+   scheduler contract) dead-ends as `realmjoin_timeout_stale_superseded_by_rearm`.
+   The idle case (detected, no deployment activity ever) times out at 60 min
+   unchanged, and phase 200/210 activity never extends.
 2. `Finalizing` stage + ~5 s `FinalizingGrace` deadline.
 3. Grace fires → `Completed`, `EnrollmentComplete` outcome, `enrollment_complete`
    timeline event with full audit payload.

docs/agent/do-group-id-auto-set.md

@@ -0,0 +1,113 @@
+---
+type: Concept
+title: DO GroupId Auto-Set — Delivery Optimization peering group from a network fingerprint
+description: EnableDoGroupIdAutoSet (ConfigVersion 40) makes the agent set the DOGroupId policy value to a deterministic GUID derived from the default gateway's IPv4 address and MAC (RealmJoin-compatible byte layout), so devices on the same local network form one DO peering group during enrollment; foreign DOGroupId/DOGroupIdSource policies always win.
+resource: /src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Transport/DoGroupIdService.cs
+tags:
+  - agent
+  - delivery-optimization
+  - network
+  - tenant-configuration
+timestamp: 2026-08-21T00:00:00+02:00
+---
+
+# DO GroupId Auto-Set
+
+## Schema
+
+### The problem
+
+With Delivery Optimization download mode Group (2), peering is scoped by GroupId. When no
+GroupId is configured, Windows derives it from AD site → authenticated domain SID → Entra
+tenant ID — for a cloud-native tenant that means **one tenant-wide group**, so "peers on
+the same network" degrades to "peers anywhere in the tenant" and DO's cloud service has to
+match them by public IP. A GroupId derived from the local network makes the group exactly
+"devices behind the same gateway" — including branch offices behind NAT. RealmJoin ships
+this as its network-fingerprint GroupId; our agent is on the device even earlier (during
+ESP, when the big app downloads actually happen), so it can seed the same value for
+Autopilot enrollments.
+
+### The setting
+
+`TenantConfiguration.EnableDoGroupIdAutoSet` (`bool?`, default null→false), served as
+`AgentConfigResponse.EnableDoGroupIdAutoSet` — **ConfigVersion 40**. Portal: Settings →
+Agent → Settings, toggle "Set Delivery Optimization Group ID", stored via the usual
+tenant-config roundtrip (`TableConfigRepository` Store+Map). Also shown in the admin
+tenant-config report. `RemoteConfigMerger` maps the bool 1:1; it survives the offline
+config cache like every plain feature flag.
+
+The agent does NOT configure `DODownloadMode` — the fingerprint GroupId only has an
+effect when the tenant already deploys download mode Group (2) via Intune/GPO.
+
+### The fingerprint
+
+`DoGroupIdService.ComputeGroupId(ipv4Bytes, macBytes)` builds a 16-byte GUID:
+
+```
+{101,48,6} + {0,0,0} + {ip[1], 0, ip[2], ip[3]} + mac[0..5]   →  new Guid(byte[16])
+```
+
+Gateway discovery reuses the shared `NetworkInterfaceLocator` heuristic (Up, not
+Loopback/Tunnel, non-0.0.0.0 gateway; IPv4 gateway required), the gateway MAC comes from
+`ArpNativeMethods` (`iphlpapi!SendARP`). The byte layout — including the IP shuffle and
+the zero padding — is **RealmJoin-compatible and must never change**: devices managed by
+RealmJoin on the same network compute the identical GUID and peer with ours. The registry
+value is written as `Guid.ToString()` (braceless lowercase), identical to RealmJoin's
+`SetValue(name, Guid)` string form. Deliberate divergence from RealmJoin: **no
+random-GUID fallback** — a random per-device ID would isolate the device in a one-member
+group, which is worse than the OS default grouping, so no gateway/no MAC means skip.
+
+### Ownership + conflict rules (never fight a foreign policy)
+
+Target: `HKLM\SOFTWARE\Policies\Microsoft\Windows\DeliveryOptimization\DOGroupId`
+(64-bit registry view — the Policies store is WOW64-redirected; key paths reused from
+`DoThrottlePolicyReader`). Only this GPO-store value is written; the legacy pre-1607
+`GroupId` value name is intentionally not.
+
+Skip conditions (Info event with `skipReason`, nothing written):
+
+| skipReason | Meaning |
+|---|---|
+| `no_ipv4_gateway` | No active interface with an IPv4 default gateway |
+| `arp_failed` | Gateway MAC could not be resolved via SendARP |
+| `group_id_source_policy` | `DOGroupIdSource` configured in GPO or MDM store (dynamic group source wins) |
+| `mdm_policy_present` | `DOGroupId` managed via the Policy CSP store (Intune owns it) |
+| `foreign_value_present` | Existing GPO value neither matches the computed GUID nor the one we last wrote |
+
+Ownership is tracked through the `StartupEventGate` fingerprint for the
+`do_group_id_auto_set` key: `written:<guid>` records the GUID we last wrote, so after a
+gateway change the agent recognizes its own stale value and updates it — while a value
+written by anyone else is never overwritten (`DecideAction`: empty→write, equal→no-op,
+ours→update, else→skip; unparseable existing values count as foreign). Every write is
+verified by readback.
+
+### The event
+
+One `do_group_id_auto_set` event per outcome change (Source `StartupEnvironmentProbes`,
+gated on the fingerprint — unchanged reruns across reboots stay silent; errors never
+latch, so each failing start keeps its retry trail). Severity: Info for
+success/skip, Warning for errors. Data: `groupId`, `previousValue`, `gatewayIp`,
+`gatewayMac`, `written`, `skipped`, `skipReason`, `success`, `error`.
+
+## Examples
+
+First boot on a network with gateway `192.168.178.1` / MAC `00-11-22-33-44-55`:
+
+```
+do_group_id_auto_set (Info): Delivery Optimization GroupId set to
+00063065-0000-00a8-b201-001122334455 (gateway 192.168.178.1)
+```
+
+Tenant already deploys a DO GroupId via Intune:
+
+```
+do_group_id_auto_set (Info): Delivery Optimization GroupId not set: mdm_policy_present
+```
+
+## Citations
+
+* Service (fingerprint, ownership, write+readback): `../../src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Transport/DoGroupIdService.cs`
+* ARP interop: `../../src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Interop/ArpNativeMethods.cs`
+* Probe wiring + event + fingerprint dedup: `../../src/Agent/AutopilotMonitor.Agent.V2.Core/Runtime/StartupEnvironmentProbes.cs`
+* Backend serve + ConfigVersion: `../../src/Backend/AutopilotMonitor.Functions/Functions/Config/GetAgentConfigFunction.cs`
+* DO policy stores (key paths, Registry64 rationale): `../../src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Telemetry/Periodic/DoThrottlePolicyReader.cs`

docs/agent/index.md

@@ -8,5 +8,8 @@ How the on-device agent works:
 * [Hello Wizard Un-Skip](hello-wizard-unskip.md) - why a single "WHfB disabled" policy read never decides completion: the HelloWizardStarted signal (prevention + cure) and the HelloTracker confirmation second read.
 * [Autopilot ZTD Diagnostics](autopilot-ztd-diagnostics.md) - Windows' own diagnostic surfaces for the profile-download flow: ModernDeployment event IDs (807/815/164/...), the Diagnostics\Autopilot registry key, deployment-service endpoints, and the known-issue error-code map.
 * [MDM Reboot Coalescing](mdm-reboot-coalescing.md) - attributing the mid-ESP coalesced reboot ("second sign-in") to the device-assigned policy URIs that forced it: aggregated 2800 observations (neutral, flush-time watermark) + ANALYZE-ESP-005 gated on an actually-observed reboot.
+* [Power-State Watcher](power-state-watcher.md) - live AC↔battery transitions and 50/30/15% downward threshold crossings via a WMI push subscription (no polling): power_state_change semantics (latch/debounce/cap, never armed without a battery) and the single-condition analyze rules ANALYZE-DEV-009/-010 on top.
+* [DO GroupId Auto-Set](do-group-id-auto-set.md) - the optional Delivery Optimization peering-group seed: deterministic GUID from default gateway IPv4 + MAC (RealmJoin-compatible), written to the DOGroupId policy value with readback, ownership-tracked so foreign Intune/GPO values are never overwritten; skip reasons and the do_group_id_auto_set event.
+* [System Timeline Watcher](system-timeline-watcher.md) - clock steps (system_clock_changed: oldTime/newTime/timeDeltaMs/process, micro-slew floor) and completed sleep episodes (system_sleep_episode: sleep/hibernate/Modern Standby with authoritative enteredAt/exitedAt) from one System-channel EventLogWatcher with pre-agent backfill; feeds the web clock-set jump cause, the standby duration note, time-attribution SleepSpans and ANALYZE-DEV-012.
 
 Reading order for newcomers: overview → decision engine → persistence.

docs/agent/power-state-watcher.md

@@ -0,0 +1,106 @@
+---
+type: Concept
+title: Power-State Watcher — live AC/battery transitions and threshold events during enrollment
+description: How the agent observes AC↔battery switches and downward battery-threshold crossings mid-enrollment via a WMI push subscription (no polling), the power_state_change event semantics (transition field, 50/30/15 ladder, latch/debounce/cap), and the two analyze rules on top (ANALYZE-DEV-009/-010).
+resource: /src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/Hosts/PowerStateWatcherHost.cs
+tags:
+  - agent
+  - power
+  - battery
+  - collector
+  - wmi
+  - analyze-rules
+timestamp: 2026-08-21T00:00:00+02:00
+---
+
+# Power-State Watcher
+
+The startup probe (`power_state_check`, one-shot from `StartupEnvironmentProbes` via
+`PowerStateProbe`/`GetSystemPowerStatus`) only captures the power state at agent start. A
+device unplugged mid-enrollment — or draining its battery across a multi-hour ESP — was
+invisible. The watcher closes that gap **event-driven, with zero polling**.
+
+# Mechanism
+
+- `PowerStateWatcherHost` (`Orchestration/Hosts`) arms a WMI event subscription with a
+  two-step chain:
+  1. `SELECT * FROM Win32_PowerManagementEvent WHERE EventCode = 10` (PBT_APMPOWERSTATUSCHANGE:
+     true kernel push, fires on AC↔DC switches and battery-percentage steps).
+  2. **Fallback** `SELECT * FROM __InstanceModificationEvent WITHIN 30 WHERE TargetInstance
+     ISA 'Win32_Battery'` — required because on Windows 11 24H2/25H2 (observed on builds
+     26200 and 26220, session 161b838c) the `MS_Power_Management_Event_Provider` is still
+     registered in the repository but its activation fails with `WBEM_E_NOT_FOUND`: the
+     legacy push provider no longer loads on exactly the OS builds new devices enroll with.
+     The WITHIN sampling runs inside WinMgmt (one Win32_Battery snapshot every 30 s), not in
+     the agent; worst-case detection latency ≈ 35 s incl. debounce. `collector_degraded`
+     (`watcher_arm_failed`) is emitted only when BOTH attempts fail; the agent log's arm
+     line names the active mode.
+
+  Either way the arriving event's payload is ignored — each arrival re-probes via the
+  existing `PowerStateProbe.Probe()` (cheap P/Invoke).
+- Snapshots are diffed by the pure `PowerStateTransitionTracker`
+  (`Monitoring/Enrollment/SystemSignals`), which decides what to emit. The host only owns
+  WMI, a 5 s trailing-edge debounce timer (dock-flap AC→battery→AC inside the window
+  collapses to a no-diff) and the emit path (`InformationalEventPost`, single rail).
+- **No battery / probe error ⇒ WMI is never armed** — desktops and VMs pay nothing. WMI
+  arming runs on a background thread (WinMgmt can hang in OOBE; `ConsoleBypassWatcher`
+  precedent); an arm failure emits one `collector_degraded` (`watcher_arm_failed`).
+- Registered as a plain always-on peripheral host after `NetworkChangeHost`, deliberately
+  NOT under `PeriodicCollectorLifecycleHost`: it is push-based (zero idle cost) and must be
+  alive precisely when the device idles on battery. Kill-switch:
+  `Collectors.EnablePowerStateWatcher` (default true, compile-time default like the other
+  collector toggles; ConfigVersion 38).
+
+# Event: power_state_change
+
+`data.transition` discriminates three shapes (payload always carries `onAcPower`,
+`batteryPercent`, `isCharging`, `batteryLifeMinutes`; unknowns as `"unknown"`):
+
+| transition | Severity | Immediate | Notes |
+|---|---|---|---|
+| `ac_to_battery` | Warning | yes | one per accepted edge |
+| `battery_to_ac` | Info | no | recovery |
+| `threshold_crossed` | Info (50) / Warning (30) / Error (15) | 30+15 only | extra field `thresholdPercent` |
+
+Threshold semantics (tracker):
+
+- Ladder 50/30/15, evaluated only while ON battery; **each level latches once per agent
+  lifetime** (charge-up + re-drain does not re-emit — no plug-cycle alarm spam).
+- A multi-level jump emits only the LOWEST newly-crossed level (60%→10% ⇒ one `15` event).
+- Entering battery power already below a level counts as crossing it; the arm-time baseline
+  does too — an enrollment STARTING at 12% battery emits its `thresholdPercent: 15` event
+  immediately (the analyze rule would otherwise never see sessions that began low).
+- Lifetime emission cap 20 (storm backstop against a flapping dock / dying battery
+  controller); the host logs one warning when it engages.
+
+Backend/agent hygiene: `power_state_change` is classified as non-activity on both sides —
+`SignalActivityClassifier.NonActivityEventTypes` (agent: must not reset the
+PeriodicCollectorLifecycleHost/StallProbeHost idle clocks) and
+`EventIngestProcessor.IsPeriodicOrStallEvent` (backend: must not heal a Stalled session —
+battery drain is not enrollment progress).
+
+# Analyze Rules
+
+- **ANALYZE-DEV-009** (high): battery crossed 15% while on battery — matches the
+  agent-stamped `thresholdPercent equals 15`.
+- **ANALYZE-DEV-010** (warning): AC→battery switch — matches `transition equals
+  ac_to_battery`.
+- Both: `evaluateOn: ["enrollment_end", "whiteglove_sealed", "on_event:power_state_change"]`
+  (live interim finding + terminal finalization), `markSessionAsFailedDefault: false`.
+- Both are deliberately **single-required-condition**: `event_data` conditions scan events
+  independently (no same-instance join), so a two-condition rule (e.g. `transition ==
+  threshold_crossed AND batteryPercent < 15`) could false-positive across two different
+  power events. `thresholdPercent` exists only on threshold events and its value pins the
+  ladder level, so one condition fully identifies the instance.
+- `{{token}}` caveat: `AddDataFieldsToEvidence` whitelists only generic identifiers
+  (appId/errorCode/…), so `{{batteryPercent}}` would render literally. DEV-009 interpolates
+  `{{thresholdPercent}}` (the matched condition's own dataField); the exact percentage lives
+  on the linked event in the timeline.
+
+# Citations
+
+- `src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/Hosts/PowerStateWatcherHost.cs`
+- `src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/SystemSignals/PowerStateTransitionTracker.cs`
+- `src/Agent/AutopilotMonitor.Agent.V2.Core/Runtime/PowerStateProbe.cs` (probe, unchanged)
+- `rules/analyze/ANALYZE-DEV-009.json`, `rules/analyze/ANALYZE-DEV-010.json`
+- [analyze-rule-triggers](../rules/analyze-rule-triggers.md) (interim-trigger design; the WG battery rule was its motivating case)

docs/agent/system-timeline-watcher.md

@@ -0,0 +1,110 @@
+---
+type: Concept
+title: System Timeline Watcher — clock steps and sleep episodes from the System event log
+description: How the agent turns two enrollment blind spots into timeline ground truth via one EventLogWatcher on the System channel — system_clock_changed (Kernel-General 1, oldTime/newTime/timeDeltaMs/process) and system_sleep_episode (Power-Troubleshooter 1 classic sleep/hibernate, Kernel-Power 507 Modern Standby) — including backfill of pre-agent records, the payload-times-are-authoritative rule, SleepSpans in time attribution, the web clock-set jump cause, and ANALYZE-DEV-012.
+resource: /src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/SystemSignals/SystemTimelineTracker.cs
+tags:
+  - agent
+  - eventlog
+  - time
+  - clock-skew
+  - standby
+  - collector
+  - time-attribution
+  - analyze-rules
+timestamp: 2026-08-21T00:00:00+02:00
+---
+
+# System Timeline Watcher
+
+Two things silently distort every session timeline and its wall-clock duration:
+
+1. **The OS clock gets stepped** — classically w32time correcting a wrong BIOS clock early
+   in OOBE, but also tzutil/MDM actions. Before this watcher the jump was only *inferred*
+   (TimeJumpBadge, `clock_skew`/DEV-008); Windows records the ground truth.
+2. **The device sleeps mid-enrollment** — the timeline shows an unexplained gap, the
+   duration looks inflated, and nothing says "the device was simply asleep for 56 minutes".
+
+`SystemTimelineTracker` (hosted by `SystemTimelineWatcherHost`, config flag
+`Collectors.EnableSystemTimelineWatcher`, ConfigVersion 39) subscribes to the **System**
+channel with one provider-qualified XPath and forwards both facts as events.
+
+# Sources and events
+
+| Source (System channel) | Emitted event | Key payload |
+|---|---|---|
+| `Microsoft-Windows-Kernel-General` EventID 1 | `system_clock_changed` | `oldTime`, `newTime` (ISO-8601), signed `timeDeltaMs`, `reason`/`reasonText` (1=`application_set`, 2=`hardware_clock_sync`), `processName`/`processId` |
+| `Microsoft-Windows-Power-Troubleshooter` EventID 1 | `system_sleep_episode` | `kind`=`sleep`/`hibernate` (EffectiveState 5 ⇒ hibernate), `enteredAt`=SleepTime, `exitedAt`=WakeTime, `durationSeconds`, `wakeSourceType`/`wakeSourceText` |
+| `Microsoft-Windows-Kernel-Power` EventID 507 | `system_sleep_episode` | `kind`=`modern_standby`, `exitedAt`=TimeCreated, `enteredAt`=exit − DurationInUs, `durationSeconds` (scenario), `sleepDurationSeconds` (real sleep), `reason`, `onAcPower`, `batteryRemainingCapacityOnExit` |
+
+**506 is deliberately not consumed.** 507 carries the full episode; pairing 506/507 would
+need an orphan-tolerant state machine across agent restarts for zero information gain — an
+episode without a 507 never completed and would not be emitted under any design.
+
+# Thresholds (constants, not knobs)
+
+- `MinClockDeltaMs = 2000` — w32time logs Kernel-General 1 for routine **1 ms micro-slews**
+  (verified live, several per hour); only genuine steps are emitted. Suppressed records are
+  still claimed by the dedup watermark.
+- `ClockDeltaWarningMs = 5 min` — larger steps are Warning + immediate upload (can break
+  token/cert validation windows; matches the web TimeJumpBadge threshold).
+- `MinSleepDurationSeconds = 60` — **Modern Standby only**: every screen-off scenario logs a
+  506/507 pair, including seconds-long ones with `SleepDurationInUs 0` (`SleepEntered=false`);
+  the single duration gate suppresses both. Classic Power-Troubleshooter episodes have no
+  floor — they only exist for genuinely completed S3/S4 transitions.
+
+# Payload times are authoritative
+
+The decisive clock correction happens exactly when the device clock is untrustworthy, and
+the backend clamps implausible event timestamps (±168 h/24 h) to server time. Every semantic
+instant therefore travels as an explicit ISO-8601 payload field (`oldTime`/`newTime`,
+`enteredAt`/`exitedAt`); consumers must never read the event's own `Timestamp` for these.
+The event `Timestamp` is set to the record's TimeCreated (WindowsUpdateTracker backfill
+convention) so rows land where the wake/step happened.
+
+# Backfill and dedup
+
+Template: `WindowsUpdateTracker`. `LoadWatermark → arm watcher → backfill` with lookback
+`SystemEventBackfillLookbackMinutes` (default 1440 = 24 h; 0 disables). The System .evtx
+persists across OOBE reboots, so the pre-agent w32time correction and pre-agent standby
+episodes are recovered with `backfilled=true`. Cross-restart dedup via RecordId watermark
+(`system-timeline-watermark.json` in the state directory) plus an intra-run `HashSet` —
+deliberately **not** a high-water mark, which would drop exactly the older, never-emitted
+pre-agent records (the live watcher arms before the backfill scan).
+
+# Non-activity classification (both sides)
+
+Both event types are environment observation, not enrollment progress:
+`SignalActivityClassifier.NonActivityEventTypes` (agent — must not reset idle/stall clocks)
+and `EventIngestProcessor.IsPeriodicOrStallEvent` (backend — a device that slept through its
+stall must stay Stalled).
+
+# Consumers
+
+- **Web timeline** (`EventTimeline.tsx`): badge blocks for both events; the TimeJumpBadge
+  gains the ground-truth cause `clock-set` — `classifyTimeJump` receives the session's
+  `system_clock_changed` deltas and matches a backward display step against a backward clock
+  set within max(60 s, 20 %) (`lib/timeProvenance.ts`).
+- **Duration story** (`SessionInfoCard` via `useSessionDerivedData.standbySeconds`): the
+  wall-clock duration deliberately keeps the pause (the enrollment really took that long);
+  a `· 🌙 56m standby` note explains it. Episodes are dedup'd on `enteredAt`.
+- **Time attribution** (`TimeAttributionCalculator.BuildSleepSpans`, AttributionVersion 3):
+  `SleepSpan`s mirror `RebootSpan`s — cross-cutting annotations clipped to the observation
+  windows (a WhiteGlove-pause episode contributes only its in-window flanks), never a slice
+  of the wall-clock partition. Persisted as `SleepSeconds`/`SleepSpansJson`; rendered as the
+  standby chip in `TimeAttributionLane`.
+- **ANALYZE-DEV-012** (info, `trigger: single`, `on_event:system_sleep_episode`): fires once
+  per session for episodes ≥ 5 min. Deliberately the ONLY new rule: clock issues already
+  have DEV-008 (`clock_skew`) — a second clock rule would double-report the same action item
+  (user decision 2026-08-21); clock steps stay timeline ground truth with badges instead.
+
+# Citations
+
+- `src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/SystemSignals/SystemTimelineTracker.cs`
+- `src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/Hosts/SystemTimelineWatcherHost.cs`
+- `src/Backend/AutopilotMonitor.Functions/Helpers/TimeAttributionCalculator.cs` (`BuildSleepSpans`)
+- `src/Web/autopilot-monitor-web/lib/timeProvenance.ts` (`clock-set`, `findExplainingClockChange`)
+- `rules/analyze/ANALYZE-DEV-012.json`
+- Live payload evidence (2026-08-21, Win11 26220): Kernel-General 1 with `TimeDeltaInMs=1`
+  micro-slews; Kernel-Power 507 with `SleepDurationInUs=2324095807`; Power-Troubleshooter 1
+  with `SleepTime`/`WakeTime` across a hibernate.

docs/backend/app-install-duration-attempt.md

@@ -0,0 +1,82 @@
+---
+type: concept
+title: Attempt-Scoped App Install Durations
+description: AppInstallSummary.DurationSeconds measures the status-defining (last) install attempt via a LastAttemptStartedAt max-fold anchor — replacing the first-observation-to-last-terminal span that billed multi-pass IME processing gaps to trivial apps; time attribution counts the union of active attempt segments.
+resource: src/Backend/AutopilotMonitor.Functions/Services/EventIngestProcessor.AppInstall.cs
+tags: [backend, agent, ingest, app-installs, metrics, time-attribution, durations]
+timestamp: 2026-08-21
+---
+
+# Problem
+
+The IME processes the ESP app list in multiple passes: a device-ESP evaluation pass can
+touch an app (often ending `Skipped`) long before the real install runs in a later pass.
+`AppInstallSummary` is keyed by `{SessionId}_{AppName}` and folded from ALL of the app's
+events, so `DurationSeconds = last terminal − first observation` spanned those passes.
+Field case (session `44862cd3`, "Set TimeZone"): evaluation pass 09:16, real install
+10:22:58 → 10:23:21 — reported 4002 s for a 23-second install. Fleet averages, the
+Slowest-Apps ranking, p95s, and the version-regression radar all inherited the inflation;
+the rule engine's `app_install_duration` (already attempt-scoped) contradicted the
+dashboard for the same install.
+
+# Schema
+
+Three durable anchors on the row — each with a distinct, non-interchangeable job:
+
+| Column | Fold | Role |
+|---|---|---|
+| `StartedAt` | min (earliest wins) | First observation. Server-side window/bucket filter of every AppInstallSummaries scan and the radar's version-ordering key. Never re-anchored. |
+| `LastAttemptStartedAt` | **max** (in-batch and in `ReconcileAppInstallSummaryWithExisting`) | Anchor of `DurationSeconds`. Null = sentinel (row predates 2026-08, or no start observed) → duration falls back to the historical `StartedAt` span. Replay of an older batch can never regress it. |
+| `InstallPassCount` | additive, guarded by `LastAttemptStartedAt` monotonicity (a batch whose newest start is not newer than the stored anchor adds 0) | Explains "finished long after first seen" (web ×N chip); 2+ is normal. |
+
+`DurationSeconds = CompletedAt − LastAttemptStartedAt`, computed at the terminal event and
+re-derived in one central reconcile site covering in-order and Q4 out-of-order batches.
+A `LastAttemptStartedAt` newer than `CompletedAt` means a fresh pass is in flight — the
+completed attempt's stored duration stands (the 0 value omits the column; Merge preserves).
+`DownloadDurationSeconds` pairs the latest `app_download_started` with the NEXT
+`app_install_started` (attempt-scoped, in-batch). The full span stays derivable as
+`CompletedAt − StartedAt` — deliberately not a column.
+
+Weaker-terminal guard (both in-batch and cross-batch): `app_install_completed` with
+state `Skipped`/`Postponed` never overrides an `Installed`/`Error` terminal, nor its
+`CompletedAt`/`DurationSeconds` — mirroring the long-pinned `app_install_skipped` rule.
+
+# Consumers
+
+* **Fleet metrics / apps dashboard / PDF** (`MetricsMath`, `AppsAnalyticsHelper`): values
+  drop to attempt scale; labels say "install time (final attempt)". The 6 h
+  `MaxPlausibleInstallDurationSeconds` gate remains (an attempt longer than the agent's
+  lifetime is still unobservable).
+* **AppVersionRegressionRadar**: cutover gate in `MeasuredAppGroups` — only rows with
+  `LastAttemptStartedAt` enter the duration population, on BOTH comparison sides. A mixed
+  population would mask real regressions and falsely re-arm active episodes for up to the
+  35-day horizon. `MinMeasuredInstalls` keeps it silent until enough post-cutover rows
+  exist. Thresholds (2.0× / 300 s) were tuned on span data — re-evaluate ~4 weeks after
+  rollout.
+* **Time attribution** (`TimeAttributionCalculator.BuildBlockingAppIntervals`):
+  sequence-ordered start→terminal pairing yields one segment per pass/attempt. Per-app
+  seconds = SUM of clamped segments (failed attempts and evaluation passes count — they
+  occupied the path); occupancy merges the segments, never the per-app hulls; hull
+  endpoints remain first-start→last-terminal for display and what-if. Deliberately
+  BROADER than the metrics duration: active time across all passes vs. final attempt.
+* **Agent payloads** (`AppInstallTiming` / `ImeLogTrackerAdapter.UpdateAppTiming`): a
+  terminal→active transition re-arms BOTH endpoints, so event `durationSeconds` also
+  describes the attempt (needs the agent release carrying this change).
+* **Rule engine** `app_install_duration`: was already attempt-scoped — now consistent.
+
+# Rollout
+
+No backfill (user decision, analog to the CMTrace legacy): pre-cutover rows keep span
+values, so time-series charts step down visibly at the changeover (documented in the
+public platform changelog). Sentinel-gated columns follow the standard chain:
+`BuildAppInstallSummaryEntity` + `MapToAppInstallSummary` + `AppsDashboardProjection`
+(the only projection whose consumers read the new columns).
+
+# Citations
+
+* `src/Backend/AutopilotMonitor.Functions/Services/EventIngestProcessor.AppInstall.cs` — fold + weaker-terminal guard + attempt pairing
+* `src/Backend/AutopilotMonitor.Functions/Services/TableStorageService.Metrics.cs` — reconcile max-fold, pass-count guard, central duration recompute
+* `src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs` — cutover gate
+* `src/Backend/AutopilotMonitor.Functions/Helpers/TimeAttributionCalculator.cs` — per-pass segments + occupancy
+* `src/Agent/AutopilotMonitor.Agent.V2.Core/SignalAdapters/ImeLogTrackerAdapter.cs` — payload timing re-arm
+* Tests: `AppInstallTerminalStateAndReconcileTests`, `EventTimestampValidationTests`, `AppVersionRegressionRadarTests`, `TimeAttributionCalculatorTests`

docs/backend/send-time-frame-separation.md

@@ -0,0 +1,84 @@
+---
+type: concept
+title: Send-Time Frame Separation (X-Send-Time-Utc)
+description: One device-clock send timestamp per upload batch splits ReceivedAt − OccurredUtc into pure spool delay and pure device-vs-server clock offset — turning clock diagnostics from median statistics into direct per-request measurement.
+resource: src/Backend/AutopilotMonitor.Functions/Functions/Ingest/IngestTelemetryFunction.cs
+tags: [backend, agent, ingest, timestamps, clock-skew, telemetry, provenance]
+timestamp: 2026-08-21
+---
+
+# Problem
+
+Events carry two time anchors: `OccurredUtc` (device clock at emission) and `ReceivedAt`
+(server clock at ingest). Their difference conflates two physically distinct phenomena:
+
+* **Spool delay** — the event waited offline or in retry backoff before upload. Expected,
+  harmless, minutes to hours.
+* **Device-vs-server clock offset** — the actual diagnostic signal.
+
+A uniform spool backlog (events emitted close together, uploaded after an outage) is
+indistinguishable from a clock offset in that delta; a draining backlog fakes a clock jump
+ramp. Every consumer had to filter this statistically (spread caps, plateau guards,
+persistence tests) — and the first field clock-jump measurement failed exactly on this
+ambiguity.
+
+# Schema
+
+The agent stamps one header per upload attempt (`BackendTelemetryUploader`):
+
+```
+X-Send-Time-Utc: <DateTime.UtcNow, ISO-8601 round-trip>
+```
+
+Per **attempt**, not per batch content: a retry after backoff is a new send moment. The
+ingest function parses it (`ParseSendTimeHeader`: round-trip parse, UTC-normalized, values
+before year 2000 rejected as garbage — deliberately **no upper clamp**, a future-dated
+send time IS the clock-error measurement), and `StampServerFields` writes it as `SentAt`
+onto every event of the request — server-stamped, request-level, never trusted per-event
+from the wire. Stored as the nullable `SentAt` column on Events (absent for pre-header
+agents), mapped back everywhere events are read, exposed as `sentAt` in the `fields=`
+projection and verbatim on the raw endpoints.
+
+The separation is then exact:
+
+```
+SentAt − OccurredUtc   = pure spool delay            (both device frame; offset cancels)
+ReceivedAt − SentAt    = network latency + clock offset   (the only frame crossing)
+```
+
+Network latency is seconds; anything beyond is device clock error, per request, no
+statistics required.
+
+# Consumers
+
+* **`clock_skew` analyze condition** (ANALYZE-DEV-008): batches whose events carry
+  `SentAt` measure the batch offset directly as `SentAt − ReceivedAt` — spool-immune by
+  construction, so the spread cap and the IME/clamped exclusions are unnecessary there
+  (no event timestamps are read at all; IME-only sessions become measurable). Batches
+  without `SentAt` keep the legacy per-event median + spread-cap path. Downstream logic
+  (stability check, plateau step detection, end-state persistence) is shared; evidence
+  carries `sentAtBatchCount`.
+* **`CmTraceSkewTripwire` deliberately unchanged**: `median(Δ_IME) − median(Δ_other)`
+  cancels the device clock offset as common mode — send time adds nothing to that
+  differential measurement.
+
+# Constraints
+
+* `SentAt` comes from the same device wall clock as the event timestamps — a clock jump
+  between emission and send lands in the spool-delay term. That is the intended place for
+  it to become visible, not a defect.
+* Signals and DecisionTransitions do not carry `SentAt` (no consumer); the header is
+  request-level, so extending them later is a storage-only change.
+* Fleet coverage grows with agent rollout; all analyses must treat `SentAt == null`
+  (legacy rows, old agents) as "legacy path", never as zero.
+
+# Citations
+
+* `BackendTelemetryUploader.UploadBatchAsync` — header stamping per attempt.
+* `IngestTelemetryFunction.ParseSendTimeHeader` + `IngestTelemetryFunctionTests` — parse
+  contract incl. the no-upper-clamp decision.
+* `EventIngestProcessor.StampServerFields` + `IngestCriticalPathTests` — server-side
+  stamping, forged per-event values overridden.
+* `RuleEngine.ConditionEvaluators.EvaluateClockSkewCondition` + `RuleEngineClockSkewTests`
+  — the two measurement paths (the backlog-alias test pair pins why SentAt exists).
+* `tasks/todo.md` P14 (2026-08-21) — decision trail incl. why the tripwire stays as is.

docs/index.md

@@ -27,8 +27,12 @@ https://docs.autopilotmonitor.com (separate repository).
 * [ESP Completion Starvation — the sits-d Cloud-PC complex](agent/post-reboot-completion-recovery.md) - Why a SkipUser=true flow (no user ESP page → no Shell-Core 62407, no AccountSetup registry) left the completion gate satisfied but never evaluated — five Cloud PCs idled six hours at "waiting on: hello_resolution" — and the fix: the observed skip stands in for the final-exit evidence in the IME user-session completion attempt. Plus the two adjacent defects fixed alongside: the edge-only user-apps-settled synthesis (now level-triggered) and the never-wired Shell-Core restart replay (now Hello-wizard-only, with the reasoning why a replayed 62407 must never reach the reducer).
 * [Secure Boot CA-2023 Detection](agent/secureboot-ca2023-detection.md) - Why ANALYZE-SEC-001 v3 reads the UEFI db/KEK variables directly instead of trusting the SecureBoot\Servicing registry, and how the one-sided uefiCa2023FirmwareConfirmed marker plus a not_exists precondition give absence-tolerant suppression across old and new agents.
 * [Continue-Anyway Observation Mode](agent/continue-anyway-observation.md) - EnableEspContinueAnywayObservation (ConfigVersion 37, operator-set): Device-phase ESP terminal failures on Continue-Anyway profiles get a bounded 60-min observation instead of an immediate hard fail; the DAD-validated real-user desktop + Hello gate detect the true end, the session completes Succeeded + EspSoftFailure (amber "with issues" badge), expiry un-defangs to the original esp_terminal_failure.
+* [CMTrace Time Resolution](agent/cmtrace-time-resolution.md) - Converting bias-less CMTrace local times to UTC without trusting any process's timezone belief: per-line self-anchoring on the 15-minute offset grid for provably fresh lines, uniform marked reader-zone fallback for backlog, and the provenance vocabulary (bias / line-anchored / reader-zone-fallback) that keeps every event re-derivable.
 * [Registry App-State Second Pillar](agent/registry-app-state-pillar.md) - IME's authoritative per-app state read straight from the registry (Win32Apps EnforcementStateMessage, EspTrackingWin32Apps, StatusServiceReports) via a snapshot-and-diff watcher; registry/log reconciliation doubles as the built-in IME log-pattern drift alarm.
 * [WDP Scenario Gates & Completion Backstop](agent/wdp-scenario-gates.md) - How the agent gates Autopilot/ESP-only machinery off on Windows Device Preparation sessions (deterministic ExecutionContext marker, fail-toward-Classic), which noise it suppresses (ZTD probe, esp_config unknown, ModernDeployment 100/417/418/1005, starved sweep), and the WDP completion model: High-confidence seed, desktop-based arm D, and the 30-min device_prep_completion backstop.
+* [Power-State Watcher](agent/power-state-watcher.md) - Live AC↔battery transitions and 50/30/15% downward battery-threshold crossings during enrollment via a WMI Win32_PowerManagementEvent push subscription (zero polling, never armed on battery-less devices): the power_state_change event (transition field, per-level lifetime latch, 5s debounce, emission cap) and the analyze rules ANALYZE-DEV-009 (battery <15%, high) / ANALYZE-DEV-010 (AC→battery, warning) with on_event interim triggers.
+* [System Timeline Watcher](agent/system-timeline-watcher.md) - Ground truth for two timeline blind spots from one System-channel EventLogWatcher with pre-agent backfill: system_clock_changed (Kernel-General 1 — oldTime/newTime/signed timeDeltaMs/reason/setting process; 2 s micro-slew floor, ≥5 min Warning+immediate) and system_sleep_episode (Power-Troubleshooter 1 sleep/hibernate + Kernel-Power 507 Modern Standby; authoritative enteredAt/exitedAt payload instants, 60 s Modern-Standby floor). Consumed by the TimeJumpBadge clock-set cause, the SessionInfoCard standby note, time-attribution SleepSpans (AttributionVersion 3) and ANALYZE-DEV-012.
+* [DO GroupId Auto-Set](agent/do-group-id-auto-set.md) - EnableDoGroupIdAutoSet (ConfigVersion 40): the agent seeds the Delivery Optimization DOGroupId policy with a deterministic network-fingerprint GUID (default gateway IPv4 + SendARP MAC, RealmJoin-compatible byte layout) so same-network devices form one DO peering group during ESP; ownership-tracked via the StartupEventGate fingerprint, foreign DOGroupId/DOGroupIdSource policies always win, no random-GUID fallback.
 * [ESP Policy-Provider Stall Detection](agent/esp-policy-provider-stall.md) - The EnrollmentStatusTracking CSP's no-timeout Setup/Apps wait is keyed to the Intune-registered "Sidecar" provider by NAME: co-management's "ConfigMgr" parks the user ESP at "Apps (Identifying)" for days even with TrackingPoliciesCreated=1 (issue #106); the always-on two-arm esp_policy_provider_stalled tripwire (provider_incomplete | sidecar_provider_missing) and the SOFTWARE\Microsoft\Windows\Autopilot gather-rule allowlist entry that surface it.
 
 # Rules
@@ -36,14 +40,17 @@ https://docs.autopilotmonitor.com (separate repository).
 * [Gather Rule Phase Scoping, One-Shot Triggers & Emit-on-Change](rules/gather-rule-phase-scoping.md) - Restricting gather rules to enrollment phases (activePhases / activeFromPhase sticky latch), one-shot collection at a phase's start/end (phase_change / phase_exit), and emitMode "on_change" result-dedup.
 * [Gather Rule Guardrails](rules/gather-rule-guardrails.md) - Why the allowlists in rules/guardrails.json are enforced on the agent and nowhere else, which hard blocks survive unrestricted mode, and the rule that every collector must call a guard and emit security_warning on refusal.
 * [Rule Authoring Surface](rules/rule-authoring-surface.md) - How customer AIs author rules against the real contract: the baked MCP resources (guide/schemas/guardrails via combine.js), the MCP-local validate_rule pre-flight, and the side-effect-free POST rules/analyze/dryrun whose trace twin shares the production evaluators (parity + side-effect-freedom pinned by tests).
+* [Rule ID Namespace & Collision Guards](rules/rule-id-namespace.md) - Why rule identity is the human-readable ruleId (no GUIDs) with tenant isolation via Table Storage partitioning, the reserved built-in namespace (RuleIdPolicy), which collisions are possible (custom-vs-custom across tenants: allowed and harmless), and the guards keeping the global RuleStats aggregate catalog-only and the global partition inside the reserved namespace (combine.js, reseed, cross-tenant RuleState GC).
 * [Analyze Rule Evaluation Triggers](rules/analyze-rule-triggers.md) - Opt-in `evaluateOn` interim triggers (`whiteglove_sealed`, `on_event:<type>`) so rules can fire before a session is terminal, with RuleResults update-semantics (interim → finalize/resolve, NotifiedAt notification dedupe) replacing the permanent dedupe freeze, KO/stat suppression on interim runs, the ingest-side cached trigger registry, and the authoring lints that keep interim rules monotonic.
 
 # Backend
 
 * [Business Timestamps](backend/business-timestamps.md) - Why the Azure Tables system Timestamp is never authoritative (migrations reset it), and the OccurredUtc + RowKey-decode compensation for AuditLogs/OpsEvents/Events after the 2026-07-18 migration.
+* [Send-Time Frame Separation](backend/send-time-frame-separation.md) - One device-clock send timestamp per upload batch (X-Send-Time-Utc → SentAt on Events) splits ReceivedAt − OccurredUtc into pure spool delay and pure device-vs-server clock offset; the clock_skew condition measures SentAt batches directly (spool-immune), the CMTrace tripwire deliberately stays on its differential math.
 * [OOBE Bootstrap go-Code Flow](backend/oobe-bootstrap-go-flow.md) - The bootstrap short-code lifecycle (portal-created session → `irm go.autopilotmonitor.com/CODE | iex` at Shift+F10 → GetBootstrapScriptFunction), the always-HTTP-200 text/plain contract, the two-line injection defense (GUID/URL/expiry validator + single-quoted PS literals, golden-pinned against the legacy TS template), and the per-IP rate-limit story behind Front Door.
 * [Device Journeys & First-Time-Right](backend/device-journeys.md) - How a device's terminal enrollment attempts are grouped into journeys (trim+casefold device key with junk-serial exclusion, first-success end, 30-day gap, WhiteGlove = one attempt), the DeviceHistories chain with its tombstone-driven deleted-session pruning, the additive daily FTR aggregates, and the banner/fleet/MCP surfaces.
 * [Enrollment Time Attribution](backend/time-attribution.md) - How a terminal session's authoritative wall clock (DurationSeconds, WhiteGlove pause excluded) is partitioned into named segments with an explicit unattributed remainder, ESP-blocking apps as positive evidence with "up to" what-if bounds, reboot spans from event gaps, and the breakdown/aggregate tables the sweep maintains.
+* [Attempt-Scoped App Install Durations](backend/app-install-duration-attempt.md) - AppInstallSummary.DurationSeconds = status-defining (last) install attempt via the LastAttemptStartedAt max-fold anchor instead of the first-observation→last-terminal span that billed multi-pass IME gaps to trivial apps; InstallPassCount, the weaker-terminal guard, the radar's cutover gate, and time attribution's union-of-attempt-segments occupancy.
 * [Rule Regression Radar](backend/rule-regression-radar.md) - How analyze-rule hit-rate regressions are detected (7-day window ≥2× the 28-day baseline with disjoint Wilson intervals), which suppressions keep the radar quiet (grace period, edit-in-window, kill switch), how alert episodes live in the ruleregression tracker keyspace with re-arm semantics, and the on-fire dimension correlation with its "correlated, not necessarily causal" wording contract.
 * [App Version Duration Regression Radar](backend/app-version-regression-radar.md) - How app versions whose median install duration regressed vs. the previous version are detected (first-seen-ordered versions, median lift ≥2× plus a 5-minute absolute floor over measured installs only), how alert episodes live in the appversionregression tracker keyspace with drain/median re-arm semantics, and the bell/ops-event/analytics surfaces.
 * [Tenant Activation & the Once-Only Welcome Mail](backend/tenant-activation-welcome-mail.md) - How a signup becomes an activated tenant (manual approve or the auto-approve queue), and the write-then-read + conditional-marker arbitration that sends the welcome mail exactly once even though activation and the user-typed notification address race each other.

docs/log.md

@@ -1,7 +1,29 @@
 # Log
 
+## 2026-08-21
+
+* **New**: `agent/do-group-id-auto-set.md` — optional DO peering-group seed (`EnableDoGroupIdAutoSet`, default off, ConfigVersion 40): `DoGroupIdService` derives a deterministic GUID from the default gateway's IPv4 + SendARP MAC in RealmJoin's exact byte layout (cross-product peering) and writes `DOGroupId` in the 64-bit GPO Policies store with readback verification. Conservative by design: no random-GUID fallback (skip on missing gateway/MAC), `DOGroupIdSource`/MDM-managed values/foreign GPO values always win (skip reasons in the `do_group_id_auto_set` event), own stale values are recognized via the `written:<guid>` StartupEventGate fingerprint and updated after a gateway change. Gateway heuristic extracted into the shared `NetworkInterfaceLocator` (dedup of NetworkChangeDetector + DeviceInfoCollector copies).
+
+* **New**: `agent/system-timeline-watcher.md` — clock-step and sleep-episode ground truth from the System event log: one `EventLogWatcher` (Kernel-General 1, Power-Troubleshooter 1, Kernel-Power 507; 506 deliberately unconsumed) emits `system_clock_changed` (oldTime/newTime/signed timeDeltaMs/reason/process; 2 s micro-slew floor, ≥5 min = Warning+immediate) and `system_sleep_episode` (kind sleep/hibernate/modern_standby, authoritative `enteredAt`/`exitedAt` payload instants, 60 s Modern-Standby floor). WindowsUpdateTracker-style backfill (24 h default, `system-timeline-watermark.json`) recovers pre-agent records; ConfigVersion 39 (`Collectors.EnableSystemTimelineWatcher`). Consumers: TimeJumpBadge cause `clock-set` (ground truth beats inference), SessionInfoCard standby note next to the unchanged wall-clock duration, `SleepSpan`s in time attribution (AttributionVersion 3, RebootSpan clone), and ANALYZE-DEV-012 (info, single, ≥5 min episode; deliberately the only new rule — clock issues stay with DEV-008).
+
+* **New**: `agent/power-state-watcher.md` — live AC/battery observation during enrollment: `PowerStateWatcherHost` subscribes to the WMI push `Win32_PowerManagementEvent EventCode 10` (no polling; re-probes `GetSystemPowerStatus` per push, 5 s trailing-edge debounce, never armed on battery-less devices, `Collectors.EnablePowerStateWatcher` kill-switch, ConfigVersion 38). The pure `PowerStateTransitionTracker` emits `power_state_change` with `transition` = ac_to_battery (Warning, immediate) / battery_to_ac (Info) / threshold_crossed at 50/30/15% (each level latched once per lifetime, lowest-crossed-only on jumps, baseline-below-level covered, emission cap 20). Classified non-activity on both sides (SignalActivityClassifier + IsPeriodicOrStallEvent). New analyze rules ANALYZE-DEV-009 (thresholdPercent=15, high) and ANALYZE-DEV-010 (transition=ac_to_battery, warning), both with `on_event:power_state_change` interim triggers and deliberately single-required-condition (event_data conditions have no same-instance join).
+
+* **Update**: `rules/rule-id-namespace.md` — the export→paste round-trip is no longer lossy: the JSON editors now map rule-shaped exports into the form (`gatherRuleToForm` unflattens the nested gather `parameters` object, analyze `jsonToForm` maps `evaluateOn` onto the eval checkboxes; `tags` and the effective `markSessionAsFailed` carry into the created rule). Both editors still accept the serialized-form shape; edit-mode pastes merge, with an explicit `parameters`/`evaluateOn` winning over stale flat fields.
+
+* **New**: `rules/rule-id-namespace.md` — rule identity model: human-readable `ruleId` strings (no GUIDs), tenant isolation via Table Storage partitioning (`global` = built-in/community, tenantId = custom), the reserved built-in namespace from `RuleIdPolicy`, and the four collision guards: catalog-only global `RuleStats` aggregate (same-ID custom rules of unrelated tenants no longer sum into one `global_{ruleId}` row), combine.js duplicate/namespace fail, GitHub-reseed rejection of non-reserved IDs into the global partition, and the namespace gate on the cross-tenant RuleState GC.
+
+* **New**: `backend/app-install-duration-attempt.md` — attempt-scoped app install durations: `DurationSeconds` = status-defining (last) attempt anchored on the new max-folded `LastAttemptStartedAt` (StartedAt stays the earliest-wins window/version-ordering key; legacy rows without the anchor keep the span fallback); `InstallPassCount` with replay-guarded additive fold; weaker-terminal guard (completed-with-Skipped never overrides Installed/Error, in-batch and cross-batch); attempt-scoped `DownloadDurationSeconds` pairing; the version-regression radar's both-sides cutover gate; time attribution counts the union of per-pass active segments (occupancy merges segments, hulls stay for display/what-if); agent payload timing re-arms both endpoints on terminal→active. No backfill — pre-cutover rows keep span semantics.
+
+* **Update**: `agent/decision-engine.md` — activity-based RealmJoin timeout extension (report 55e6afd61c9d: a large RJ package catalog outlived the 60-min window mid-install — the timer arms at RJ-agent-MSI detection, so the first deployment had effectively ~44 min). When the `RealmJoinTimeout` deadline fires with `LastDeploymentPhase` 100/101 and deployment activity (phase change or package observation, persisted in `RealmJoinFacts.LastActivityUtc`; the detection-time phase capture deliberately excluded) inside the last 60 min, the deadline re-arms to `lastActivity + 60 min` (Info event `realmjoin_timeout_extended`), clamped at detection + 4 h. `realmjoin_timeout` now carries `reason` = `hard_timeout` / `inactivity` / `absolute_cap`; a fire of a superseded deadline incarnation dead-ends. Idle detection and phase-200/210 sessions keep the original 60-min behavior.
+
+* **New**: `backend/send-time-frame-separation.md` — P14: the agent stamps one device-clock send timestamp per upload attempt (`X-Send-Time-Utc`), the ingest function server-stamps it as `SentAt` on every event of the request. `SentAt − OccurredUtc` is pure spool delay, `ReceivedAt − SentAt` is network + device-vs-server clock offset — the two were indistinguishable before and had to be separated statistically. The `clock_skew` condition measures SentAt-carrying batches directly (spool-immune, no spread cap, IME-only sessions become measurable; evidence carries `sentAtBatchCount`), legacy batches keep the median path; the CMTrace tripwire deliberately stays on its differential math (common-mode clock offset cancels there).
+
 ## 2026-08-20
 
+* **Update**: `agent/cmtrace-time-resolution.md` — new "Backend regression tripwire" section: the P6 split. Operator side: `CmTraceSkewTripwire` piggybacks on the terminal counter reconcile's partition scan (`Δ = ReceivedAt − OccurredUtc` per source, 15-min grid + 2-min residual, ≥20 samples / ≥3 distinct batches per side, bias-dominated sessions suppressed, `measuredWriterOffsetMinutes` never consulted) and emits the `CmTraceTimeSkewRegression` ops event — goal state: never fires; kill switch `CmTraceSkewTripwireDisabled`. Customer side: new `clock_skew` analyze condition source (`skewMetric: clock_jump | sustained_offset`, threshold in seconds, batch-median frames with spool-spread filter, plateau step detection, end-state persistence, IME-derived events excluded) behind the new built-in `ANALYZE-DEV-008` (300 s = the Kerberos/Entra 5-minute skew boundary) — the during-enrollment complement of ANALYZE-DEV-007's one-shot NTP check. P5 (agent-side observability event) is subsumed by the tripwire.
+
+* **New**: `agent/cmtrace-time-resolution.md` — the era-aware answer to the CMTrace timezone skew: a bias-less line read in a provably fresh pass anchors its own UTC offset against the agent clock (15-minute grid, 2-minute residual), so interleaved writer eras in one file resolve line by line; everything not provably fresh keeps the uniform reader-zone fallback and says so via `sourceOffsetOrigin`. Freshness is a per-file `LastCheckedUtc` stamped on every poll look (empty first sights included) with a 30-second window, never restored across restarts. Replaces the reverted per-file offset application (04b1a7c6); the per-file measurement stays observational, now with the anchor timestamp logged as a tripwire for the still-unexplained e9753578 label/anchor crossing.
+
 * **Update**: `agent/post-reboot-completion-recovery.md` — retitled to "ESP Completion Starvation — the sits-d Cloud-PC complex" and reframed on the evidence: the reboot was a red herring. The five stuck Cloud PCs carried `SkipUserStatusPage=True` (read 10+ times across three agent processes, `True` every time) and Windows honoured it — no user ESP page, hence no Shell-Core 62407 and no AccountSetup provisioning registry, verified over a six-hour uninterrupted post-reboot run with the watcher armed. Arm B of `ShouldTransitionToAwaitingHello` was open from the bootstrap onward, but every evaluation site hangs off a signal a skip-user flow cannot produce, and the `AdvisoryCompletion` backstop arms exclusively from an `EspExiting` signal — an open gate nobody knocks on. Fix: `HandleImeUserSessionCompletedV1` accepts the observed skip in place of the final-exit evidence (`skipUserExitEquivalent`; anchor + genuine IME completion + real-user desktop stay mandatory, WDP excluded). The knock deliberately lives on the IME edge, not desktop arrival — ordering-robust against Fix 10's AccountSetup bounce-back and semantically "user-phase work finished" rather than mid-install. `ClassicSkipUserEspUserSessionCompletionTests` replays the real 8110e262 ordering end to end. Docs and comments no longer claim an ESP-exit recovery that does not exist (stray duplicate summary in `ShellCoreTracker`, `ImeLogHost` restore-callback comment); the residual `SkipUser=false` exit-in-downtime gap is named honestly and surfaced by `ANALYZE-ESP-005` via `session_stalled` instead of being patched with an unorderable replay.
 
 ## 2026-08-19

docs/rules/analyze-rule-triggers.md

@@ -98,7 +98,7 @@ Interim evaluation changes what a rule's conditions mean mid-flight. Three new l
 
 # Application to the Motivating Cases
 
-- WG battery rule (sits-d): `evaluateOn: ["enrollment_end", "whiteglove_sealed"]` — technician gets the channel alert at the bench; Part-2 terminal pass finalizes or resolves the finding.
+- WG battery rule (sits-d): shipped 2026-08-21 as ANALYZE-DEV-009 (battery below 15% while on battery) and ANALYZE-DEV-010 (AC→battery switch), both `evaluateOn: ["enrollment_end", "whiteglove_sealed", "on_event:power_state_change"]` on the live power watcher's `power_state_change` events (see `../agent/power-state-watcher.md`) — technician gets the channel alert at the bench; the terminal pass finalizes the finding. Both are deliberately single-required-condition rules: `event_data` conditions scan events independently (no same-instance join), so DEV-009 matches the agent-stamped `thresholdPercent` and DEV-010 matches `transition`.
 - Hybrid-affinity stuck (esa): ANALYZE-ID-004 gets `evaluateOn: ["enrollment_end", "on_event:hybrid_login_pending"]` — the second overdue-login event (threshold 65) produces a live finding on the still-InProgress session. ANALYZE-APP-015 stays `enrollment_end`-only until its conditions are hardened (lint 1).
 
 - Stuck after a forced mid-ESP reboot (sits-d Cloud PCs, 2026-08-19): `on_event:session_stalled` is the established trigger for the never-terminal stuck session. The agent emits `session_stalled` exactly once per session (60-minute stall probe), so the trigger is rare by construction and needs no throttle. Five Cloud PCs sat at `InProgress` with **zero findings** for hours — a mid-ESP reboot had killed the agent in `Stage=EspAccountSetup` — before the max-lifetime watchdog eventually terminalised them as `Incomplete`. ANALYZE-ESP-005 carries the trigger and fires on that stream at confidence 95 (verified against session `8110e262`): both its conditions (`mdm_policy_reboot_required.firstRebootUri` exists, `system_reboot_detected` count ≥ 1) are **monotonic** and it has no terminal preconditions, so lint 1 does not apply. ANALYZE-APP-016 is interim-safe for the same reason (`app_install_starved` count ≥ 1 only ever grows).

docs/rules/rule-id-namespace.md

@@ -0,0 +1,47 @@
+---
+type: concept
+title: Rule ID Namespace & Collision Guards
+description: How gather/analyze rule identity is scoped (tenant partition vs global partition), why there are no GUIDs, which collisions are possible, and the guards that keep the reserved built-in namespace and the global RuleStats aggregate clean.
+resource: backend, rules
+tags: [rules, ruleid, namespace, collision, rulestats, tenant-isolation]
+timestamp: 2026-08-21
+---
+
+# Schema
+
+Rule identity is the human-readable `ruleId` string — there are no GUIDs, deliberately: the ID appears in logs, mails, notifications, RuleResults, the agent config payload, and docs, and tenant isolation is provided by Table Storage partitioning instead.
+
+| Store | PartitionKey | RowKey | Content |
+|---|---|---|---|
+| `GatherRules` / `AnalyzeRules` | `"global"` | ruleId | Built-in + community rules (shared, all tenants) |
+| `GatherRules` / `AnalyzeRules` | tenantId | ruleId | Custom rules (visible only to that tenant) |
+| `RuleStates` | tenantId | ruleId | Per-tenant enable/notify overrides — built-in/community rules ONLY (custom rules fold state into their own row) |
+| `RuleStats` | date | `{tenantId}_{ruleId}` and `global_{ruleId}` | Daily fire/eval telemetry; the global row is catalog-only (see guards) |
+
+Namespace split (`RuleIdPolicy.cs`, shared model):
+
+- **Reserved built-in namespace**: `(ANALYZE|GATHER)-<CATEGORY>-<NUMBER>` with `CATEGORY != CUSTOM`, case-insensitive, including currently unused numbers (gaps = retired rules that may return).
+- **Tenant namespace**: everything else — `ANALYZE-CUSTOM-NNN` (portal suggestion), `-CUSTOM` suffixes, org prefixes (`CONTOSO-WIFI-001`), freeform.
+
+# Collision model
+
+- **Custom vs built-in**: impossible via API — `CreateRuleAsync`/`UpdateRuleAsync` reject reserved IDs (409) and check existence against `global` ∪ own tenant partition. Legacy debris is neutralized at merge time: global wins, tenant copy dropped with a warning (pinned by `RuleMergeCollisionGuardTests`, motivated by the 5ca2b350 duplicate-key incident).
+- **Custom vs custom across tenants**: allowed and harmless — separate partitions, separate evaluation, separate RuleResults/tenant stats. Two tenants both using `ANALYZE-CUSTOM-101` never interact.
+- **JSON copy between tenants** (export → paste into create editor): goes through the same create path, so an ID already taken in the receiving tenant surfaces as 409 — the user renames. There is no bulk import endpoint. The JSON editors accept both shapes — a rule export and the serialized form — via `gatherRuleToForm` / `jsonToForm` (web `types.ts` of each rules page): nested gather `parameters` are unflattened, analyze `evaluateOn` maps onto the eval checkboxes, and `tags` plus the effective `markSessionAsFailed` survive the import.
+
+# Guards (all enforced, 2026-08-21)
+
+1. **Global RuleStats aggregate is catalog-only.** The `global_{ruleId}` row would otherwise sum same-ID custom rules of unrelated tenants (title/severity last-writer-wins). Analyze gates on `rule.IsBuiltIn || rule.IsCommunity` (`AnalyzeOnEnrollmentEndHandler`), gather gates on `RuleIdPolicy.IsReservedBuiltInId` (`EventIngestProcessor.RuleStats`) because agent events carry no flag — valid because custom rules can never occupy the reserved pattern.
+2. **Catalog build fails on namespace violations.** `rules/scripts/combine.js` rejects duplicate IDs (case-insensitive) and any gather/analyze built-in outside the reserved pattern; `BuiltInRuleCatalogPolicyTests` pins the same invariants on the embedded resource actually deployed.
+3. **GitHub reseed rejects non-reserved IDs** before writing to the `global` partition (`ReseedFromGitHubFunction`) — a seeded `*-CUSTOM-*` rule would silently shadow every tenant's same-ID custom rule at merge time.
+4. **Cross-tenant RuleState GC is namespace-gated.** `DeleteRuleStatesForRuleIdAcrossTenantsAsync` deletes by bare RowKey across all partitions; it now refuses non-reserved IDs with `failed=-1` (callers then skip the global catalog delete, same contract as enumeration failure).
+
+Invariant chain: schema pattern + combine.js + reseed guard ⇒ the `global` partition only ever contains reserved-pattern IDs ⇒ the pattern is a safe built-in/custom discriminator everywhere no `IsBuiltIn` flag is available.
+
+# Citations
+
+- `src/Shared/AutopilotMonitor.Shared/Models/Rules/RuleIdPolicy.cs` — reserved pattern + rationale
+- `src/Backend/AutopilotMonitor.Functions/Services/AnalyzeRuleService.cs`, `GatherRuleService.cs` — create/update guards, merge collision guard
+- `src/Backend/AutopilotMonitor.Functions/Services/TableStorageService.Rules.cs` — key schemes, cross-tenant GC guard
+- `src/Backend/AutopilotMonitor.Functions.Tests/BuiltInRuleCatalogPolicyTests.cs`, `RuleIdReservationTests.cs`, `RuleMergeCollisionGuardTests.cs`
+- `rules/scripts/combine.js` — build-time namespace/duplicate guard

rules/analyze/ANALYZE-DEV-008.json

@@ -0,0 +1,69 @@
+{
+  "$schema": "../schema/analyze-rule.schema.json",
+  "ruleId": "ANALYZE-DEV-008",
+  "title": "Device Clock Wrong During Enrollment — Jump or Sustained Offset",
+  "description": "The device's clock changed by five or more minutes mid-session (clock jump) or ran five or more minutes off server time for the whole session (sustained offset), measured against the server receive frame of every uploaded event. Complements ANALYZE-DEV-007, which is a one-shot NTP check at agent startup and misses devices where NTP was unreachable or the clock changed later. IME-log-derived events are excluded from the measurement.",
+  "severity": "warning",
+  "category": "device",
+  "version": "1.0.0",
+  "author": "Autopilot Monitor",
+  "enabled": true,
+  "evaluateOn": [
+    "enrollment_end",
+    "whiteglove_sealed"
+  ],
+  "trigger": "single",
+  "baseConfidence": 60,
+  "confidenceThreshold": 50,
+  "conditions": [
+    {
+      "signal": "clock_jump",
+      "source": "clock_skew",
+      "skewMetric": "clock_jump",
+      "operator": "gte",
+      "value": "300",
+      "required": false
+    },
+    {
+      "signal": "sustained_offset",
+      "source": "clock_skew",
+      "skewMetric": "sustained_offset",
+      "operator": "gte",
+      "value": "300",
+      "required": false
+    }
+  ],
+  "confidenceFactors": [],
+  "explanation": "This device's {{skewSummary}} (five-minute threshold). A clock that is off by five or more minutes breaks time-sensitive enrollment mechanisms: Kerberos tolerates at most 5 minutes of skew (Hybrid Join), Entra ID token validation allows about 5 minutes on token lifetimes, and freshly issued SCEP/PKCS certificates can be rejected as \"not yet valid\" when the clock is more than ~10 minutes behind the CA.\n\nUnlike ANALYZE-DEV-007 (a one-shot NTP comparison at agent startup), this finding is measured across the whole session against the server's receive time — it also catches devices where the NTP check could not run (UDP 123 blocked) or where the clock changed after startup (time sync correcting a wrong RTC, Windows auto-timezone, manual change).",
+  "remediation": [
+    {
+      "title": "Fix the device clock and time source",
+      "steps": [
+        "Check the BIOS/RTC clock and the CMOS battery if the wrong time recurs on the same hardware.",
+        "At OOBE, run 'w32tm /resync /force' (Shift+F10 command prompt) to sync with time.windows.com.",
+        "Ensure UDP port 123 to time.windows.com is open in the deployment network.",
+        "Review 'Set time automatically' and 'Set time zone automatically' behavior on the deployment image — automatic timezone changes mid-enrollment show up as clock jumps."
+      ]
+    }
+  ],
+  "relatedDocs": [
+    {
+      "title": "Microsoft Learn: Windows Autopilot known issues — device provisioning can fail (clock skew)",
+      "url": "https://learn.microsoft.com/en-us/autopilot/known-issues"
+    },
+    {
+      "title": "Microsoft Learn: Windows Autopilot requirements — Networking (NTP)",
+      "url": "https://learn.microsoft.com/en-us/autopilot/requirements?tabs=networking"
+    }
+  ],
+  "markSessionAsFailedDefault": false,
+  "tags": [
+    "device",
+    "clock-skew",
+    "clock-jump",
+    "time-sync",
+    "kerberos",
+    "certificates",
+    "known-issue"
+  ]
+}

rules/analyze/ANALYZE-DEV-009.json

@@ -0,0 +1,48 @@
+{
+  "$schema": "../schema/analyze-rule.schema.json",
+  "ruleId": "ANALYZE-DEV-009",
+  "title": "Battery Critically Low During Enrollment",
+  "description": "Detects that the device's battery dropped to 15% or less while enrolling on battery power (power_state_change threshold event from the agent's live power watcher). A device dying mid-enrollment leaves a half-provisioned state that typically needs a full reset; this rule surfaces the risk while there is still time to plug the device in. Uses a single required condition on the agent-stamped thresholdPercent field (the data field 'transition' on the event is unrelated to this rule's 'trigger' property).",
+  "severity": "high",
+  "category": "device",
+  "version": "1.0.0",
+  "enabled": true,
+  "evaluateOn": [
+    "enrollment_end",
+    "whiteglove_sealed",
+    "on_event:power_state_change"
+  ],
+  "trigger": "single",
+  "baseConfidence": 90,
+  "confidenceThreshold": 60,
+  "conditions": [
+    {
+      "signal": "battery_threshold_15",
+      "source": "event_data",
+      "eventType": "power_state_change",
+      "dataField": "thresholdPercent",
+      "operator": "equals",
+      "value": "15",
+      "required": true
+    }
+  ],
+  "explanation": "The device's battery fell below **{{thresholdPercent}}%** while the enrollment was running on battery power. If the battery drains completely mid-enrollment, the device is left in a half-provisioned state — apps, policies, or the user profile may be incomplete, and in most cases the device has to be reset and re-enrolled. The agent detected the threshold crossing live via a Windows power-status notification; the exact percentage at that moment is recorded on the matched power_state_change event in the session timeline.",
+  "remediation": [
+    {
+      "title": "Secure power for the running enrollment",
+      "steps": [
+        "Connect the device to AC power immediately — the enrollment continues normally once power is stable.",
+        "If the device shut down before completing, check whether the session reached the desktop; if not, reset the device (Autopilot reset or reimage) and re-enroll it plugged in.",
+        "For technician/White Glove flows, make AC power part of the bench checklist — pre-provisioning on battery is the most common source of this alert.",
+        "If this fires across many devices of one model, review that model's battery health (the hardware_spec event carries design vs. full-charge capacity)."
+      ]
+    }
+  ],
+  "markSessionAsFailedDefault": false,
+  "tags": [
+    "device",
+    "power",
+    "battery",
+    "environment"
+  ]
+}

rules/analyze/ANALYZE-DEV-010.json

@@ -0,0 +1,48 @@
+{
+  "$schema": "../schema/analyze-rule.schema.json",
+  "ruleId": "ANALYZE-DEV-010",
+  "title": "Enrollment Switched From AC to Battery Power",
+  "description": "Detects that the device lost AC power and switched to battery while the enrollment was running (power_state_change event with transition ac_to_battery from the agent's live power watcher). Uses a single required condition so the match is pinned to one event instance; the event payload carries the battery percentage at the moment of the switch. The agent debounces power flapping (5s) so a brief unplug/replug does not produce this event.",
+  "severity": "warning",
+  "category": "device",
+  "version": "1.0.0",
+  "enabled": true,
+  "evaluateOn": [
+    "enrollment_end",
+    "whiteglove_sealed",
+    "on_event:power_state_change"
+  ],
+  "trigger": "single",
+  "baseConfidence": 85,
+  "confidenceThreshold": 60,
+  "conditions": [
+    {
+      "signal": "switched_to_battery",
+      "source": "event_data",
+      "eventType": "power_state_change",
+      "dataField": "transition",
+      "operator": "equals",
+      "value": "ac_to_battery",
+      "required": true
+    }
+  ],
+  "explanation": "The device switched from AC to battery power mid-enrollment. Enrollments are power-hungry — app downloads, Windows Update and disk encryption drain a battery quickly, and Windows may also throttle CPU and network on battery, slowing the enrollment down. The battery percentage at the moment of the switch is recorded on the matched power_state_change event in the session timeline; if the device stayed on battery, look there for subsequent threshold events (50/30/15%) — a later battery_to_ac event means power was restored.",
+  "remediation": [
+    {
+      "title": "Restore AC power",
+      "steps": [
+        "Reconnect the device to AC power; the enrollment continues normally.",
+        "Check the session timeline for a subsequent battery_to_ac event (power restored) or threshold_crossed events (battery draining) to judge urgency.",
+        "If this alert is frequent in a deployment area, check docking stations/USB-C hubs for loose power delivery — a flapping dock is a common cause.",
+        "Make 'plugged in during setup' part of the end-user/technician enrollment instructions."
+      ]
+    }
+  ],
+  "markSessionAsFailedDefault": false,
+  "tags": [
+    "device",
+    "power",
+    "battery",
+    "environment"
+  ]
+}

rules/analyze/ANALYZE-DEV-012.json

@@ -0,0 +1,49 @@
+{
+  "$schema": "../schema/analyze-rule.schema.json",
+  "ruleId": "ANALYZE-DEV-012",
+  "title": "Device Entered Standby During Enrollment",
+  "description": "Detects that the device completed a sleep, hibernate or Modern Standby episode of at least 5 minutes while the enrollment was running (system_sleep_episode event from the agent's system timeline watcher, recorded retroactively at wake from the Windows event log — pre-agent episodes are backfilled). Uses a single required condition on the episode's durationSeconds so the match is pinned to one event instance and the interpolated duration is the matched value. Short Modern Standby screen-off scenarios (under 60 s of real sleep) never emit the event, and this rule adds a 5-minute floor so brief lid-close moments do not fire it.",
+  "severity": "info",
+  "category": "device",
+  "version": "1.0.0",
+  "enabled": true,
+  "evaluateOn": [
+    "enrollment_end",
+    "whiteglove_sealed",
+    "on_event:system_sleep_episode"
+  ],
+  "trigger": "single",
+  "baseConfidence": 90,
+  "confidenceThreshold": 60,
+  "conditions": [
+    {
+      "signal": "slept_during_enrollment",
+      "source": "event_data",
+      "eventType": "system_sleep_episode",
+      "dataField": "durationSeconds",
+      "operator": "gte",
+      "value": "300",
+      "required": true
+    }
+  ],
+  "explanation": "The device was asleep for {{durationSeconds}} seconds during the enrollment window. Nothing progresses while the device sleeps — downloads pause, the IME stops processing and the ESP simply waits — so the wall-clock enrollment duration includes this pause and can look much slower than the enrollment actually was. The matched system_sleep_episode event in the session timeline carries the exact enter/exit times, the episode kind (sleep, hibernate or Modern Standby) and, for Modern Standby, whether the device was on AC power. A long unexplained gap in the timeline right before that event is this pause, not missing telemetry.",
+  "remediation": [
+    {
+      "title": "Keep the device awake during enrollment",
+      "steps": [
+        "Check the matched system_sleep_episode event in the timeline for the episode bounds and kind — the enrollment duration minus the episode duration is the real active time.",
+        "If the device slept on battery, connect AC power during setup; Windows sleeps far more aggressively on battery.",
+        "Instruct users/technicians to keep the lid open and the device powered until the enrollment finishes.",
+        "For recurring cases, review the power plan applied during OOBE/ESP (e.g. via provisioning or Intune policy) — consider disabling sleep on AC for the enrollment window."
+      ]
+    }
+  ],
+  "markSessionAsFailedDefault": false,
+  "tags": [
+    "device",
+    "power",
+    "standby",
+    "sleep",
+    "environment"
+  ]
+}

rules/dist/analyze-rules.json

@@ -1516,6 +1516,216 @@
         "known-issue"
       ]
     },
+    {
+      "ruleId": "ANALYZE-DEV-008",
+      "title": "Device Clock Wrong During Enrollment — Jump or Sustained Offset",
+      "description": "The device's clock changed by five or more minutes mid-session (clock jump) or ran five or more minutes off server time for the whole session (sustained offset), measured against the server receive frame of every uploaded event. Complements ANALYZE-DEV-007, which is a one-shot NTP check at agent startup and misses devices where NTP was unreachable or the clock changed later. IME-log-derived events are excluded from the measurement.",
+      "severity": "warning",
+      "category": "device",
+      "version": "1.0.0",
+      "author": "Autopilot Monitor",
+      "enabled": true,
+      "evaluateOn": [
+        "enrollment_end",
+        "whiteglove_sealed"
+      ],
+      "trigger": "single",
+      "baseConfidence": 60,
+      "confidenceThreshold": 50,
+      "conditions": [
+        {
+          "signal": "clock_jump",
+          "source": "clock_skew",
+          "skewMetric": "clock_jump",
+          "operator": "gte",
+          "value": "300",
+          "required": false
+        },
+        {
+          "signal": "sustained_offset",
+          "source": "clock_skew",
+          "skewMetric": "sustained_offset",
+          "operator": "gte",
+          "value": "300",
+          "required": false
+        }
+      ],
+      "confidenceFactors": [],
+      "explanation": "This device's {{skewSummary}} (five-minute threshold). A clock that is off by five or more minutes breaks time-sensitive enrollment mechanisms: Kerberos tolerates at most 5 minutes of skew (Hybrid Join), Entra ID token validation allows about 5 minutes on token lifetimes, and freshly issued SCEP/PKCS certificates can be rejected as \"not yet valid\" when the clock is more than ~10 minutes behind the CA.\n\nUnlike ANALYZE-DEV-007 (a one-shot NTP comparison at agent startup), this finding is measured across the whole session against the server's receive time — it also catches devices where the NTP check could not run (UDP 123 blocked) or where the clock changed after startup (time sync correcting a wrong RTC, Windows auto-timezone, manual change).",
+      "remediation": [
+        {
+          "title": "Fix the device clock and time source",
+          "steps": [
+            "Check the BIOS/RTC clock and the CMOS battery if the wrong time recurs on the same hardware.",
+            "At OOBE, run 'w32tm /resync /force' (Shift+F10 command prompt) to sync with time.windows.com.",
+            "Ensure UDP port 123 to time.windows.com is open in the deployment network.",
+            "Review 'Set time automatically' and 'Set time zone automatically' behavior on the deployment image — automatic timezone changes mid-enrollment show up as clock jumps."
+          ]
+        }
+      ],
+      "relatedDocs": [
+        {
+          "title": "Microsoft Learn: Windows Autopilot known issues — device provisioning can fail (clock skew)",
+          "url": "https://learn.microsoft.com/en-us/autopilot/known-issues"
+        },
+        {
+          "title": "Microsoft Learn: Windows Autopilot requirements — Networking (NTP)",
+          "url": "https://learn.microsoft.com/en-us/autopilot/requirements?tabs=networking"
+        }
+      ],
+      "markSessionAsFailedDefault": false,
+      "tags": [
+        "device",
+        "clock-skew",
+        "clock-jump",
+        "time-sync",
+        "kerberos",
+        "certificates",
+        "known-issue"
+      ]
+    },
+    {
+      "ruleId": "ANALYZE-DEV-009",
+      "title": "Battery Critically Low During Enrollment",
+      "description": "Detects that the device's battery dropped to 15% or less while enrolling on battery power (power_state_change threshold event from the agent's live power watcher). A device dying mid-enrollment leaves a half-provisioned state that typically needs a full reset; this rule surfaces the risk while there is still time to plug the device in. Uses a single required condition on the agent-stamped thresholdPercent field (the data field 'transition' on the event is unrelated to this rule's 'trigger' property).",
+      "severity": "high",
+      "category": "device",
+      "version": "1.0.0",
+      "enabled": true,
+      "evaluateOn": [
+        "enrollment_end",
+        "whiteglove_sealed",
+        "on_event:power_state_change"
+      ],
+      "trigger": "single",
+      "baseConfidence": 90,
+      "confidenceThreshold": 60,
+      "conditions": [
+        {
+          "signal": "battery_threshold_15",
+          "source": "event_data",
+          "eventType": "power_state_change",
+          "dataField": "thresholdPercent",
+          "operator": "equals",
+          "value": "15",
+          "required": true
+        }
+      ],
+      "explanation": "The device's battery fell below **{{thresholdPercent}}%** while the enrollment was running on battery power. If the battery drains completely mid-enrollment, the device is left in a half-provisioned state — apps, policies, or the user profile may be incomplete, and in most cases the device has to be reset and re-enrolled. The agent detected the threshold crossing live via a Windows power-status notification; the exact percentage at that moment is recorded on the matched power_state_change event in the session timeline.",
+      "remediation": [
+        {
+          "title": "Secure power for the running enrollment",
+          "steps": [
+            "Connect the device to AC power immediately — the enrollment continues normally once power is stable.",
+            "If the device shut down before completing, check whether the session reached the desktop; if not, reset the device (Autopilot reset or reimage) and re-enroll it plugged in.",
+            "For technician/White Glove flows, make AC power part of the bench checklist — pre-provisioning on battery is the most common source of this alert.",
+            "If this fires across many devices of one model, review that model's battery health (the hardware_spec event carries design vs. full-charge capacity)."
+          ]
+        }
+      ],
+      "markSessionAsFailedDefault": false,
+      "tags": [
+        "device",
+        "power",
+        "battery",
+        "environment"
+      ]
+    },
+    {
+      "ruleId": "ANALYZE-DEV-010",
+      "title": "Enrollment Switched From AC to Battery Power",
+      "description": "Detects that the device lost AC power and switched to battery while the enrollment was running (power_state_change event with transition ac_to_battery from the agent's live power watcher). Uses a single required condition so the match is pinned to one event instance; the event payload carries the battery percentage at the moment of the switch. The agent debounces power flapping (5s) so a brief unplug/replug does not produce this event.",
+      "severity": "warning",
+      "category": "device",
+      "version": "1.0.0",
+      "enabled": true,
+      "evaluateOn": [
+        "enrollment_end",
+        "whiteglove_sealed",
+        "on_event:power_state_change"
+      ],
+      "trigger": "single",
+      "baseConfidence": 85,
+      "confidenceThreshold": 60,
+      "conditions": [
+        {
+          "signal": "switched_to_battery",
+          "source": "event_data",
+          "eventType": "power_state_change",
+          "dataField": "transition",
+          "operator": "equals",
+          "value": "ac_to_battery",
+          "required": true
+        }
+      ],
+      "explanation": "The device switched from AC to battery power mid-enrollment. Enrollments are power-hungry — app downloads, Windows Update and disk encryption drain a battery quickly, and Windows may also throttle CPU and network on battery, slowing the enrollment down. The battery percentage at the moment of the switch is recorded on the matched power_state_change event in the session timeline; if the device stayed on battery, look there for subsequent threshold events (50/30/15%) — a later battery_to_ac event means power was restored.",
+      "remediation": [
+        {
+          "title": "Restore AC power",
+          "steps": [
+            "Reconnect the device to AC power; the enrollment continues normally.",
+            "Check the session timeline for a subsequent battery_to_ac event (power restored) or threshold_crossed events (battery draining) to judge urgency.",
+            "If this alert is frequent in a deployment area, check docking stations/USB-C hubs for loose power delivery — a flapping dock is a common cause.",
+            "Make 'plugged in during setup' part of the end-user/technician enrollment instructions."
+          ]
+        }
+      ],
+      "markSessionAsFailedDefault": false,
+      "tags": [
+        "device",
+        "power",
+        "battery",
+        "environment"
+      ]
+    },
+    {
+      "ruleId": "ANALYZE-DEV-012",
+      "title": "Device Entered Standby During Enrollment",
+      "description": "Detects that the device completed a sleep, hibernate or Modern Standby episode of at least 5 minutes while the enrollment was running (system_sleep_episode event from the agent's system timeline watcher, recorded retroactively at wake from the Windows event log — pre-agent episodes are backfilled). Uses a single required condition on the episode's durationSeconds so the match is pinned to one event instance and the interpolated duration is the matched value. Short Modern Standby screen-off scenarios (under 60 s of real sleep) never emit the event, and this rule adds a 5-minute floor so brief lid-close moments do not fire it.",
+      "severity": "info",
+      "category": "device",
+      "version": "1.0.0",
+      "enabled": true,
+      "evaluateOn": [
+        "enrollment_end",
+        "whiteglove_sealed",
+        "on_event:system_sleep_episode"
+      ],
+      "trigger": "single",
+      "baseConfidence": 90,
+      "confidenceThreshold": 60,
+      "conditions": [
+        {
+          "signal": "slept_during_enrollment",
+          "source": "event_data",
+          "eventType": "system_sleep_episode",
+          "dataField": "durationSeconds",
+          "operator": "gte",
+          "value": "300",
+          "required": true
+        }
+      ],
+      "explanation": "The device was asleep for {{durationSeconds}} seconds during the enrollment window. Nothing progresses while the device sleeps — downloads pause, the IME stops processing and the ESP simply waits — so the wall-clock enrollment duration includes this pause and can look much slower than the enrollment actually was. The matched system_sleep_episode event in the session timeline carries the exact enter/exit times, the episode kind (sleep, hibernate or Modern Standby) and, for Modern Standby, whether the device was on AC power. A long unexplained gap in the timeline right before that event is this pause, not missing telemetry.",
+      "remediation": [
+        {
+          "title": "Keep the device awake during enrollment",
+          "steps": [
+            "Check the matched system_sleep_episode event in the timeline for the episode bounds and kind — the enrollment duration minus the episode duration is the real active time.",
+            "If the device slept on battery, connect AC power during setup; Windows sleeps far more aggressively on battery.",
+            "Instruct users/technicians to keep the lid open and the device powered until the enrollment finishes.",
+            "For recurring cases, review the power plan applied during OOBE/ESP (e.g. via provisioning or Intune policy) — consider disabling sleep on AC for the enrollment window."
+          ]
+        }
+      ],
+      "markSessionAsFailedDefault": false,
+      "tags": [
+        "device",
+        "power",
+        "standby",
+        "sleep",
+        "environment"
+      ]
+    },
     {
       "ruleId": "ANALYZE-ENRL-001",
       "title": "Enrollment Failed",

rules/schema/analyze-rule.schema.json

@@ -169,7 +169,12 @@
         "source": {
           "type": "string",
           "description": "Source of the signal.",
-          "enum": ["event_type", "event_data", "event_data_array", "phase_duration", "event_count", "app_install_duration", "event_correlation"]
+          "enum": ["event_type", "event_data", "event_data_array", "phase_duration", "event_count", "app_install_duration", "event_correlation", "clock_skew"]
+        },
+        "skewMetric": {
+          "type": "string",
+          "description": "For clock_skew only: which device-clock metric to evaluate. clock_jump = persistent step in the device's clock frame mid-session; sustained_offset = whole session ran on a clock off by at least the threshold. value is the threshold in seconds; operator is limited to gt/gte on the magnitude. IME-log-derived events are excluded from the measurement.",
+          "enum": ["clock_jump", "sustained_offset"]
         },
         "eventType": {
           "type": "string",

rules/scripts/combine.js

@@ -13,18 +13,26 @@ const rulesRoot = path.resolve(__dirname, '..');
 
 // ── Rule combination ────────────────────────────────────────────────────────
 
+// Shipped gather/analyze rules must stay inside the reserved built-in namespace:
+// (ANALYZE|GATHER)-<CATEGORY>-<NNN> with CATEGORY !== CUSTOM. The CUSTOM category is
+// the sanctioned tenant namespace (RuleIdPolicy.cs) — a built-in shipped there would
+// silently shadow every tenant's same-ID custom rule at merge time (global wins).
+const RESERVED_BUILTIN_ID = /^(ANALYZE|GATHER)-(?!CUSTOM-)[A-Z]+-\d{3}$/;
+
 const configs = [
   {
     dir: path.join(rulesRoot, 'gather'),
     output: path.join(rulesRoot, 'dist', 'gather-rules.json'),
     schema: '../schema/gather-rule.schema.json',
-    idField: 'ruleId'
+    idField: 'ruleId',
+    reservedNamespace: RESERVED_BUILTIN_ID
   },
   {
     dir: path.join(rulesRoot, 'analyze'),
     output: path.join(rulesRoot, 'dist', 'analyze-rules.json'),
     schema: '../schema/analyze-rule.schema.json',
-    idField: 'ruleId'
+    idField: 'ruleId',
+    reservedNamespace: RESERVED_BUILTIN_ID
   },
   {
     dir: path.join(rulesRoot, 'ime-log-patterns'),
@@ -37,12 +45,27 @@ const configs = [
 for (const config of configs) {
   const files = fs.readdirSync(config.dir).filter(f => f.endsWith('.json')).sort();
   const rules = [];
+  const seenIds = new Map(); // lowercased id -> filename (case variants collide for humans and RuleIdPolicy)
 
   for (const file of files) {
     const content = fs.readFileSync(path.join(config.dir, file), 'utf8');
     const rule = JSON.parse(content);
     // Remove $schema from individual entries (it's on the wrapper)
     delete rule['$schema'];
+
+    const id = rule[config.idField] || '';
+    const idKey = id.toLowerCase();
+    if (seenIds.has(idKey)) {
+      console.error(`ERROR: duplicate ${config.idField} "${id}" in ${file} (already defined in ${seenIds.get(idKey)})`);
+      process.exit(1);
+    }
+    seenIds.set(idKey, file);
+
+    if (config.reservedNamespace && !config.reservedNamespace.test(id)) {
+      console.error(`ERROR: ${file}: ${config.idField} "${id}" is outside the reserved built-in namespace ${config.reservedNamespace} — built-ins must never use the tenant CUSTOM namespace`);
+      process.exit(1);
+    }
+
     rules.push(rule);
   }
 

scripts/CustomerSetup/Grant-AutopilotMonitorAddOn.ps1

@@ -28,10 +28,13 @@
         (validates Windows 365 Cloud PCs against the tenant's Cloud PC inventory --
          Cloud PCs are never Autopilot-registered, so this enables agent monitoring
          of Cloud PC first-connect enrollment)
+      - All                    -> every optional permission above, in one run
+        (also works with -Revoke to remove all optional grants at once)
 
 .PARAMETER Permissions
-    Microsoft Graph application permission names to grant directly. Use when the admin UI
-    rendered a copy-paste command for you, or when you have a specific list in mind.
+    Microsoft Graph application permission names to grant directly. Use when you copied the
+    permission list from the admin UI ("Copy permissions"), or when you have a specific list
+    in mind.
 
 .PARAMETER TenantId
     Tenant ID (GUID) or verified domain. Optional -- defaults to the signed-in context.
@@ -47,12 +50,16 @@
     .\Grant-AutopilotMonitorAddOn.ps1 -ClientId "<your-client-id>" -Features ScriptDisplayNames
 
 .EXAMPLE
-    # Same effect, using the explicit-permission form (what the admin UI generates):
+    # Same effect, using the explicit-permission form:
     .\Grant-AutopilotMonitorAddOn.ps1 `
         -ClientId "<your-client-id>" `
         -Permissions "DeviceManagementScripts.Read.All" `
         -TenantId "contoso.onmicrosoft.com"
 
+.EXAMPLE
+    # Grant every optional capability in one run:
+    .\Grant-AutopilotMonitorAddOn.ps1 -ClientId "<your-client-id>" -Features All
+
 .EXAMPLE
     # Verify current state only, no changes:
     .\Grant-AutopilotMonitorAddOn.ps1 -ClientId "<your-client-id>" -Features ScriptDisplayNames -VerifyOnly
@@ -65,6 +72,12 @@
     Requires:
       - Microsoft.Graph.Authentication PowerShell module (auto-installs if missing).
       - Sign-in as Global Administrator OR Privileged Role Administrator OR Cloud Application Administrator.
+
+    Sign-in behaviour:
+      In Azure Cloud Shell the script signs in via the ambient identity endpoint (a delegated
+      token for the already-signed-in user) - no device-code prompt, which Conditional Access
+      policies commonly block. Outside Cloud Shell it falls back to a normal interactive
+      Microsoft Graph sign-in. -TenantId only applies to the interactive fallback.
       - The Autopilot Monitor app must be admin-consented in your tenant first
         (its service principal must exist before grants can be added).
 
@@ -80,7 +93,7 @@ param(
     [string]$ClientId,
 
     [Parameter(Mandatory = $true, ParameterSetName = 'ByFeatures')]
-    [ValidateSet('ScriptDisplayNames', 'W365CloudPcValidation')]
+    [ValidateSet('All', 'ScriptDisplayNames', 'W365CloudPcValidation')]
     [string[]]$Features,
 
     [Parameter(Mandatory = $true, ParameterSetName = 'ByPermissions')]
@@ -106,7 +119,11 @@ $FeatureCatalog = @{
 }
 
 # Translate Features -> Permissions when caller used the high-level form.
+# 'All' is a script-side meta-value: it expands to every catalog feature.
 if ($PSCmdlet.ParameterSetName -eq 'ByFeatures') {
+    if ($Features -contains 'All') {
+        $Features = @($FeatureCatalog.Keys)
+    }
     $Permissions = @()
     foreach ($f in $Features) {
         $Permissions += $FeatureCatalog[$f]
@@ -133,7 +150,25 @@ if ($TenantId) { $connectParams['TenantId'] = $TenantId }
 
 Write-Host ""
 Write-Host "[Auth] Connecting to Microsoft Graph..." -ForegroundColor Cyan
-Connect-MgGraph @connectParams | Out-Null
+
+# Preferred path: ambient identity. In Azure Cloud Shell the local identity endpoint issues a
+# delegated Graph token for the signed-in user, which avoids the device-code flow that
+# Conditional Access policies commonly block. Outside Azure this throws and we fall back to
+# an interactive sign-in with explicit scopes.
+$identityConnected = $false
+try {
+    Connect-MgGraph -Identity -NoWelcome -ErrorAction Stop | Out-Null
+    # An ambient identity can exist yet hold no Graph permissions (e.g. a plain VM managed
+    # identity) - probe with a read before committing to this session.
+    Invoke-MgGraphRequest -Method GET -Uri "https://graph.microsoft.com/v1.0/servicePrincipals?`$select=id&`$top=1" -ErrorAction Stop | Out-Null
+    $identityConnected = $true
+    Write-Host "[Auth] Connected via ambient identity (Azure Cloud Shell / managed identity)." -ForegroundColor Green
+}
+catch {
+    if (Get-MgContext) { Disconnect-MgGraph -ErrorAction SilentlyContinue | Out-Null }
+    Write-Host "[Auth] No usable ambient identity - falling back to interactive sign-in..." -ForegroundColor Yellow
+    Connect-MgGraph @connectParams | Out-Null
+}
 
 $ctx = Get-MgContext
 if (-not $ctx) {
@@ -144,7 +179,10 @@ Write-Host "[Auth] Signed in as : $($ctx.Account)"
 Write-Host "[Auth] Tenant       : $($ctx.TenantId)"
 Write-Host "[Auth] Granted scopes: $($ctx.Scopes -join ', ')"
 
-if (-not ($ctx.Scopes -contains 'AppRoleAssignment.ReadWrite.All')) {
+# Scope check only applies to the interactive path: an ambient-identity (Cloud Shell) token
+# carries a fixed scope set (incl. Directory.AccessAsUser.All) instead of the requested scopes,
+# and its effective rights follow the signed-in user's directory role.
+if (-not $identityConnected -and -not ($ctx.Scopes -contains 'AppRoleAssignment.ReadWrite.All')) {
     Write-Warning "Scope 'AppRoleAssignment.ReadWrite.All' was NOT granted. The signed-in user likely lacks the required role (Global Admin / Privileged Role Admin / Cloud App Admin)."
     if (-not $VerifyOnly) { return }
 }

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Configuration/RemoteConfigMergerCompletenessTests.cs

@@ -37,6 +37,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Configuration
             nameof(AgentConfigResponse.EnrollmentSummaryLaunchRetrySeconds),
             nameof(AgentConfigResponse.NtpServer),
             nameof(AgentConfigResponse.EnableTimezoneAutoSet),
+            nameof(AgentConfigResponse.EnableDoGroupIdAutoSet),
             nameof(AgentConfigResponse.DiagnosticsUploadEnabled),
             nameof(AgentConfigResponse.DiagnosticsUploadMode),
             nameof(AgentConfigResponse.DiagnosticsLogPaths),

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Configuration/RemoteConfigMergerTests.cs

@@ -43,6 +43,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Configuration
             EnrollmentSummaryLaunchRetrySeconds = 300,
             NtpServer = "pool.ntp.org",
             EnableTimezoneAutoSet = true,
+            EnableDoGroupIdAutoSet = true,
             DiagnosticsUploadEnabled = true,
             DiagnosticsUploadMode = "OnFailure",
             DiagnosticsLogPaths = new List<DiagnosticsLogPath>
@@ -83,6 +84,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Configuration
             Assert.Equal(300, agent.EnrollmentSummaryLaunchRetrySeconds);
             Assert.Equal("pool.ntp.org", agent.NtpServer);
             Assert.True(agent.EnableTimezoneAutoSet);
+            Assert.True(agent.EnableDoGroupIdAutoSet);
             Assert.True(agent.DiagnosticsUploadEnabled);
             Assert.Equal("OnFailure", agent.DiagnosticsUploadMode);
             Assert.Single(agent.DiagnosticsLogPaths);

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceCalibratorFileIsolationTests.cs

@@ -0,0 +1,109 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime;
+using AutopilotMonitor.Agent.V2.Core.Tests.Harness;
+using AutopilotMonitor.Shared.Models;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
+{
+    /// <summary>
+    /// Pins the per-FILE isolation of the offset measurement across a full read cycle.
+    ///
+    /// <para>
+    /// Background (2026-08-20, session e9753578): the field showed "+02:00 measured for
+    /// IntuneManagementExtension.log" although that file held no +2-era line — the anchor had
+    /// crossed file boundaries. The committed code was proven innocent (this very scenario is
+    /// green here); the leak lived in a binary built from an uncommitted tree. This test keeps
+    /// the property pinned so a real regression of the file scoping can never ship silently
+    /// again — it replays the exact field pass structure: a NEW file appearing mid-run with a
+    /// different writer era than the file already being tailed.
+    /// </para>
+    /// </summary>
+    public sealed class CmTraceCalibratorFileIsolationTests
+    {
+        private static readonly DateTime T0 = new DateTime(2026, 8, 20, 12, 13, 0, DateTimeKind.Utc);
+
+        private static List<ImeLogPattern> Patterns() => new List<ImeLogPattern>
+        {
+            new ImeLogPattern
+            {
+                PatternId = "T-MARK", Category = "always", Enabled = true,
+                Pattern = @"marker (?<n>\d+)",
+                Action = "noop",
+                Parameters = new Dictionary<string, string>(),
+            },
+        };
+
+        private static string Line(string message, DateTime utcInstant, TimeSpan writerOffset)
+        {
+            var local = utcInstant + writerOffset;
+            return $"<![LOG[{message}]LOG]!><time=\"{local:HH:mm:ss.fffffff}\" date=\"{local:M-d-yyyy}\" " +
+                   "component=\"X\" context=\"\" type=\"1\" thread=\"1\" file=\"\">";
+        }
+
+        [Fact]
+        public async Task NewFileWithOtherEra_MustNotRecalibrateTheOldFile()
+        {
+            var pdt = TimeSpan.FromHours(-7);   // IME service era
+            var cest = TimeSpan.FromHours(2);   // fresh child-process era
+
+            using var tmp = new TempDirectory();
+            var now = T0;
+            var tracker = new ImeLogTracker(
+                logFolder: tmp.Path,
+                patterns: Patterns(),
+                logger: new AgentLogger(tmp.Path, AgentLogLevel.Info));
+            try
+            {
+                tracker.UtcNowProvider = () => now;
+                var imeLog = Path.Combine(tmp.Path, "IntuneManagementExtension.log");
+                var execLog = Path.Combine(tmp.Path, "AgentExecutor.log");
+
+                // Pass 1: IME.log first sight (no calibration).
+                File.AppendAllText(imeLog, Line("marker 1", now, pdt) + Environment.NewLine);
+                await tracker.CheckLogFilesAsync(CancellationToken.None);
+
+                // Pass 2: IME.log grew -> measures -7.
+                now = T0.AddSeconds(10);
+                File.AppendAllText(imeLog, Line("marker 2", now, pdt) + Environment.NewLine);
+                await tracker.CheckLogFilesAsync(CancellationToken.None);
+
+                TimeSpan imeMeasured;
+                Assert.True(tracker.OffsetCalibrator.TryGetOffset("IntuneManagementExtension.log", out imeMeasured));
+                Assert.Equal(pdt, imeMeasured);
+
+                // Pass 3: AgentExecutor.log appears for the FIRST time with fresh +2-era lines
+                // while IME.log grows too — the exact field pass structure. The +2 anchor must
+                // never land under IME.log's key.
+                now = T0.AddSeconds(20);
+                File.AppendAllText(execLog, Line("marker 3", now, cest) + Environment.NewLine);
+                File.AppendAllText(imeLog, Line("marker 4", now, pdt) + Environment.NewLine);
+                await tracker.CheckLogFilesAsync(CancellationToken.None);
+
+                Assert.True(tracker.OffsetCalibrator.TryGetOffset("IntuneManagementExtension.log", out imeMeasured));
+                Assert.Equal(pdt, imeMeasured);
+
+                // Pass 4: both grow — each file measures its own writer's era.
+                now = T0.AddSeconds(30);
+                File.AppendAllText(execLog, Line("marker 5", now, cest) + Environment.NewLine);
+                File.AppendAllText(imeLog, Line("marker 6", now, pdt) + Environment.NewLine);
+                await tracker.CheckLogFilesAsync(CancellationToken.None);
+
+                TimeSpan execMeasured;
+                Assert.True(tracker.OffsetCalibrator.TryGetOffset("AgentExecutor.log", out execMeasured));
+                Assert.Equal(cest, execMeasured);
+                Assert.True(tracker.OffsetCalibrator.TryGetOffset("IntuneManagementExtension.log", out imeMeasured));
+                Assert.Equal(pdt, imeMeasured);
+            }
+            finally
+            {
+                tracker.Dispose();
+            }
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceLogParserTests.cs

@@ -67,29 +67,34 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
             Assert.Equal("EnforcementState: Installing app X", entry.Message);
             Assert.Equal("AppEnforce", entry.Component);
             Assert.Equal(1, entry.Type);
-            Assert.NotEqual(default, entry.Timestamp);
+            Assert.True(entry.HasTimestamp);
+            Assert.NotEqual(default, entry.LocalTimestamp);
+            // Bias-less line: the parser refuses to guess the writer's zone, so no UTC value.
+            Assert.Null(entry.BiasMinutes);
+            Assert.Null(entry.TimestampUtc);
+            Assert.Equal(DateTimeKind.Unspecified, entry.LocalTimestamp.Kind);
         }
 
-        // ── Structurally valid but unparseable timestamp → UtcNow fallback ────
+        // ── Structurally valid but unparseable timestamp → flagged, not invented ──
 
         [Fact]
-        public void TryParseLine_falls_back_to_utcnow_for_unparseable_timestamp()
+        public void TryParseLine_flags_unparseable_timestamp_instead_of_inventing_one()
         {
             // time/date satisfy the regex character classes ([\d:.]+ / [\d-]+) so the line MATCHES,
-            // but "13-45-2026" / "25:99:99" fail every DateTime format → the parser falls back to
-            // DateTime.UtcNow (CmTraceLogParser.cs:57) instead of throwing.
-            var before = DateTime.UtcNow;
+            // but "13-45-2026" / "25:99:99" fail every DateTime format. The parser used to stamp
+            // DateTime.UtcNow here, which made a fabricated value indistinguishable from a real
+            // one downstream. It now reports HasTimestamp=false and leaves the choice of fallback
+            // to the caller, which is the only party that knows what a safe default is in context.
             var line = CmTraceLine("some message", "25:99:99.0000000", "13-45-2026");
 
             var ok = CmTraceLogParser.TryParseLine(line, out var entry);
-            var after = DateTime.UtcNow;
 
             Assert.True(ok);
             Assert.NotNull(entry);
             Assert.Equal("some message", entry.Message);
-            // Don't assert an exact instant — only that the fallback stamped a fresh "now"
-            // (a successfully-parsed date would land in 2026, far outside this window).
-            Assert.InRange(entry.Timestamp, before.AddSeconds(-5), after.AddSeconds(5));
+            Assert.False(entry.HasTimestamp);
+            Assert.Equal(default, entry.LocalTimestamp);
+            Assert.Null(entry.TimestampUtc);
         }
 
         // ── UTC-bias suffix on the time field → honored, not dropped ──────────
@@ -108,10 +113,14 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
 
             Assert.True(ok);
             Assert.NotNull(entry);
+            // A writer-declared bias IS the fact we otherwise have to measure, so it is honored
+            // and resolved to UTC right here — unlike the bias-less form.
+            Assert.Equal(expectedOffsetMinutes, entry.BiasMinutes);
+            Assert.NotNull(entry.TimestampUtc);
             Assert.Equal(
                 new DateTime(2026, 7, 29, 11, 46, 19, DateTimeKind.Utc).AddTicks(226610).AddMinutes(expectedOffsetMinutes),
-                entry.Timestamp);
-            Assert.Equal(DateTimeKind.Utc, entry.Timestamp.Kind);
+                entry.TimestampUtc!.Value);
+            Assert.Equal(DateTimeKind.Utc, entry.TimestampUtc!.Value.Kind);
         }
 
         // ── Oversized line → parses, no throw, no truncation of the message ───

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceOffsetCalibratorTests.cs

@@ -0,0 +1,190 @@
+using System;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
+{
+    /// <summary>
+    /// Pins the measurement contract of <see cref="CmTraceOffsetCalibrator"/>.
+    ///
+    /// <para>
+    /// The cases are taken from real sessions: +1 h (GMT to W. Europe, session bfff9b1c) and
+    /// -17 h (a writer left on the Pacific OOBE default while the agent had moved to
+    /// E. Australia). The backlog case is the one the residual guard cannot catch on its own and
+    /// is the reason the freshness rule exists.
+    /// </para>
+    /// </summary>
+    public class CmTraceOffsetCalibratorTests
+    {
+        private const string Source = "IntuneManagementExtension.log";
+        private static readonly DateTime UtcNow = new DateTime(2026, 08, 20, 07, 31, 46, DateTimeKind.Utc);
+
+        /// <summary>A line written "now" by a writer that believes it is at <paramref name="offset"/>.</summary>
+        private static DateTime LineWrittenNow(TimeSpan offset, DateTime utcNow)
+            => DateTime.SpecifyKind(utcNow + offset, DateTimeKind.Unspecified);
+
+        [Theory]
+        [InlineData(2)]     // CEST — the bfff9b1c writer
+        [InlineData(1)]     // BST — what the agent wrongly assumed there
+        [InlineData(-7)]    // PDT — the OOBE default seen in the -17 h sessions
+        [InlineData(10)]    // E. Australia
+        [InlineData(14)]    // Line Islands, the upper bound
+        [InlineData(-12)]   // Dateline, the lower bound
+        public void MeasuresWholeHourOffsets(int hours)
+        {
+            var sut = new CmTraceOffsetCalibrator();
+            var offset = TimeSpan.FromHours(hours);
+
+            Assert.True(sut.TryCalibrate(Source, LineWrittenNow(offset, UtcNow), UtcNow));
+
+            TimeSpan measured;
+            Assert.True(sut.TryGetOffset(Source, out measured));
+            Assert.Equal(offset, measured);
+        }
+
+        [Theory]
+        [InlineData(330)]   // India, UTC+5:30
+        [InlineData(345)]   // Nepal, UTC+5:45
+        [InlineData(570)]   // Adelaide, UTC+9:30 — the +30 min sessions in the field data
+        public void MeasuresQuarterHourOffsets(int minutes)
+        {
+            var sut = new CmTraceOffsetCalibrator();
+            var offset = TimeSpan.FromMinutes(minutes);
+
+            Assert.True(sut.TryCalibrate(Source, LineWrittenNow(offset, UtcNow), UtcNow));
+
+            TimeSpan measured;
+            Assert.True(sut.TryGetOffset(Source, out measured));
+            Assert.Equal(offset, measured);
+        }
+
+        [Fact]
+        public void AbsorbsPollAndFlushLatency()
+        {
+            // The line was written a moment before we parsed it. That lag must vanish into the
+            // grid rather than shift the measured offset.
+            var sut = new CmTraceOffsetCalibrator();
+            var lineLocal = LineWrittenNow(TimeSpan.FromHours(2), UtcNow.AddMilliseconds(-450));
+
+            Assert.True(sut.TryCalibrate(Source, lineLocal, UtcNow));
+
+            TimeSpan measured;
+            Assert.True(sut.TryGetOffset(Source, out measured));
+            Assert.Equal(TimeSpan.FromHours(2), measured);
+        }
+
+        [Fact]
+        public void RejectsBacklogLine_EvenWhenItRoundsCleanly()
+        {
+            // THE case the residual guard cannot catch alone: a line exactly 30 minutes old is a
+            // clean multiple of the grid, so it rounds with zero residual — and would calibrate
+            // the offset half an hour wrong. Only the caller's freshness rule prevents this from
+            // ever being offered; this test pins that a 30-minute-old line does not silently
+            // produce the true offset.
+            var sut = new CmTraceOffsetCalibrator();
+            var thirtyMinutesOld = LineWrittenNow(TimeSpan.FromHours(2), UtcNow.AddMinutes(-30));
+
+            Assert.True(sut.TryCalibrate(Source, thirtyMinutesOld, UtcNow));
+
+            TimeSpan measured;
+            Assert.True(sut.TryGetOffset(Source, out measured));
+            Assert.Equal(TimeSpan.FromMinutes(90), measured);
+            Assert.NotEqual(TimeSpan.FromHours(2), measured);
+        }
+
+        [Fact]
+        public void RejectsOffGridCandidate()
+        {
+            // 7 minutes off the grid: not fresh, and not a timezone either.
+            var sut = new CmTraceOffsetCalibrator();
+            var offGrid = LineWrittenNow(TimeSpan.FromHours(2), UtcNow.AddMinutes(-7));
+
+            Assert.False(sut.TryCalibrate(Source, offGrid, UtcNow));
+
+            TimeSpan ignored;
+            Assert.False(sut.TryGetOffset(Source, out ignored));
+        }
+
+        [Fact]
+        public void RejectsOffsetOutsideAnyRealTimezone()
+        {
+            var sut = new CmTraceOffsetCalibrator();
+            var absurd = LineWrittenNow(TimeSpan.FromHours(20), UtcNow);
+
+            Assert.False(sut.TryCalibrate(Source, absurd, UtcNow));
+        }
+
+        [Fact]
+        public void SelfHeals_WhenTheWritingProcessPicksUpANewZone()
+        {
+            // The writer restarts mid-session and now believes CEST instead of the stale BST.
+            var sut = new CmTraceOffsetCalibrator();
+            Assert.True(sut.TryCalibrate(Source, LineWrittenNow(TimeSpan.FromHours(1), UtcNow), UtcNow));
+
+            var later = UtcNow.AddMinutes(5);
+            Assert.True(sut.TryCalibrate(Source, LineWrittenNow(TimeSpan.FromHours(2), later), later));
+
+            TimeSpan measured;
+            Assert.True(sut.TryGetOffset(Source, out measured));
+            Assert.Equal(TimeSpan.FromHours(2), measured);
+        }
+
+        [Fact]
+        public void IgnoresAnchorOlderThanTheCurrentOne()
+        {
+            var sut = new CmTraceOffsetCalibrator();
+            Assert.True(sut.TryCalibrate(Source, LineWrittenNow(TimeSpan.FromHours(2), UtcNow), UtcNow));
+
+            // An out-of-order line from before the current anchor must not move the offset back.
+            var earlier = UtcNow.AddMinutes(-10);
+            Assert.False(sut.TryCalibrate(Source, LineWrittenNow(TimeSpan.FromHours(1), earlier), earlier));
+
+            TimeSpan measured;
+            Assert.True(sut.TryGetOffset(Source, out measured));
+            Assert.Equal(TimeSpan.FromHours(2), measured);
+        }
+
+        [Fact]
+        public void KeepsSourcesIndependent()
+        {
+            // IntuneManagementExtension.log and AppWorkload.log are written by different
+            // processes and may hold different beliefs.
+            var sut = new CmTraceOffsetCalibrator();
+            Assert.True(sut.TryCalibrate("IntuneManagementExtension.log", LineWrittenNow(TimeSpan.FromHours(2), UtcNow), UtcNow));
+            Assert.True(sut.TryCalibrate("AppWorkload.log", LineWrittenNow(TimeSpan.FromHours(-7), UtcNow), UtcNow));
+
+            TimeSpan ime, appWorkload;
+            Assert.True(sut.TryGetOffset("IntuneManagementExtension.log", out ime));
+            Assert.True(sut.TryGetOffset("AppWorkload.log", out appWorkload));
+            Assert.Equal(TimeSpan.FromHours(2), ime);
+            Assert.Equal(TimeSpan.FromHours(-7), appWorkload);
+        }
+
+        [Fact]
+        public void ResolvesTheRealFieldLine_FromSessionBfff9b1c()
+        {
+            // Raw line: <![LOG[Agent version is: 1.104.102.0]LOG]!><time="09:31:46.5192284" ...>
+            // Server-side ReceivedAt puts the true UTC at 07:31:46.4. The old code produced
+            // 08:31:46.5192284 — local minus the agent's stale +1 h belief.
+            var sut = new CmTraceOffsetCalibrator();
+            var trueUtc = new DateTime(2026, 08, 20, 07, 31, 46, 400, DateTimeKind.Utc);
+            var lineLocal = new DateTime(2026, 08, 20, 09, 31, 46, 519, DateTimeKind.Unspecified);
+
+            Assert.True(sut.TryCalibrate(Source, lineLocal, trueUtc));
+
+            DateTime resolved;
+            Assert.True(sut.TryResolveUtc(Source, lineLocal, out resolved));
+            Assert.Equal(DateTimeKind.Utc, resolved.Kind);
+            Assert.Equal(new DateTime(2026, 08, 20, 07, 31, 46, 519, DateTimeKind.Utc), resolved);
+        }
+
+        [Fact]
+        public void ReportsUncalibratedSource_SoTheCallerCanFlagIt()
+        {
+            var sut = new CmTraceOffsetCalibrator();
+
+            DateTime resolved;
+            Assert.False(sut.TryResolveUtc(Source, UtcNow, out resolved));
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/ImeLogTrackerLineAnchoringTests.cs

@@ -0,0 +1,441 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime;
+using AutopilotMonitor.Agent.V2.Core.Tests.Harness;
+using AutopilotMonitor.Shared.Logging;
+using AutopilotMonitor.Shared.Models;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
+{
+    /// <summary>
+    /// Per-line self-anchoring — the era-aware successor to the reverted per-file offset
+    /// application (04b1a7c6).
+    ///
+    /// <para>
+    /// The property under test: a line read in a provably FRESH pass resolves to the instant it
+    /// was written, whatever timezone its writer believed — and neighbouring lines from writers
+    /// with DIFFERENT beliefs each resolve to their own era, because no cross-line state is
+    /// involved. That interleaving (fixture: AgentExecutor.log with PDT and CEST children in one
+    /// file, flipping both ways) is exactly what broke every cross-line anchor design.
+    /// </para>
+    ///
+    /// <para>
+    /// The freshness boundary is equally load-bearing: backlog (first sight, restart catch-up,
+    /// stalled polls) must NEVER anchor, because an old line's age can round onto the 15-minute
+    /// offset grid. Those paths keep the uniform reader-zone fallback.
+    /// </para>
+    /// </summary>
+    public sealed class ImeLogTrackerLineAnchoringTests
+    {
+        private static readonly DateTime T0 = new DateTime(2026, 8, 20, 12, 13, 0, DateTimeKind.Utc);
+
+        private static List<ImeLogPattern> Patterns() => new List<ImeLogPattern>
+        {
+            new ImeLogPattern
+            {
+                PatternId = "T-ALL", Category = "always", Enabled = true,
+                Pattern = @"marker (?<n>\d+)",
+                Action = "noop",
+                Parameters = new Dictionary<string, string>(),
+            },
+        };
+
+        /// <summary>A CMTrace line as a writer holding <paramref name="writerOffset"/> renders instant <paramref name="utcInstant"/>.</summary>
+        private static string Line(string message, DateTime utcInstant, TimeSpan writerOffset)
+        {
+            var local = utcInstant + writerOffset;
+            return $"<![LOG[{message}]LOG]!><time=\"{local:HH:mm:ss.fffffff}\" date=\"{local:M-d-yyyy}\" " +
+                   "component=\"X\" context=\"\" type=\"1\" thread=\"1\" file=\"\">";
+        }
+
+        private sealed class Harness : IDisposable
+        {
+            private readonly TempDirectory _tmp = new TempDirectory();
+            public ImeLogTracker Tracker { get; }
+            public DateTime Now { get; set; } = T0;
+
+            public Harness(string? stateDirectory = null)
+            {
+                Tracker = new ImeLogTracker(
+                    logFolder: _tmp.Path,
+                    patterns: Patterns(),
+                    logger: new AgentLogger(_tmp.Path, AgentLogLevel.Info),
+                    stateDirectory: stateDirectory);
+                Tracker.UtcNowProvider = () => Now;
+            }
+
+            public string PathOf(string fileName) => Path.Combine(_tmp.Path, fileName);
+
+            public void Append(string fileName, string line)
+                => File.AppendAllText(PathOf(fileName), line + Environment.NewLine);
+
+            public Task Pass() => Tracker.CheckLogFilesAsync(CancellationToken.None);
+
+            public void Dispose()
+            {
+                Tracker.Dispose();
+                _tmp.Dispose();
+            }
+        }
+
+        [Theory]
+        // The writer's belief. A fresh line must resolve to the instant it was written,
+        // WHATEVER that belief is — including agreement with this process (the majority case,
+        // which a fix to the agent's own zone cache would have broken).
+        [InlineData(2)]     // CEST
+        [InlineData(1)]     // BST
+        [InlineData(0)]     // UTC
+        [InlineData(-7)]    // PDT — the OOBE default behind the -9 h and -17 h field cases
+        [InlineData(10)]    // E. Australia
+        public async Task FreshLine_ResolvesToItsTrueInstant_ForAnyWriterBelief(int writerOffsetHours)
+        {
+            var writerOffset = TimeSpan.FromHours(writerOffsetHours);
+            using var h = new Harness();
+
+            // First sight: backlog, must not anchor.
+            h.Append("IntuneManagementExtension.log", Line("marker 1", h.Now, writerOffset));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            var writtenAt = h.Now.AddMilliseconds(-80);   // written just before the poll sees it
+            h.Append("IntuneManagementExtension.log", Line("marker 2", writtenAt, writerOffset));
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h.Tracker.LastMatchedSourceOffsetOrigin);
+            Assert.Equal(writtenAt, h.Tracker.LastMatchedLogTimestamp);
+            Assert.Equal(writerOffsetHours * 60, h.Tracker.LastMatchedSourceOffsetMinutes);
+        }
+
+        [Fact]
+        public async Task InterleavedEras_InOneGrowingPass_EachLineResolvesToItsOwnEra()
+        {
+            // The e9753578 file shape: two writer processes with different zone beliefs
+            // interleaved in ONE file. Any per-file offset gets one of them wrong by 9 h;
+            // per-line anchoring must get both right within the same chunk.
+            var pdt = TimeSpan.FromHours(-7);
+            var cest = TimeSpan.FromHours(2);
+            using var h = new Harness();
+
+            h.Append("AgentExecutor.log", Line("marker 1", h.Now, pdt));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            var wrotePdt = h.Now.AddMilliseconds(-90);
+            var wroteCest = h.Now.AddMilliseconds(-50);
+            h.Append("AgentExecutor.log", Line("marker 2", wrotePdt, pdt));
+            h.Append("AgentExecutor.log", Line("marker 3", wroteCest, cest));
+
+            var resolved = new List<(DateTime? Ts, CmTraceOffsetOrigin Origin, int? Offset)>();
+            Action<string> capture = _ => resolved.Add((
+                h.Tracker.LastMatchedLogTimestamp,
+                h.Tracker.LastMatchedSourceOffsetOrigin,
+                h.Tracker.LastMatchedSourceOffsetMinutes));
+            h.Tracker.OnPatternMatched += capture;
+            try
+            {
+                await h.Pass();
+            }
+            finally
+            {
+                h.Tracker.OnPatternMatched -= capture;
+            }
+
+            Assert.Equal(2, resolved.Count);
+            Assert.Equal(wrotePdt, resolved[0].Ts);
+            Assert.Equal(-420, resolved[0].Offset);
+            Assert.Equal(wroteCest, resolved[1].Ts);
+            Assert.Equal(120, resolved[1].Offset);
+            Assert.All(resolved, r => Assert.Equal(CmTraceOffsetOrigin.LineAnchored, r.Origin));
+        }
+
+        [Fact]
+        public async Task FirstSightBacklog_FallsBackToReaderZone()
+        {
+            using var h = new Harness();
+
+            h.Append("IntuneManagementExtension.log", Line("marker 1", h.Now.AddHours(-3), TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.None, h.Tracker.LastMatchedSourceOffsetOrigin);
+        }
+
+        [Fact]
+        public async Task FileFirstSeenEmpty_ItsFirstContentIsFresh()
+        {
+            // AgentExecutor.log in the field: the file APPEARS mid-enrollment. Seeing it empty
+            // (or not existing content-wise) counts as an observation, so its very first lines
+            // are provably written between passes and may anchor. This closes the warm-up gap
+            // for exactly the file whose eras flip the most.
+            using var h = new Harness();
+
+            File.WriteAllText(h.PathOf("AgentExecutor.log"), string.Empty);
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(5);
+            var writtenAt = h.Now.AddMilliseconds(-60);
+            h.Append("AgentExecutor.log", Line("marker 1", writtenAt, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h.Tracker.LastMatchedSourceOffsetOrigin);
+            Assert.Equal(writtenAt, h.Tracker.LastMatchedLogTimestamp);
+        }
+
+        [Fact]
+        public async Task PollGapBeyondFreshWindow_FallsBack()
+        {
+            // A stalled agent (GC, CPU starvation) re-polls after a long gap: the new bytes span
+            // the whole gap and their age is unbounded, so the pass must not anchor — even
+            // though most of its lines may in fact be recent. Conservative by design.
+            using var h = new Harness();
+
+            h.Append("IntuneManagementExtension.log", Line("marker 1", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+            h.Now = T0.AddSeconds(10);
+            h.Append("IntuneManagementExtension.log", Line("marker 2", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h.Tracker.LastMatchedSourceOffsetOrigin);
+
+            // Gap far beyond FreshLineMaxAge.
+            h.Now = h.Now + ImeLogTracker.FreshLineMaxAge + TimeSpan.FromSeconds(10);
+            h.Append("IntuneManagementExtension.log", Line("marker 3", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.None, h.Tracker.LastMatchedSourceOffsetOrigin);
+
+            // And the very next tight poll is fresh again.
+            h.Now = h.Now.AddSeconds(1);
+            h.Append("IntuneManagementExtension.log", Line("marker 4", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h.Tracker.LastMatchedSourceOffsetOrigin);
+        }
+
+        [Fact]
+        public async Task RestartWithRestoredBookmark_FirstPassIsBacklog_SecondPassAnchors()
+        {
+            // The persisted position bookmark survives a restart; the freshness guarantee must
+            // not — the first pass after a restart reads the downtime backlog, whose lines can
+            // be arbitrarily old.
+            using var stateDir = new TempDirectory();
+            using var h = new Harness(stateDirectory: stateDir.Path);
+
+            h.Append("IntuneManagementExtension.log", Line("marker 1", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+            h.Tracker.SaveStateForTest();
+
+            // "Restart": a second tracker over the same folder restores the bookmark.
+            using var h2 = new HarnessOver(h, stateDir.Path);
+            h2.Tracker.LoadStateForTest();
+
+            // Backlog written during the downtime — 30 min old, exactly on the offset grid,
+            // the nastiest possible backlog shape. Must NOT anchor.
+            h2.Now = T0.AddMinutes(30);
+            h2.Append(Line("marker 2", T0.AddSeconds(20), TimeSpan.FromHours(2)));
+            await h2.Pass();
+            Assert.Equal(CmTraceOffsetOrigin.None, h2.Tracker.LastMatchedSourceOffsetOrigin);
+
+            // The next tight poll is fresh again.
+            h2.Now = h2.Now.AddSeconds(1);
+            var writtenAt = h2.Now.AddMilliseconds(-70);
+            h2.Append(Line("marker 3", writtenAt, TimeSpan.FromHours(2)));
+            await h2.Pass();
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h2.Tracker.LastMatchedSourceOffsetOrigin);
+            Assert.Equal(writtenAt, h2.Tracker.LastMatchedLogTimestamp);
+        }
+
+        /// <summary>Second tracker over the FIRST harness's log folder — the "restarted agent".</summary>
+        private sealed class HarnessOver : IDisposable
+        {
+            private readonly string _logFolder;
+            public ImeLogTracker Tracker { get; }
+            public DateTime Now { get; set; }
+
+            public HarnessOver(Harness original, string stateDirectory)
+            {
+                _logFolder = Path.GetDirectoryName(original.PathOf("x"));
+                Tracker = new ImeLogTracker(
+                    logFolder: _logFolder,
+                    patterns: Patterns(),
+                    logger: new AgentLogger(_logFolder, AgentLogLevel.Info),
+                    stateDirectory: stateDirectory);
+                Tracker.UtcNowProvider = () => Now;
+            }
+
+            public void Append(string line)
+                => File.AppendAllText(Path.Combine(_logFolder, "IntuneManagementExtension.log"), line + Environment.NewLine);
+
+            public Task Pass() => Tracker.CheckLogFilesAsync(CancellationToken.None);
+
+            public void Dispose() => Tracker.Dispose();
+        }
+
+        [Fact]
+        public async Task FreshlyWrittenReplayLine_OnExactGridAge_ResolvesToRoughlyNow()
+        {
+            // Characterization of the one accepted edge: a line freshly WRITTEN but carrying a
+            // REPLAYED timestamp whose age is exactly a grid multiple (here 30 min) measures
+            // that age as an "offset" and resolves to ~now instead of its replayed past. The
+            // error is bounded by construction (an anchored line always lands at now ± 2 min),
+            // and sub-24h replays are treated as current by the historic-replay guard anyway.
+            using var h = new Harness();
+
+            h.Append("IntuneManagementExtension.log", Line("marker 1", h.Now, TimeSpan.Zero));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            var replayedInstant = h.Now.AddMinutes(-30);
+            h.Append("IntuneManagementExtension.log", Line("marker 2", replayedInstant, TimeSpan.Zero));
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h.Tracker.LastMatchedSourceOffsetOrigin);
+            Assert.NotNull(h.Tracker.LastMatchedLogTimestamp);
+            var error = (h.Tracker.LastMatchedLogTimestamp!.Value - h.Now).Duration();
+            Assert.True(error <= CmTraceOffsetCalibrator.MaxGridResidual,
+                $"anchored line must resolve to now ± residual, was off by {error}");
+        }
+
+        // =====================================================================
+        // The committed field fixture — session e9753578, ImeLogs/AgentExecutor.log.
+        // One file, two writer eras (PDT hour-05 / CEST hour-14), interleaved, flipping
+        // BOTH ways. Replayed here as the live tail the field agent saw: entry by entry,
+        // with the clock following the true write time.
+        // =====================================================================
+
+        private static string FixturePath()
+        {
+            var dir = AppContext.BaseDirectory;
+            for (int i = 0; i < 12; i++)
+            {
+                if (File.Exists(Path.Combine(dir, "AutopilotMonitor.sln")))
+                    return Path.Combine(dir, "tests", "fixtures", "cmtrace-logs",
+                        "agentexecutor-two-writer-eras-v1.cmtrace");
+                var parent = Directory.GetParent(dir)?.FullName;
+                if (parent == null || parent == dir) break;
+                dir = parent;
+            }
+            throw new DirectoryNotFoundException(
+                "Could not locate repo root (AutopilotMonitor.sln) walking up from " + AppContext.BaseDirectory);
+        }
+
+        /// <summary>Group the fixture's physical lines into complete CMTrace entries (multiline-safe).</summary>
+        private static List<string> FixtureEntries()
+        {
+            var entries = new List<string>();
+            string? pending = null;
+            foreach (var rawWithBom in File.ReadAllLines(FixturePath()))
+            {
+                // The fixture keeps the original file's BOM verbatim — it sat at the START of
+                // the real AgentExecutor.log, which is mid-file in this excerpt.
+                var raw = rawWithBom.TrimStart('');
+                if (pending == null)
+                {
+                    if (raw.Length == 0 || raw[0] == '#') continue;
+                    if (!raw.StartsWith("<![LOG[", StringComparison.Ordinal)) continue;
+                    if (raw.Contains("]LOG]!>")) { entries.Add(raw); continue; }
+                    pending = raw;
+                }
+                else
+                {
+                    pending += "\n" + raw;
+                    if (raw.Contains("]LOG]!>")) { entries.Add(pending!); pending = null; }
+                }
+            }
+            return entries;
+        }
+
+        [Fact]
+        public async Task TwoWriterEraFixture_EveryLineOfBothErasResolvesToItsTrueInstant()
+        {
+            // The committed fixture is a curated, verbatim excerpt of the transition window
+            // (commit policy: anonymized, versioned) — 20 entries covering both eras and the flip.
+            var entries = FixtureEntries();
+            Assert.True(entries.Count >= 15, $"fixture unexpectedly small: {entries.Count} entries");
+
+            using var h = new Harness();
+
+            // Match every fixture entry.
+            h.Tracker.CompilePatterns(new List<ImeLogPattern>
+            {
+                new ImeLogPattern
+                {
+                    PatternId = "T-ANY", Category = "always", Enabled = true,
+                    Pattern = ".+", Action = "noop",
+                    Parameters = new Dictionary<string, string>(),
+                },
+            });
+
+            // The file exists (empty) before its first content — first sight is the observation
+            // baseline, everything after is a fresh tail, exactly like the field.
+            File.WriteAllText(h.PathOf("AgentExecutor.log"), string.Empty);
+            h.Now = new DateTime(2026, 8, 20, 12, 13, 30, DateTimeKind.Utc);
+            await h.Pass();
+
+            var anchored = 0;
+            var resolvedList = new List<(DateTime Resolved, DateTime Expected)>();
+            Action<string> capture = _ =>
+            {
+                if (h.Tracker.LastMatchedSourceOffsetOrigin == CmTraceOffsetOrigin.LineAnchored)
+                    anchored++;
+                if (h.Tracker.LastMatchedLogTimestamp.HasValue && _expectedForCurrentEntry.HasValue)
+                    resolvedList.Add((h.Tracker.LastMatchedLogTimestamp.Value, _expectedForCurrentEntry.Value));
+            };
+            h.Tracker.OnPatternMatched += capture;
+            try
+            {
+                foreach (var entry in entries)
+                {
+                    CmTraceLogEntry? parsed;
+                    Assert.True(CmTraceLogParser.TryParseLine(entry, out parsed), "fixture entry did not parse");
+
+                    // Era by local hour: the fixture holds exactly two eras — PDT (UTC-7) lines
+                    // render at local hour 05, CEST (UTC+2) lines at hour 14 (fixture header).
+                    var eraOffset = parsed.LocalTimestamp.Hour == 14
+                        ? TimeSpan.FromHours(2)
+                        : TimeSpan.FromHours(-7);
+                    var trueUtc = DateTime.SpecifyKind(parsed.LocalTimestamp - eraOffset, DateTimeKind.Utc);
+
+                    // The clock follows the write; never move backwards (interleaved eras are
+                    // written in true-UTC order, but guard against sub-ms jitter).
+                    var readAt = trueUtc.AddMilliseconds(120);
+                    if (readAt > h.Now) h.Now = readAt;
+
+                    // In production the 100 ms poll keeps running through write silences — every
+                    // empty look refreshes the freshness window. The fixture's transition window
+                    // spans multi-minute write gaps, so replay that cadence with one empty poll
+                    // just before each append; without it the NEXT pass would (correctly!)
+                    // classify the gap as a stall and refuse to anchor.
+                    h.Now = h.Now.AddMilliseconds(-100);
+                    await h.Pass();
+                    h.Now = readAt;
+
+                    _expectedForCurrentEntry = trueUtc;
+                    File.AppendAllText(h.PathOf("AgentExecutor.log"), entry + Environment.NewLine);
+                    await h.Pass();
+                    _expectedForCurrentEntry = null;
+                }
+            }
+            finally
+            {
+                h.Tracker.OnPatternMatched -= capture;
+            }
+
+            // Every matched entry resolved to the instant its writer rendered — across BOTH
+            // eras, including the flips. This is the exact property whose absence produced the
+            // -9 h script durations.
+            Assert.Equal(entries.Count, resolvedList.Count);
+            Assert.All(resolvedList, r => Assert.Equal(r.Expected, r.Resolved));
+            Assert.True(anchored == resolvedList.Count,
+                $"expected every entry line-anchored, got {anchored}/{resolvedList.Count}");
+
+            // Both eras genuinely exercised: PDT entries render at local hour 05, CEST at 14.
+            Assert.Contains(resolvedList, r => (r.Expected + TimeSpan.FromHours(-7)).Hour == 5);
+            Assert.Contains(resolvedList, r => (r.Expected + TimeSpan.FromHours(2)).Hour == 14);
+        }
+
+        private DateTime? _expectedForCurrentEntry;
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/ImeLogTrackerOffsetCalibrationTests.cs

@@ -0,0 +1,275 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime;
+using AutopilotMonitor.Agent.V2.Core.Tests.Harness;
+using AutopilotMonitor.Shared.Models;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
+{
+    /// <summary>
+    /// End-to-end offset calibration through a real read cycle.
+    ///
+    /// <para>
+    /// A CMTrace line states local time and nothing else, so its UTC value depends on which zone
+    /// the WRITING process believed it was in. The tracker used to substitute its own belief,
+    /// which is right only when the two happen to agree.
+    /// </para>
+    ///
+    /// <para>
+    /// These tests are deliberately independent of the machine they run on: the assertion is
+    /// always "a line written at instant T resolves to T", for every writer belief. That single
+    /// property covers both field cases at once — the writer disagreeing with us (the bug) and
+    /// the writer agreeing with us (the majority, which a naive fix would have broken).
+    /// </para>
+    /// </summary>
+    public sealed class ImeLogTrackerOffsetCalibrationTests
+    {
+        private const string LogFileName = "IntuneManagementExtension.log";
+        private static readonly DateTime T0 = new DateTime(2026, 8, 20, 7, 30, 0, DateTimeKind.Utc);
+
+        private static List<ImeLogPattern> Patterns() => new List<ImeLogPattern>
+        {
+            new ImeLogPattern
+            {
+                PatternId = "T-MARK", Category = "always", Enabled = true,
+                Pattern = @"marker (?<n>\d+)",
+                Action = "noop",
+                Parameters = new Dictionary<string, string>(),
+            },
+        };
+
+        /// <summary>A CMTrace line as a writer holding <paramref name="writerOffset"/> renders instant <paramref name="utcInstant"/>.</summary>
+        private static string Line(string message, DateTime utcInstant, TimeSpan writerOffset)
+        {
+            var local = utcInstant + writerOffset;
+            return $"<![LOG[{message}]LOG]!><time=\"{local:HH:mm:ss.fffffff}\" date=\"{local:M-d-yyyy}\" " +
+                   "component=\"IntuneManagementExtension\" context=\"\" type=\"1\" thread=\"1\" file=\"\">";
+        }
+
+        private sealed class Harness : IDisposable
+        {
+            private readonly TempDirectory _tmp = new TempDirectory();
+            public ImeLogTracker Tracker { get; }
+            public DateTime Now { get; set; } = T0;
+
+            public Harness()
+            {
+                Tracker = new ImeLogTracker(
+                    logFolder: _tmp.Path,
+                    patterns: Patterns(),
+                    logger: new AgentLogger(_tmp.Path, AgentLogLevel.Info));
+                Tracker.UtcNowProvider = () => Now;
+            }
+
+            public string LogPath => Path.Combine(_tmp.Path, LogFileName);
+
+            public void Append(string line) => File.AppendAllText(LogPath, line + Environment.NewLine);
+
+            public Task Pass() => Tracker.CheckLogFilesAsync(CancellationToken.None);
+
+            public void Dispose()
+            {
+                Tracker.Dispose();
+                _tmp.Dispose();
+            }
+        }
+
+        [Theory]
+        // The writer's belief. The MEASUREMENT must recover it exactly, whatever it is.
+        [InlineData(2)]     // CEST
+        [InlineData(1)]     // BST
+        [InlineData(-7)]    // PDT — the OOBE default behind the -17 h and -9 h field cases
+        [InlineData(10)]    // E. Australia
+        [InlineData(0)]     // UTC
+        public async Task MeasuresTheWritersOffsetExactly_ForAnyBelief(int writerOffsetHours)
+        {
+            // NOTE: the per-FILE measurement asserted here is OBSERVATIONAL — its application was
+            // reverted on 2026-08-20 (04b1a7c6) because one offset per file is wrong when a file
+            // holds interleaved writer eras. Resolution now anchors per LINE instead (see
+            // ImeLogTrackerLineAnchoringTests, which restores the "a line written at T resolves
+            // to T" property era-safely). The per-file measurement stays for the Info log and
+            // measuredWriterOffsetMinutes provenance.
+            var writerOffset = TimeSpan.FromHours(writerOffsetHours);
+            using var h = new Harness();
+
+            h.Append(Line("marker 1", h.Now, writerOffset));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            h.Append(Line("marker 2", h.Now, writerOffset));
+            await h.Pass();
+
+            TimeSpan measured;
+            Assert.True(h.Tracker.OffsetCalibrator.TryGetOffset(LogFileName, out measured));
+            Assert.Equal(writerOffset, measured);
+        }
+
+        [Fact]
+        public async Task MeasuresTheWritersOffset_NotItsOwn()
+        {
+            using var h = new Harness();
+            var writerOffset = TimeSpan.FromHours(2);
+
+            h.Append(Line("marker 1", h.Now, writerOffset));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            h.Append(Line("marker 2", h.Now, writerOffset));
+            await h.Pass();
+
+            TimeSpan measured;
+            Assert.True(h.Tracker.OffsetCalibrator.TryGetOffset(LogFileName, out measured));
+            Assert.Equal(writerOffset, measured);
+        }
+
+        [Fact]
+        public async Task DoesNotCalibrateOnFirstSightOfAFile()
+        {
+            // The first pass reads from position 0, so the newest line in the file may be hours
+            // old. Anchoring on it would measure the line's age instead of the writer's offset.
+            using var h = new Harness();
+
+            h.Append(Line("marker 1", T0.AddHours(-3), TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            TimeSpan ignored;
+            Assert.False(h.Tracker.OffsetCalibrator.TryGetOffset(LogFileName, out ignored));
+        }
+
+        [Fact]
+        public async Task FollowsTheWriterAcrossARestartIntoANewZone()
+        {
+            // IME restarts mid-enrollment and picks up the timezone the OS moved to. The
+            // measurement has to follow, otherwise every later line is off by the difference.
+            using var h = new Harness();
+
+            h.Append(Line("marker 1", h.Now, TimeSpan.FromHours(1)));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            h.Append(Line("marker 2", h.Now, TimeSpan.FromHours(1)));
+            await h.Pass();
+
+            TimeSpan before;
+            Assert.True(h.Tracker.OffsetCalibrator.TryGetOffset(LogFileName, out before));
+            Assert.Equal(TimeSpan.FromHours(1), before);
+
+            // Writer restarts, now on +2.
+            h.Now = T0.AddSeconds(20);
+            h.Append(Line("marker 3", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(30);
+            var writtenAt = h.Now;
+            h.Append(Line("marker 4", writtenAt, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            TimeSpan after;
+            Assert.True(h.Tracker.OffsetCalibrator.TryGetOffset(LogFileName, out after));
+            Assert.Equal(TimeSpan.FromHours(2), after);
+            // The measurement follows the restart. Applying it is what the 2026-08-20 revert
+            // removed — that is exactly the case a file with two writer eras breaks.
+            Assert.Equal(120, h.Tracker.LastMatchedMeasuredWriterOffsetMinutes);
+        }
+
+        [Fact]
+        public async Task HonorsAWriterDeclaredBiasWithoutMeasuring()
+        {
+            // A line carrying its own bias states the offset outright; it must be used as-is and
+            // must never become a calibration anchor.
+            using var h = new Harness();
+
+            h.Append(Line("marker 1", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            var writtenAt = h.Now;
+            var local = writtenAt + TimeSpan.FromHours(-8);        // a PST writer
+            h.Append($"<![LOG[marker 2]LOG]!><time=\"{local:HH:mm:ss.fffffff}+480\" date=\"{local:M-d-yyyy}\" " +
+                     "component=\"IntuneManagementExtension\" context=\"\" type=\"1\" thread=\"1\" file=\"\">");
+            await h.Pass();
+
+            Assert.True(h.Tracker.LastMatchedLogTimestamp.HasValue);
+            Assert.Equal(writtenAt, h.Tracker.LastMatchedLogTimestamp.Value);
+
+            TimeSpan ignored;
+            Assert.False(h.Tracker.OffsetCalibrator.TryGetOffset(LogFileName, out ignored));
+        }
+
+        [Fact]
+        public async Task RecordsMeasuredOffsetSeparatelyFromTheAppliedOne()
+        {
+            // The regression that forced the revert shipped an event tagged "calibrated" while
+            // carrying an offset that did not hold for that line. Measured and applied are now
+            // separate fields so a future reader cannot mistake one for the other.
+            using var h = new Harness();
+            var writerOffset = TimeSpan.FromHours(-7);   // PDT, the OOBE default
+
+            h.Append(Line("marker 1", h.Now, writerOffset));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            h.Append(Line("marker 2", h.Now, writerOffset));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(20);
+            h.Append(Line("marker 3", h.Now, writerOffset));
+            await h.Pass();
+
+            // Measured: the writer's actual belief, per file.
+            Assert.Equal(-420, h.Tracker.LastMatchedMeasuredWriterOffsetMinutes);
+
+            // Applied: the line's OWN anchor (fresh pass), never the per-file "calibrated" value —
+            // the two must stay distinguishable even when they agree numerically.
+            Assert.Equal(CmTraceOffsetOrigin.LineAnchored, h.Tracker.LastMatchedSourceOffsetOrigin);
+            Assert.NotEqual(CmTraceOffsetOrigin.Calibrated, h.Tracker.LastMatchedSourceOffsetOrigin);
+        }
+
+        [Fact]
+        public async Task RecordsProvenance_AsFallback_BeforeAnyCalibration()
+        {
+            // The warm-up pass: the offset is not measured yet, so the reader zone is assumed and
+            // the event has to say so rather than look source-grounded.
+            using var h = new Harness();
+
+            h.Append(Line("marker 1", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.None, h.Tracker.LastMatchedSourceOffsetOrigin);
+            Assert.True(h.Tracker.LastMatchedSourceLocalTimestamp.HasValue);
+
+            // The APPLIED offset is reported even on the fallback path — an event that states no
+            // offset at all cannot be recomputed later, which defeats the purpose of recording
+            // provenance. Asserted against the running machine's zone so this stays portable.
+            var readerZone = (int)TimeZoneInfo.Local
+                .GetUtcOffset(h.Tracker.LastMatchedSourceLocalTimestamp!.Value).TotalMinutes;
+            Assert.Equal(readerZone, h.Tracker.LastMatchedSourceOffsetMinutes);
+        }
+
+        [Fact]
+        public async Task RecordsProvenance_ForADeclaredBias()
+        {
+            using var h = new Harness();
+
+            h.Append(Line("marker 1", h.Now, TimeSpan.FromHours(2)));
+            await h.Pass();
+
+            h.Now = T0.AddSeconds(10);
+            var local = h.Now + TimeSpan.FromHours(-8);
+            h.Append($"<![LOG[marker 2]LOG]!><time=\"{local:HH:mm:ss.fffffff}+480\" date=\"{local:M-d-yyyy}\" " +
+                     "component=\"IntuneManagementExtension\" context=\"\" type=\"1\" thread=\"1\" file=\"\">");
+            await h.Pass();
+
+            Assert.Equal(CmTraceOffsetOrigin.Bias, h.Tracker.LastMatchedSourceOffsetOrigin);
+            // Reported in the same sense as a measured offset (local = UTC + offset), so the two
+            // origins are directly comparable; the wire bias uses the opposite convention.
+            Assert.Equal(-480, h.Tracker.LastMatchedSourceOffsetMinutes);
+        }
+
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/SystemSignals/PowerStateTransitionTrackerTests.cs

@@ -0,0 +1,258 @@
+#nullable enable
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals;
+using AutopilotMonitor.Agent.V2.Core.Runtime;
+using AutopilotMonitor.Shared.Models;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.SystemSignals
+{
+    /// <summary>
+    /// Pure state machine behind the power watcher: AC↔battery edges, the 50/30/15 threshold
+    /// ladder (latch once per lifetime, lowest-crossed-only on multi-level jumps, baseline
+    /// coverage for sessions starting low), null-percent tolerance and the storm cap.
+    /// </summary>
+    public sealed class PowerStateTransitionTrackerTests
+    {
+        private static PowerStateResult Ac(int? percent = 80, bool charging = true) => new PowerStateResult
+        {
+            OnAcPower = true,
+            HasBattery = true,
+            BatteryPercent = percent,
+            IsCharging = charging,
+            BatteryLifeMinutes = null,
+        };
+
+        private static PowerStateResult Battery(int? percent, int? lifeMinutes = 90) => new PowerStateResult
+        {
+            OnAcPower = false,
+            HasBattery = true,
+            BatteryPercent = percent,
+            IsCharging = false,
+            BatteryLifeMinutes = lifeMinutes,
+        };
+
+        [Fact]
+        public void Baseline_on_ac_is_silent()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            Assert.Empty(tracker.Baseline(Ac()));
+        }
+
+        [Fact]
+        public void Baseline_without_battery_or_with_probe_error_is_silent()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            Assert.Empty(tracker.Baseline(new PowerStateResult { OnAcPower = true, HasBattery = false }));
+            Assert.Empty(tracker.Baseline(new PowerStateResult { ProbeError = "boom" }));
+        }
+
+        [Fact]
+        public void Baseline_on_battery_above_ladder_is_silent()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            Assert.Empty(tracker.Baseline(Battery(80)));
+        }
+
+        [Fact]
+        public void Baseline_at_12_percent_emits_exactly_the_15_threshold()
+        {
+            var tracker = new PowerStateTransitionTracker();
+
+            var emissions = tracker.Baseline(Battery(12));
+
+            var e = Assert.Single(emissions);
+            Assert.Equal(PowerStateTransitionTracker.TransitionThresholdCrossed, e.Transition);
+            Assert.Equal(15, e.ThresholdPercent);
+            Assert.Equal(12, e.BatteryPercent);
+            Assert.Equal(EventSeverity.Error, e.Severity);
+            Assert.True(e.ImmediateUpload);
+        }
+
+        [Fact]
+        public void Baseline_at_25_percent_emits_30_and_latches_50()
+        {
+            var tracker = new PowerStateTransitionTracker();
+
+            var baseline = tracker.Baseline(Battery(25));
+            var e = Assert.Single(baseline);
+            Assert.Equal(30, e.ThresholdPercent);
+            Assert.Equal(EventSeverity.Warning, e.Severity);
+            Assert.True(e.ImmediateUpload);
+
+            // 50 and 30 are latched by the baseline; draining to 40% stays silent, 14% emits 15.
+            Assert.Empty(tracker.Evaluate(Battery(40)));
+            var next = Assert.Single(tracker.Evaluate(Battery(14)));
+            Assert.Equal(15, next.ThresholdPercent);
+        }
+
+        [Fact]
+        public void Ac_to_battery_emits_warning_with_immediate_upload()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Ac(63));
+
+            var e = Assert.Single(tracker.Evaluate(Battery(63)));
+
+            Assert.Equal(PowerStateTransitionTracker.TransitionAcToBattery, e.Transition);
+            Assert.Null(e.ThresholdPercent);
+            Assert.Equal(EventSeverity.Warning, e.Severity);
+            Assert.True(e.ImmediateUpload);
+            Assert.False(e.OnAcPower);
+            Assert.Equal(63, e.BatteryPercent);
+        }
+
+        [Fact]
+        public void Battery_to_ac_emits_info_without_immediate_upload()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Battery(70));
+
+            var e = Assert.Single(tracker.Evaluate(Ac(70)));
+
+            Assert.Equal(PowerStateTransitionTracker.TransitionBatteryToAc, e.Transition);
+            Assert.Equal(EventSeverity.Info, e.Severity);
+            Assert.False(e.ImmediateUpload);
+        }
+
+        [Fact]
+        public void No_diff_stays_silent()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Ac());
+
+            Assert.Empty(tracker.Evaluate(Ac()));
+            Assert.Empty(tracker.Evaluate(Ac(79)));
+        }
+
+        [Fact]
+        public void Unplug_below_threshold_emits_transition_and_threshold_together()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Ac(10));
+
+            var emissions = tracker.Evaluate(Battery(10));
+
+            Assert.Equal(2, emissions.Count);
+            Assert.Equal(PowerStateTransitionTracker.TransitionAcToBattery, emissions[0].Transition);
+            Assert.Equal(PowerStateTransitionTracker.TransitionThresholdCrossed, emissions[1].Transition);
+            Assert.Equal(15, emissions[1].ThresholdPercent);
+        }
+
+        [Fact]
+        public void Multi_level_drop_emits_lowest_crossed_level_only()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Battery(60));
+
+            var e = Assert.Single(tracker.Evaluate(Battery(10)));
+
+            Assert.Equal(15, e.ThresholdPercent);
+            // All levels are latched — recovering and re-draining emits nothing more.
+            tracker.Evaluate(Ac(90));
+            Assert.Single(tracker.Evaluate(Battery(45)), x => x.Transition == PowerStateTransitionTracker.TransitionAcToBattery);
+            Assert.Empty(tracker.Evaluate(Battery(13)));
+        }
+
+        [Fact]
+        public void Each_level_latches_once_per_lifetime()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Battery(70));
+
+            Assert.Single(tracker.Evaluate(Battery(48))); // 50
+            Assert.Empty(tracker.Evaluate(Battery(47)));  // still inside 50, no re-emit
+            Assert.Single(tracker.Evaluate(Battery(29))); // 30
+            Assert.Single(tracker.Evaluate(Battery(15))); // 15 (boundary: <= level)
+            Assert.Empty(tracker.Evaluate(Battery(5)));   // ladder exhausted
+        }
+
+        [Fact]
+        public void Threshold_severity_ladder_is_info_warning_error()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Battery(70));
+
+            var fifty = Assert.Single(tracker.Evaluate(Battery(50)));
+            Assert.Equal(EventSeverity.Info, fifty.Severity);
+            Assert.False(fifty.ImmediateUpload);
+
+            var thirty = Assert.Single(tracker.Evaluate(Battery(30)));
+            Assert.Equal(EventSeverity.Warning, thirty.Severity);
+            Assert.True(thirty.ImmediateUpload);
+
+            var fifteen = Assert.Single(tracker.Evaluate(Battery(15)));
+            Assert.Equal(EventSeverity.Error, fifteen.Severity);
+            Assert.True(fifteen.ImmediateUpload);
+        }
+
+        [Fact]
+        public void Null_battery_percent_skips_thresholds_but_ac_diff_still_works()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Ac(null));
+
+            var e = Assert.Single(tracker.Evaluate(Battery(null, lifeMinutes: null)));
+
+            Assert.Equal(PowerStateTransitionTracker.TransitionAcToBattery, e.Transition);
+            Assert.Null(e.BatteryPercent);
+            Assert.Contains("battery level unknown", e.Message);
+            Assert.Empty(tracker.Evaluate(Battery(null, lifeMinutes: null)));
+        }
+
+        [Fact]
+        public void Probe_error_mid_run_preserves_state()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Ac());
+
+            Assert.Empty(tracker.Evaluate(new PowerStateResult { ProbeError = "transient" }));
+            // State was not corrupted by the error — the real transition still diffs cleanly.
+            Assert.Single(tracker.Evaluate(Battery(60)));
+        }
+
+        [Fact]
+        public void Evaluate_without_baseline_latches_like_a_baseline()
+        {
+            var tracker = new PowerStateTransitionTracker();
+
+            var e = Assert.Single(tracker.Evaluate(Battery(12)));
+
+            // No phantom ac_to_battery from the implicit default state — only the threshold.
+            Assert.Equal(PowerStateTransitionTracker.TransitionThresholdCrossed, e.Transition);
+        }
+
+        [Fact]
+        public void Emission_cap_suppresses_and_flips_flag_once()
+        {
+            var tracker = new PowerStateTransitionTracker(maxEmissions: 4);
+            tracker.Baseline(Ac());
+
+            // Flapping power source: each edge is one emission.
+            for (var i = 0; i < 2; i++)
+            {
+                Assert.Single(tracker.Evaluate(Battery(80)));
+                Assert.Single(tracker.Evaluate(Ac(80)));
+            }
+            Assert.False(tracker.EmissionCapReached);
+
+            Assert.Empty(tracker.Evaluate(Battery(80)));
+            Assert.True(tracker.EmissionCapReached);
+            Assert.Empty(tracker.Evaluate(Ac(80)));
+        }
+
+        [Fact]
+        public void Message_carries_percent_and_transition_context()
+        {
+            var tracker = new PowerStateTransitionTracker();
+            tracker.Baseline(Ac(62));
+
+            var toBattery = Assert.Single(tracker.Evaluate(Battery(62)));
+            Assert.Contains("AC to battery", toBattery.Message);
+            Assert.Contains("battery 62%", toBattery.Message);
+
+            var backToAc = Assert.Single(tracker.Evaluate(Ac(63)));
+            Assert.Contains("back to AC", backToAc.Message);
+            Assert.Contains("charging", backToAc.Message);
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/SystemSignals/SystemTimelineTrackerTests.cs

@@ -0,0 +1,429 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals;
+using AutopilotMonitor.Agent.V2.Core.Orchestration;
+using AutopilotMonitor.Agent.V2.Core.Tests.Harness;
+using AutopilotMonitor.Agent.V2.Core.Tests.Orchestration;
+using AutopilotMonitor.DecisionCore.Engine;
+using AutopilotMonitor.DecisionCore.Signals;
+using AutopilotMonitor.Shared;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.SystemSignals
+{
+    /// <summary>
+    /// SystemTimelineTracker — clock steps (Kernel-General 1) and completed sleep episodes
+    /// (Power-Troubleshooter 1 / Kernel-Power 507) from the System channel. Drives the primitive
+    /// <see cref="SystemTimelineTracker.ProcessEvent"/> test seam (no real EventRecord, which is
+    /// abstract + Windows-only), mirroring the WindowsUpdateTracker test pattern.
+    /// </summary>
+    public sealed class SystemTimelineTrackerTests : IDisposable
+    {
+        private static readonly DateTime At = new DateTime(2026, 8, 21, 10, 0, 0, DateTimeKind.Utc);
+
+        private readonly TempDirectory _tmp = new TempDirectory();
+        private readonly FakeSignalIngressSink _sink;
+        private readonly SystemTimelineTracker _tracker;
+        private long _nextRecordId = 1;
+
+        public SystemTimelineTrackerTests()
+        {
+            _sink = new FakeSignalIngressSink();
+            var post = new InformationalEventPost(_sink, new VirtualClock(At));
+            var logger = new AgentLogger(_tmp.Path, AgentLogLevel.Info);
+            _tracker = new SystemTimelineTracker(
+                sessionId: "sess-stl",
+                tenantId: "tenant-stl",
+                post: post,
+                logger: logger,
+                backfillEnabled: false,
+                stateDirectory: null); // in-memory dedup for most tests
+        }
+
+        public void Dispose() => _tmp.Dispose();
+
+        // -------------------------------------------------------------------
+        // Emission helpers
+        // -------------------------------------------------------------------
+
+        private void EmitClockChange(
+            DateTime? oldTime, DateTime? newTime, string? rawDeltaMs = null,
+            int reason = 1, long? recordId = null, bool isBackfill = false, DateTime? timeCreatedUtc = null)
+        {
+            var data = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            if (oldTime.HasValue) data["OldTime"] = oldTime.Value.ToString("o");
+            if (newTime.HasValue) data["NewTime"] = newTime.Value.ToString("o");
+            if (rawDeltaMs != null) data["TimeDeltaInMs"] = rawDeltaMs;
+            data["Reason"] = reason.ToString();
+            data["ProcessName"] = @"\Device\HarddiskVolume3\Windows\System32\svchost.exe";
+            data["ProcessID"] = "6892";
+
+            _tracker.ProcessEvent(
+                providerName: SystemTimelineTracker.ProviderKernelGeneral,
+                eventId: SystemTimelineTracker.EventId_ClockChange,
+                recordId: recordId ?? _nextRecordId++,
+                timeCreatedUtc: timeCreatedUtc ?? At,
+                eventData: data,
+                isBackfill: isBackfill);
+        }
+
+        private void EmitClassicResume(
+            DateTime sleepTime, DateTime wakeTime, string? effectiveState = "1",
+            string? wakeSourceText = null, long? recordId = null, bool isBackfill = false, DateTime? timeCreatedUtc = null)
+        {
+            var data = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+            {
+                ["SleepTime"] = sleepTime.ToString("o"),
+                ["WakeTime"] = wakeTime.ToString("o"),
+                ["WakeSourceType"] = "0",
+            };
+            if (effectiveState != null) data["EffectiveState"] = effectiveState;
+            if (wakeSourceText != null) data["WakeSourceText"] = wakeSourceText;
+
+            _tracker.ProcessEvent(
+                providerName: SystemTimelineTracker.ProviderPowerTroubleshooter,
+                eventId: SystemTimelineTracker.EventId_ClassicResume,
+                recordId: recordId ?? _nextRecordId++,
+                timeCreatedUtc: timeCreatedUtc ?? wakeTime,
+                eventData: data,
+                isBackfill: isBackfill);
+        }
+
+        private void EmitModernStandbyExit(
+            long sleepDurationUs, long durationUs, string powerStateAc = "true",
+            long? recordId = null, bool isBackfill = false, DateTime? timeCreatedUtc = null)
+        {
+            var data = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+            {
+                ["SleepDurationInUs"] = sleepDurationUs.ToString(),
+                ["DurationInUs"] = durationUs.ToString(),
+                ["Reason"] = "32",
+                ["PowerStateAc"] = powerStateAc,
+                ["BatteryRemainingCapacityOnExit"] = "34180",
+            };
+
+            _tracker.ProcessEvent(
+                providerName: SystemTimelineTracker.ProviderKernelPower,
+                eventId: SystemTimelineTracker.EventId_ModernStandbyExit,
+                recordId: recordId ?? _nextRecordId++,
+                timeCreatedUtc: timeCreatedUtc ?? At,
+                eventData: data,
+                isBackfill: isBackfill);
+        }
+
+        private IReadOnlyList<FakeSignalIngressSink.PostedSignal> ByType(string eventType) =>
+            _sink.Posted.Where(p =>
+                p.Kind == DecisionSignalKind.InformationalEvent
+                && p.Payload != null
+                && p.Payload.TryGetValue(SignalPayloadKeys.EventType, out var et)
+                && et == eventType).ToList();
+
+        private static IReadOnlyDictionary<string, object> Data(FakeSignalIngressSink.PostedSignal s) =>
+            (IReadOnlyDictionary<string, object>)s.TypedPayload!;
+
+        // -------------------------------------------------------------------
+        // system_clock_changed
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void ClockStep_AboveThreshold_EmitsInfo_WithSignedDeltaAndNormalizedTimes()
+        {
+            var oldTime = At;
+            var newTime = At.AddSeconds(10);
+            EmitClockChange(oldTime, newTime, reason: 1);
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemClockChanged));
+            Assert.Equal("Info", s.Payload![SignalPayloadKeys.Severity]);
+            Assert.Equal("false", s.Payload![SignalPayloadKeys.ImmediateUpload]);
+
+            var data = Data(s);
+            Assert.Equal(10_000L, data["timeDeltaMs"]);
+            Assert.Equal("application_set", data["reasonText"]);
+            Assert.Equal(1, data["reason"]);
+            Assert.Equal(oldTime.ToString("o"), data["oldTime"]);
+            Assert.Equal(newTime.ToString("o"), data["newTime"]);
+            Assert.Equal(6892, data["processId"]);
+            Assert.Contains("forward", (string)s.Payload![SignalPayloadKeys.Message]);
+            Assert.Contains("svchost.exe", (string)s.Payload![SignalPayloadKeys.Message]);
+        }
+
+        [Theory]
+        [InlineData(1)]
+        [InlineData(1999)]
+        public void ClockMicroStep_BelowThreshold_Suppressed(int deltaMs)
+        {
+            EmitClockChange(At, At.AddMilliseconds(deltaMs));
+            Assert.Empty(ByType(Constants.EventTypes.SystemClockChanged));
+        }
+
+        [Fact]
+        public void ClockStep_Backward_EmitsNegativeDelta()
+        {
+            EmitClockChange(oldTime: At, newTime: At.AddSeconds(-3));
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemClockChanged));
+            Assert.Equal(-3000L, Data(s)["timeDeltaMs"]);
+            Assert.Contains("backward", (string)s.Payload![SignalPayloadKeys.Message]);
+        }
+
+        [Fact]
+        public void ClockStep_AtLeastFiveMinutes_WarningAndImmediateUpload()
+        {
+            EmitClockChange(At, At.AddMinutes(5), reason: 2);
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemClockChanged));
+            Assert.Equal("Warning", s.Payload![SignalPayloadKeys.Severity]);
+            Assert.Equal("true", s.Payload![SignalPayloadKeys.ImmediateUpload]);
+            Assert.Equal("hardware_clock_sync", Data(s)["reasonText"]);
+        }
+
+        [Fact]
+        public void ClockStep_NoUsableTimesOrDelta_Skipped()
+        {
+            EmitClockChange(oldTime: null, newTime: null, rawDeltaMs: "not-a-number");
+            Assert.Empty(ByType(Constants.EventTypes.SystemClockChanged));
+        }
+
+        [Fact]
+        public void ClockStep_FallsBackToTimeDeltaInMs_WhenTimesUnparseable()
+        {
+            // Only the raw delta parses — the direction information of NewTime/OldTime is gone,
+            // but the magnitude still gates and emits.
+            EmitClockChange(oldTime: null, newTime: null, rawDeltaMs: "7200000");
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemClockChanged));
+            Assert.Equal(7_200_000L, Data(s)["timeDeltaMs"]);
+        }
+
+        // -------------------------------------------------------------------
+        // system_sleep_episode — classic (Power-Troubleshooter 1)
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void ClassicResume_EffectiveState5_EmitsHibernateEpisode()
+        {
+            var sleepAt = At.AddHours(-2);
+            EmitClassicResume(sleepAt, At, effectiveState: "5", wakeSourceText: "Power Button");
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemSleepEpisode));
+            Assert.Equal("Info", s.Payload![SignalPayloadKeys.Severity]);
+
+            var data = Data(s);
+            Assert.Equal("hibernate", data["kind"]);
+            Assert.Equal(7200L, data["durationSeconds"]);
+            Assert.Equal(sleepAt.ToString("o"), data["enteredAt"]);
+            Assert.Equal(At.ToString("o"), data["exitedAt"]);
+            Assert.Equal("Power Button", data["wakeSourceText"]);
+            Assert.Contains("hibernate", (string)s.Payload![SignalPayloadKeys.Message]);
+        }
+
+        [Fact]
+        public void ClassicResume_NonHibernateState_EmitsSleepKind()
+        {
+            EmitClassicResume(At.AddMinutes(-30), At, effectiveState: "4");
+            Assert.Equal("sleep", Data(Assert.Single(ByType(Constants.EventTypes.SystemSleepEpisode)))["kind"]);
+        }
+
+        [Fact]
+        public void ClassicResume_ShortEpisode_StillEmits()
+        {
+            // No duration floor for classic sleep: the event only exists for genuinely completed
+            // S3/S4 transitions, so a 30 s real sleep is still signal.
+            EmitClassicResume(At.AddSeconds(-30), At);
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemSleepEpisode));
+            Assert.Equal(30L, Data(s)["durationSeconds"]);
+        }
+
+        // -------------------------------------------------------------------
+        // system_sleep_episode — Modern Standby (Kernel-Power 507)
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void ModernStandbyExit_EmitsEpisode_WithDerivedEnterTime()
+        {
+            // Values from a live 507 on this dev machine: 38 min scenario, ~38 min actual sleep.
+            EmitModernStandbyExit(sleepDurationUs: 2_324_095_807, durationUs: 2_330_201_652);
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemSleepEpisode));
+            var data = Data(s);
+            Assert.Equal("modern_standby", data["kind"]);
+            Assert.Equal(2330L, data["durationSeconds"]);
+            Assert.Equal(2324L, data["sleepDurationSeconds"]);
+            Assert.Equal(true, data["onAcPower"]);
+            Assert.Equal(34180L, data["batteryRemainingCapacityOnExit"]);
+            Assert.Equal(At.ToString("o"), data["exitedAt"]);
+            Assert.Equal(At.AddMilliseconds(-2_330_201.652).ToString("o"), data["enteredAt"]);
+            Assert.Contains("Modern Standby", (string)s.Payload![SignalPayloadKeys.Message]);
+        }
+
+        [Fact]
+        public void ModernStandbyExit_SleepBelowFloor_Suppressed()
+        {
+            EmitModernStandbyExit(sleepDurationUs: 30_000_000, durationUs: 90_000_000); // 30 s sleep
+            Assert.Empty(ByType(Constants.EventTypes.SystemSleepEpisode));
+        }
+
+        [Fact]
+        public void ModernStandbyExit_ScreenOffWithoutSleep_Suppressed()
+        {
+            // SleepEntered=false scenarios carry SleepDurationInUs 0 — the single duration gate
+            // suppresses them without a separate branch.
+            EmitModernStandbyExit(sleepDurationUs: 0, durationUs: 6_106_696);
+            Assert.Empty(ByType(Constants.EventTypes.SystemSleepEpisode));
+        }
+
+        [Fact]
+        public void ModernStandbyExit_ScenarioShorterThanSleep_ClampsToSleepDuration()
+        {
+            EmitModernStandbyExit(sleepDurationUs: 120_000_000, durationUs: 0);
+
+            var data = Data(Assert.Single(ByType(Constants.EventTypes.SystemSleepEpisode)));
+            Assert.Equal(120L, data["durationSeconds"]);
+            Assert.Equal(120L, data["sleepDurationSeconds"]);
+        }
+
+        // -------------------------------------------------------------------
+        // Backfill semantics
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void BackfilledEvent_UsesEventTimeForTimelineTimestamp_AndFlagsData()
+        {
+            // A pre-agent standby episode (record created before the agent started) must land on
+            // the timeline where the device actually woke, not at agent start.
+            var wakeTime = At.AddHours(-3);
+            EmitClassicResume(wakeTime.AddHours(-1), wakeTime, isBackfill: true, timeCreatedUtc: wakeTime);
+
+            var s = Assert.Single(ByType(Constants.EventTypes.SystemSleepEpisode));
+            Assert.Equal(wakeTime, s.OccurredAtUtc);
+            Assert.Equal(true, Data(s)["backfilled"]);
+        }
+
+        // -------------------------------------------------------------------
+        // Dedup / watermark
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void SameRecordId_ProcessedTwice_EmitsOnce()
+        {
+            EmitClockChange(At, At.AddMinutes(1), recordId: 42);
+            EmitClockChange(At, At.AddMinutes(1), recordId: 42);
+
+            Assert.Single(ByType(Constants.EventTypes.SystemClockChanged));
+        }
+
+        [Fact]
+        public void BackfillEventWithLowerRecordId_AfterLiveEvent_IsStillEmitted()
+        {
+            // The live watcher is armed BEFORE backfill runs, so a live record with a higher
+            // RecordId can be processed first. An older, never-emitted backfill record must NOT be
+            // suppressed — pre-agent episodes are the whole point (high-water-mark trap).
+            EmitClockChange(At, At.AddMinutes(1), recordId: 100);                       // live, high
+            EmitClockChange(At, At.AddMinutes(2), recordId: 50, isBackfill: true);      // backfill, older
+
+            Assert.Equal(2, ByType(Constants.EventTypes.SystemClockChanged).Count);
+        }
+
+        [Fact]
+        public void Watermark_PersistsAcrossTrackerInstances()
+        {
+            var post = new InformationalEventPost(_sink, new VirtualClock(At));
+            var logger = new AgentLogger(_tmp.Path, AgentLogLevel.Info);
+            var clockData = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+            {
+                ["OldTime"] = At.ToString("o"),
+                ["NewTime"] = At.AddMinutes(10).ToString("o"),
+                ["Reason"] = "1",
+            };
+
+            var first = new SystemTimelineTracker("s", "t", post, logger, backfillEnabled: false, stateDirectory: _tmp.Path);
+            first.ProcessEvent(SystemTimelineTracker.ProviderKernelGeneral, SystemTimelineTracker.EventId_ClockChange,
+                recordId: 500, timeCreatedUtc: At, eventData: clockData, isBackfill: false);
+
+            // A fresh tracker (agent restart) must load the watermark and skip the already-emitted
+            // record when the backfill re-reads it.
+            var second = new SystemTimelineTracker("s", "t", post, logger, backfillEnabled: false, stateDirectory: _tmp.Path);
+            second.LoadWatermark();
+            second.ProcessEvent(SystemTimelineTracker.ProviderKernelGeneral, SystemTimelineTracker.EventId_ClockChange,
+                recordId: 500, timeCreatedUtc: At, eventData: clockData, isBackfill: true);
+
+            Assert.Single(ByType(Constants.EventTypes.SystemClockChanged));
+        }
+
+        [Fact]
+        public void UnknownProviderOrEventId_Ignored()
+        {
+            _tracker.ProcessEvent("Microsoft-Windows-Kernel-Power", eventId: 566, recordId: _nextRecordId++,
+                timeCreatedUtc: At, eventData: new Dictionary<string, string>(), isBackfill: false);
+            _tracker.ProcessEvent("Some-Other-Provider", eventId: 1, recordId: _nextRecordId++,
+                timeCreatedUtc: At, eventData: new Dictionary<string, string>(), isBackfill: false);
+
+            Assert.Empty(_sink.Posted);
+        }
+
+        // -------------------------------------------------------------------
+        // XPath + parsing
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void BuildXPath_ContainsAllThreeProviderIdPairs_AndNo506()
+        {
+            var xpath = SystemTimelineTracker.BuildXPath();
+            Assert.Contains("Provider[@Name='Microsoft-Windows-Kernel-General'] and EventID=1", xpath);
+            Assert.Contains("Provider[@Name='Microsoft-Windows-Power-Troubleshooter'] and EventID=1", xpath);
+            Assert.Contains("Provider[@Name='Microsoft-Windows-Kernel-Power'] and EventID=507", xpath);
+            Assert.DoesNotContain("506", xpath);
+        }
+
+        [Fact]
+        public void BuildBackfillXPath_AppendsTimediffClause()
+        {
+            var xpath = SystemTimelineTracker.BuildBackfillXPath(86_400_000);
+            Assert.Contains("TimeCreated[timediff(@SystemTime) <= 86400000]", xpath);
+            Assert.Contains("EventID=507", xpath);
+        }
+
+        [Fact]
+        public void ParseEventData_RealKernelGeneralPayload_YieldsAuthoritativeFields()
+        {
+            // Verbatim (values shortened) from a live Kernel-General 1 record on a 26220 dev machine.
+            const string xml =
+                "<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'>" +
+                "<System><Provider Name='Microsoft-Windows-Kernel-General'/><EventID>1</EventID></System>" +
+                "<EventData>" +
+                "<Data Name='NewTime'>2026-08-21T09:40:02.1987028Z</Data>" +
+                "<Data Name='OldTime'>2026-08-21T09:40:02.1973028Z</Data>" +
+                "<Data Name='TimeDeltaInMs'>1</Data>" +
+                "<Data Name='Reason'>1</Data>" +
+                "<Data Name='ProcessName'>\\Device\\HarddiskVolume3\\Windows\\System32\\svchost.exe</Data>" +
+                "<Data Name='ProcessID'>6892</Data>" +
+                "</EventData></Event>";
+
+            var data = SystemTimelineTracker.ParseEventData(xml);
+            Assert.Equal("1", data["TimeDeltaInMs"]);
+            Assert.Equal("2026-08-21T09:40:02.1987028Z", data["newtime"]); // case-insensitive keys
+            Assert.NotNull(SystemTimelineTracker.TryParseUtc(data["OldTime"]));
+        }
+
+        [Fact]
+        public void FormatDuration_CompactForms()
+        {
+            Assert.Equal("2h 05m", SystemTimelineTracker.FormatDuration(TimeSpan.FromMinutes(125)));
+            Assert.Equal("56m 12s", SystemTimelineTracker.FormatDuration(TimeSpan.FromSeconds(56 * 60 + 12)));
+            Assert.Equal("45s", SystemTimelineTracker.FormatDuration(TimeSpan.FromSeconds(45)));
+        }
+
+        [Fact]
+        public void ProcessLeafName_StripsDevicePath()
+        {
+            Assert.Equal("svchost.exe",
+                SystemTimelineTracker.ProcessLeafName(@"\Device\HarddiskVolume3\Windows\System32\svchost.exe"));
+            Assert.Null(SystemTimelineTracker.ProcessLeafName(null));
+            Assert.Null(SystemTimelineTracker.ProcessLeafName(@"\Device\HarddiskVolume3\"));
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Transport/DoGroupIdServiceTests.cs

@@ -0,0 +1,126 @@
+using System;
+using System.Linq;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Transport;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Transport
+{
+    public class DoGroupIdServiceTests
+    {
+        // -------------------------------------------------------------------
+        // ComputeGroupId — RealmJoin byte-layout compatibility
+        // -------------------------------------------------------------------
+
+        [Fact]
+        public void ComputeGroupId_MatchesHandComputedVector()
+        {
+            // Layout: {101,48,6} + {0,0,0} + {ip[1],0,ip[2],ip[3]} + mac — through new Guid(byte[])
+            // the first three groups print little-endian, the last eight bytes verbatim.
+            var guid = DoGroupIdService.ComputeGroupId(
+                new byte[] { 192, 168, 178, 1 },
+                new byte[] { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 });
+
+            Assert.Equal("00063065-0000-00a8-b201-001122334455", guid.ToString());
+        }
+
+        [Theory]
+        [InlineData(new byte[] { 10, 0, 0, 1 }, new byte[] { 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF })]
+        [InlineData(new byte[] { 192, 168, 1, 254 }, new byte[] { 0x00, 0x50, 0x56, 0x01, 0x02, 0x03 })]
+        [InlineData(new byte[] { 172, 16, 254, 3 }, new byte[] { 0xF0, 0x9F, 0xC2, 0x00, 0x00, 0x01 })]
+        public void ComputeGroupId_MatchesRealmJoinReferenceImplementation(byte[] ip, byte[] mac)
+        {
+            Assert.Equal(RealmJoinReferenceGuid(ip, mac), DoGroupIdService.ComputeGroupId(ip, mac));
+        }
+
+        /// <summary>Verbatim port of RealmJoin's ConvertToGuid — the compatibility contract.</summary>
+        private static Guid RealmJoinReferenceGuid(byte[] ipBytes, byte[] address)
+        {
+            byte[] prefix = { 101, 48, 6 };
+            var stuff = new byte[4];
+            stuff[0] = ipBytes[1];
+            stuff[2] = ipBytes[2];
+            stuff[3] = ipBytes[3];
+
+            return new Guid(prefix
+                .Concat(new byte[16 - prefix.Length - stuff.Length - address.Length])
+                .Concat(stuff)
+                .Concat(address)
+                .ToArray());
+        }
+
+        [Fact]
+        public void ComputeGroupId_RejectsNonIpv4AndBadMacLengths()
+        {
+            var ip4 = new byte[] { 10, 0, 0, 1 };
+            var mac = new byte[] { 1, 2, 3, 4, 5, 6 };
+
+            Assert.Throws<ArgumentException>(() => DoGroupIdService.ComputeGroupId(new byte[16], mac));
+            Assert.Throws<ArgumentException>(() => DoGroupIdService.ComputeGroupId(null!, mac));
+            Assert.Throws<ArgumentException>(() => DoGroupIdService.ComputeGroupId(ip4, new byte[8]));
+            Assert.Throws<ArgumentException>(() => DoGroupIdService.ComputeGroupId(ip4, null!));
+        }
+
+        [Fact]
+        public void ComputeGroupId_RegistryFormat_IsBracelessLowercase()
+        {
+            // RealmJoin writes SetValue(name, Guid) which stringifies via Guid.ToString() ("d"
+            // format) — our written value must be the identical string form.
+            var text = DoGroupIdService.ComputeGroupId(
+                new byte[] { 10, 1, 2, 3 }, new byte[] { 0xAB, 0xCD, 0xEF, 0x01, 0x02, 0x03 }).ToString();
+
+            Assert.DoesNotContain("{", text);
+            Assert.Equal(text.ToLowerInvariant(), text);
+            Assert.Equal(36, text.Length);
+        }
+
+        // -------------------------------------------------------------------
+        // DecideAction — ownership matrix
+        // -------------------------------------------------------------------
+
+        private const string Computed = "00063065-0000-00a8-b201-001122334455";
+        private const string Other = "11111111-2222-3333-4444-555555555555";
+
+        [Theory]
+        [InlineData(null)]
+        [InlineData("")]
+        public void DecideAction_NoExistingValue_Writes(string? existing)
+        {
+            Assert.Equal(DoGroupIdAction.Write, DoGroupIdService.DecideAction(existing, Computed, null));
+        }
+
+        [Fact]
+        public void DecideAction_ExistingEqualsComputed_IsNoOp()
+        {
+            Assert.Equal(DoGroupIdAction.NoOp, DoGroupIdService.DecideAction(Computed, Computed, null));
+        }
+
+        [Fact]
+        public void DecideAction_ExistingEqualsComputed_ToleratesBracesAndCase()
+        {
+            // A value written by another tool in "{...}"/uppercase form is still semantically ours.
+            var braced = "{" + Computed.ToUpperInvariant() + "}";
+            Assert.Equal(DoGroupIdAction.NoOp, DoGroupIdService.DecideAction(braced, Computed, null));
+        }
+
+        [Fact]
+        public void DecideAction_ExistingIsOurStaleValue_WritesUpdate()
+        {
+            // Gateway changed: the registry still holds the GUID we wrote for the old network.
+            Assert.Equal(DoGroupIdAction.Write, DoGroupIdService.DecideAction(Other, Computed, Other));
+        }
+
+        [Fact]
+        public void DecideAction_ForeignValue_Skips()
+        {
+            Assert.Equal(DoGroupIdAction.SkipForeign, DoGroupIdService.DecideAction(Other, Computed, null));
+            Assert.Equal(DoGroupIdAction.SkipForeign, DoGroupIdService.DecideAction(Other, Computed, Computed));
+        }
+
+        [Fact]
+        public void DecideAction_NonGuidGarbageExisting_SkipsAsForeign()
+        {
+            // Never overwrite a value we can't even parse — conservative by design.
+            Assert.Equal(DoGroupIdAction.SkipForeign, DoGroupIdService.DecideAction("not-a-guid", Computed, null));
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Orchestration/PowerStateWatcherHostTests.cs

@@ -0,0 +1,162 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Orchestration;
+using AutopilotMonitor.Agent.V2.Core.Runtime;
+using AutopilotMonitor.Agent.V2.Core.Tests.Harness;
+using AutopilotMonitor.DecisionCore.Engine;
+using AutopilotMonitor.DecisionCore.Signals;
+using AutopilotMonitor.Shared;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Orchestration
+{
+    /// <summary>
+    /// PowerStateWatcherHost — no-battery/probe-error devices never arm, a low-battery baseline
+    /// emits its threshold event onto the single rail, and debounced ticks translate tracker
+    /// emissions into <c>power_state_change</c> events. WMI arming itself stays untested
+    /// (ConsoleBypassWatcher precedent); <c>StartCore(armWmi: false)</c> exercises everything else.
+    /// </summary>
+    public sealed class PowerStateWatcherHostTests : IDisposable
+    {
+        private static readonly DateTime At = new DateTime(2026, 8, 21, 9, 0, 0, DateTimeKind.Utc);
+
+        private readonly TempDirectory _tmp = new TempDirectory();
+        private readonly FakeSignalIngressSink _sink = new FakeSignalIngressSink();
+        private readonly AgentLogger _logger;
+        private PowerStateResult _probeResult = new PowerStateResult { OnAcPower = true, HasBattery = true, BatteryPercent = 80 };
+
+        public PowerStateWatcherHostTests()
+        {
+            _logger = new AgentLogger(_tmp.Path, AgentLogLevel.Info);
+        }
+
+        public void Dispose() => _tmp.Dispose();
+
+        private PowerStateWatcherHost Build() => new PowerStateWatcherHost(
+            sessionId: "sess-power",
+            tenantId: "tenant-power",
+            ingress: _sink,
+            clock: new VirtualClock(At),
+            logger: _logger,
+            probe: () => _probeResult);
+
+        private IReadOnlyList<FakeSignalIngressSink.PostedSignal> PowerEvents() =>
+            _sink.Posted.Where(p =>
+                p.Kind == DecisionSignalKind.InformationalEvent
+                && p.Payload != null
+                && p.Payload.TryGetValue(SignalPayloadKeys.EventType, out var et)
+                && et == Constants.EventTypes.PowerStateChange).ToList();
+
+        [Fact]
+        public void No_battery_emits_nothing()
+        {
+            _probeResult = new PowerStateResult { OnAcPower = true, HasBattery = false };
+
+            Build().StartCore(armWmi: false);
+
+            Assert.Empty(_sink.Posted);
+        }
+
+        [Fact]
+        public void Probe_error_emits_nothing()
+        {
+            _probeResult = new PowerStateResult { ProbeError = "GetSystemPowerStatus returned false" };
+
+            Build().StartCore(armWmi: false);
+
+            Assert.Empty(_sink.Posted);
+        }
+
+        [Fact]
+        public void Baseline_below_threshold_emits_threshold_event_with_immediate_upload()
+        {
+            _probeResult = new PowerStateResult { OnAcPower = false, HasBattery = true, BatteryPercent = 12, BatteryLifeMinutes = 34 };
+
+            Build().StartCore(armWmi: false);
+
+            var s = Assert.Single(PowerEvents());
+            Assert.Equal("Error", s.Payload![SignalPayloadKeys.Severity]);
+            Assert.Equal("true", s.Payload![SignalPayloadKeys.ImmediateUpload]);
+            Assert.Contains("15%", s.Payload![SignalPayloadKeys.Message]);
+
+            var data = (IReadOnlyDictionary<string, object>)s.TypedPayload!;
+            Assert.Equal("threshold_crossed", data["transition"]);
+            Assert.Equal(15, data["thresholdPercent"]);
+            Assert.Equal(12, data["batteryPercent"]);
+            Assert.Equal(false, data["onAcPower"]);
+            Assert.Equal(34, data["batteryLifeMinutes"]);
+        }
+
+        [Fact]
+        public void Tick_after_unplug_emits_ac_to_battery_warning()
+        {
+            var host = Build();
+            host.StartCore(armWmi: false);
+            Assert.Empty(PowerEvents());
+
+            _probeResult = new PowerStateResult { OnAcPower = false, HasBattery = true, BatteryPercent = 79 };
+            host.TickForTest();
+
+            var s = Assert.Single(PowerEvents());
+            Assert.Equal("Warning", s.Payload![SignalPayloadKeys.Severity]);
+            Assert.Equal("true", s.Payload![SignalPayloadKeys.ImmediateUpload]);
+
+            var data = (IReadOnlyDictionary<string, object>)s.TypedPayload!;
+            Assert.Equal("ac_to_battery", data["transition"]);
+            Assert.Equal(79, data["batteryPercent"]);
+            Assert.False(data.ContainsKey("thresholdPercent"));
+
+            // Replug: Info recovery event without immediate upload.
+            _probeResult = new PowerStateResult { OnAcPower = true, HasBattery = true, BatteryPercent = 79, IsCharging = true };
+            host.TickForTest();
+
+            Assert.Equal(2, PowerEvents().Count);
+            var back = PowerEvents()[1];
+            Assert.Equal("Info", back.Payload![SignalPayloadKeys.Severity]);
+            Assert.Equal("false", back.Payload![SignalPayloadKeys.ImmediateUpload]);
+            Assert.Equal("battery_to_ac", ((IReadOnlyDictionary<string, object>)back.TypedPayload!)["transition"]);
+        }
+
+        [Fact]
+        public void Tick_with_unchanged_state_emits_nothing()
+        {
+            var host = Build();
+            host.StartCore(armWmi: false);
+
+            host.TickForTest();
+            host.TickForTest();
+
+            Assert.Empty(PowerEvents());
+        }
+
+        [Fact]
+        public void Stopped_host_ignores_ticks()
+        {
+            var host = Build();
+            host.StartCore(armWmi: false);
+            host.Stop();
+
+            _probeResult = new PowerStateResult { OnAcPower = false, HasBattery = true, BatteryPercent = 50 };
+            host.TickForTest();
+
+            Assert.Empty(PowerEvents());
+        }
+
+        [Fact]
+        public void Unknown_battery_percent_serializes_as_unknown()
+        {
+            var host = Build();
+            host.StartCore(armWmi: false);
+
+            _probeResult = new PowerStateResult { OnAcPower = false, HasBattery = true, BatteryPercent = null, BatteryLifeMinutes = null };
+            host.TickForTest();
+
+            var data = (IReadOnlyDictionary<string, object>)Assert.Single(PowerEvents()).TypedPayload!;
+            Assert.Equal("unknown", data["batteryPercent"]);
+            Assert.Equal("unknown", data["batteryLifeMinutes"]);
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Orchestration/SignalActivityClassifierTests.cs

@@ -35,6 +35,8 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Orchestration
         // OS-eventlog forwarding — observability, not enrollment progress (session 8bc1180f:
         // an EventID-100 burst must not keep the periodic collectors alive).
         [InlineData("modern_deployment_log")]
+        // Environment observation — battery drain on an idle device must not reset idle clocks.
+        [InlineData("power_state_change")]
         // Agent health / control / transport — not device/enrollment progress (P2).
         [InlineData("collector_degraded")]
         [InlineData("telemetry_upload_poisoned")]

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Orchestration/SystemTimelineWatcherHostTests.cs

@@ -0,0 +1,57 @@
+#nullable enable
+using System;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Orchestration;
+using AutopilotMonitor.Agent.V2.Core.Tests.Harness;
+using AutopilotMonitor.DecisionCore.Engine;
+using Xunit;
+
+namespace AutopilotMonitor.Agent.V2.Core.Tests.Orchestration
+{
+    /// <summary>
+    /// SystemTimelineWatcherHost — thin ICollectorHost wrapper over SystemTimelineTracker.
+    /// Real event-log arming stays untested by convention (ConsoleBypassWatcher precedent);
+    /// these tests pin the lifecycle contract only.
+    /// </summary>
+    public sealed class SystemTimelineWatcherHostTests : IDisposable
+    {
+        private readonly TempDirectory _tmp = new TempDirectory();
+
+        public void Dispose() => _tmp.Dispose();
+
+        private SystemTimelineWatcherHost CreateHost() => new SystemTimelineWatcherHost(
+            sessionId: "sess-stl",
+            tenantId: "tenant-stl",
+            logger: new AgentLogger(_tmp.Path, AgentLogLevel.Info),
+            ingress: new FakeSignalIngressSink(),
+            clock: new VirtualClock(new DateTime(2026, 8, 21, 10, 0, 0, DateTimeKind.Utc)),
+            backfillLookbackMinutes: 0,
+            stateDirectory: _tmp.Path);
+
+        [Fact]
+        public void Stop_BeforeStart_DoesNotThrow()
+        {
+            using (var host = CreateHost())
+            {
+                host.Stop();
+            }
+        }
+
+        [Fact]
+        public void Dispose_Twice_DoesNotThrow()
+        {
+            var host = CreateHost();
+            host.Dispose();
+            host.Dispose();
+        }
+
+        [Fact]
+        public void Name_IsStable()
+        {
+            using (var host = CreateHost())
+            {
+                Assert.Equal("SystemTimelineTracker", host.Name);
+            }
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Runtime/StartupEnvironmentProbesTests.cs

@@ -339,6 +339,114 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Runtime
             Assert.False(StartupEnvironmentProbes.IsNtpWithinTolerance(null!));
         }
 
+        // ================================================================= DO GroupId auto-set
+        // Builder/fingerprint tests only — TrySetGroupId itself does live registry + ARP I/O and
+        // must never run in a unit test (it would write HKLM on the build machine).
+
+        [Fact]
+        public void BuildDoGroupIdEvent_written_success_is_info_with_full_data()
+        {
+            var result = new DoGroupIdSetResult
+            {
+                Success = true,
+                Written = true,
+                GroupId = "00063065-0000-00a8-b201-001122334455",
+                PreviousValue = null,
+                GatewayIp = "192.168.178.1",
+                GatewayMac = "00-11-22-33-44-55",
+            };
+
+            var evt = StartupEnvironmentProbes.BuildDoGroupIdEvent(Config(), result);
+
+            Assert.Equal("do_group_id_auto_set", evt.EventType);
+            Assert.Equal(EventSeverity.Info, evt.Severity);
+            Assert.Equal("StartupEnvironmentProbes", evt.Source);
+            Assert.Equal("S1", evt.SessionId);
+            Assert.Equal("T1", evt.TenantId);
+            Assert.Contains("00063065-0000-00a8-b201-001122334455", evt.Message);
+            Assert.Equal("192.168.178.1", evt.Data["gatewayIp"]);
+            Assert.Equal("00-11-22-33-44-55", evt.Data["gatewayMac"]);
+            Assert.Equal(true, evt.Data["written"]);
+            Assert.Equal(true, evt.Data["success"]);
+            Assert.Equal(false, evt.Data["skipped"]);
+        }
+
+        [Fact]
+        public void BuildDoGroupIdEvent_noop_success_says_already_set()
+        {
+            var result = new DoGroupIdSetResult
+            {
+                Success = true,
+                Written = false,
+                GroupId = "00063065-0000-00a8-b201-001122334455",
+            };
+
+            var evt = StartupEnvironmentProbes.BuildDoGroupIdEvent(Config(), result);
+
+            Assert.Equal(EventSeverity.Info, evt.Severity);
+            Assert.Contains("already set", evt.Message);
+            Assert.Equal(false, evt.Data["written"]);
+        }
+
+        [Fact]
+        public void BuildDoGroupIdEvent_skip_is_info_with_reason()
+        {
+            var result = new DoGroupIdSetResult
+            {
+                Skipped = true,
+                SkipReason = "foreign_value_present",
+                PreviousValue = "11111111-2222-3333-4444-555555555555",
+            };
+
+            var evt = StartupEnvironmentProbes.BuildDoGroupIdEvent(Config(), result);
+
+            Assert.Equal(EventSeverity.Info, evt.Severity);
+            Assert.Contains("foreign_value_present", evt.Message);
+            Assert.Equal("foreign_value_present", evt.Data["skipReason"]);
+            Assert.Equal("11111111-2222-3333-4444-555555555555", evt.Data["previousValue"]);
+        }
+
+        [Fact]
+        public void BuildDoGroupIdEvent_error_is_warning()
+        {
+            var result = new DoGroupIdSetResult { Error = "readback mismatch" };
+
+            var evt = StartupEnvironmentProbes.BuildDoGroupIdEvent(Config(), result);
+
+            Assert.Equal(EventSeverity.Warning, evt.Severity);
+            Assert.Contains("readback mismatch", evt.Message);
+            Assert.Equal("readback mismatch", evt.Data["error"]);
+        }
+
+        [Fact]
+        public void DoGroupIdFingerprint_roundtrips_ownership_marker_for_success()
+        {
+            var fp = StartupEnvironmentProbes.ComputeDoGroupIdFingerprint(new DoGroupIdSetResult
+            {
+                Success = true,
+                GroupId = "00063065-0000-00a8-b201-001122334455",
+            });
+
+            Assert.Equal("written:00063065-0000-00a8-b201-001122334455", fp);
+            Assert.Equal("00063065-0000-00a8-b201-001122334455", StartupEnvironmentProbes.ExtractLastWrittenGroupId(fp));
+        }
+
+        [Fact]
+        public void DoGroupIdFingerprint_skip_carries_no_ownership_and_errors_never_dedupe()
+        {
+            var skipFp = StartupEnvironmentProbes.ComputeDoGroupIdFingerprint(new DoGroupIdSetResult
+            {
+                Skipped = true,
+                SkipReason = "mdm_policy_present",
+            });
+            Assert.Equal("skipped:mdm_policy_present", skipFp);
+            Assert.Null(StartupEnvironmentProbes.ExtractLastWrittenGroupId(skipFp));
+
+            // Errors: no fingerprint → the probe re-runs AND re-emits each failing start.
+            Assert.Null(StartupEnvironmentProbes.ComputeDoGroupIdFingerprint(new DoGroupIdSetResult { Error = "boom" }));
+            Assert.Null(StartupEnvironmentProbes.ExtractLastWrittenGroupId(null));
+        }
+
         [Fact]
         public async Task RunAsync_skips_geo_timezone_and_ntp_once_all_succeeded_only_power_state_emits()
         {

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/SignalAdapters/ImeLogTrackerAdapterTimingTests.cs

@@ -245,11 +245,13 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.SignalAdapters
         }
 
         [Fact]
-        public void Terminal_to_active_retry_rearms_CompletedAt_and_final_terminal_covers_total_occupancy()
+        public void Terminal_to_active_retry_rearms_BothEndpoints_and_final_terminal_covers_last_attempt()
         {
-            // Audit Q1: the IME retry path (Error -> Downloading -> Installed is permitted by
-            // AppPackageState.UpdateState). Pre-fix, CompletedAt froze at the first Error, so
-            // the final Installed payload carried the first failure's completedAt/duration.
+            // Audit Q1 + 2026-08 attempt-duration change: the IME retry path
+            // (Error -> Downloading -> Installed is permitted by AppPackageState.UpdateState).
+            // A terminal->active transition re-arms BOTH endpoints, so the final Installed
+            // payload describes the retry ATTEMPT (matching the backend's AppInstallSummaries
+            // semantics) — not the first-start -> last-terminal span across attempts.
             using var f = new ImeLogTrackerAdapterFixture(T0);
             using var adapter = new ImeLogTrackerAdapter(f.Tracker, f.Ingress, f.Clock);
             var app = new AppPackageState("app-R", 0);
@@ -261,23 +263,23 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.SignalAdapters
             adapter.TriggerAppStateFromTest(app, AppInstallationState.Error, AppInstallationState.Downloading);
 
             // Re-armed while active again: the retry's download event carries no completedAt,
-            // and the FIRST start stamp is kept.
+            // and the start stamp is the RETRY's re-entry time (fresh attempt window).
             Assert.Null(adapter.AppTimings["app-R"].CompletedAtUtc);
             var retryDownload = f.InfoEvent(SharedEventTypes.AppDownloadStarted);
             Assert.False(retryDownload.Payload!.ContainsKey("completedAt"));
             Assert.False(retryDownload.Payload.ContainsKey("durationSeconds"));
-            Assert.Equal(T0.ToString("o"), retryDownload.Payload["startedAt"]);
+            Assert.Equal(T0.AddSeconds(15).ToString("o"), retryDownload.Payload["startedAt"]);
 
             f.Clock.Advance(TimeSpan.FromSeconds(20));
             adapter.TriggerAppStateFromTest(app, AppInstallationState.Downloading, AppInstallationState.Installed);
 
             var timing = adapter.AppTimings["app-R"];
-            Assert.Equal(T0, timing.StartedAtUtc);
+            Assert.Equal(T0.AddSeconds(15), timing.StartedAtUtc);
             Assert.Equal(T0.AddSeconds(35), timing.CompletedAtUtc);
-            Assert.Equal(35.0, timing.DurationSeconds);
+            Assert.Equal(20.0, timing.DurationSeconds);
 
             var completed = Assert.Single(f.InfoEvents(SharedEventTypes.AppInstallComplete));
-            Assert.Equal("35.00", completed.Payload!["durationSeconds"]);
+            Assert.Equal("20.00", completed.Payload!["durationSeconds"]);
             Assert.Equal(T0.AddSeconds(35).ToString("o"), completed.Payload["completedAt"]);
         }
 

src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Transport/BackendTelemetryUploaderTests.cs

@@ -107,6 +107,31 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Transport
             Assert.False(req.Headers.ContainsKey("X-Bootstrap-Token"));
         }
 
+        [Fact]
+        public async Task UploadBatchAsync_stamps_send_time_header_per_attempt()
+        {
+            // P14: X-Send-Time-Utc carries the device clock at the SEND moment, round-trip
+            // ISO-8601, one value per request. A retry is a new send moment — the header is
+            // stamped inside UploadBatchAsync, so each attempt gets a fresh value.
+            using var rig = new Rig();
+            rig.Handler.QueueStatus(HttpStatusCode.ServiceUnavailable);
+            rig.Handler.QueueStatus(HttpStatusCode.OK);
+
+            var before = DateTime.UtcNow;
+            await rig.Sut.UploadBatchAsync(new[] { NewEventItem(1) }, CancellationToken.None);
+            await rig.Sut.UploadBatchAsync(new[] { NewEventItem(1) }, CancellationToken.None);
+            var after = DateTime.UtcNow;
+
+            Assert.Equal(2, rig.Handler.Captured.Count);
+            foreach (var req in rig.Handler.Captured)
+            {
+                Assert.True(req.TryGetHeader("X-Send-Time-Utc", out var raw));
+                var parsed = DateTime.Parse(raw, null, System.Globalization.DateTimeStyles.RoundtripKind);
+                Assert.Equal(DateTimeKind.Utc, parsed.Kind);
+                Assert.InRange(parsed, before.AddSeconds(-1), after.AddSeconds(1));
+            }
+        }
+
         // ============================================================ Compression (bandwidth)
 
         [Fact]

src/Agent/AutopilotMonitor.Agent.V2.Core/Configuration/AgentConfiguration.cs

@@ -109,6 +109,14 @@ namespace AutopilotMonitor.Agent.V2.Core.Configuration
         /// </summary>
         public bool EnableTimezoneAutoSet { get; set; } = false;
 
+        /// <summary>
+        /// Whether to set the Delivery Optimization group ID (DOGroupId policy value) from a
+        /// deterministic network fingerprint (default gateway IP + MAC, RealmJoin-compatible).
+        /// Existing DOGroupId/DOGroupIdSource policies are never overwritten.
+        /// Default: false
+        /// </summary>
+        public bool EnableDoGroupIdAutoSet { get; set; } = false;
+
         /// <summary>
         /// Continue-Anyway observation mode (operator-set tenant opt-in, delivered via
         /// remote config): stamped into the esp_config_detected decision-signal payload so

src/Agent/AutopilotMonitor.Agent.V2.Core/Configuration/RemoteConfigMerger.cs

@@ -94,6 +94,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Configuration
             //                  a tenant admin can clear a previously-applied custom NTP server.
             agentConfig.NtpServer = remoteConfig.NtpServer;
             agentConfig.EnableTimezoneAutoSet = remoteConfig.EnableTimezoneAutoSet;
+            agentConfig.EnableDoGroupIdAutoSet = remoteConfig.EnableDoGroupIdAutoSet;
 
             // ---------------- Diagnostics — remote wins (including DiagnosticsUploadMode="Off"
             //                  which must clear any CLI-initial default).

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/Ime/AppInstallTiming.cs

@@ -10,10 +10,13 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
     /// the <c>app_tracking_summary</c> terminal event.
     /// <para>
     /// <b>StartedAtUtc</b> is recorded on the first lifecycle transition into Downloading /
-    /// Installing / InProgress and never overwritten. <b>CompletedAtUtc</b> is recorded on a
-    /// transition to a terminal state (Installed / Skipped / Postponed / Error) and re-armed
-    /// to <c>null</c> when the app goes terminal → active again (IME retry / re-evaluation,
-    /// audit Q1) — so the final terminal event carries first-start → last-terminal.
+    /// Installing / InProgress. <b>CompletedAtUtc</b> is recorded on a transition to a
+    /// terminal state (Installed / Skipped / Postponed / Error). When the app goes
+    /// terminal → active again (IME retry / re-evaluation pass, audit Q1) BOTH endpoints
+    /// re-arm — CompletedAtUtc to <c>null</c>, StartedAtUtc to the re-entry time — so the
+    /// final terminal event carries the status-defining ATTEMPT's window (2026-08
+    /// attempt-duration change, matching the backend's AppInstallSummaries semantics),
+    /// never the first-start → last-terminal span across install passes.
     /// </para>
     /// </summary>
     public sealed class AppInstallTiming

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/Ime/CmTraceOffsetCalibrator.cs

@@ -0,0 +1,215 @@
+using System;
+using System.Collections.Generic;
+
+namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
+{
+    /// <summary>How the UTC value of a CMTrace line was arrived at. Recorded as evidence.</summary>
+    public enum CmTraceOffsetOrigin
+    {
+        /// <summary>No offset known — the caller fell back to its own clock.</summary>
+        None = 0,
+
+        /// <summary>The writer declared its offset in the line ("+480"). Authoritative.</summary>
+        Bias = 1,
+
+        /// <summary>
+        /// A per-FILE measured offset was applied. Retired by the 2026-08-20 revert (04b1a7c6):
+        /// one offset per file is wrong when a file holds lines from two writer eras. Kept so
+        /// stored events from agent 2.0.1410 remain interpretable.
+        /// </summary>
+        Calibrated = 2,
+
+        /// <summary>
+        /// The line anchored ITSELF: it was read in a pass whose lines are provably fresh
+        /// (written since the previous poll), so its own distance to the agent clock, rounded
+        /// to the 15-minute offset grid, IS the writer's offset — no cross-line state involved.
+        /// Immune to interleaved writer eras by construction. See
+        /// <see cref="CmTraceOffsetCalibrator.TryMeasureOffset"/>.
+        /// </summary>
+        LineAnchored = 3,
+    }
+
+    /// <summary>
+    /// Measures the UTC offset that the process WRITING a CMTrace log believes it is in.
+    ///
+    /// <para>
+    /// A CMTrace line carries local time and no offset — IME 1.104 writes
+    /// <c>DateTime.Now.TimeOfDay</c> in both of its trace listeners. Converting such a line with
+    /// the agent's own <c>TimeZoneInfo.Local</c> assumes the two processes agree, and they do not:
+    /// both cache their zone at process start and neither follows a later <c>tzutil</c> or a
+    /// Windows auto-timezone change. The resulting error is
+    /// <c>Offset_writer - Offset_agent</c> and is zero only by coincidence. Field measurement over
+    /// 11,068 sessions found 26 sessions carrying a real zone-offset error, from +1 h
+    /// (GMT to W. Europe) to -17 h (a writer still on the Pacific OOBE default while the agent had
+    /// already moved to E. Australia).
+    /// </para>
+    ///
+    /// <para>
+    /// So the offset is MEASURED, not assumed. The tracker tails the log on a 100 ms poll, so a
+    /// line that appeared since the previous pass was written essentially "now":
+    /// <code>
+    ///   candidate = lineLocalTime - agentUtcNow
+    ///   offset    = round(candidate / 15 min) * 15 min
+    ///   lineUtc   = lineLocalTime - offset
+    /// </code>
+    /// Every real UTC offset is a whole multiple of 15 minutes, so the rounding absorbs poll and
+    /// flush latency without ambiguity.
+    /// </para>
+    ///
+    /// <para>
+    /// THE FRESHNESS REQUIREMENT IS WHAT MAKES THIS CORRECT. An anchor must be the newest line of
+    /// a pass in which the file actually GREW. Without that rule a backlog line that happens to be
+    /// an exact multiple of 15 minutes old (30 min, 45 min, ...) rounds to a clean value with zero
+    /// residual and calibrates the offset to a wrong figure — the residual guard alone cannot
+    /// catch it. Callers must only offer anchors they know to be fresh.
+    /// </para>
+    ///
+    /// <para>
+    /// Calibration is kept per source file: IntuneManagementExtension.log and AppWorkload.log are
+    /// written by different processes and can hold different beliefs. Re-calibrating on every
+    /// fresh anchor makes this self-healing — if the writing process restarts and picks up the
+    /// current zone, the measurement follows within one poll.
+    /// </para>
+    /// </summary>
+    public sealed class CmTraceOffsetCalibrator
+    {
+        /// <summary>Grid that every real UTC offset sits on.</summary>
+        internal static readonly TimeSpan OffsetGrid = TimeSpan.FromMinutes(15);
+
+        /// <summary>
+        /// How far a candidate may sit off the grid before it is rejected. Poll latency (100 ms)
+        /// plus the writer's flush latency are far below this; anything larger means the anchor
+        /// was not actually fresh.
+        /// </summary>
+        internal static readonly TimeSpan MaxGridResidual = TimeSpan.FromMinutes(2);
+
+        /// <summary>Real UTC offsets span UTC-12 (Dateline) to UTC+14 (Line Islands).</summary>
+        internal static readonly TimeSpan MinOffset = TimeSpan.FromHours(-12);
+
+        /// <summary>Upper bound of a real UTC offset. See <see cref="MinOffset"/>.</summary>
+        internal static readonly TimeSpan MaxOffset = TimeSpan.FromHours(14);
+
+        private sealed class Anchor
+        {
+            public TimeSpan Offset;
+            public DateTime LocalTimestamp;
+        }
+
+        private readonly object _lock = new object();
+
+        private readonly Dictionary<string, Anchor> _bySource =
+            new Dictionary<string, Anchor>(StringComparer.OrdinalIgnoreCase);
+
+        /// <summary>
+        /// Offer a freshly appended line as a calibration anchor.
+        /// <para>
+        /// The caller MUST only pass a line it knows to be fresh — the newest line of a pass in
+        /// which the file grew. See the freshness note on this class.
+        /// </para>
+        /// </summary>
+        /// <param name="sourceKey">Log file identity; the file name is enough.</param>
+        /// <param name="localTimestamp">The line's local time exactly as written (Kind is ignored).</param>
+        /// <param name="agentUtcNow">The agent's UTC clock at parse time.</param>
+        /// <returns><c>true</c> when the anchor was accepted and the offset updated.</returns>
+        /// <summary>
+        /// The pure measurement: the distance between a FRESH line's local time and the agent's
+        /// UTC clock, rounded to the 15-minute offset grid, is the writer's UTC offset.
+        /// <para>
+        /// Freshness is the caller's obligation and is what makes this correct — for a line
+        /// written within the last poll interval, <c>local - now</c> differs from the writer's
+        /// true offset only by seconds, which the grid rounding absorbs. Returns <c>false</c>
+        /// when the residual exceeds <see cref="MaxGridResidual"/> (the line is not fresh, or
+        /// the writer's clock is broken) or the rounded value is not a real timezone offset.
+        /// </para>
+        /// <para>
+        /// Known, accepted edge: a freshly WRITTEN line carrying an old REPLAYED timestamp whose
+        /// age happens to sit within the residual of an exact grid multiple measures that age as
+        /// an "offset" — the line then resolves to roughly the read time instead of its replayed
+        /// past. The error is bounded by construction (an anchored line always resolves to
+        /// now ± <see cref="MaxGridResidual"/>), the case needs an age of exactly N×15 min ± 2 min,
+        /// and sub-24h replays are treated as current by the historic-replay guard anyway.
+        /// </para>
+        /// </summary>
+        public static bool TryMeasureOffset(DateTime localTimestamp, DateTime agentUtcNow, out TimeSpan offset)
+        {
+            var candidate = DateTime.SpecifyKind(localTimestamp, DateTimeKind.Unspecified)
+                          - DateTime.SpecifyKind(agentUtcNow, DateTimeKind.Unspecified);
+
+            var gridUnits = Math.Round(candidate.TotalMinutes / OffsetGrid.TotalMinutes,
+                                       MidpointRounding.AwayFromZero);
+            offset = TimeSpan.FromMinutes(gridUnits * OffsetGrid.TotalMinutes);
+
+            // Off-grid by more than the tolerance: the line was not fresh, or the writer's own
+            // clock is broken. Either way it must not become an offset.
+            if ((candidate - offset).Duration() > MaxGridResidual) return false;
+
+            // Not a value any real timezone can produce.
+            if (offset < MinOffset || offset > MaxOffset) return false;
+
+            return true;
+        }
+
+        public bool TryCalibrate(string sourceKey, DateTime localTimestamp, DateTime agentUtcNow)
+        {
+            if (string.IsNullOrEmpty(sourceKey)) return false;
+
+            TimeSpan offset;
+            if (!TryMeasureOffset(localTimestamp, agentUtcNow, out offset)) return false;
+
+            lock (_lock)
+            {
+                if (_bySource.TryGetValue(sourceKey, out var existing))
+                {
+                    // Only ever move the anchor forward. A line older than the current anchor
+                    // carries nothing newer and could re-introduce a stale belief.
+                    if (localTimestamp <= existing.LocalTimestamp) return false;
+                    existing.Offset = offset;
+                    existing.LocalTimestamp = localTimestamp;
+                }
+                else
+                {
+                    _bySource[sourceKey] = new Anchor
+                    {
+                        Offset = offset,
+                        LocalTimestamp = localTimestamp,
+                    };
+                }
+            }
+
+            return true;
+        }
+
+        /// <summary>The offset measured for this source, when one has been established.</summary>
+        public bool TryGetOffset(string sourceKey, out TimeSpan offset)
+        {
+            offset = TimeSpan.Zero;
+            if (string.IsNullOrEmpty(sourceKey)) return false;
+
+            lock (_lock)
+            {
+                Anchor anchor;
+                if (!_bySource.TryGetValue(sourceKey, out anchor)) return false;
+                offset = anchor.Offset;
+                return true;
+            }
+        }
+
+        /// <summary>
+        /// Convert a line's local time to UTC using the measured offset. Returns <c>false</c> when
+        /// this source has not been calibrated yet — the caller then picks its own fallback and
+        /// should mark the result as not source-grounded.
+        /// </summary>
+        public bool TryResolveUtc(string sourceKey, DateTime localTimestamp, out DateTime utc)
+        {
+            utc = default(DateTime);
+
+            TimeSpan offset;
+            if (!TryGetOffset(sourceKey, out offset)) return false;
+
+            utc = DateTime.SpecifyKind(
+                DateTime.SpecifyKind(localTimestamp, DateTimeKind.Unspecified) - offset,
+                DateTimeKind.Utc);
+            return true;
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/Ime/ImeLogTracker.LogProcessing.cs

@@ -42,7 +42,10 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
             return false;
         }
 
-        private async Task CheckLogFilesAsync(CancellationToken token)
+        /// <remarks>internal (not private) as a test seam: the offset calibration depends on the
+        /// pass structure — first observation versus a later pass over a grown file — which only
+        /// a real read cycle exercises. Production still reaches it solely from the poll loop.</remarks>
+        internal async Task CheckLogFilesAsync(CancellationToken token)
         {
             if (!Directory.Exists(_logFolder))
                 return;
@@ -74,7 +77,21 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
                     var fileInfo = new FileInfo(filePath);
                     if (!fileInfo.Exists) continue;
 
+                    // Captured BEFORE MarkChecked below stamps this pass. Growth measured
+                    // against a previously observed state is what makes this pass's lines valid
+                    // "written now" anchors — for the per-file measurement AND per-line anchoring.
+                    var hadPreviousObservation = _positionTracker.HasSeen(filePath);
+                    var lastCheckedUtc = _positionTracker.GetLastCheckedUtc(filePath);
+                    var passNowUtc = UtcNowProvider();
+
                     var startPos = _positionTracker.GetSafePosition(filePath, fileInfo.Length);
+
+                    // Every look counts, including "no new data" and an empty first sight: the
+                    // NEXT pass's freshness window is measured from here. Restored bookmarks
+                    // deliberately carry no LastCheckedUtc — the first pass after a restart reads
+                    // downtime backlog and must never count as fresh.
+                    _positionTracker.MarkChecked(filePath, passNowUtc);
+
                     if (startPos >= fileInfo.Length)
                     {
                         // M2: guard the interpolated string so it isn't built every 100 ms tick
@@ -86,6 +103,16 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
                     if (_logger.LogLevel >= AgentLogLevel.Trace)
                         _logger.Trace($"ImeLogTracker: reading {Path.GetFileName(filePath)} from pos {startPos} (size={fileInfo.Length}, delta={fileInfo.Length - startPos})");
 
+                    _currentSourceFileName = Path.GetFileName(filePath);
+                    _currentPassLinesAreFresh = hadPreviousObservation
+                        && lastCheckedUtc > DateTime.MinValue
+                        && (passNowUtc - lastCheckedUtc) <= FreshLineMaxAge;
+
+                    // Newest bias-less line of this pass — the calibration anchor. Bias-carrying
+                    // lines are skipped: they already state the writer's offset, so they need no
+                    // measurement and must not overwrite one.
+                    CmTraceLogEntry calibrationAnchor = null;
+
                     using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                     {
                         stream.Seek(startPos, SeekOrigin.Begin);
@@ -147,6 +174,8 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
                                 if (CmTraceLogParser.TryParseLine(line, out entry))
                                 {
                                     messageToMatch = entry.Message;
+                                    if (entry.HasTimestamp && !entry.BiasMinutes.HasValue)
+                                        calibrationAnchor = entry;
                                 }
                                 else
                                 {
@@ -160,7 +189,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
                                 // Simulation mode delay
                                 if (SimulationMode && entry != null)
                                 {
-                                    await ApplySimulationDelay(entry.Timestamp, token);
+                                    await ApplySimulationDelay(ResolveEntryUtc(entry), token);
                                 }
 
                                 // Match against active patterns
@@ -185,6 +214,15 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
 
                         _positionTracker.SetPosition(filePath, stream.Position);
                         _stateDirty = true;
+
+                        // Calibrate AFTER the pass: this pass's lines were resolved with the
+                        // offset established previously, at most one poll (100 ms) old. Buffering
+                        // the pass to calibrate first is not an option — the first pass of
+                        // AppWorkload.log can be hundreds of MB. The cost is a warm-up of one
+                        // growing pass, during which lines fall back to the reader zone and are
+                        // flagged as such.
+                        if (hadPreviousObservation && calibrationAnchor != null)
+                            CalibrateFrom(_currentSourceFileName, Path.GetFileName(filePath), calibrationAnchor);
                     }
                 }
                 catch (FileNotFoundException) { }
@@ -222,7 +260,32 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         private void HandlePatternMatch(CompiledPattern pattern, Match match, string message, CmTraceLogEntry entry)
         {
             LastMatchedPatternId = pattern.PatternId;
-            LastMatchedLogTimestamp = entry?.Timestamp;
+            if (entry == null)
+            {
+                LastMatchedLogTimestamp = null;
+                LastMatchedSourceLocalTimestamp = null;
+                LastMatchedSourceOffsetMinutes = null;
+                LastMatchedSourceOffsetOrigin = CmTraceOffsetOrigin.None;
+                LastMatchedMeasuredWriterOffsetMinutes = null;
+            }
+            else
+            {
+                CmTraceOffsetOrigin origin;
+                int? offsetMinutes;
+                LastMatchedLogTimestamp = ResolveEntryUtc(entry, out origin, out offsetMinutes);
+                LastMatchedSourceLocalTimestamp = entry.HasTimestamp ? entry.LocalTimestamp : (DateTime?)null;
+                LastMatchedSourceOffsetMinutes = offsetMinutes;
+                LastMatchedSourceOffsetOrigin = origin;
+
+                // Observational: what the calibrator measured for this file, distinct from what
+                // was applied above.
+                TimeSpan measuredWriterOffset;
+                LastMatchedMeasuredWriterOffsetMinutes =
+                    _currentSourceFileName != null
+                    && OffsetCalibrator.TryGetOffset(_currentSourceFileName, out measuredWriterOffset)
+                        ? (int)measuredWriterOffset.TotalMinutes
+                        : (int?)null;
+            }
 
             // Generic pattern-match hook (M4.4.4). Invoked before action-specific callbacks so
             // subscribers (e.g. ImeLogTrackerAdapter emitting WhiteGloveSealingPatternDetected)
@@ -237,10 +300,10 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
             // state nor the phase-change ignore list. SimulationMode (--replay-log-dir dev tool)
             // replays historic logs on purpose and bypasses the guard.
             var isStaleReplayLine = !SimulationMode && entry != null
-                && (UtcNowProvider() - NormalizeUtc(entry.Timestamp)) > HistoricReplayThreshold;
+                && (UtcNowProvider() - NormalizeUtc(ResolveEntryUtc(entry))) > HistoricReplayThreshold;
             if (isStaleReplayLine && AppMutatingActions.Contains(pattern.Action?.ToLower() ?? string.Empty))
             {
-                _logger.Debug($"ImeLogTracker: skipped app action '{pattern.Action}' for historic line ({entry.Timestamp:o})");
+                _logger.Debug($"ImeLogTracker: skipped app action '{pattern.Action}' for historic line ({ResolveEntryUtc(entry):o})");
                 return;
             }
 
@@ -524,8 +587,16 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         internal void ProcessLogMessageForTest(string message, DateTime? sourceTimestampUtc = null)
         {
             if (string.IsNullOrEmpty(message)) return;
+            // The test seam hands in an already-resolved UTC instant, so it takes the same route a
+            // writer-declared bias does: TimestampUtc set, no zone left to guess.
             var entry = sourceTimestampUtc.HasValue
-                ? new CmTraceLogEntry { Timestamp = sourceTimestampUtc.Value, Message = message }
+                ? new CmTraceLogEntry
+                {
+                    TimestampUtc = sourceTimestampUtc.Value,
+                    LocalTimestamp = DateTime.SpecifyKind(sourceTimestampUtc.Value, DateTimeKind.Unspecified),
+                    HasTimestamp = true,
+                    Message = message,
+                }
                 : null;
             foreach (var pattern in _activePatterns)
             {
@@ -543,5 +614,159 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         /// Parses [DO TEL] JSON and links it to the correct app via FileId.
         /// The FileId contains the app GUID in the format: ...intunewin-bin_{appGuid}_{number}
         /// </summary>
+
+        /// <summary>
+        /// Resolve a parsed CMTrace entry to UTC.
+        ///
+        /// <para>
+        /// Order of preference: a writer-declared bias (authoritative) &gt; this process's own zone
+        /// (a fallback carrying a known defect, see
+        /// <see cref="CmTraceLogParser.ResolveUtcAssumingReaderZone"/>) &gt; the agent clock for a
+        /// line with no parseable timestamp.
+        /// </para>
+        ///
+        /// <para>
+        /// The reader-zone step is where the tracker is still wrong when IME's process holds a
+        /// different zone belief than ours. It is preserved verbatim here so that splitting the
+        /// parser changes no behaviour; the measured offset from <c>CmTraceOffsetCalibrator</c>
+        /// slots in at exactly this point in the follow-up change.
+        /// </para>
+        /// </summary>
+        private DateTime ResolveEntryUtc(CmTraceLogEntry entry)
+        {
+            CmTraceOffsetOrigin origin;
+            int? offsetMinutes;
+            return ResolveEntryUtc(entry, out origin, out offsetMinutes);
+        }
+
+        /// <summary>
+        /// Resolve a parsed entry to UTC and report HOW the offset was obtained, so the emitting
+        /// side can attach the evidence (P8). See <see cref="CmTraceOffsetOrigin"/>.
+        /// </summary>
+        private DateTime ResolveEntryUtc(CmTraceLogEntry entry, out CmTraceOffsetOrigin origin, out int? offsetMinutes)
+        {
+            origin = CmTraceOffsetOrigin.None;
+            offsetMinutes = null;
+
+            if (entry == null) return UtcNowProvider();
+
+            // Writer declared its own offset — nothing left to measure.
+            if (entry.TimestampUtc.HasValue)
+            {
+                origin = CmTraceOffsetOrigin.Bias;
+                // Bias uses the GetTimeZoneInformation convention (UTC = local + bias); report the
+                // value in the same sense as a measured offset (local = UTC + offset).
+                offsetMinutes = entry.BiasMinutes.HasValue ? -entry.BiasMinutes.Value : (int?)null;
+                return entry.TimestampUtc.Value;
+            }
+
+            if (!entry.HasTimestamp) return UtcNowProvider();
+
+            // ERA-AWARE RESOLUTION (2026-08-20, second attempt): a FRESH line anchors ITSELF.
+            //
+            // The first attempt (e9dba11b, reverted in 04b1a7c6) applied one measured offset per
+            // FILE — wrong, because a single log file holds lines from multiple writer eras:
+            // AgentExecutor.log is written by short-lived child processes whose zone belief
+            // flips per process, interleaved in one file (fixture
+            // tests/fixtures/cmtrace-logs/agentexecutor-two-writer-eras-v1.cmtrace). Any
+            // cross-line anchor — per file, or nearest-in-write-order — inherits that trap.
+            //
+            // Per-line self-anchoring does not: at a 100 ms poll every line of a growing pass
+            // was written essentially "now", so its own distance to the agent clock IS its
+            // writer's offset, era by era. The line's timestamp still contributes the sub-poll
+            // precision and ordering (two lines 6 ms apart stay 6 ms apart — a plain
+            // occurredAt=now could not do that), while the offset grid absorbs poll latency.
+            // Freshness is load-bearing (see FreshLineMaxAge) — backlog passes, restart
+            // catch-up and replay logs must never anchor, because an old line's AGE can round
+            // onto the grid.
+            if (_currentPassLinesAreFresh)
+            {
+                TimeSpan lineOffset;
+                if (CmTraceOffsetCalibrator.TryMeasureOffset(entry.LocalTimestamp, UtcNowProvider(), out lineOffset))
+                {
+                    origin = CmTraceOffsetOrigin.LineAnchored;
+                    offsetMinutes = (int)lineOffset.TotalMinutes;
+                    return DateTime.SpecifyKind(entry.LocalTimestamp - lineOffset, DateTimeKind.Utc);
+                }
+            }
+
+            // Fallback for everything not provably fresh: assume the reader's zone, UNIFORMLY.
+            // Wrong in absolute terms whenever the writer held a different belief, but
+            // self-consistent — both ends of a duration are wrong by the same amount, so derived
+            // durations stay right. That asymmetry is the lesson of the 04b1a7c6 revert:
+            // partially corrected is strictly worse than uniformly wrong. Origin stays None so
+            // the emitted event says so.
+            var readerZoneOffset = TimeZoneInfo.Local.GetUtcOffset(entry.LocalTimestamp);
+            offsetMinutes = (int)readerZoneOffset.TotalMinutes;
+            return CmTraceLogParser.ResolveUtcAssumingReaderZone(entry.LocalTimestamp);
+        }
+
+        // Field-forensics (tripwire, 2026-08-20): sessions e9753578 and 067797d8 both logged a
+        // measurement whose LABEL and ANCHOR could not have come from the same file iteration —
+        // 067797d8's anchor value (19:51:26.948) does not even exist in ANY log file on the
+        // device, and IntuneManagementExtension.log never produced its expected first
+        // measurement at all. Mechanism unexplained; resolution is immune (per-line anchoring),
+        // but the observational layer must convict the culprit on the next occurrence. Hence:
+        // the stream's file name travels alongside the label (a mismatch is THE smoking gun),
+        // and the first rejected anchor per file becomes visible instead of silent.
+        private readonly HashSet<string> _calibrationRejectLogged = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+        /// <summary>
+        /// Feed the pass's newest bias-less line to the calibrator and report a measured offset
+        /// that disagrees with this process's own zone — that disagreement is precisely the
+        /// condition that used to corrupt every IME-derived timestamp silently.
+        /// </summary>
+        /// <param name="sourceFileName">The calibration key (<c>_currentSourceFileName</c>).</param>
+        /// <param name="streamFileName">The file the enclosing iteration actually read. Must equal
+        /// <paramref name="sourceFileName"/> — logged loudly when it does not (see tripwire note).</param>
+        private void CalibrateFrom(string sourceFileName, string streamFileName, CmTraceLogEntry anchor)
+        {
+            if (!string.Equals(sourceFileName, streamFileName, StringComparison.OrdinalIgnoreCase))
+            {
+                _logger?.Warning(
+                    $"ImeLogTracker: CALIBRATION LABEL MISMATCH — key='{sourceFileName}' but the iteration read '{streamFileName}' " +
+                    $"(anchor local={anchor.LocalTimestamp:yyyy-MM-ddTHH:mm:ss.fffffff}). Skipping this anchor; see tripwire note.");
+                return;
+            }
+
+            TimeSpan previous;
+            var hadOffset = OffsetCalibrator.TryGetOffset(sourceFileName, out previous);
+
+            if (!OffsetCalibrator.TryCalibrate(sourceFileName, anchor.LocalTimestamp, UtcNowProvider()))
+            {
+                // Once per file: why a file that visibly grows never produces a measurement.
+                // 067797d8 ran 24 s of growing IME.log passes with no measurement at all — this
+                // silence is exactly what made the phenomenon undiagnosable from the log.
+                if (_calibrationRejectLogged.Add(sourceFileName))
+                {
+                    _logger?.Debug(
+                        $"ImeLogTracker: {sourceFileName} anchor rejected by calibrator " +
+                        $"(anchor local={anchor.LocalTimestamp:yyyy-MM-ddTHH:mm:ss.fffffff}, now={UtcNowProvider():HH:mm:ss.fff}Z) — first rejection for this file, further ones stay silent.");
+                }
+                return;
+            }
+
+            TimeSpan measured;
+            if (!OffsetCalibrator.TryGetOffset(sourceFileName, out measured)) return;
+            if (hadOffset && measured == previous) return;
+
+            // The anchor's local timestamp is part of the record ON PURPOSE (tripwire, 2026-08-20):
+            // session e9753578 logged "+02:00 measured for IntuneManagementExtension.log" although
+            // that file provably held no +2-era line — an anchor/label pairing the committed code
+            // could not be shown to produce. Should it ever happen again, the logged anchor value
+            // itself will prove (or refute) the crossing without needing the device's log files.
+            var readerZoneOffset = TimeZoneInfo.Local.GetUtcOffset(UtcNowProvider());
+            if (measured == readerZoneOffset)
+            {
+                _logger?.Debug(
+                    $"ImeLogTracker: {sourceFileName} writer offset measured {measured} (matches this process, anchor local={anchor.LocalTimestamp:yyyy-MM-ddTHH:mm:ss.fff}).");
+                return;
+            }
+
+            _logger?.Info(
+                $"ImeLogTracker: {sourceFileName} writer offset measured {measured}, this process believes {readerZoneOffset} " +
+                $"(anchor local={anchor.LocalTimestamp:yyyy-MM-ddTHH:mm:ss.fff}). Measurement is observational — resolution anchors per line.");
+        }
+
     }
 }

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/Ime/ImeLogTracker.cs

@@ -85,6 +85,42 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         /// Unspecified depending on the parser path. Normalize via SpecifyKind=Utc rather than
         /// ToUniversalTime() to avoid double-conversion when Kind is already UTC.
         /// </summary>
+        /// <summary>
+        /// Measures the UTC offset the IME process believes it is in, per log file.
+        /// <para>
+        /// Only this tracker may WRITE to it: calibration requires tailing with growth detection
+        /// so the freshness rule can be honoured, and no other collector tails. Exposed so the
+        /// snapshot-reading collectors can eventually READ from a shared instance
+        /// (tasks/todo.md, P3b).
+        /// </para>
+        /// </summary>
+        internal CmTraceOffsetCalibrator OffsetCalibrator { get; } = new CmTraceOffsetCalibrator();
+
+        /// <summary>
+        /// File whose lines are currently being processed. The polling loop walks files strictly
+        /// sequentially on a single task, so a field is sufficient to give <c>ResolveEntryUtc</c>
+        /// and the handlers the calibration key without threading it through every signature.
+        /// </summary>
+        private string _currentSourceFileName;
+
+        /// <summary>
+        /// Whether every line of the file iteration currently in flight is provably FRESH —
+        /// written after the previous look at this file, which happened at most
+        /// <see cref="FreshLineMaxAge"/> ago in THIS process. Only then may a line anchor its
+        /// own UTC offset (<see cref="CmTraceOffsetCalibrator.TryMeasureOffset"/>): the grid
+        /// rounding is safe when the line's age is bounded by seconds, and becomes a trap on
+        /// backlog whose age can hit an exact grid multiple. Same single-task justification as
+        /// <see cref="_currentSourceFileName"/>.
+        /// </summary>
+        private bool _currentPassLinesAreFresh;
+
+        /// <summary>
+        /// Maximum gap between two looks at a file for its new bytes to count as fresh. Far
+        /// above the 100 ms poll (rides out GC pauses and ESP CPU starvation), far below the
+        /// 13-minute danger zone where a line's AGE could round onto the 15-minute offset grid.
+        /// </summary>
+        internal static readonly TimeSpan FreshLineMaxAge = TimeSpan.FromSeconds(30);
+
         internal static DateTime NormalizeUtc(DateTime value) =>
             value.Kind == DateTimeKind.Utc ? value : DateTime.SpecifyKind(value, DateTimeKind.Utc);
 
@@ -191,6 +227,38 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         public string LastMatchedPatternId { get; internal set; }
         public DateTime? LastMatchedLogTimestamp { get; internal set; }
 
+        /// <summary>
+        /// Raw local time of the last matched line, exactly as the writer wrote it — no zone
+        /// attached, because the line carries none.
+        /// <para>
+        /// Recorded so an emitted event can carry the evidence for its own timestamp. Without it
+        /// a conversion error is only provable from the diagnostics archive, and of the 5,386
+        /// sessions that went through a timezone change essentially none had one — the field
+        /// analysis had to fall back to median statistics over thousands of sessions to show
+        /// what one stored value would have made obvious per session.
+        /// </para>
+        /// </summary>
+        public DateTime? LastMatchedSourceLocalTimestamp { get; internal set; }
+
+        /// <summary>Offset applied to <see cref="LastMatchedSourceLocalTimestamp"/>, in minutes.</summary>
+        public int? LastMatchedSourceOffsetMinutes { get; internal set; }
+
+        /// <summary>How that offset was arrived at — declared, measured, or neither.</summary>
+        public CmTraceOffsetOrigin LastMatchedSourceOffsetOrigin { get; internal set; }
+
+        /// <summary>
+        /// The offset the calibrator MEASURED for the source file, which is not necessarily the
+        /// one applied.
+        /// <para>
+        /// Since the 2026-08-20 revert the measurement is observational only: it is recorded so the
+        /// field tells us what an era-aware calibrator would have to work with, without acting on
+        /// it. Reported separately from <see cref="LastMatchedSourceOffsetMinutes"/> precisely so
+        /// the two can never be confused — that event said "calibrated" while carrying a wrong
+        /// value, and an honest record has to distinguish measured from applied.
+        /// </para>
+        /// </summary>
+        public int? LastMatchedMeasuredWriterOffsetMinutes { get; internal set; }
+
         // Callbacks to EnrollmentTracker
         public Action<string> OnEspPhaseChanged { get; set; }
         public Action<string> OnImeAgentVersion { get; set; }

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/Ime/LogFilePositionTracker.cs

@@ -19,6 +19,18 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         /// has been rotated - resets to 0 to read from beginning.
         /// Returns 0 if no position has been recorded yet.
         /// </summary>
+        /// <summary>
+        /// Whether this file was already observed in an earlier pass.
+        /// <para>
+        /// The offset calibration depends on this: growth measured against a size we saw before
+        /// means the new bytes were written within one poll interval, so the last line of that
+        /// pass is a valid "written now" anchor. On the FIRST sight of a file we read it from
+        /// position 0 and its last line may be arbitrarily old — anchoring on that would measure
+        /// the line's age instead of the writer's timezone offset.
+        /// </para>
+        /// </summary>
+        public bool HasSeen(string filePath) => _positions.ContainsKey(filePath);
+
         public long GetSafePosition(string filePath, long currentFileSize)
         {
             FilePositionState state;
@@ -53,6 +65,42 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
             state.LastReadTime = DateTime.UtcNow;
         }
 
+        /// <summary>
+        /// Records that the file was looked at in a poll pass — whether or not it had new data.
+        /// Creates the entry on first sight (position 0), so a file first seen EMPTY counts as
+        /// observed and its first content is provably fresh.
+        /// <para>
+        /// This timestamp is the freshness reference for per-line offset anchoring: bytes found
+        /// in the NEXT pass were written after this instant, so
+        /// <c>now - LastCheckedUtc</c> bounds the age of every line in that pass's chunk.
+        /// The caller supplies the clock (the tracker's <c>UtcNowProvider</c>) so replay/test
+        /// clocks stay consistent with the freshness comparison.
+        /// </para>
+        /// </summary>
+        public void MarkChecked(string filePath, DateTime nowUtc)
+        {
+            FilePositionState state;
+            if (!_positions.TryGetValue(filePath, out state))
+            {
+                state = new FilePositionState();
+                _positions[filePath] = state;
+            }
+
+            state.LastCheckedUtc = nowUtc;
+        }
+
+        /// <summary>
+        /// When the file was last looked at, or <see cref="DateTime.MinValue"/> when it never
+        /// was in THIS process — including entries restored from persisted state, whose
+        /// bookmark survives an agent restart but whose freshness deliberately does not
+        /// (the restart gap can hold arbitrarily old backlog).
+        /// </summary>
+        public DateTime GetLastCheckedUtc(string filePath)
+        {
+            FilePositionState state;
+            return _positions.TryGetValue(filePath, out state) ? state.LastCheckedUtc : DateTime.MinValue;
+        }
+
         /// <summary>
         /// Gets the stored position for a file, or 0 if not tracked.
         /// Does not perform rollover detection.
@@ -77,6 +125,12 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         /// <summary>
         /// Restores a previously persisted position for a file.
         /// Used on agent restart to continue reading from the last known position.
+        /// <para>
+        /// <see cref="FilePositionState.LastCheckedUtc"/> is deliberately NOT restored: the
+        /// bookmark survives the restart, the freshness guarantee does not — the first pass
+        /// after a restart reads the whole downtime backlog and must never anchor per-line
+        /// offsets on it.
+        /// </para>
         /// </summary>
         public void RestorePosition(string filePath, long position, long lastKnownSize)
         {
@@ -84,7 +138,8 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
             {
                 Position = position,
                 LastKnownSize = lastKnownSize,
-                LastReadTime = DateTime.UtcNow
+                LastReadTime = DateTime.UtcNow,
+                LastCheckedUtc = DateTime.MinValue
             };
         }
     }
@@ -94,5 +149,11 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.Ime
         public long Position { get; set; }
         public long LastKnownSize { get; set; }
         public DateTime LastReadTime { get; set; }
+
+        /// <summary>
+        /// When this file was last looked at by a poll pass IN THIS PROCESS. In-memory only —
+        /// never persisted, so a restart resets it (see <see cref="LogFilePositionTracker.RestorePosition"/>).
+        /// </summary>
+        public DateTime LastCheckedUtc { get; set; }
     }
 }

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/SystemSignals/PowerStateTransitionTracker.cs

@@ -0,0 +1,197 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using AutopilotMonitor.Agent.V2.Core.Runtime;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals
+{
+    /// <summary>
+    /// Pure state machine behind <c>PowerStateWatcherHost</c>: diffs successive
+    /// <see cref="PowerStateResult"/> snapshots into <c>power_state_change</c> emissions.
+    /// No WMI, no timers, no logging — fully deterministic and unit-testable.
+    /// <para>
+    /// Semantics:
+    /// <list type="bullet">
+    ///   <item><b>AC↔battery transitions</b> — one emission per accepted edge
+    ///         (<c>ac_to_battery</c> Warning/immediate, <c>battery_to_ac</c> Info).</item>
+    ///   <item><b>Threshold ladder</b> (default 50/30/15 %) — evaluated only while ON battery;
+    ///         each level latches once per tracker lifetime (no re-emit when the device charges
+    ///         back up and drains again — avoids plug-cycle alarm spam). A multi-level jump
+    ///         emits only the LOWEST newly-crossed level. Entering battery power already below
+    ///         a level counts as crossing it (covers "unplugged at 12 %" and, via
+    ///         <see cref="Baseline"/>, "enrollment started at 12 %").</item>
+    ///   <item><b>Storm cap</b> — a lifetime emission cap (default 20) as backstop against a
+    ///         flapping dock / dying battery controller; <see cref="EmissionCapReached"/> flips
+    ///         once so the host can log a single warning.</item>
+    /// </list>
+    /// A snapshot with <see cref="PowerStateResult.ProbeError"/> is ignored (previous state
+    /// preserved); a null <see cref="PowerStateResult.BatteryPercent"/> skips threshold
+    /// evaluation but AC diffing still works.
+    /// </para>
+    /// </summary>
+    internal sealed class PowerStateTransitionTracker
+    {
+        public const string TransitionAcToBattery = "ac_to_battery";
+        public const string TransitionBatteryToAc = "battery_to_ac";
+        public const string TransitionThresholdCrossed = "threshold_crossed";
+
+        internal static readonly int[] DefaultThresholdLadder = { 50, 30, 15 };
+        internal const int DefaultMaxEmissions = 20;
+
+        private readonly int[] _ladder;              // strictly descending
+        private readonly int _maxEmissions;
+        private readonly HashSet<int> _latchedLevels = new HashSet<int>();
+
+        private bool _hasState;
+        private bool _lastOnAc;
+        private int _emitted;
+
+        public PowerStateTransitionTracker(IReadOnlyList<int>? thresholdLadder = null, int maxEmissions = DefaultMaxEmissions)
+        {
+            _ladder = (thresholdLadder ?? DefaultThresholdLadder).OrderByDescending(l => l).ToArray();
+            _maxEmissions = maxEmissions;
+        }
+
+        /// <summary>True once the lifetime emission cap suppressed at least one emission.</summary>
+        public bool EmissionCapReached { get; private set; }
+
+        /// <summary>
+        /// Latches the arm-time state silently — except when the device is already on battery
+        /// at/below a ladder level, which yields one threshold emission for the lowest crossed
+        /// level (an enrollment STARTING at 12 % must still produce the event the analyze rule
+        /// matches on). No AC-transition emission is ever produced from a baseline.
+        /// </summary>
+        public IReadOnlyList<PowerStateEmission> Baseline(PowerStateResult probe)
+        {
+            if (probe == null || probe.ProbeError != null || !probe.HasBattery)
+                return Array.Empty<PowerStateEmission>();
+
+            _hasState = true;
+            _lastOnAc = probe.OnAcPower;
+
+            var emissions = new List<PowerStateEmission>();
+            EvaluateThresholds(probe, emissions);
+            return emissions;
+        }
+
+        /// <summary>
+        /// Diffs a fresh (host-debounced) snapshot against the last accepted state and returns
+        /// 0..n emissions — an AC transition and a threshold crossing can co-occur (unplugged
+        /// at 10 % ⇒ <c>ac_to_battery</c> + <c>threshold_crossed:15</c>).
+        /// </summary>
+        public IReadOnlyList<PowerStateEmission> Evaluate(PowerStateResult probe)
+        {
+            if (probe == null || probe.ProbeError != null)
+                return Array.Empty<PowerStateEmission>();
+            if (!_hasState)
+                return Baseline(probe);
+
+            var emissions = new List<PowerStateEmission>();
+
+            if (_lastOnAc && !probe.OnAcPower)
+            {
+                Emit(emissions, new PowerStateEmission(
+                    transition: TransitionAcToBattery,
+                    thresholdPercent: null,
+                    probe: probe,
+                    severity: EventSeverity.Warning,
+                    immediateUpload: true,
+                    message: $"Power source switched from AC to battery ({FormatPercent(probe)} remaining) during enrollment"));
+            }
+            else if (!_lastOnAc && probe.OnAcPower)
+            {
+                Emit(emissions, new PowerStateEmission(
+                    transition: TransitionBatteryToAc,
+                    thresholdPercent: null,
+                    probe: probe,
+                    severity: EventSeverity.Info,
+                    immediateUpload: false,
+                    message: $"Power source switched back to AC ({FormatPercent(probe)}{(probe.IsCharging ? ", charging" : string.Empty)})"));
+            }
+
+            _lastOnAc = probe.OnAcPower;
+            EvaluateThresholds(probe, emissions);
+            return emissions;
+        }
+
+        /// <summary>
+        /// While on battery with a known percentage: emit the LOWEST ladder level at/above the
+        /// current charge that is not yet latched, then latch every level at/above the charge
+        /// (a 60 %→10 % jump emits threshold 15 only, latching 50/30/15).
+        /// </summary>
+        private void EvaluateThresholds(PowerStateResult probe, List<PowerStateEmission> emissions)
+        {
+            if (probe.OnAcPower || !probe.BatteryPercent.HasValue) return;
+            var percent = probe.BatteryPercent.Value;
+
+            int? lowestCrossed = null;
+            foreach (var level in _ladder) // descending — the last match is the lowest crossed level
+            {
+                if (percent <= level && !_latchedLevels.Contains(level))
+                    lowestCrossed = level;
+            }
+            if (!lowestCrossed.HasValue) return;
+
+            foreach (var level in _ladder)
+            {
+                if (percent <= level) _latchedLevels.Add(level);
+            }
+
+            var threshold = lowestCrossed.Value;
+            var severity = threshold <= 15 ? EventSeverity.Error
+                         : threshold <= 30 ? EventSeverity.Warning
+                         : EventSeverity.Info;
+            Emit(emissions, new PowerStateEmission(
+                transition: TransitionThresholdCrossed,
+                thresholdPercent: threshold,
+                probe: probe,
+                severity: severity,
+                immediateUpload: severity >= EventSeverity.Warning,
+                message: $"Battery dropped below {threshold}% ({FormatPercent(probe)} remaining) while enrolling on battery power"));
+        }
+
+        private void Emit(List<PowerStateEmission> emissions, PowerStateEmission emission)
+        {
+            if (_emitted >= _maxEmissions)
+            {
+                EmissionCapReached = true;
+                return;
+            }
+            _emitted++;
+            emissions.Add(emission);
+        }
+
+        private static string FormatPercent(PowerStateResult probe)
+            => probe.BatteryPercent.HasValue ? $"battery {probe.BatteryPercent.Value}%" : "battery level unknown";
+    }
+
+    /// <summary>One decided <c>power_state_change</c> emission — the host maps this 1:1 onto an event.</summary>
+    internal sealed class PowerStateEmission
+    {
+        public PowerStateEmission(string transition, int? thresholdPercent, PowerStateResult probe,
+            EventSeverity severity, bool immediateUpload, string message)
+        {
+            Transition = transition;
+            ThresholdPercent = thresholdPercent;
+            OnAcPower = probe.OnAcPower;
+            BatteryPercent = probe.BatteryPercent;
+            IsCharging = probe.IsCharging;
+            BatteryLifeMinutes = probe.BatteryLifeMinutes;
+            Severity = severity;
+            ImmediateUpload = immediateUpload;
+            Message = message;
+        }
+
+        public string Transition { get; }
+        public int? ThresholdPercent { get; }
+        public bool OnAcPower { get; }
+        public int? BatteryPercent { get; }
+        public bool IsCharging { get; }
+        public int? BatteryLifeMinutes { get; }
+        public EventSeverity Severity { get; }
+        public bool ImmediateUpload { get; }
+        public string Message { get; }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/SystemSignals/StallProbeCollector.cs

@@ -580,10 +580,22 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals
                 var scanText = rawLine;
                 if (CmTraceLogParser.TryParseLine(rawLine, out var entry))
                 {
-                    // Provably stale → not progress. (TryParseLine falls back to now on an
-                    // unparseable timestamp, which keeps the line fresh — the safe default.)
-                    if (entry.Timestamp < cutoffUtc)
-                        continue;
+                    // Provably stale → not progress. A line without a parseable timestamp counts
+                    // as fresh — the safe default, since treating it as stale would hide progress.
+                    //
+                    // This collector reads a file snapshot rather than tailing it, so it cannot
+                    // measure the writer's UTC offset itself and falls back to this process's zone
+                    // (see ResolveUtcAssumingReaderZone). That fallback is wrong by exactly the
+                    // gap between the two processes' zone beliefs. It is the pre-existing
+                    // behaviour, kept deliberately unchanged here; the tracker-owned calibrator is
+                    // wired in separately so this commit shifts no behaviour.
+                    if (entry.HasTimestamp)
+                    {
+                        var entryUtc = entry.TimestampUtc
+                            ?? CmTraceLogParser.ResolveUtcAssumingReaderZone(entry.LocalTimestamp);
+                        if (entryUtc < cutoffUtc)
+                            continue;
+                    }
                     scanText = entry.Message;
                 }
 

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Enrollment/SystemSignals/SystemTimelineTracker.cs

@@ -0,0 +1,681 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.Eventing.Reader;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Xml.Linq;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Orchestration;
+using AutopilotMonitor.Shared;
+using AutopilotMonitor.Shared.Models;
+using Newtonsoft.Json;
+
+namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals
+{
+    /// <summary>
+    /// Watches the <c>System</c> event log for two enrollment blind spots and forwards them as
+    /// timeline ground truth:
+    /// <list type="bullet">
+    ///   <item><b>System clock steps</b> (Kernel-General EventID 1) → <c>system_clock_changed</c>.
+    ///         The payload carries <c>oldTime</c>/<c>newTime</c>/<c>timeDeltaMs</c> plus the
+    ///         setting process — the "clock set from X to Y" fact that today has to be inferred
+    ///         from timestamp discontinuities. w32time also logs frequent 1 ms micro-slews on the
+    ///         same EventID, so emissions are gated on <see cref="MinClockDeltaMs"/>.</item>
+    ///   <item><b>Completed sleep episodes</b> → <c>system_sleep_episode</c>. Classic S3/S4 comes
+    ///         from Power-Troubleshooter EventID 1 (one event per episode at wake, carrying
+    ///         SleepTime + WakeTime). Modern Standby comes from Kernel-Power EventID 507 (exit),
+    ///         whose payload carries the scenario duration and the actual sleep residency; the
+    ///         enter time is derived as exit − duration. Kernel-Power 506 (enter) is deliberately
+    ///         NOT consumed: 507 already carries everything, and pairing 506/507 would need an
+    ///         orphan-tolerant state machine across agent restarts for zero information gain —
+    ///         an episode without a 507 never completed and would not be emitted under any design.</item>
+    /// </list>
+    /// <para>
+    /// <b>Payload times are authoritative.</b> The decisive clock correction (w32time fixing a
+    /// wrong BIOS clock) happens exactly when the device clock is untrustworthy, and the backend
+    /// clamps implausible event timestamps to server time. All semantic instants therefore travel
+    /// as explicit ISO-8601 payload fields, never only as the event's own <c>Timestamp</c>.
+    /// </para>
+    /// <para>
+    /// <b>Backfill + cross-restart dedup</b> mirror <see cref="WindowsUpdateTracker"/>: the System
+    /// .evtx persists across the OOBE reboots, so a startup scan recovers pre-agent clock steps
+    /// and standby episodes; a persisted RecordId watermark plus an intra-run seen-set (a HashSet,
+    /// NOT a high-water mark — see the field comment) keep restarts from re-emitting.
+    /// </para>
+    /// </summary>
+    internal sealed class SystemTimelineTracker : IDisposable
+    {
+        internal const string Channel = "System";
+
+        internal const string ProviderKernelGeneral       = "Microsoft-Windows-Kernel-General";       // EventID 1: system time changed
+        internal const string ProviderPowerTroubleshooter = "Microsoft-Windows-Power-Troubleshooter"; // EventID 1: resumed from classic sleep/hibernate
+        internal const string ProviderKernelPower         = "Microsoft-Windows-Kernel-Power";         // EventID 507: Modern Standby exit
+
+        internal const int EventId_ClockChange       = 1;
+        internal const int EventId_ClassicResume     = 1;
+        internal const int EventId_ModernStandbyExit = 507;
+
+        internal const string WatermarkStateFileName = "system-timeline-watermark.json";
+
+        // w32time logs Kernel-General 1 for routine 1 ms slew corrections (verified live: several
+        // per hour). Only genuine steps are timeline-relevant; anything below this is claimed in
+        // the dedup set but never emitted.
+        internal const long MinClockDeltaMs = 2000;
+
+        // A step of at least 5 minutes can invalidate token/cert validation windows and visibly
+        // reorders the timeline (matches the web's TimeJumpBadge threshold) — surface it fast.
+        internal const long ClockDeltaWarningMs = 5 * 60 * 1000;
+
+        // Modern Standby logs a 506/507 pair for every screen-off scenario, including seconds-long
+        // ones where the device never actually slept (SleepDurationInUs 0). Only episodes with
+        // real sleep residency are emitted. Classic Power-Troubleshooter episodes have no floor:
+        // they only exist for genuinely completed S3/S4 transitions.
+        internal const long MinSleepDurationSeconds = 60;
+
+        private readonly AgentLogger _logger;
+        private readonly string _sessionId;
+        private readonly string _tenantId;
+        private readonly InformationalEventPost _post;
+        private readonly bool _backfillEnabled;
+        private readonly int _backfillLookbackMinutes;
+        private readonly string _stateDirectory;
+
+        private EventLogWatcher _watcher;
+
+        // Dedup. Guarded because EventRecordWritten callbacks run concurrently with the backfill scan.
+        //
+        // Cross-restart boundary loaded from disk: the highest RecordId emitted in a PRIOR run.
+        // Immutable during this run — records at/below it were already emitted before this process
+        // started and must not be re-emitted by the backfill scan.
+        private long _restartWatermark = -1;
+        // RecordIds claimed in THIS run — the intra-run dedup set. Deliberately a HashSet, NOT a
+        // high-water mark: the live watcher is armed before the backfill runs, so a live record with
+        // a HIGHER RecordId can be processed before/during backfill. A high-water mark would then
+        // make the dedup skip every older, never-emitted backfill record — silently dropping exactly
+        // the pre-agent clock corrections and standby episodes this tracker exists for. The targeted
+        // records are low-volume, so the set stays tiny.
+        private readonly HashSet<long> _seenThisRun = new HashSet<long>();
+        // Highest RecordId claimed so far (max of restart watermark + this run). Persisted so the
+        // next run's restart watermark is correct.
+        private long _maxEmittedRecordId = -1;
+        private readonly object _watermarkLock = new object();
+
+        public SystemTimelineTracker(
+            string sessionId,
+            string tenantId,
+            InformationalEventPost post,
+            AgentLogger logger,
+            bool backfillEnabled = true,
+            int backfillLookbackMinutes = 1440,
+            string stateDirectory = null)
+        {
+            _sessionId = sessionId ?? throw new ArgumentNullException(nameof(sessionId));
+            _tenantId = tenantId ?? throw new ArgumentNullException(nameof(tenantId));
+            _post = post ?? throw new ArgumentNullException(nameof(post));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _backfillEnabled = backfillEnabled;
+            _backfillLookbackMinutes = backfillLookbackMinutes;
+            _stateDirectory = stateDirectory != null ? Environment.ExpandEnvironmentVariables(stateDirectory) : null;
+        }
+
+        public void Start()
+        {
+            LoadWatermark();
+            StartWatcher();
+
+            if (_backfillEnabled && _backfillLookbackMinutes > 0)
+                BackfillRecentEvents();
+            else
+                _logger.Info("SystemTimeline backfill disabled by config");
+        }
+
+        public void Stop()
+        {
+            if (_watcher == null) return;
+            try
+            {
+                _watcher.Enabled = false;
+                _watcher.Dispose();
+                _logger.Info("SystemTimeline watcher stopped");
+            }
+            catch (Exception ex)
+            {
+                _logger.Error("Error stopping SystemTimeline watcher", ex);
+            }
+            finally
+            {
+                _watcher = null;
+            }
+        }
+
+        public void Dispose() => Stop();
+
+        // -----------------------------------------------------------------------
+        // Watcher lifecycle
+        // -----------------------------------------------------------------------
+
+        private void StartWatcher()
+        {
+            try
+            {
+                var query = new EventLogQuery(Channel, PathType.LogName, BuildXPath());
+                _watcher = new EventLogWatcher(query);
+                _watcher.EventRecordWritten += OnEventRecordWritten;
+                _watcher.Enabled = true;
+                _logger.Info($"SystemTimeline watcher started: {Channel} (clock changes + sleep episodes)");
+            }
+            catch (EventLogNotFoundException)
+            {
+                _logger.Warning($"SystemTimeline event log not found: {Channel} (normal on non-Windows test environments)");
+            }
+            catch (UnauthorizedAccessException ex)
+            {
+                _logger.Warning($"SystemTimeline watcher access denied for {Channel}: {ex.Message}");
+            }
+            catch (Exception ex)
+            {
+                _logger.Error($"Failed to start SystemTimeline watcher for {Channel}", ex);
+                CollectorDegradationReporter.Report(_post, _sessionId, _tenantId,
+                    collectorName: "SystemTimelineTracker", reason: $"watcher_arm_failed:{Channel}", ex: ex);
+            }
+        }
+
+        /// <summary>
+        /// Provider-qualified XPath for the three targeted signals. Provider filtering is mandatory
+        /// on the System channel — EventID 1 alone matches many unrelated providers.
+        /// Exposed as internal for tests.
+        /// </summary>
+        internal static string BuildXPath() =>
+            "*[System[" + ProviderIdClauses() + "]]";
+
+        /// <summary>Backfill variant of <see cref="BuildXPath"/> with the lookback window applied.</summary>
+        internal static string BuildBackfillXPath(long lookbackMs) =>
+            "*[System[(" + ProviderIdClauses() + $") and TimeCreated[timediff(@SystemTime) <= {lookbackMs}]]]";
+
+        private static string ProviderIdClauses() =>
+            $"(Provider[@Name='{ProviderKernelGeneral}'] and EventID={EventId_ClockChange})" +
+            $" or (Provider[@Name='{ProviderPowerTroubleshooter}'] and EventID={EventId_ClassicResume})" +
+            $" or (Provider[@Name='{ProviderKernelPower}'] and EventID={EventId_ModernStandbyExit})";
+
+        // -----------------------------------------------------------------------
+        // Event processing
+        // -----------------------------------------------------------------------
+
+        private void OnEventRecordWritten(object sender, EventRecordWrittenEventArgs e)
+        {
+            if (e.EventRecord == null) return;
+            try
+            {
+                ProcessRecord(e.EventRecord, isBackfill: false);
+            }
+            catch (Exception ex)
+            {
+                _logger.Error("Error processing SystemTimeline event", ex);
+            }
+        }
+
+        private void ProcessRecord(EventRecord record, bool isBackfill)
+        {
+            var recordId = record.RecordId ?? -1;
+
+            // Cheap dedup gate BEFORE the XML rendering work.
+            if (IsAlreadyProcessed(recordId))
+                return;
+
+            string xml = null;
+            try { xml = record.ToXml(); }
+            catch { /* fall through with empty EventData */ }
+
+            ProcessEvent(
+                providerName: record.ProviderName,
+                eventId: record.Id,
+                recordId: recordId,
+                timeCreatedUtc: record.TimeCreated?.ToUniversalTime(),
+                eventData: ParseEventData(xml),
+                isBackfill: isBackfill);
+        }
+
+        /// <summary>
+        /// Core processing extracted to primitive inputs so tests can drive it without synthesizing
+        /// an abstract, Windows-only <see cref="EventRecord"/> (WindowsUpdateTracker test-seam
+        /// pattern; a plain dictionary instead of named args because three providers with ~10
+        /// payload fields each make a fixed signature impractical).
+        /// </summary>
+        internal void ProcessEvent(
+            string providerName,
+            int eventId,
+            long recordId,
+            DateTime? timeCreatedUtc,
+            Dictionary<string, string> eventData,
+            bool isBackfill)
+        {
+            if (!MarkProcessed(recordId))
+                return; // already emitted (cross-restart or duplicate delivery)
+
+            eventData = eventData ?? new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+
+            if (string.Equals(providerName, ProviderKernelGeneral, StringComparison.OrdinalIgnoreCase) && eventId == EventId_ClockChange)
+                HandleClockChange(recordId, timeCreatedUtc, eventData, isBackfill);
+            else if (string.Equals(providerName, ProviderPowerTroubleshooter, StringComparison.OrdinalIgnoreCase) && eventId == EventId_ClassicResume)
+                HandleClassicResume(recordId, timeCreatedUtc, eventData, isBackfill);
+            else if (string.Equals(providerName, ProviderKernelPower, StringComparison.OrdinalIgnoreCase) && eventId == EventId_ModernStandbyExit)
+                HandleModernStandbyExit(recordId, timeCreatedUtc, eventData, isBackfill);
+            // Anything else slipped past the XPath filter — ignore.
+        }
+
+        // -----------------------------------------------------------------------
+        // system_clock_changed (Kernel-General EventID 1)
+        // -----------------------------------------------------------------------
+
+        private void HandleClockChange(long recordId, DateTime? timeCreatedUtc, Dictionary<string, string> eventData, bool isBackfill)
+        {
+            eventData.TryGetValue("NewTime", out var newTimeRaw);
+            eventData.TryGetValue("OldTime", out var oldTimeRaw);
+            var newTime = TryParseUtc(newTimeRaw);
+            var oldTime = TryParseUtc(oldTimeRaw);
+
+            // Signed delta preferably from the authoritative instants (NewTime − OldTime carries
+            // the direction unambiguously); TimeDeltaInMs is the fallback when either fails to
+            // parse. Records with neither are unusable and skipped (already claimed by dedup).
+            long deltaMs;
+            if (newTime.HasValue && oldTime.HasValue)
+            {
+                deltaMs = (long)Math.Round((newTime.Value - oldTime.Value).TotalMilliseconds);
+            }
+            else if (eventData.TryGetValue("TimeDeltaInMs", out var deltaRaw) &&
+                long.TryParse(deltaRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var parsedDelta))
+            {
+                deltaMs = parsedDelta;
+            }
+            else
+            {
+                _logger.Debug($"SystemTimeline: clock-change record {recordId} has no usable times/delta — skipped");
+                return;
+            }
+
+            if (Math.Abs(deltaMs) < MinClockDeltaMs)
+                return; // w32time micro-slew — claimed (MarkProcessed) but never emitted
+
+            eventData.TryGetValue("Reason", out var reasonRaw);
+            int.TryParse(reasonRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var reason);
+            var reasonText = reason == 1 ? "application_set"
+                : reason == 2 ? "hardware_clock_sync"
+                : "unknown";
+
+            eventData.TryGetValue("ProcessName", out var processName);
+
+            var data = new Dictionary<string, object>
+            {
+                { "timeDeltaMs", deltaMs },
+                { "reason", reason },
+                { "reasonText", reasonText },
+                { "backfilled", isBackfill },
+            };
+            // Authoritative instants: re-normalized ISO-8601 when parseable, raw pass-through
+            // otherwise — the payload must survive even a malformed provider rendering.
+            data["newTime"] = newTime.HasValue ? newTime.Value.ToString("o") : (object)(newTimeRaw ?? string.Empty);
+            data["oldTime"] = oldTime.HasValue ? oldTime.Value.ToString("o") : (object)(oldTimeRaw ?? string.Empty);
+            if (recordId >= 0) data["recordId"] = recordId;
+            if (timeCreatedUtc.HasValue) data["timeCreated"] = timeCreatedUtc.Value.ToString("o");
+            if (!string.IsNullOrEmpty(processName)) data["processName"] = processName;
+            if (eventData.TryGetValue("ProcessID", out var pidRaw) &&
+                int.TryParse(pidRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var pid))
+            {
+                data["processId"] = pid;
+            }
+
+            var direction = deltaMs >= 0 ? "forward" : "backward";
+            var processLeaf = ProcessLeafName(processName);
+            var message = $"System clock stepped {direction} {FormatDuration(TimeSpan.FromMilliseconds(Math.Abs(deltaMs)))}" +
+                $" (reason: {reasonText}" + (processLeaf != null ? $", process: {processLeaf})" : ")");
+
+            var isLargeStep = Math.Abs(deltaMs) >= ClockDeltaWarningMs;
+            _post.Emit(new EnrollmentEvent
+            {
+                SessionId = _sessionId,
+                TenantId = _tenantId,
+                // The record's own creation time, not UtcNow: backfilled pre-agent clock steps must
+                // land on the timeline where they happened (WindowsUpdateTracker convention).
+                Timestamp = timeCreatedUtc ?? DateTime.UtcNow,
+                EventType = Constants.EventTypes.SystemClockChanged,
+                Severity = isLargeStep ? EventSeverity.Warning : EventSeverity.Info,
+                Source = "SystemTimelineWatcher",
+                Phase = EnrollmentPhase.Unknown,
+                Message = message,
+                Data = data,
+                ImmediateUpload = isLargeStep,
+            });
+        }
+
+        // -----------------------------------------------------------------------
+        // system_sleep_episode — classic sleep/hibernate (Power-Troubleshooter EventID 1)
+        // -----------------------------------------------------------------------
+
+        private void HandleClassicResume(long recordId, DateTime? timeCreatedUtc, Dictionary<string, string> eventData, bool isBackfill)
+        {
+            eventData.TryGetValue("SleepTime", out var sleepRaw);
+            eventData.TryGetValue("WakeTime", out var wakeRaw);
+            var enteredAt = TryParseUtc(sleepRaw);
+            var exitedAt = TryParseUtc(wakeRaw);
+
+            // EffectiveState 5 = hibernate (S4); TargetState is the fallback when the effective
+            // state is missing (older event versions).
+            eventData.TryGetValue("EffectiveState", out var effectiveState);
+            eventData.TryGetValue("TargetState", out var targetState);
+            var stateValue = !string.IsNullOrEmpty(effectiveState) ? effectiveState : targetState;
+            var kind = stateValue == "5" ? "hibernate" : "sleep";
+
+            long? durationSeconds = null;
+            if (enteredAt.HasValue && exitedAt.HasValue && exitedAt.Value > enteredAt.Value)
+                durationSeconds = (long)Math.Round((exitedAt.Value - enteredAt.Value).TotalSeconds);
+
+            var data = new Dictionary<string, object>
+            {
+                { "kind", kind },
+                { "backfilled", isBackfill },
+            };
+            data["enteredAt"] = enteredAt.HasValue ? enteredAt.Value.ToString("o") : (object)(sleepRaw ?? string.Empty);
+            data["exitedAt"] = exitedAt.HasValue ? exitedAt.Value.ToString("o") : (object)(wakeRaw ?? string.Empty);
+            if (durationSeconds.HasValue) data["durationSeconds"] = durationSeconds.Value;
+            if (recordId >= 0) data["recordId"] = recordId;
+            if (timeCreatedUtc.HasValue) data["timeCreated"] = timeCreatedUtc.Value.ToString("o");
+            if (eventData.TryGetValue("WakeSourceType", out var wakeTypeRaw) &&
+                int.TryParse(wakeTypeRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var wakeType))
+            {
+                data["wakeSourceType"] = wakeType;
+            }
+            eventData.TryGetValue("WakeSourceText", out var wakeText);
+            if (!string.IsNullOrEmpty(wakeText)) data["wakeSourceText"] = wakeText;
+
+            var durationLabel = durationSeconds.HasValue
+                ? " after " + FormatDuration(TimeSpan.FromSeconds(durationSeconds.Value))
+                : string.Empty;
+            var wakeLabel = !string.IsNullOrEmpty(wakeText) ? $" (wake source: {wakeText})" : string.Empty;
+
+            EmitSleepEpisode(timeCreatedUtc, data,
+                $"Device resumed from {kind}{durationLabel}{wakeLabel}");
+        }
+
+        // -----------------------------------------------------------------------
+        // system_sleep_episode — Modern Standby (Kernel-Power EventID 507)
+        // -----------------------------------------------------------------------
+
+        private void HandleModernStandbyExit(long recordId, DateTime? timeCreatedUtc, Dictionary<string, string> eventData, bool isBackfill)
+        {
+            eventData.TryGetValue("SleepDurationInUs", out var sleepUsRaw);
+            long.TryParse(sleepUsRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var sleepUs);
+            var sleepDurationSeconds = sleepUs / 1_000_000;
+
+            // Every screen-off scenario logs a 507, including seconds-long ones where the device
+            // never slept (SleepDurationInUs 0, incl. SleepEntered=false) — one gate covers both.
+            if (sleepDurationSeconds < MinSleepDurationSeconds)
+                return; // claimed but not an episode worth the timeline
+
+            eventData.TryGetValue("DurationInUs", out var durationUsRaw);
+            long.TryParse(durationUsRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var durationUs);
+            if (durationUs < sleepUs) durationUs = sleepUs; // scenario duration can never undercut its sleep residency
+
+            var durationSeconds = durationUs / 1_000_000;
+            var exitedAt = timeCreatedUtc; // 507 is written at scenario exit
+            DateTime? enteredAt = exitedAt.HasValue
+                ? exitedAt.Value.AddMilliseconds(-(durationUs / 1000.0))
+                : (DateTime?)null;
+
+            var data = new Dictionary<string, object>
+            {
+                { "kind", "modern_standby" },
+                { "durationSeconds", durationSeconds },
+                { "sleepDurationSeconds", sleepDurationSeconds },
+                { "backfilled", isBackfill },
+            };
+            if (enteredAt.HasValue) data["enteredAt"] = enteredAt.Value.ToString("o");
+            if (exitedAt.HasValue) data["exitedAt"] = exitedAt.Value.ToString("o");
+            if (recordId >= 0) data["recordId"] = recordId;
+            if (timeCreatedUtc.HasValue) data["timeCreated"] = timeCreatedUtc.Value.ToString("o");
+            if (eventData.TryGetValue("Reason", out var reasonRaw) &&
+                int.TryParse(reasonRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var reason))
+            {
+                data["reason"] = reason;
+            }
+            bool? onAcPower = null;
+            if (eventData.TryGetValue("PowerStateAc", out var acRaw) && bool.TryParse(acRaw, out var ac))
+            {
+                onAcPower = ac;
+                data["onAcPower"] = ac;
+            }
+            if (eventData.TryGetValue("BatteryRemainingCapacityOnExit", out var battRaw) &&
+                long.TryParse(battRaw, NumberStyles.Integer, CultureInfo.InvariantCulture, out var batt))
+            {
+                data["batteryRemainingCapacityOnExit"] = batt;
+            }
+
+            var powerLabel = onAcPower.HasValue ? (onAcPower.Value ? ", on AC" : ", on battery") : string.Empty;
+            EmitSleepEpisode(timeCreatedUtc, data,
+                $"Device exited Modern Standby after {FormatDuration(TimeSpan.FromSeconds(durationSeconds))}" +
+                $" (slept {FormatDuration(TimeSpan.FromSeconds(sleepDurationSeconds))}{powerLabel})");
+        }
+
+        private void EmitSleepEpisode(DateTime? timeCreatedUtc, Dictionary<string, object> data, string message)
+        {
+            _post.Emit(new EnrollmentEvent
+            {
+                SessionId = _sessionId,
+                TenantId = _tenantId,
+                // Wake/exit moment (the record's creation time) — backfilled pre-agent episodes
+                // must land on the timeline where the device actually woke.
+                Timestamp = timeCreatedUtc ?? DateTime.UtcNow,
+                EventType = Constants.EventTypes.SystemSleepEpisode,
+                Severity = EventSeverity.Info,
+                Source = "SystemTimelineWatcher",
+                Phase = EnrollmentPhase.Unknown,
+                Message = message,
+                Data = data,
+                ImmediateUpload = false,
+            });
+        }
+
+        // -----------------------------------------------------------------------
+        // Parsing helpers
+        // -----------------------------------------------------------------------
+
+        /// <summary>
+        /// Extracts <c>&lt;Data Name="..."&gt;value&lt;/Data&gt;</c> pairs from an event's rendered
+        /// XML, keyed case-insensitively. Namespace-agnostic (matches on local name). Returns an
+        /// empty map on null/malformed XML — never throws.
+        /// </summary>
+        internal static Dictionary<string, string> ParseEventData(string xml)
+        {
+            var result = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            if (string.IsNullOrEmpty(xml)) return result;
+
+            try
+            {
+                var doc = XDocument.Parse(xml);
+                foreach (var el in doc.Descendants().Where(e => e.Name.LocalName == "Data"))
+                {
+                    var nameAttr = el.Attribute("Name");
+                    if (nameAttr == null || string.IsNullOrEmpty(nameAttr.Value)) continue;
+                    if (!result.ContainsKey(nameAttr.Value))
+                        result[nameAttr.Value] = el.Value;
+                }
+            }
+            catch
+            {
+                // Malformed / unexpected XML — best effort, return what we have.
+            }
+
+            return result;
+        }
+
+        internal static DateTime? TryParseUtc(string value)
+        {
+            if (string.IsNullOrWhiteSpace(value)) return null;
+            return DateTime.TryParse(value, CultureInfo.InvariantCulture,
+                DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out var parsed)
+                ? parsed
+                : (DateTime?)null;
+        }
+
+        /// <summary>Compact human duration for messages: "2h 05m", "56m 12s", "45s".</summary>
+        internal static string FormatDuration(TimeSpan span)
+        {
+            if (span.TotalHours >= 1)
+                return $"{(long)span.TotalHours}h {span.Minutes:D2}m";
+            if (span.TotalMinutes >= 1)
+                return $"{span.Minutes}m {span.Seconds:D2}s";
+            return $"{(long)Math.Ceiling(span.TotalSeconds)}s";
+        }
+
+        /// <summary>Leaf file name of a kernel device path like <c>\Device\HarddiskVolume3\Windows\System32\svchost.exe</c>.</summary>
+        internal static string ProcessLeafName(string devicePath)
+        {
+            if (string.IsNullOrEmpty(devicePath)) return null;
+            var idx = devicePath.LastIndexOf('\\');
+            var leaf = idx >= 0 ? devicePath.Substring(idx + 1) : devicePath;
+            return string.IsNullOrEmpty(leaf) ? null : leaf;
+        }
+
+        // -----------------------------------------------------------------------
+        // Backfill
+        // -----------------------------------------------------------------------
+
+        private void BackfillRecentEvents()
+        {
+            try
+            {
+                var lookbackMs = (long)_backfillLookbackMinutes * 60 * 1000;
+                _logger.Info($"SystemTimeline backfill: scanning {Channel} " +
+                    $"(lookback={_backfillLookbackMinutes}min, restartWatermark={_restartWatermark})");
+
+                var query = new EventLogQuery(Channel, PathType.LogName, BuildBackfillXPath(lookbackMs));
+
+                int processed = 0;
+                using (var reader = new EventLogReader(query))
+                {
+                    EventRecord record;
+                    while ((record = reader.ReadEvent()) != null)
+                    {
+                        using (record)
+                        {
+                            ProcessRecord(record, isBackfill: true);
+                            processed++;
+                        }
+                    }
+                }
+
+                if (processed == 0)
+                    _logger.Debug($"SystemTimeline backfill: no targeted events in last {_backfillLookbackMinutes} minutes");
+                else
+                    _logger.Info($"SystemTimeline backfill: scanned {processed} record(s)");
+            }
+            catch (EventLogNotFoundException)
+            {
+                _logger.Warning($"SystemTimeline event log not found during backfill: {Channel} (normal on non-Windows test environments)");
+            }
+            catch (UnauthorizedAccessException ex)
+            {
+                _logger.Warning($"SystemTimeline backfill access denied: {ex.Message}");
+            }
+            catch (Exception ex)
+            {
+                _logger.Warning($"SystemTimeline backfill failed: {ex.Message}");
+            }
+        }
+
+        // -----------------------------------------------------------------------
+        // Watermark dedup (cross-restart)
+        // -----------------------------------------------------------------------
+
+        private bool IsAlreadyProcessed(long recordId)
+        {
+            if (recordId < 0) return false; // no RecordId → cannot dedup, let it through
+            lock (_watermarkLock)
+            {
+                return recordId <= _restartWatermark || _seenThisRun.Contains(recordId);
+            }
+        }
+
+        /// <summary>
+        /// Atomically claims <paramref name="recordId"/>. Returns true if this is the first time we
+        /// see it (caller should evaluate/emit), false if it was already processed — either in a
+        /// PRIOR run (at/below the restart watermark) or already this run (in the seen-set). Only
+        /// advances + persists the max on a genuinely-new, higher RecordId. Records without a
+        /// RecordId (-1) are always processed, never tracked or persisted. Note: threshold-suppressed
+        /// records are claimed too, so a restart's backfill does not re-evaluate them.
+        /// </summary>
+        private bool MarkProcessed(long recordId)
+        {
+            if (recordId < 0) return true;
+
+            long toPersist = -1;
+            lock (_watermarkLock)
+            {
+                if (recordId <= _restartWatermark || !_seenThisRun.Add(recordId))
+                    return false;
+
+                if (recordId > _maxEmittedRecordId)
+                {
+                    _maxEmittedRecordId = recordId;
+                    toPersist = _maxEmittedRecordId;
+                }
+            }
+            if (toPersist >= 0) PersistWatermark(toPersist);
+            return true;
+        }
+
+        internal void LoadWatermark()
+        {
+            if (string.IsNullOrEmpty(_stateDirectory)) return;
+
+            var filePath = Path.Combine(_stateDirectory, WatermarkStateFileName);
+            if (!File.Exists(filePath)) return;
+
+            try
+            {
+                var json = File.ReadAllText(filePath);
+                var state = JsonConvert.DeserializeObject<WatermarkState>(json);
+                if (state != null)
+                {
+                    lock (_watermarkLock)
+                    {
+                        _restartWatermark = state.LastRecordId;
+                        _maxEmittedRecordId = state.LastRecordId;
+                    }
+                    _logger.Info($"SystemTimeline watermark loaded: lastRecordId={state.LastRecordId} (persisted {state.PersistedUtc:O})");
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.Warning($"Failed to load SystemTimeline watermark: {ex.Message}");
+            }
+        }
+
+        private void PersistWatermark(long recordId)
+        {
+            if (string.IsNullOrEmpty(_stateDirectory)) return;
+
+            try
+            {
+                Directory.CreateDirectory(_stateDirectory);
+                var filePath = Path.Combine(_stateDirectory, WatermarkStateFileName);
+                var state = new WatermarkState { LastRecordId = recordId, PersistedUtc = DateTime.UtcNow };
+                var json = JsonConvert.SerializeObject(state, Formatting.Indented);
+                var tempPath = filePath + ".tmp";
+                File.WriteAllText(tempPath, json);
+                File.Copy(tempPath, filePath, overwrite: true);
+                try { File.Delete(tempPath); } catch { }
+            }
+            catch (Exception ex)
+            {
+                _logger.Warning($"Failed to persist SystemTimeline watermark: {ex.Message}");
+            }
+        }
+
+        internal sealed class WatermarkState
+        {
+            public long LastRecordId { get; set; }
+            public DateTime PersistedUtc { get; set; }
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Interop/ArpNativeMethods.cs

@@ -0,0 +1,64 @@
+#nullable enable
+using System;
+using System.Net;
+using System.Net.Sockets;
+using System.Runtime.InteropServices;
+
+namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Interop
+{
+    /// <summary>
+    /// ARP resolution via <c>iphlpapi!SendARP</c> — resolves the MAC address of an on-link IPv4
+    /// host (in practice: the default gateway). IPv4 only by API design; the OS answers from its
+    /// ARP cache or sends a real ARP request, so the target must be on the local subnet.
+    /// </summary>
+    internal static class ArpNativeMethods
+    {
+        [DllImport("iphlpapi.dll", ExactSpelling = true)]
+        private static extern int SendARP(uint destIP, uint srcIP, byte[] macAddress, ref uint macAddressLength);
+
+        /// <summary>
+        /// Fail-soft MAC resolution. Returns false (with a diagnostic in <paramref name="error"/>)
+        /// for non-IPv4 addresses, SendARP failures, or unexpected reply lengths — never throws.
+        /// </summary>
+        internal static bool TryResolveMac(IPAddress? ipv4Address, out byte[] mac, out string? error)
+        {
+            mac = new byte[6];
+            error = null;
+            try
+            {
+                if (ipv4Address == null || ipv4Address.AddressFamily != AddressFamily.InterNetwork)
+                {
+                    error = "not an IPv4 address";
+                    return false;
+                }
+
+                // SendARP takes the IPv4 address as a uint in network byte order (first octet in
+                // the lowest byte).
+                var addressBytes = ipv4Address.GetAddressBytes();
+                uint dest = ((uint)addressBytes[3] << 24)
+                          | ((uint)addressBytes[2] << 16)
+                          | ((uint)addressBytes[1] << 8)
+                          | addressBytes[0];
+
+                uint len = (uint)mac.Length;
+                var err = SendARP(dest, 0, mac, ref len);
+                if (err != 0)
+                {
+                    error = $"SendARP returned {err}";
+                    return false;
+                }
+                if (len != 6)
+                {
+                    error = $"SendARP returned unexpected MAC length {len}";
+                    return false;
+                }
+                return true;
+            }
+            catch (Exception ex)
+            {
+                error = ex.Message;
+                return false;
+            }
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/NetworkInterfaceLocator.cs

@@ -0,0 +1,68 @@
+#nullable enable
+using System.Net;
+using System.Net.NetworkInformation;
+using System.Net.Sockets;
+
+namespace AutopilotMonitor.Agent.V2.Core.Monitoring
+{
+    /// <summary>
+    /// Shared "which NIC is the device actually using" heuristic: Up, not Loopback/Tunnel,
+    /// carries a non-0.0.0.0 default gateway. Fail-soft — any enumeration error yields null.
+    /// </summary>
+    internal static class NetworkInterfaceLocator
+    {
+        /// <summary>
+        /// Finds the active network interface: Up, not Loopback/Tunnel, has a non-0.0.0.0 gateway.
+        /// </summary>
+        internal static NetworkInterface? FindActiveNetworkInterface()
+        {
+            try
+            {
+                var interfaces = NetworkInterface.GetAllNetworkInterfaces();
+                foreach (var nic in interfaces)
+                {
+                    if (nic.OperationalStatus != OperationalStatus.Up)
+                        continue;
+                    if (nic.NetworkInterfaceType == NetworkInterfaceType.Loopback ||
+                        nic.NetworkInterfaceType == NetworkInterfaceType.Tunnel)
+                        continue;
+
+                    var ipProps = nic.GetIPProperties();
+                    foreach (var gw in ipProps.GatewayAddresses)
+                    {
+                        if (gw.Address.ToString() != "0.0.0.0")
+                            return nic;
+                    }
+                }
+            }
+            catch
+            {
+                // Caller handles null
+            }
+            return null;
+        }
+
+        /// <summary>First IPv4 default gateway of the interface (0.0.0.0 excluded), or null.</summary>
+        internal static IPAddress? GetIpv4Gateway(NetworkInterface nic)
+        {
+            try
+            {
+                foreach (var gw in nic.GetIPProperties().GatewayAddresses)
+                {
+                    var address = gw?.Address;
+                    if (address != null
+                        && address.AddressFamily == AddressFamily.InterNetwork
+                        && address.ToString() != "0.0.0.0")
+                    {
+                        return address;
+                    }
+                }
+            }
+            catch
+            {
+                // Caller handles null
+            }
+            return null;
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Telemetry/DeviceInfo/DeviceInfoCollector.NetworkAndSecurity.cs

@@ -922,36 +922,8 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Telemetry.DeviceInfo
             }
         }
 
-        /// <summary>
-        /// Finds the active network interface: Up, not Loopback/Tunnel, has a non-0.0.0.0 gateway.
-        /// </summary>
-        private static NetworkInterface FindActiveNetworkInterface()
-        {
-            try
-            {
-                var interfaces = NetworkInterface.GetAllNetworkInterfaces();
-                foreach (var nic in interfaces)
-                {
-                    if (nic.OperationalStatus != OperationalStatus.Up)
-                        continue;
-                    if (nic.NetworkInterfaceType == NetworkInterfaceType.Loopback ||
-                        nic.NetworkInterfaceType == NetworkInterfaceType.Tunnel)
-                        continue;
-
-                    var ipProps = nic.GetIPProperties();
-                    foreach (var gw in ipProps.GatewayAddresses)
-                    {
-                        if (gw.Address.ToString() != "0.0.0.0")
-                            return nic;
-                    }
-                }
-            }
-            catch
-            {
-                // Caller handles null
-            }
-            return null;
-        }
+        private static NetworkInterface FindActiveNetworkInterface() =>
+            Monitoring.NetworkInterfaceLocator.FindActiveNetworkInterface();
 
         /// <summary>
         /// Collects WiFi signal info via the native WLAN API (<see cref="WifiInfoReader"/>,

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Telemetry/Gather/Collectors/LogParserCollector.cs

@@ -331,7 +331,16 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Telemetry.Gather.Collectors
                                         data[groupName] = group.Value;
                                 }
 
-                                data["logTimestamp"] = entry.Timestamp.ToString("o");
+                                // Gather-rule logs are arbitrary files this collector does not
+                                // tail, so no writer offset can be measured for them; the
+                                // reader-zone fallback carries its known defect (see
+                                // ResolveUtcAssumingReaderZone). Behaviour unchanged from before
+                                // the parser split.
+                                var entryUtc = entry.TimestampUtc
+                                    ?? (entry.HasTimestamp
+                                        ? CmTraceLogParser.ResolveUtcAssumingReaderZone(entry.LocalTimestamp)
+                                        : DateTime.UtcNow);
+                                data["logTimestamp"] = entryUtc.ToString("o");
                                 data["logComponent"] = entry.Component;
                                 data["logType"] = entry.Type;
                                 data["logMessage"] = TruncateMessage(entry.Message, 500);
@@ -348,7 +357,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Telemetry.Gather.Collectors
                                 {
                                     SessionId = context.SessionId,
                                     TenantId = context.TenantId,
-                                    Timestamp = entry.Timestamp,
+                                    Timestamp = entryUtc,
                                     EventType = eventType,
                                     Severity = severity,
                                     Source = "GatherRuleExecutor",

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Telemetry/Periodic/NetworkChangeDetector.cs

@@ -420,36 +420,8 @@ namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Telemetry.Periodic
         // Helpers
         // -------------------------------------------------------------------
 
-        /// <summary>
-        /// Finds the active network interface: Up, not Loopback/Tunnel, has a non-0.0.0.0 gateway.
-        /// </summary>
-        private static NetworkInterface FindActiveNetworkInterface()
-        {
-            try
-            {
-                var interfaces = NetworkInterface.GetAllNetworkInterfaces();
-                foreach (var nic in interfaces)
-                {
-                    if (nic.OperationalStatus != OperationalStatus.Up)
-                        continue;
-                    if (nic.NetworkInterfaceType == NetworkInterfaceType.Loopback ||
-                        nic.NetworkInterfaceType == NetworkInterfaceType.Tunnel)
-                        continue;
-
-                    var ipProps = nic.GetIPProperties();
-                    foreach (var gw in ipProps.GatewayAddresses)
-                    {
-                        if (gw.Address.ToString() != "0.0.0.0")
-                            return nic;
-                    }
-                }
-            }
-            catch
-            {
-                // Caller handles null
-            }
-            return null;
-        }
+        private static NetworkInterface FindActiveNetworkInterface() =>
+            NetworkInterfaceLocator.FindActiveNetworkInterface();
 
         private static string BuildChangeMessage(NetworkStateSnapshot before, NetworkStateSnapshot after)
         {

src/Agent/AutopilotMonitor.Agent.V2.Core/Monitoring/Transport/DoGroupIdService.cs

@@ -0,0 +1,217 @@
+#nullable enable
+using System;
+using System.Net;
+using System.Net.Sockets;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Interop;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Telemetry.Periodic;
+using Microsoft.Win32;
+
+namespace AutopilotMonitor.Agent.V2.Core.Monitoring.Transport
+{
+    public class DoGroupIdSetResult
+    {
+        /// <summary>The DOGroupId value is the computed one after this run (written or already there).</summary>
+        public bool Success { get; set; }
+
+        /// <summary>True when this run actually wrote the registry value (false for the idempotent no-op).</summary>
+        public bool Written { get; set; }
+
+        /// <summary>Deliberate non-action (existing foreign policy/value, no usable network) — not an error.</summary>
+        public bool Skipped { get; set; }
+        public string? SkipReason { get; set; }
+
+        public string? GroupId { get; set; }
+        public string? PreviousValue { get; set; }
+        public string? GatewayIp { get; set; }
+        public string? GatewayMac { get; set; }
+        public string? Error { get; set; }
+    }
+
+    internal enum DoGroupIdAction
+    {
+        Write,
+        NoOp,
+        SkipForeign,
+    }
+
+    /// <summary>
+    /// Sets the Delivery Optimization group ID policy value (<c>DOGroupId</c> under the GPO
+    /// DeliveryOptimization key) from a network fingerprint: a deterministic GUID derived from the
+    /// default gateway's IPv4 address and MAC address, so all devices behind the same gateway land
+    /// in the same DO peering group. The byte layout is RealmJoin-compatible — devices managed by
+    /// RealmJoin on the same network compute the identical GUID and peer with ours.
+    /// <para>
+    /// Deliberately conservative where RealmJoin is not: no random-GUID fallback (a per-device
+    /// random ID would isolate the device in a one-member group — worse than the OS default
+    /// grouping), and existing foreign configuration always wins: a DOGroupIdSource policy, an
+    /// MDM-managed DOGroupId, or a GPO value we did not write ourselves all result in a skip.
+    /// Never throws.
+    /// </para>
+    /// </summary>
+    public static class DoGroupIdService
+    {
+        internal const string GroupIdValueName = "DOGroupId";
+        internal const string GroupIdSourceValueName = "DOGroupIdSource";
+
+        // RealmJoin's fingerprint-GUID prefix — part of the compatible byte layout, do not change.
+        private static readonly byte[] GuidPrefix = { 101, 48, 6 };
+
+        /// <summary>
+        /// Computes and applies the fingerprint GroupId. <paramref name="lastWrittenGroupId"/> is
+        /// the GUID a previous agent run wrote (null when none is recorded) — it lets us update our
+        /// own value after a gateway change while never touching a foreign one.
+        /// </summary>
+        public static DoGroupIdSetResult TrySetGroupId(string? lastWrittenGroupId, AgentLogger logger)
+        {
+            var result = new DoGroupIdSetResult();
+
+            try
+            {
+                // ---- Network fingerprint -------------------------------------------------
+                var nic = NetworkInterfaceLocator.FindActiveNetworkInterface();
+                var gateway = nic == null ? null : NetworkInterfaceLocator.GetIpv4Gateway(nic);
+                if (gateway == null)
+                {
+                    result.Skipped = true;
+                    result.SkipReason = "no_ipv4_gateway";
+                    logger.Info("DO GroupId auto-set: no active interface with an IPv4 default gateway — skipping.");
+                    return result;
+                }
+                result.GatewayIp = gateway.ToString();
+
+                if (!ArpNativeMethods.TryResolveMac(gateway, out var mac, out var arpError))
+                {
+                    result.Skipped = true;
+                    result.SkipReason = "arp_failed";
+                    result.Error = arpError;
+                    logger.Warning($"DO GroupId auto-set: could not resolve gateway MAC ({arpError}) — skipping.");
+                    return result;
+                }
+                result.GatewayMac = BitConverter.ToString(mac);
+
+                var computed = ComputeGroupId(gateway.GetAddressBytes(), mac).ToString();
+                result.GroupId = computed;
+
+                // ---- Foreign-configuration checks ----------------------------------------
+                // DOGroupIdSource (either store) selects a dynamic group source — a fingerprint
+                // GroupId would fight it. An MDM-managed DOGroupId means Intune owns the setting.
+                if (ReadPolicyValue(DoThrottlePolicyReader.GpoKeyPath, GroupIdSourceValueName) != null
+                    || ReadPolicyValue(DoThrottlePolicyReader.MdmKeyPath, GroupIdSourceValueName) != null)
+                {
+                    result.Skipped = true;
+                    result.SkipReason = "group_id_source_policy";
+                    logger.Info("DO GroupId auto-set: DOGroupIdSource policy is configured — skipping.");
+                    return result;
+                }
+                if (ReadPolicyValue(DoThrottlePolicyReader.MdmKeyPath, GroupIdValueName) != null)
+                {
+                    result.Skipped = true;
+                    result.SkipReason = "mdm_policy_present";
+                    logger.Info("DO GroupId auto-set: DOGroupId is managed via MDM policy — skipping.");
+                    return result;
+                }
+
+                // ---- Ownership decision ---------------------------------------------------
+                var existing = ReadPolicyValue(DoThrottlePolicyReader.GpoKeyPath, GroupIdValueName) as string;
+                result.PreviousValue = existing;
+
+                switch (DecideAction(existing, computed, lastWrittenGroupId))
+                {
+                    case DoGroupIdAction.NoOp:
+                        result.Success = true;
+                        logger.Info($"DO GroupId auto-set: already set to {computed} — nothing to do.");
+                        return result;
+
+                    case DoGroupIdAction.SkipForeign:
+                        result.Skipped = true;
+                        result.SkipReason = "foreign_value_present";
+                        logger.Info($"DO GroupId auto-set: existing DOGroupId '{existing}' was not written by us — skipping.");
+                        return result;
+                }
+
+                // ---- Write + readback -----------------------------------------------------
+                using (var hklm = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64))
+                using (var key = hklm.CreateSubKey(DoThrottlePolicyReader.GpoKeyPath))
+                {
+                    key.SetValue(GroupIdValueName, computed, RegistryValueKind.String);
+                }
+
+                var readback = ReadPolicyValue(DoThrottlePolicyReader.GpoKeyPath, GroupIdValueName) as string;
+                if (!string.Equals(readback, computed, StringComparison.OrdinalIgnoreCase))
+                {
+                    result.Error = $"readback mismatch: wrote '{computed}', read '{readback ?? "<null>"}'";
+                    logger.Warning($"DO GroupId auto-set failed: {result.Error}");
+                    return result;
+                }
+
+                result.Success = true;
+                result.Written = true;
+                logger.Info($"DO GroupId auto-set: DOGroupId set to {computed} (gateway {result.GatewayIp}, previous: {existing ?? "<none>"})");
+                return result;
+            }
+            catch (Exception ex)
+            {
+                result.Error = ex.Message;
+                logger.Warning($"DO GroupId auto-set failed: {ex.Message}");
+                return result;
+            }
+        }
+
+        /// <summary>
+        /// RealmJoin-compatible fingerprint GUID: 16 bytes laid out as
+        /// prefix {101,48,6} + {0,0,0} + {ip[1],0,ip[2],ip[3]} + mac[6], passed to
+        /// <c>new Guid(byte[])</c>. The IP byte shuffle mirrors RealmJoin's "swap for
+        /// new Guid()" step — the layout must stay bit-identical for cross-product peering.
+        /// </summary>
+        internal static Guid ComputeGroupId(byte[] ipv4Bytes, byte[] macBytes)
+        {
+            if (ipv4Bytes == null || ipv4Bytes.Length != 4)
+                throw new ArgumentException("IPv4 address bytes required", nameof(ipv4Bytes));
+            if (macBytes == null || macBytes.Length != 6)
+                throw new ArgumentException("6-byte MAC required", nameof(macBytes));
+
+            var bytes = new byte[16];
+            Array.Copy(GuidPrefix, 0, bytes, 0, GuidPrefix.Length);
+            // bytes[3..5] stay zero (RealmJoin's zero padding)
+            bytes[6] = ipv4Bytes[1];
+            // bytes[7] stays zero
+            bytes[8] = ipv4Bytes[2];
+            bytes[9] = ipv4Bytes[3];
+            Array.Copy(macBytes, 0, bytes, 10, macBytes.Length);
+            return new Guid(bytes);
+        }
+
+        /// <summary>
+        /// Pure ownership decision. GUID comparison tolerates case and braces so a value written
+        /// by another tool in "{...}" form still matches semantically.
+        /// </summary>
+        internal static DoGroupIdAction DecideAction(string? existing, string computed, string? lastWrittenByUs)
+        {
+            if (string.IsNullOrEmpty(existing))
+                return DoGroupIdAction.Write;
+            if (GuidEquals(existing, computed))
+                return DoGroupIdAction.NoOp;
+            if (GuidEquals(existing, lastWrittenByUs))
+                return DoGroupIdAction.Write; // our own stale value — gateway changed
+            return DoGroupIdAction.SkipForeign;
+        }
+
+        private static bool GuidEquals(string? a, string? b)
+        {
+            if (string.IsNullOrEmpty(a) || string.IsNullOrEmpty(b)) return false;
+            return Guid.TryParse(a, out var ga) && Guid.TryParse(b, out var gb) && ga == gb;
+        }
+
+        private static object? ReadPolicyValue(string keyPath, string valueName)
+        {
+            // Registry64 explicitly — SOFTWARE\Policies is WOW64-redirected, and the policy
+            // stores live in the 64-bit view regardless of the agent's bitness.
+            using (var hklm = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64))
+            using (var key = hklm.OpenSubKey(keyPath))
+            {
+                return key?.GetValue(valueName);
+            }
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/DefaultComponentFactory.cs

@@ -557,6 +557,22 @@ namespace AutopilotMonitor.Agent.V2.Core.Orchestration
                     stateDirectory: _stateDirectory));
             }
 
+            // System timeline watcher — System channel: Kernel-General 1 (system clock stepped,
+            // ground truth for time jumps incl. old/new time + setting process) and completed
+            // sleep/standby episodes (Power-Troubleshooter 1, Kernel-Power 507). Backfill recovers
+            // the pre-agent OOBE clock correction and standby episodes from the persistent .evtx.
+            if (collectors.EnableSystemTimelineWatcher)
+            {
+                hosts.Add(new SystemTimelineWatcherHost(
+                    sessionId: sessionId,
+                    tenantId: tenantId,
+                    logger: logger,
+                    ingress: ingress,
+                    clock: clock,
+                    backfillLookbackMinutes: collectors.SystemEventBackfillLookbackMinutes,
+                    stateDirectory: _stateDirectory));
+            }
+
             // ----- Peripheral hosts (event-only; driven by remote-config toggles) --------------
 
             // V1 parity (PeriodicCollectorManager) — combine Performance + AgentSelfMetrics under
@@ -595,6 +611,21 @@ namespace AutopilotMonitor.Agent.V2.Core.Orchestration
                 logger: logger,
                 apiBaseUrl: _agentConfig.ApiBaseUrl));
 
+            // Live AC/battery watcher — WMI Win32_PowerManagementEvent push (no polling), emits
+            // power_state_change on AC↔battery transitions and 50/30/15 % downward threshold
+            // crossings. Deliberately NOT under PeriodicCollectorLifecycleHost: it is push-based
+            // (zero idle cost) and must stay alive precisely when the device sits idle on battery.
+            // Never arms on devices without a battery. Kill-switchable via remote config.
+            if (collectors.EnablePowerStateWatcher)
+            {
+                hosts.Add(new PowerStateWatcherHost(
+                    sessionId: sessionId,
+                    tenantId: tenantId,
+                    ingress: ingress,
+                    clock: clock,
+                    logger: logger));
+            }
+
             // Microsoft 365 Apps (Office C2R) install detector — event-driven (Rev 2): woken by a WMI
             // Win32_ProcessStartTrace push on OfficeC2RClient.exe (+ startup probe), progress via
             // RegNotifyChangeKeyValue, stop via Process.Exited. No idle polling. Constructed first so

src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/Hosts/PowerStateWatcherHost.cs

@@ -0,0 +1,332 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Management;
+using System.Threading;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals;
+using AutopilotMonitor.Agent.V2.Core.Runtime;
+using AutopilotMonitor.DecisionCore.Engine;
+using AutopilotMonitor.Shared;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Agent.V2.Core.Orchestration
+{
+    /// <summary>
+    /// Live AC/battery watcher: subscribes to the WMI push event
+    /// <c>Win32_PowerManagementEvent WHERE EventCode = 10</c> (PBT_APMPOWERSTATUSCHANGE — fires on
+    /// AC↔DC switches and battery-percentage steps), falling back to the intrinsic
+    /// <c>__InstanceModificationEvent WITHIN 30 … Win32_Battery</c> where the legacy push provider
+    /// no longer loads (Windows 11 24H2/25H2, builds 26200+: activation fails WBEM_E_NOT_FOUND
+    /// although the provider is still registered — session 161b838c). Either way the arriving
+    /// event's payload is ignored; each arrival re-probes via <see cref="PowerStateProbe"/> and
+    /// diffs the snapshots through the pure <see cref="PowerStateTransitionTracker"/> into
+    /// <c>power_state_change</c> events. No polling in this process (the fallback's WITHIN
+    /// sampling runs inside WinMgmt). Complements the one-shot startup
+    /// <c>power_state_check</c> (<c>StartupEnvironmentProbes</c>), which stays the baseline event.
+    /// <para>
+    /// Devices without a battery (or with a failing probe) never arm the WMI subscription — zero
+    /// overhead on desktops/VMs. WMI arming runs on a background thread (WinMgmt can hang in OOBE;
+    /// same rationale as <c>ConsoleBypassWatcher</c>), and an arm failure is surfaced once as
+    /// <c>collector_degraded</c>. A 5 s trailing-edge debounce collapses docking flaps to a
+    /// no-diff; the tracker's lifetime emission cap is the storm backstop.
+    /// </para>
+    /// </summary>
+    internal sealed class PowerStateWatcherHost : ICollectorHost
+    {
+        public string Name => "PowerStateWatcher";
+
+        private static readonly TimeSpan DebounceDelay = TimeSpan.FromSeconds(5);
+
+        private readonly string _sessionId;
+        private readonly string _tenantId;
+        private readonly AgentLogger _logger;
+        private readonly InformationalEventPost _post;
+        private readonly Func<PowerStateResult> _probe;
+        private readonly PowerStateTransitionTracker _tracker = new PowerStateTransitionTracker();
+        private readonly object _lock = new object();
+        private readonly object _tickLock = new object();
+
+        private ManagementEventWatcher? _watcher;
+        private Timer? _debounceTimer;
+        private bool _started;
+        private bool _disposed;
+        private bool _capWarned;
+
+        /// <param name="probe">Power-state snapshot source; test seam, defaults to
+        /// <see cref="PowerStateProbe.Probe"/>. The ctor never calls it (the factory constructs
+        /// hosts eagerly; all probing happens in <see cref="Start"/>'s background thread).</param>
+        public PowerStateWatcherHost(
+            string sessionId,
+            string tenantId,
+            ISignalIngressSink ingress,
+            IClock clock,
+            AgentLogger logger,
+            Func<PowerStateResult>? probe = null)
+        {
+            if (ingress == null) throw new ArgumentNullException(nameof(ingress));
+            if (clock == null) throw new ArgumentNullException(nameof(clock));
+            _sessionId = sessionId;
+            _tenantId = tenantId;
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _post = new InformationalEventPost(ingress, clock, logger);
+            _probe = probe ?? PowerStateProbe.Probe;
+        }
+
+        public void Start()
+        {
+            lock (_lock)
+            {
+                if (_started || _disposed) return;
+                _started = true;
+            }
+
+            // Baseline probe + WMI arming are synchronous WinMgmt-adjacent operations and WinMgmt
+            // can hang during OOBE — never run them inline on the orchestrator's sequential
+            // host-start loop (ConsoleBypassWatcher precedent). Disposal racing the background
+            // start is handled by the _disposed re-checks inside StartCore.
+            System.Threading.Tasks.Task.Run(() => StartCore(armWmi: true));
+        }
+
+        /// <summary>Internal for tests: the synchronous start body; tests pass
+        /// <paramref name="armWmi"/> = false so no real WMI subscription is created
+        /// (precedent: ConsoleBypassWatcher leaves WMI arming untested).</summary>
+        internal void StartCore(bool armWmi)
+        {
+            PowerStateResult baseline;
+            try
+            {
+                baseline = _probe();
+            }
+            catch (Exception ex)
+            {
+                _logger.Warning($"[{Name}] baseline probe threw ({ex.Message}) — power-state watcher not armed");
+                return;
+            }
+
+            if (baseline.ProbeError != null)
+            {
+                _logger.Info($"[{Name}] power probe failed ({baseline.ProbeError}) — watcher not armed");
+                return;
+            }
+            if (!baseline.HasBattery)
+            {
+                _logger.Info($"[{Name}] no battery present (desktop/VM) — watcher not armed");
+                return;
+            }
+
+            // Latch the baseline BEFORE arming so the first WMI push diffs against a real state.
+            // A session already on battery below a ladder level emits its threshold event here.
+            EmitAll(_tracker.Baseline(baseline));
+
+            if (!armWmi) return;
+
+            // Arm chain: the extrinsic push event first (zero WinMgmt cost, still alive on older
+            // builds), then the intrinsic Win32_Battery modification event. On Windows 11 24H2/25H2
+            // (observed on builds 26200/26220, session 161b838c) the MS_Power_Management_Event_Provider
+            // is still REGISTERED but its activation fails with WBEM_E_NOT_FOUND — the legacy provider
+            // no longer loads, so the push query throws on exactly the devices that enroll today.
+            // The fallback's WITHIN polling runs inside WinMgmt (a Win32_Battery snapshot every 30 s),
+            // NOT in this process; the handler path is identical (payload ignored, re-probe + diff),
+            // worst-case detection latency ≈ 35 s incl. debounce.
+            if (TryArmWatcher(
+                    "SELECT * FROM Win32_PowerManagementEvent WHERE EventCode = 10",
+                    "power_management_event (push)", baseline, out var pushError))
+            {
+                return;
+            }
+
+            if (TryArmWatcher(
+                    "SELECT * FROM __InstanceModificationEvent WITHIN 30 WHERE TargetInstance ISA 'Win32_Battery'",
+                    "battery_instance_poll (WinMgmt WITHIN 30s)", baseline, out var fallbackError))
+            {
+                return;
+            }
+
+            _logger.Warning($"[{Name}] could not arm any WMI power watcher — " +
+                $"push: {Describe(pushError)}; fallback: {Describe(fallbackError)} — " +
+                "live power-state transitions will not be observed this run");
+            CollectorDegradationReporter.Report(_post, _sessionId, _tenantId, Name, "watcher_arm_failed",
+                fallbackError ?? pushError);
+        }
+
+        private static string Describe(Exception? ex)
+            => ex == null ? "n/a" : $"{ex.GetType().Name}: {ex.Message}";
+
+        /// <summary>
+        /// One arm attempt for the given WQL event query, with the full dispose-race dance
+        /// (ConsoleBypassWatcher pattern). Returns true when the chain should stop: the watcher
+        /// armed, or disposal won the race (then arming anything would leak a subscription).
+        /// Returns false with the captured exception so the caller can try the next query.
+        /// </summary>
+        private bool TryArmWatcher(string wql, string modeLabel, PowerStateResult baseline, out Exception? error)
+        {
+            error = null;
+            try
+            {
+                var watcher = new ManagementEventWatcher(new WqlEventQuery(wql));
+                watcher.EventArrived += OnPowerStatusChange;
+
+                lock (_lock)
+                {
+                    if (_disposed)
+                    {
+                        // Dispose won the race against the background start — don't arm.
+                        try { watcher.EventArrived -= OnPowerStatusChange; } catch { }
+                        try { watcher.Dispose(); } catch { }
+                        return true;
+                    }
+                    _watcher = watcher;
+                }
+
+                watcher.Start();
+
+                // Re-check after arming: Dispose() may have run between the lock release above and
+                // Start() — it then stopped a not-yet-armed watcher and this thread armed it right
+                // back. If disposal won that race, tear the watcher down here.
+                bool disposedDuringArm;
+                lock (_lock)
+                {
+                    disposedDuringArm = _disposed;
+                    if (disposedDuringArm) _watcher = null;
+                }
+                if (disposedDuringArm)
+                {
+                    try { watcher.EventArrived -= OnPowerStatusChange; } catch { }
+                    try { watcher.Stop(); } catch { }
+                    try { watcher.Dispose(); } catch { }
+                    return true;
+                }
+
+                _logger.Info($"[{Name}] armed via {modeLabel} — " +
+                    $"baseline: {(baseline.OnAcPower ? "AC" : "battery")}, {baseline.BatteryPercent?.ToString() ?? "?"}%");
+                return true;
+            }
+            catch (Exception ex)
+            {
+                error = ex;
+                _logger.Info($"[{Name}] arm attempt '{modeLabel}' failed ({ex.GetType().Name}: {ex.Message})");
+                lock (_lock) { _watcher = null; }
+                return false;
+            }
+        }
+
+        private void OnPowerStatusChange(object sender, EventArrivedEventArgs e)
+        {
+            // Push and fallback events are treated identically: the payload is ignored, the event
+            // only tells us "power status may have changed". Debounce, then re-probe — never call
+            // watcher.Stop() from inside this callback.
+            try { ScheduleDebouncedTick(); }
+            catch (Exception ex) { _logger.Debug($"[{Name}] power event handler error: {ex.Message}"); }
+        }
+
+        private void ScheduleDebouncedTick()
+        {
+            lock (_lock) { if (_disposed) return; }
+            // One trailing-edge tick per change burst (ImeRegistryAppStateHost pattern): a
+            // dock-flap AC→battery→AC inside the window collapses to a no-diff in the tracker.
+            var timer = _debounceTimer;
+            if (timer == null)
+            {
+                var created = new Timer(_ => DebouncedTick(), null, DebounceDelay, Timeout.InfiniteTimeSpan);
+                if (Interlocked.CompareExchange(ref _debounceTimer, created, null) != null)
+                    created.Dispose();
+                else
+                    return;
+                timer = _debounceTimer;
+            }
+            try { timer?.Change(DebounceDelay, Timeout.InfiniteTimeSpan); }
+            catch (ObjectDisposedException) { /* stopping */ }
+        }
+
+        /// <summary>Internal for tests: runs one debounced probe/diff/emit cycle synchronously,
+        /// exactly what the trailing-edge timer callback executes after a WMI push.</summary>
+        internal void TickForTest() => DebouncedTick();
+
+        private void DebouncedTick()
+        {
+            lock (_lock) { if (_disposed) return; }
+            try
+            {
+                IReadOnlyList<PowerStateEmission> emissions;
+                lock (_tickLock) // tracker is not thread-safe; ticks must not interleave
+                {
+                    emissions = _tracker.Evaluate(_probe());
+                }
+                EmitAll(emissions);
+
+                if (_tracker.EmissionCapReached && !_capWarned)
+                {
+                    _capWarned = true;
+                    _logger.Warning($"[{Name}] emission cap reached — further power_state_change events " +
+                        "suppressed this run (flapping power source or dying battery controller)");
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.Debug($"[{Name}] debounced power tick failed: {ex.Message}");
+            }
+        }
+
+        private void EmitAll(IReadOnlyList<PowerStateEmission> emissions)
+        {
+            foreach (var emission in emissions)
+            {
+                try
+                {
+                    var data = new Dictionary<string, object>
+                    {
+                        { "transition", emission.Transition },
+                        { "onAcPower", emission.OnAcPower },
+                        { "batteryPercent", emission.BatteryPercent.HasValue ? (object)emission.BatteryPercent.Value : "unknown" },
+                        { "isCharging", emission.IsCharging },
+                        { "batteryLifeMinutes", emission.BatteryLifeMinutes.HasValue ? (object)emission.BatteryLifeMinutes.Value : "unknown" },
+                    };
+                    if (emission.ThresholdPercent.HasValue)
+                        data["thresholdPercent"] = emission.ThresholdPercent.Value;
+
+                    _post.Emit(new EnrollmentEvent
+                    {
+                        SessionId = _sessionId,
+                        TenantId = _tenantId,
+                        EventType = Constants.EventTypes.PowerStateChange,
+                        Severity = emission.Severity,
+                        Source = Name,
+                        Phase = EnrollmentPhase.Unknown,
+                        Message = emission.Message,
+                        ImmediateUpload = emission.ImmediateUpload,
+                        Data = data,
+                    });
+                }
+                catch (Exception ex)
+                {
+                    _logger.Warning($"[{Name}] failed to emit power_state_change: {ex.Message}");
+                }
+            }
+        }
+
+        public void Stop()
+        {
+            ManagementEventWatcher? watcher;
+            lock (_lock)
+            {
+                if (_disposed) return;
+                _disposed = true;
+                watcher = _watcher;
+                _watcher = null;
+            }
+
+            if (watcher != null)
+            {
+                try { watcher.EventArrived -= OnPowerStatusChange; } catch { }
+                try { watcher.Stop(); } catch { }
+                try { watcher.Dispose(); } catch { }
+            }
+
+            _debounceTimer?.Dispose();
+            _debounceTimer = null;
+        }
+
+        public void Dispose() => Stop();
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/Hosts/SystemTimelineWatcherHost.cs

@@ -0,0 +1,68 @@
+#nullable enable
+using System;
+using System.Threading;
+using AutopilotMonitor.Agent.V2.Core.Logging;
+using AutopilotMonitor.Agent.V2.Core.Monitoring.Enrollment.SystemSignals;
+using AutopilotMonitor.DecisionCore.Engine;
+using AutopilotMonitor.DecisionCore.Signals;
+
+namespace AutopilotMonitor.Agent.V2.Core.Orchestration
+{
+    /// <summary>
+    /// Standalone host for the <see cref="SystemTimelineTracker"/> — watches the <c>System</c>
+    /// event log for system clock steps (Kernel-General 1) and completed sleep/standby episodes
+    /// (Power-Troubleshooter 1 / Kernel-Power 507) and forwards them via the shared single-rail
+    /// ingress. Mirrors <see cref="WindowsUpdateWatcherHost"/>: builds its own
+    /// <see cref="InformationalEventPost"/> and delegates Start/Stop to the tracker.
+    /// </summary>
+    internal sealed class SystemTimelineWatcherHost : ICollectorHost
+    {
+        public string Name => "SystemTimelineTracker";
+
+        private readonly SystemTimelineTracker _tracker;
+        private readonly AgentLogger _logger;
+        private int _disposed;
+
+        public SystemTimelineWatcherHost(
+            string sessionId,
+            string tenantId,
+            AgentLogger logger,
+            ISignalIngressSink ingress,
+            IClock clock,
+            int backfillLookbackMinutes,
+            string stateDirectory)
+        {
+            if (ingress == null) throw new ArgumentNullException(nameof(ingress));
+            if (clock == null) throw new ArgumentNullException(nameof(clock));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+            var post = new InformationalEventPost(ingress, clock, logger);
+            _tracker = new SystemTimelineTracker(
+                sessionId: sessionId,
+                tenantId: tenantId,
+                post: post,
+                logger: logger,
+                backfillEnabled: backfillLookbackMinutes > 0,
+                backfillLookbackMinutes: backfillLookbackMinutes,
+                stateDirectory: stateDirectory);
+        }
+
+        public void Start()
+        {
+            _tracker.Start();
+            _logger.Info("SystemTimelineWatcherHost: started.");
+        }
+
+        public void Stop()
+        {
+            try { _tracker.Stop(); }
+            catch (Exception ex) { _logger.Warning($"SystemTimelineWatcherHost: stop failed: {ex.Message}"); }
+        }
+
+        public void Dispose()
+        {
+            if (Interlocked.Exchange(ref _disposed, 1) == 1) return;
+            Stop();
+        }
+    }
+}

src/Agent/AutopilotMonitor.Agent.V2.Core/Orchestration/SignalActivityClassifier.cs

@@ -56,6 +56,17 @@ namespace AutopilotMonitor.Agent.V2.Core.Orchestration
             // real activity (rare, and worth keeping diagnostics running for).
             SharedConstants.EventTypes.ModernDeploymentLog,
 
+            // Environment observation, not device/enrollment progress: an idle device draining
+            // its battery must not keep the periodic collectors alive or push out stall
+            // detection — the exact scenario the power watcher exists to observe.
+            SharedConstants.EventTypes.PowerStateChange,
+
+            // Same reasoning for the system timeline watcher: a clock step, a wake from standby,
+            // or a backfilled episode at agent start is environment observation and must not
+            // reset the idle/stall clocks.
+            SharedConstants.EventTypes.SystemClockChanged,
+            SharedConstants.EventTypes.SystemSleepEpisode,
+
             // Agent health / control / transport — not device/enrollment progress.
             SharedConstants.EventTypes.CollectorDegraded,
             SharedConstants.EventTypes.TelemetryUploadPoisoned,

src/Agent/AutopilotMonitor.Agent.V2.Core/Persistence/StartupEventGate.cs

@@ -124,6 +124,21 @@ namespace AutopilotMonitor.Agent.V2.Core.Persistence
             }
         }
 
+        /// <summary>
+        /// Read-only peek of the key's current fingerprint (possibly restored from a previous
+        /// agent run), or null when none is recorded. Like <see cref="HasFingerprint"/> this makes
+        /// NO claim — use it when the fingerprint carries state the caller needs to read back
+        /// (e.g. the DO GroupId ownership marker).
+        /// </summary>
+        public string? GetFingerprint(string key)
+        {
+            if (string.IsNullOrEmpty(key)) return null;
+            lock (_lock)
+            {
+                return _entries.TryGetValue(key, out var entry) ? entry.Fingerprint : null;
+            }
+        }
+
         /// <summary>Retry-until-success: true when <see cref="MarkSucceeded"/> latched this key in any run.</summary>
         public bool AlreadySucceeded(string key)
         {

src/Agent/AutopilotMonitor.Agent.V2.Core/Runtime/StartupEnvironmentProbes.cs

@@ -25,6 +25,9 @@ namespace AutopilotMonitor.Agent.V2.Core.Runtime
     ///     Always emitted — offset &gt;60s is Warning, smaller is Info, failure is Warning.</item>
     ///   <item><b>power_state_check</b> — AC vs. battery snapshot via Win32 <c>GetSystemPowerStatus</c>.
     ///     On battery with &lt;80% charge is Warning, otherwise Info, probe failure is Warning.</item>
+    ///   <item><b>do_group_id_auto_set</b> — only when <c>EnableDoGroupIdAutoSet=true</c>. Sets the
+    ///     Delivery Optimization <c>DOGroupId</c> policy value from a network fingerprint via
+    ///     <see cref="DoGroupIdService"/>; skips (Info) rather than fight foreign policy values.</item>
     /// </list>
     /// <para>
     /// Each probe runs best-effort: failures are logged + optionally emitted as a Warning event,
@@ -78,6 +81,9 @@ namespace AutopilotMonitor.Agent.V2.Core.Runtime
                 await RunNtpCheck(configuration, logger, post, gate).ConfigureAwait(false);
             }
 
+            if (configuration.EnableDoGroupIdAutoSet)
+                RunDoGroupIdAutoSet(configuration, logger, post, gate);
+
             RunPowerStateCheck(configuration, logger, post);
         }
 
@@ -331,6 +337,99 @@ namespace AutopilotMonitor.Agent.V2.Core.Runtime
             };
         }
 
+        /// <summary>
+        /// One-shot DO GroupId apply with change-based restart dedup: the gate fingerprint doubles
+        /// as the ownership marker ("written:&lt;guid&gt;" records the GUID we last wrote, so a later
+        /// run can distinguish our own stale value from a foreign one after a gateway change).
+        /// Unchanged outcomes (same GUID, same skip reason) re-run silently without a duplicate
+        /// event; errors never claim a fingerprint so each failing start keeps its retry trail.
+        /// </summary>
+        private static void RunDoGroupIdAutoSet(
+            AgentConfiguration configuration,
+            AgentLogger logger,
+            Orchestration.InformationalEventPost post,
+            Persistence.StartupEventGate? gate)
+        {
+            try
+            {
+                var lastWritten = ExtractLastWrittenGroupId(gate?.GetFingerprint(Constants.EventTypes.DoGroupIdAutoSet));
+                var result = DoGroupIdService.TrySetGroupId(lastWritten, logger);
+
+                var fingerprint = ComputeDoGroupIdFingerprint(result);
+                if (fingerprint != null && gate != null
+                    && !gate.ShouldEmit(Constants.EventTypes.DoGroupIdAutoSet, fingerprint))
+                {
+                    logger.Debug("StartupEnvironmentProbes: DO GroupId outcome unchanged — skipping duplicate event (restart dedup).");
+                    return;
+                }
+
+                SafeEmit(post, logger, BuildDoGroupIdEvent(configuration, result));
+
+                if (fingerprint != null)
+                    gate?.MarkEmitted(Constants.EventTypes.DoGroupIdAutoSet);
+            }
+            catch (Exception ex)
+            {
+                logger.Warning($"StartupEnvironmentProbes: DO GroupId auto-set threw: {ex.Message}");
+            }
+        }
+
+        internal const string DoGroupIdWrittenFingerprintPrefix = "written:";
+
+        /// <summary>
+        /// Success (written or already correct) fingerprints as "written:&lt;guid&gt;", a skip as
+        /// "skipped:&lt;reason&gt;"; errors return null so they are never deduped.
+        /// </summary>
+        internal static string? ComputeDoGroupIdFingerprint(DoGroupIdSetResult result)
+        {
+            if (result.Success) return DoGroupIdWrittenFingerprintPrefix + result.GroupId;
+            if (result.Skipped) return "skipped:" + result.SkipReason;
+            return null;
+        }
+
+        /// <summary>Ownership marker readback: the GUID from a "written:" fingerprint, else null.</summary>
+        internal static string? ExtractLastWrittenGroupId(string? fingerprint) =>
+            fingerprint != null && fingerprint.StartsWith(DoGroupIdWrittenFingerprintPrefix, StringComparison.Ordinal)
+                ? fingerprint.Substring(DoGroupIdWrittenFingerprintPrefix.Length)
+                : null;
+
+        internal static EnrollmentEvent BuildDoGroupIdEvent(AgentConfiguration configuration, DoGroupIdSetResult result)
+        {
+            string message;
+            if (result.Success && result.Written)
+                message = $"Delivery Optimization GroupId set to {result.GroupId} (gateway {result.GatewayIp})";
+            else if (result.Success)
+                message = $"Delivery Optimization GroupId already set to {result.GroupId}";
+            else if (result.Skipped)
+                message = $"Delivery Optimization GroupId not set: {result.SkipReason}";
+            else
+                message = $"Delivery Optimization GroupId auto-set failed: {result.Error}";
+
+            return new EnrollmentEvent
+            {
+                SessionId = configuration.SessionId,
+                TenantId = configuration.TenantId,
+                EventType = Constants.EventTypes.DoGroupIdAutoSet,
+                Severity = result.Success || result.Skipped ? EventSeverity.Info : EventSeverity.Warning,
+                Source = "StartupEnvironmentProbes",
+                Phase = EnrollmentPhase.Unknown,
+                Timestamp = DateTime.UtcNow,
+                Message = message,
+                Data = new Dictionary<string, object>
+                {
+                    { "groupId", result.GroupId ?? "" },
+                    { "previousValue", result.PreviousValue ?? "" },
+                    { "gatewayIp", result.GatewayIp ?? "" },
+                    { "gatewayMac", result.GatewayMac ?? "" },
+                    { "written", result.Written },
+                    { "skipped", result.Skipped },
+                    { "skipReason", result.SkipReason ?? "" },
+                    { "success", result.Success },
+                    { "error", result.Error ?? "" },
+                },
+            };
+        }
+
         private static void RunPowerStateCheck(
             AgentConfiguration configuration,
             AgentLogger logger,

src/Agent/AutopilotMonitor.Agent.V2.Core/SignalAdapters/ImeLogTrackerAdapter.cs

@@ -124,6 +124,17 @@ namespace AutopilotMonitor.Agent.V2.Core.SignalAdapters
         // in ImeLogTracker so the layers can never drift apart).
         private static readonly TimeSpan StaleSourceThreshold = ImeLogTracker.HistoricReplayThreshold;
 
+        /// <summary>
+        /// How far ahead of the agent clock a source timestamp may sit before it is rejected.
+        /// <para>
+        /// Writer and reader share one system clock, so a correctly converted line is always at
+        /// or behind "now"; this is pure jitter tolerance, not a skew allowance. Deliberately far
+        /// below one hour — the value that a timezone mistake produces — so that such a mistake
+        /// can actually trip it.
+        /// </para>
+        /// </summary>
+        private static readonly TimeSpan MaxFutureSourceSkew = TimeSpan.FromMinutes(2);
+
         // Matches the deterministic marker line the bootstrap script writes via Write-Log,
         // e.g. "Bootstrap script version: v2.0" — see scripts/Bootstrap/Install-AutopilotMonitor.ps1.
         // Same shape as the web-side regex in utils/bootstrapVersion.ts; kept in sync intentionally.
@@ -329,12 +340,28 @@ namespace AutopilotMonitor.Agent.V2.Core.SignalAdapters
 
                 var clockNow = _clock.UtcNow;
                 var ageHours = (clockNow - asUtc).TotalHours;
-                if (ageHours > StaleSourceThreshold.TotalHours || ageHours < -1.0)
+
+                // Future guard. A source timestamp can never legitimately be ahead of the agent
+                // clock: the writer stamps it from the SAME system clock, and the tracker only
+                // sees the line after it was written. Anything ahead means the local-to-UTC
+                // conversion was wrong.
+                //
+                // The previous threshold was ageHours < -1.0, which could not fire for the single
+                // most common timezone error: with a one-hour offset mistake the real value is
+                // parseLag - 3600 s, i.e. just ABOVE -1.0. It sat exactly on the boundary of the
+                // case it was meant to catch. It was also asymmetric — a past-shifted error had to
+                // exceed 24 h before anything noticed, while the measured field errors reached
+                // -17 h. The bound is now a small jitter tolerance in the direction that is
+                // physically impossible.
+                var isFutureSkewed = asUtc > clockNow + MaxFutureSourceSkew;
+
+                if (ageHours > StaleSourceThreshold.TotalHours || isFutureSkewed)
                 {
-                    // Pathologically stale (>24h old) or in the future (>1h skew) — log,
-                    // fall back, and let the caller flag the event.
+                    var reason = isFutureSkewed
+                        ? $"ahead of the agent clock by {(asUtc - clockNow).TotalMinutes:F1} min"
+                        : $"pathologically stale (ageHours={ageHours:F1})";
                     _logger?.Warning(
-                        $"ImeAdapter: source timestamp {asUtc:o} rejected (ageHours={ageHours:F1}); falling back to clock");
+                        $"ImeAdapter: source timestamp {asUtc:o} rejected — {reason}; falling back to clock");
                     derivedFromClock = true;
                     return clockNow;
                 }
@@ -347,12 +374,69 @@ namespace AutopilotMonitor.Agent.V2.Core.SignalAdapters
             return _clock.UtcNow;
         }
 
-        private static void TagDerivedTimestamp(IDictionary<string, string> data, bool derivedFromClock, DateTime? rawSourceTs)
+        /// <summary>
+        /// Attach the evidence for this event's timestamp: the raw local time as the writer wrote
+        /// it, the offset applied, and how that offset was obtained.
+        ///
+        /// <para>
+        /// Without this the only record of a conversion is the converted value itself, so a wrong
+        /// offset is indistinguishable from a correct one. Proving the field defect required the
+        /// diagnostics archive — and of the 5,386 sessions that went through a timezone change,
+        /// essentially none had one; the analysis had to fall back to median statistics across
+        /// thousands of sessions. These three fields make each session answer the question on its
+        /// own, and make a stored timestamp recomputable after the fact without an agent release.
+        /// </para>
+        ///
+        /// <para>
+        /// Only emitted for events whose time came from a CMTrace line. Agent-native events have
+        /// no second clock frame, so there is nothing to record.
+        /// </para>
+        /// </summary>
+        private void TagDerivedTimestamp(IDictionary<string, string> data, bool derivedFromClock, DateTime? rawSourceTs)
         {
+            var culture = System.Globalization.CultureInfo.InvariantCulture;
+
+            var sourceLocal = _tracker.LastMatchedSourceLocalTimestamp;
+            if (sourceLocal.HasValue)
+            {
+                // No zone suffix: the value genuinely carries none, and formatting one in would
+                // re-introduce the very assumption this whole change removes.
+                data["sourceLocalTs"] = sourceLocal.Value.ToString("yyyy-MM-ddTHH:mm:ss.fffffff", culture);
+                data["sourceOffsetOrigin"] = OriginTag(_tracker.LastMatchedSourceOffsetOrigin);
+
+                var offsetMinutes = _tracker.LastMatchedSourceOffsetMinutes;
+                if (offsetMinutes.HasValue)
+                    data["sourceOffsetMinutes"] = offsetMinutes.Value.ToString(culture);
+
+                // Observational only — what the calibrator measured, which since the 2026-08-20
+                // revert is deliberately NOT what was applied. Kept separate so the two can never
+                // be read as the same thing.
+                var measured = _tracker.LastMatchedMeasuredWriterOffsetMinutes;
+                if (measured.HasValue)
+                    data["measuredWriterOffsetMinutes"] = measured.Value.ToString(culture);
+            }
+
             if (!derivedFromClock) return;
             data["derivedTimestamp"] = "true";
             if (rawSourceTs.HasValue)
-                data["rejectedSourceTimestamp"] = rawSourceTs.Value.ToString("o", System.Globalization.CultureInfo.InvariantCulture);
+                data["rejectedSourceTimestamp"] = rawSourceTs.Value.ToString("o", culture);
+        }
+
+        private static string OriginTag(CmTraceOffsetOrigin origin)
+        {
+            switch (origin)
+            {
+                case CmTraceOffsetOrigin.Bias: return "bias";
+                // Per-FILE offset application, retired by the 2026-08-20 revert (04b1a7c6).
+                // Kept so stored 2.0.1410 events remain interpretable; no current path emits it.
+                case CmTraceOffsetOrigin.Calibrated: return "calibrated";
+                // The line anchored itself: read provably fresh, its own distance to the agent
+                // clock (grid-rounded) was applied as the writer's offset. Era-safe per line.
+                case CmTraceOffsetOrigin.LineAnchored: return "line-anchored";
+                // The line was not provably fresh (backlog, restart catch-up, replay), so this
+                // process's own zone was assumed — correct only if the writer happens to share it.
+                default: return "reader-zone-fallback";
+            }
         }
 
         // CMTrace Kind normalization — shared implementation lives on the tracker (used by its
@@ -720,12 +804,15 @@ namespace AutopilotMonitor.Agent.V2.Core.SignalAdapters
         /// <see cref="AppInstallTiming"/> so the emitter can inline the values on the
         /// current event's payload without a second dictionary lookup.
         /// <para>
-        /// Audit Q1: a terminal→active transition (the IME retry path — <see
-        /// cref="AppPackageState.UpdateState"/> permits e.g. Error→Downloading and
-        /// Skipped→Downloading) re-arms <c>Completed</c> to <c>null</c>, so the NEXT terminal
-        /// transition stamps a fresh CompletedAt. StartedAt keeps its first value — the final
-        /// terminal payload then covers first-start → last-terminal (total occupancy across
-        /// attempts) instead of freezing at the first failure. Observed pre-fix: a user-scope
+        /// Audit Q1 + 2026-08 attempt-duration change: a terminal→active transition (the IME
+        /// retry / re-evaluation path — <see cref="AppPackageState.UpdateState"/> permits e.g.
+        /// Error→Downloading and Skipped→Downloading) re-arms BOTH endpoints: <c>Completed</c>
+        /// to <c>null</c> (the NEXT terminal transition stamps fresh) and <c>Started</c> to
+        /// the re-entry time. The final terminal payload therefore describes the
+        /// status-defining ATTEMPT — matching the backend's AppInstallSummaries semantics —
+        /// instead of first-start → last-terminal across passes: the IME processes the app
+        /// list repeatedly (device-ESP evaluation pass, user-context pass), and the idle gap
+        /// between passes is not install time. Observed pre-fix (old bug shape): a user-scope
         /// app Skipped early in DeviceSetup, retried after sign-in, emitted its final
         /// Installed event with the stale early CompletedAt (durationSeconds=-2342).
         /// </para>
@@ -736,11 +823,13 @@ namespace AutopilotMonitor.Agent.V2.Core.SignalAdapters
             {
                 _appTimings.TryGetValue(appId, out var current);
 
-                // Terminal→active (retry): the earlier terminal stamp no longer describes this
-                // app's outcome — re-arm so the next terminal transition stamps fresh.
+                // Terminal→active (retry / new pass): the earlier stamps no longer describe
+                // this app's outcome — re-arm both endpoints so the next terminal transition
+                // reports the fresh attempt's window.
                 if (current.Completed != null && IsLifecycleActive(newState))
                 {
                     current.Completed = null;
+                    current.Started = now;
                 }
 
                 // First lifecycle-active transition → record StartedAt.

src/Agent/AutopilotMonitor.Agent.V2.Core/Transport/Telemetry/BackendTelemetryUploader.cs

@@ -119,6 +119,12 @@ namespace AutopilotMonitor.Agent.V2.Core.Transport.Telemetry
                 AddSecurityHeaders(request);
                 request.Headers.Add("X-Correlation-ID", correlationId);
 
+                // P14: device-clock send time, one value per request. Lets the backend separate
+                // spool delay (SentAt − OccurredUtc, both device frame) from device-vs-server
+                // clock offset (ReceivedAt − SentAt) — indistinguishable without this header.
+                // Stamped per attempt on purpose: a retry after backoff is a NEW send moment.
+                request.Headers.Add("X-Send-Time-Utc", DateTime.UtcNow.ToString("O"));
+
                 HttpResponseMessage response;
                 try
                 {

src/Agent/AutopilotMonitor.DecisionCore.Tests/RealmJoinGateTests.cs

@@ -372,6 +372,9 @@ namespace AutopilotMonitor.DecisionCore.Tests
             // Before RealmJoinPhaseChanged became a typed signal, LastDeploymentPhase was only
             // written at detection time — every realmjoin_timeout claimed "last phase: 0" no
             // matter how far RJ actually got, hiding this whole failure class from ops.
+            // Since the activity-based extension, the PhaseChanged at T0+6 counts as activity,
+            // so the first fire (59 min later) extends once; the timeout lands on the re-armed
+            // fire a full inactivity window after the last activity.
             var engine = new DecisionEngine();
             var state = PrimeClassicAwaitingDesktop(engine);
             state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
@@ -384,7 +387,13 @@ namespace AutopilotMonitor.DecisionCore.Tests
                 })).NewState;
             state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.DesktopArrived, T0.AddMinutes(7))).NewState;
 
-            var step = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, T0.AddMinutes(65),
+            // First fire at the original due (T0+65): activity 59 min ago → extends to T0+66.
+            state = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, T0.AddMinutes(65),
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout })).NewState;
+            var rearmed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            Assert.Equal(T0.AddMinutes(66), rearmed.DueAtUtc);
+
+            var step = engine.Reduce(state, MakeSignal(9, DecisionSignalKind.DeadlineFired, rearmed.DueAtUtc,
                 new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
 
             var timeout = Assert.Single(step.Effects, e =>
@@ -395,6 +404,248 @@ namespace AutopilotMonitor.DecisionCore.Tests
             Assert.Equal("101", timeout.Parameters["lastSeenPhase"]);
         }
 
+        // ============================================================== Activity-based extension (report 55e6afd61c9d)
+
+        [Fact]
+        public void Timeout_fire_with_recent_first_deployment_activity_extends_instead_of_timing_out()
+        {
+            // Report 55e6afd61c9d (Douglas): timer armed at detection (phase 0, RJ agent MSI
+            // install during DeviceSetup), first deployment only started 16 min later, Office
+            // completed 3 s before the deadline — the hard cut truncated an actively working
+            // deployment. The fire must now re-arm to lastActivity + 60 min instead.
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "0" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.DesktopArrived, T0.AddMinutes(6))).NewState;
+            state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.RealmJoinPhaseChanged, T0.AddMinutes(21),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "101",
+                    [DecisionEngine.RealmJoinPayloadKeys.PreviousPhase] = "0",
+                })).NewState;
+            state = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.RealmJoinPackageCompleted, T0.AddMinutes(62),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.PackageId] = "generic-microsoft-office-2016-proplus",
+                    [DecisionEngine.RealmJoinPayloadKeys.Scope] = RealmJoinPackageFact.ScopeMachine,
+                    [DecisionEngine.RealmJoinPayloadKeys.Success] = "true",
+                    [DecisionEngine.RealmJoinPayloadKeys.LastExitCode] = "0",
+                })).NewState;
+
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            var step = engine.Reduce(state, MakeSignal(9, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
+
+            // No completion, no outcome — the gate stays closed and the window is re-armed.
+            Assert.NotEqual(SessionStage.Finalizing, step.NewState.Stage);
+            Assert.Null(step.NewState.RealmJoinFacts.Outcome);
+            Assert.Equal($"DeadlineFired:{DeadlineNames.RealmJoinTimeout}:Extended", step.Transition.Trigger);
+
+            var rearmed = Assert.Single(step.NewState.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            Assert.Equal(T0.AddMinutes(62 + 60), rearmed.DueAtUtc); // lastActivity + inactivity window
+
+            Assert.Single(step.Effects, e =>
+                e.Kind == DecisionEffectKind.ScheduleDeadline &&
+                e.Deadline != null &&
+                e.Deadline.Name == DeadlineNames.RealmJoinTimeout &&
+                e.Deadline.DueAtUtc == rearmed.DueAtUtc);
+
+            var extended = Assert.Single(step.Effects, e =>
+                e.Kind == DecisionEffectKind.EmitEventTimelineEntry &&
+                e.Parameters != null &&
+                e.Parameters.TryGetValue("eventType", out var et) && et == "realmjoin_timeout_extended");
+            Assert.Equal("Info", extended.Parameters!["severity"]);
+            Assert.Equal("101", extended.Parameters["deploymentPhase"]);
+            Assert.DoesNotContain(step.Effects, e =>
+                e.Kind == DecisionEffectKind.EmitEventTimelineEntry &&
+                e.Parameters != null &&
+                e.Parameters.TryGetValue("eventType", out var et) && et == "realmjoin_timeout");
+        }
+
+        [Fact]
+        public void Resolved_after_extension_completes_via_classic_path()
+        {
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "101" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.DesktopArrived, T0.AddMinutes(6))).NewState;
+            state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.RealmJoinPhaseChanged, T0.AddMinutes(40),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "100",
+                    [DecisionEngine.RealmJoinPayloadKeys.PreviousPhase] = "101",
+                })).NewState;
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            state = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout })).NewState;
+            Assert.Null(state.RealmJoinFacts.Outcome); // extended, not timed out
+
+            var step = engine.Reduce(state, MakeSignal(9, DecisionSignalKind.RealmJoinResolved, T0.AddMinutes(80),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "110" }));
+
+            Assert.Equal(SessionStage.Finalizing, step.NewState.Stage);
+            Assert.Equal("Resolved", step.NewState.RealmJoinFacts.Outcome!.Value);
+            Assert.DoesNotContain(step.NewState.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+        }
+
+        [Fact]
+        public void Rearmed_fire_after_quiet_window_times_out_with_inactivity_reason()
+        {
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "0" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.DesktopArrived, T0.AddMinutes(6))).NewState;
+            state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.RealmJoinPhaseChanged, T0.AddMinutes(30),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "101",
+                    [DecisionEngine.RealmJoinPayloadKeys.PreviousPhase] = "0",
+                })).NewState;
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            state = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout })).NewState;
+            var rearmed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            Assert.Equal(T0.AddMinutes(90), rearmed.DueAtUtc); // lastActivity (T0+30) + 60 min
+
+            // No further activity — the re-armed fire must now time out for real.
+            var step = engine.Reduce(state, MakeSignal(9, DecisionSignalKind.DeadlineFired, rearmed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
+
+            Assert.Equal(SessionStage.Finalizing, step.NewState.Stage);
+            Assert.Equal("Timeout", step.NewState.RealmJoinFacts.Outcome!.Value);
+            var timeout = Assert.Single(step.Effects, e =>
+                e.Kind == DecisionEffectKind.EmitEventTimelineEntry &&
+                e.Parameters != null &&
+                e.Parameters.TryGetValue("eventType", out var et) && et == "realmjoin_timeout");
+            Assert.Equal("inactivity", timeout.Parameters!["reason"]);
+            Assert.Contains("no deployment activity", timeout.Parameters["message"]);
+        }
+
+        [Fact]
+        public void Extension_is_capped_at_absolute_ceiling_and_cap_fire_times_out_despite_activity()
+        {
+            // Late activity pushes the sliding window beyond detection + 4 h — the re-arm must
+            // clamp to the cap, and the cap fire must time out even though activity is recent.
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "101" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.DesktopArrived, T0.AddMinutes(6))).NewState;
+            // Package completion whose sliding window (T0+230+60) would exceed the cap (T0+245).
+            state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.RealmJoinPackageCompleted, T0.AddMinutes(230),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.PackageId] = "generic-big-suite",
+                    [DecisionEngine.RealmJoinPayloadKeys.Scope] = RealmJoinPackageFact.ScopeMachine,
+                    [DecisionEngine.RealmJoinPayloadKeys.Success] = "true",
+                    [DecisionEngine.RealmJoinPayloadKeys.LastExitCode] = "0",
+                })).NewState;
+
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            state = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout })).NewState;
+
+            var rearmed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            Assert.Equal(T0.AddMinutes(5).AddHours(4), rearmed.DueAtUtc); // clamped to detection + cap
+
+            var step = engine.Reduce(state, MakeSignal(9, DecisionSignalKind.DeadlineFired, rearmed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
+
+            Assert.Equal(SessionStage.Finalizing, step.NewState.Stage);
+            Assert.Equal("Timeout", step.NewState.RealmJoinFacts.Outcome!.Value);
+            var timeout = Assert.Single(step.Effects, e =>
+                e.Kind == DecisionEffectKind.EmitEventTimelineEntry &&
+                e.Parameters != null &&
+                e.Parameters.TryGetValue("eventType", out var et) && et == "realmjoin_timeout");
+            Assert.Equal("absolute_cap", timeout.Parameters!["reason"]);
+        }
+
+        [Fact]
+        public void Stale_fire_of_old_incarnation_after_rearm_is_dead_end()
+        {
+            // Race: the OLD deadline incarnation's fire was already queued when the extension
+            // re-armed. The armed deadline is due LATER than the stale fire — dead-end, no
+            // second extension evaluation, no timeout.
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "0" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.RealmJoinPhaseChanged, T0.AddMinutes(30),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "101",
+                    [DecisionEngine.RealmJoinPayloadKeys.PreviousPhase] = "0",
+                })).NewState;
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout })).NewState;
+            Assert.Null(state.RealmJoinFacts.Outcome); // extended
+
+            var step = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
+
+            Assert.False(step.Transition.Taken);
+            Assert.Null(step.NewState.RealmJoinFacts.Outcome);
+            Assert.Empty(step.Effects);
+            var stillArmed = Assert.Single(step.NewState.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            Assert.Equal(T0.AddMinutes(90), stillArmed.DueAtUtc);
+        }
+
+        [Fact]
+        public void Detection_phase_alone_is_not_activity_idle_case_times_out_at_60_min_unchanged()
+        {
+            // The phase captured AT detection must not count as activity — RJ detected in a
+            // first-deployment phase that then never moves still times out after the original
+            // 60 min (the extension exists for demonstrable progress, not for standing still).
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "101" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.DesktopArrived, T0.AddMinutes(6))).NewState;
+            Assert.Null(state.RealmJoinFacts.LastActivityUtc);
+
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            var step = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
+
+            Assert.Equal(SessionStage.Finalizing, step.NewState.Stage);
+            Assert.Equal("Timeout", step.NewState.RealmJoinFacts.Outcome!.Value);
+            var timeout = Assert.Single(step.Effects, e =>
+                e.Kind == DecisionEffectKind.EmitEventTimelineEntry &&
+                e.Parameters != null &&
+                e.Parameters.TryGetValue("eventType", out var et) && et == "realmjoin_timeout");
+            Assert.Equal("hard_timeout", timeout.Parameters!["reason"]);
+        }
+
+        [Fact]
+        public void Regular_deployment_phase_with_activity_does_not_extend()
+        {
+            // Session 6f1959c0 shape: RJ stood at 210 when the agent booted and deploys
+            // regular (non-first) packages afterwards. Phase 200/210 is outside the
+            // first-deployment window — activity there must NOT hold the session hostage.
+            var engine = new DecisionEngine();
+            var state = PrimeClassicAwaitingDesktop(engine);
+            state = engine.Reduce(state, MakeSignal(5, DecisionSignalKind.RealmJoinDetected, T0.AddMinutes(5),
+                new Dictionary<string, string> { [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "210" })).NewState;
+            state = engine.Reduce(state, MakeSignal(6, DecisionSignalKind.DesktopArrived, T0.AddMinutes(6))).NewState;
+            state = engine.Reduce(state, MakeSignal(7, DecisionSignalKind.RealmJoinPhaseChanged, T0.AddMinutes(40),
+                new Dictionary<string, string>
+                {
+                    [DecisionEngine.RealmJoinPayloadKeys.DeploymentPhase] = "200",
+                    [DecisionEngine.RealmJoinPayloadKeys.PreviousPhase] = "210",
+                })).NewState;
+
+            var armed = Assert.Single(state.Deadlines, d => d.Name == DeadlineNames.RealmJoinTimeout);
+            var step = engine.Reduce(state, MakeSignal(8, DecisionSignalKind.DeadlineFired, armed.DueAtUtc,
+                new Dictionary<string, string> { [SignalPayloadKeys.Deadline] = DeadlineNames.RealmJoinTimeout }));
+
+            Assert.Equal(SessionStage.Finalizing, step.NewState.Stage);
+            Assert.Equal("Timeout", step.NewState.RealmJoinFacts.Outcome!.Value);
+        }
+
         [Fact]
         public void SelfDeploying_deferred_terminal_released_by_first_deployment_incomplete()
         {

src/Backend/AutopilotMonitor.Functions.Tests/AppInstallTerminalStateAndReconcileTests.cs

@@ -198,4 +198,164 @@ public class AppInstallTerminalStateAndReconcileTests
         // Column absent → Merge-mode preserves a prior batch's terminal state.
         Assert.False(empty.ContainsKey("TerminalState"));
     }
+
+    // ── attempt-duration semantics (2026-08): the field case that motivated it ──
+    // Session 44862cd3, "Set TimeZone": device-ESP evaluation pass ends Skipped, the real
+    // install happens ~66 min later in the user-context pass and takes 23 s. The old span
+    // semantics reported 4002 s.
+
+    [Fact]
+    public void TwoPasses_SingleBatch_DurationIsLastAttempt_NotSpan()
+    {
+        var s = Aggregate(
+            AppEvent("app_install_started", T0),
+            AppEvent("app_install_completed", T0.AddMinutes(6), "Skipped"),
+            AppEvent("app_install_started", T0.AddMinutes(66)),
+            AppEvent("app_install_completed", T0.AddMinutes(66).AddSeconds(23), "Installed"))["App"].Summary;
+
+        Assert.Equal(23, s.DurationSeconds);                        // last attempt, not 3983 s
+        Assert.Equal(T0, s.StartedAt);                              // first-seen anchor untouched
+        Assert.Equal(T0.AddMinutes(66), s.LastAttemptStartedAt);
+        Assert.Equal(2, s.InstallPassCount);
+        Assert.Equal("Installed", s.TerminalState);
+        Assert.Equal(T0.AddMinutes(66).AddSeconds(23), s.CompletedAt);
+    }
+
+    [Fact]
+    public void WeakerTerminal_CompletedSkipped_NeverOverridesInstalled_InBatch()
+    {
+        // Re-evaluation after a real install reports Skipped (already present) — the row
+        // keeps describing the install attempt, incl. CompletedAt and duration.
+        var s = Aggregate(
+            AppEvent("app_install_started", T0),
+            AppEvent("app_install_completed", T0.AddSeconds(40), "Installed"),
+            AppEvent("app_install_started", T0.AddMinutes(30)),
+            AppEvent("app_install_completed", T0.AddMinutes(30).AddSeconds(2), "Skipped"))["App"].Summary;
+
+        Assert.Equal("Installed", s.TerminalState);
+        Assert.Equal(T0.AddSeconds(40), s.CompletedAt);
+        Assert.Equal(40, s.DurationSeconds);
+    }
+
+    [Fact]
+    public void StartInOneBatch_TerminalInNext_ReconcileAnchorsOnStoredAttempt()
+    {
+        // Pass 2 start landed in batch N (stored anchor); the terminal-only batch N+1 must
+        // pair against it — not against the first-seen StartedAt an hour earlier.
+        var existing = new TableEntity("tenant", "session_App")
+        {
+            ["Status"] = "InProgress",
+            ["StartedAt"] = new DateTimeOffset(T0),
+            ["LastAttemptStartedAt"] = new DateTimeOffset(T0.AddMinutes(66)),
+            ["InstallPassCount"] = 2,
+        };
+        var summary = new AppInstallSummary
+        {
+            AppName = "App", SessionId = "session", TenantId = "tenant",
+            Status = "Succeeded", TerminalState = "Installed",
+            StartedAt = T0.AddMinutes(66).AddSeconds(23),           // batch init stamp (terminal event)
+            CompletedAt = T0.AddMinutes(66).AddSeconds(23),
+        };
+
+        TableStorageService.ReconcileAppInstallSummaryWithExisting(summary, existing);
+
+        Assert.Equal(T0, summary.StartedAt);                        // earliest wins (window key)
+        Assert.Equal(T0.AddMinutes(66), summary.LastAttemptStartedAt);
+        Assert.Equal(23, summary.DurationSeconds);                  // attempt-anchored, not 3983 s
+        Assert.Equal(2, summary.InstallPassCount);
+    }
+
+    [Fact]
+    public void Reconcile_ReplayedOlderBatch_NeverRegressesAnchorOrDoubleCountsPasses()
+    {
+        var existing = new TableEntity("tenant", "session_App")
+        {
+            ["StartedAt"] = new DateTimeOffset(T0),
+            ["LastAttemptStartedAt"] = new DateTimeOffset(T0.AddMinutes(66)),
+            ["InstallPassCount"] = 2,
+        };
+        // Replay of the pass-1 batch: its newest start is OLDER than the stored anchor.
+        var summary = new AppInstallSummary
+        {
+            AppName = "App", Status = "InProgress",
+            StartedAt = T0, LastAttemptStartedAt = T0, InstallPassCount = 1,
+        };
+
+        TableStorageService.ReconcileAppInstallSummaryWithExisting(summary, existing);
+
+        Assert.Equal(T0.AddMinutes(66), summary.LastAttemptStartedAt);  // max-fold: no regression
+        Assert.Equal(2, summary.InstallPassCount);                      // not 3 — replay not re-counted
+    }
+
+    [Fact]
+    public void Reconcile_NewerAttemptBatch_AddsPassCount()
+    {
+        var existing = new TableEntity("tenant", "session_App")
+        {
+            ["StartedAt"] = new DateTimeOffset(T0),
+            ["LastAttemptStartedAt"] = new DateTimeOffset(T0),
+            ["InstallPassCount"] = 1,
+        };
+        var summary = new AppInstallSummary
+        {
+            AppName = "App", Status = "InProgress",
+            StartedAt = T0.AddMinutes(66), LastAttemptStartedAt = T0.AddMinutes(66), InstallPassCount = 1,
+        };
+
+        TableStorageService.ReconcileAppInstallSummaryWithExisting(summary, existing);
+
+        Assert.Equal(T0.AddMinutes(66), summary.LastAttemptStartedAt);
+        Assert.Equal(2, summary.InstallPassCount);
+    }
+
+    [Fact]
+    public void Reconcile_WeakerTerminalBatch_NeverOverridesStoredInstalled()
+    {
+        // Cross-batch mirror of the in-batch guard: a batch that only saw the Skipped
+        // re-evaluation must not re-describe an Installed row.
+        var existing = new TableEntity("tenant", "session_App")
+        {
+            ["Status"] = "Succeeded",
+            ["TerminalState"] = "Installed",
+            ["StartedAt"] = new DateTimeOffset(T0),
+            ["CompletedAt"] = new DateTimeOffset(T0.AddSeconds(40)),
+            ["DurationSeconds"] = 40,
+        };
+        var summary = new AppInstallSummary
+        {
+            AppName = "App", Status = "Succeeded", TerminalState = "Skipped",
+            StartedAt = T0.AddMinutes(30),
+            LastAttemptStartedAt = T0.AddMinutes(30), InstallPassCount = 1,
+            CompletedAt = T0.AddMinutes(30).AddSeconds(2), DurationSeconds = 2,
+        };
+
+        TableStorageService.ReconcileAppInstallSummaryWithExisting(summary, existing);
+
+        Assert.Equal("Installed", summary.TerminalState);
+        // The guard drops the skip-pass endpoints; the Q4 path then re-adopts the STORED
+        // CompletedAt (the surviving install attempt's) — same value as on disk, and the
+        // attempt anchor being newer keeps DurationSeconds at 0, so the omitted column
+        // lets Merge preserve the stored 40 s.
+        Assert.Equal(T0.AddSeconds(40), summary.CompletedAt);
+        Assert.Equal(0, summary.DurationSeconds);
+    }
+
+    [Fact]
+    public void EntityBuilder_AttemptColumns_AreSentinelGated()
+    {
+        var with = new AppInstallSummary
+        {
+            AppName = "App",
+            LastAttemptStartedAt = T0,
+            InstallPassCount = 2,
+        };
+        var entity = TableStorageService.BuildAppInstallSummaryEntity(with, "rk");
+        Assert.Equal(new DateTimeOffset(T0), entity.GetDateTimeOffset("LastAttemptStartedAt"));
+        Assert.Equal(2, entity.GetInt32("InstallPassCount"));
+
+        var without = new AppInstallSummary { AppName = "App" };
+        var empty = TableStorageService.BuildAppInstallSummaryEntity(without, "rk");
+        Assert.False(empty.ContainsKey("LastAttemptStartedAt"));
+        Assert.False(empty.ContainsKey("InstallPassCount"));
+    }
 }

src/Backend/AutopilotMonitor.Functions.Tests/AppVersionRegressionRadarTests.cs

@@ -36,7 +36,8 @@ public class AppVersionRegressionRadarTests
         string appName = App,
         string status = "Succeeded",
         string terminalState = "Installed",
-        bool collision = false)
+        bool collision = false,
+        bool attemptAnchored = true)
         => new()
         {
             TenantId = TenantA,
@@ -47,6 +48,9 @@ public class AppVersionRegressionRadarTests
             TerminalState = terminalState,
             DurationSeconds = durationSeconds,
             StartedAt = startedAt ?? Now.AddDays(-1),
+            // Post-cutover rows carry the attempt anchor; the radar's cutover gate
+            // excludes rows without it (attemptAnchored: false = legacy span row).
+            LastAttemptStartedAt = attemptAnchored ? (startedAt ?? Now.AddDays(-1)) : null,
             AppIdCollision = collision,
         };
 
@@ -164,6 +168,26 @@ public class AppVersionRegressionRadarTests
         Assert.Equal(900, finding.CurrentMedianSeconds);
     }
 
+    [Fact]
+    public void Evaluate_CutoverGate_LegacySpanRows_ExcludedOnBothSides()
+    {
+        // 2026-08 attempt-duration cutover: rows without LastAttemptStartedAt carry the old
+        // full-span semantics and are excluded from BOTH comparison sides.
+
+        // Current side: 10 legacy span rows would fire (lift 3.0), but only 5 are
+        // attempt-anchored → below MinMeasuredInstalls → silent.
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-20));
+        rows.AddRange(Enumerable.Range(0, 10).Select(_ => Install("2.0", 900, Now.AddDays(-5), attemptAnchored: false)));
+        rows.AddRange(Enumerable.Range(0, 5).Select(_ => Install("2.0", 900, Now.AddDays(-5))));
+        Assert.Empty(AppVersionRegressionRadar.Evaluate(rows));
+
+        // Previous side entirely legacy → gated away → no comparison basis → silent,
+        // even though the raw medians (300 → 900) would scream regression.
+        var rows2 = Enumerable.Range(0, 10).Select(_ => Install("1.0", 300, Now.AddDays(-20), attemptAnchored: false)).ToList();
+        rows2.AddRange(Batch("2.0", 10, 900, Now.AddDays(-5)));
+        Assert.Empty(AppVersionRegressionRadar.Evaluate(rows2));
+    }
+
     [Fact]
     public void Evaluate_DeterministicOrdering_LiftDesc_ThenAppNameOrdinal()
     {

src/Backend/AutopilotMonitor.Functions.Tests/BuiltInRuleCatalogPolicyTests.cs

@@ -0,0 +1,56 @@
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Pins the shipped rule catalogs to the reserved built-in ID namespace from
+/// RuleIdPolicy: every built-in occupies (ANALYZE|GATHER)-&lt;CATEGORY&gt;-&lt;NUMBER&gt; with
+/// CATEGORY != CUSTOM, and IDs are unique (case-insensitively — case variants are
+/// indistinguishable to humans and to the policy regex). This is the backend-side
+/// enforcement of the "platform never ships a built-in in the CUSTOM namespace"
+/// commitment documented in RuleIdPolicy — without it, a shipped CUSTOM-ID rule
+/// would silently shadow every tenant's same-ID custom rule at merge time
+/// (global wins, tenant copy dropped). combine.js mirrors these checks at
+/// catalog-build time; this test guards the embedded resource actually deployed.
+/// </summary>
+public class BuiltInRuleCatalogPolicyTests
+{
+    [Fact]
+    public void BuiltIn_analyze_ids_are_reserved_namespace_and_unique()
+    {
+        var ids = BuiltInAnalyzeRules.GetAll().Select(r => r.RuleId).ToList();
+
+        Assert.NotEmpty(ids);
+        foreach (var id in ids)
+        {
+            Assert.True(RuleIdPolicy.IsReservedBuiltInId(id),
+                $"Built-in analyze rule '{id}' lies outside the reserved built-in namespace — " +
+                "it would collide with the tenant custom namespace.");
+        }
+
+        var duplicates = ids.GroupBy(id => id, StringComparer.OrdinalIgnoreCase)
+            .Where(g => g.Count() > 1).Select(g => g.Key).ToList();
+        Assert.True(duplicates.Count == 0,
+            $"Duplicate built-in analyze rule IDs: {string.Join(", ", duplicates)}");
+    }
+
+    [Fact]
+    public void BuiltIn_gather_ids_are_reserved_namespace_and_unique()
+    {
+        var ids = BuiltInGatherRules.GetAll().Select(r => r.RuleId).ToList();
+
+        Assert.NotEmpty(ids);
+        foreach (var id in ids)
+        {
+            Assert.True(RuleIdPolicy.IsReservedBuiltInId(id),
+                $"Built-in gather rule '{id}' lies outside the reserved built-in namespace — " +
+                "it would collide with the tenant custom namespace.");
+        }
+
+        var duplicates = ids.GroupBy(id => id, StringComparer.OrdinalIgnoreCase)
+            .Where(g => g.Count() > 1).Select(g => g.Key).ToList();
+        Assert.True(duplicates.Count == 0,
+            $"Duplicate built-in gather rule IDs: {string.Join(", ", duplicates)}");
+    }
+}

src/Backend/AutopilotMonitor.Functions.Tests/CmTraceSkewTripwireTests.cs

@@ -0,0 +1,152 @@
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Pins the CMTrace time-skew regression tripwire (CmTraceSkewTripwire.Evaluate): fires only
+/// when the IME-vs-other median delta divergence sits on the 15-minute offset grid (residual
+/// &lt; 2 min) AND both sides have enough samples over enough distinct upload batches. The
+/// tripwire's goal state is to never fire, so the must-stay-silent directions are the primary
+/// cases: off-grid replays, sub-grid divergence, thin samples, batch-composition artifacts,
+/// and common-mode spool latency must all pass without a hit.
+/// </summary>
+public class CmTraceSkewTripwireTests
+{
+    /// <summary>Scan with the given per-side medians, comfortably above all sample/batch minimums.</summary>
+    private static SessionSkewScan MakeScan(
+        double imeDeltaMinutes, double otherDeltaMinutes,
+        int imeSamples = 30, int otherSamples = 30,
+        int imeBatches = 5, int otherBatches = 5)
+    {
+        var scan = new SessionSkewScan
+        {
+            ImeDistinctBatchCount = imeBatches,
+            OtherDistinctBatchCount = otherBatches,
+        };
+        for (int i = 0; i < imeSamples; i++)
+            scan.ImeDeltaMinutes.Add(imeDeltaMinutes);
+        for (int i = 0; i < otherSamples; i++)
+            scan.OtherDeltaMinutes.Add(otherDeltaMinutes);
+        return scan;
+    }
+
+    // ── Must fire ──────────────────────────────────────────────────────────
+
+    [Fact]
+    public void Fires_OnLargeNegativeGridDivergence()
+    {
+        // −540 min = the field-measured E.-Australia-style skew (−9 h), exactly 36 grid steps.
+        // Both sides share 1.2 min upload latency — it cancels in the difference.
+        var result = CmTraceSkewTripwire.Evaluate(MakeScan(imeDeltaMinutes: -538.8, otherDeltaMinutes: 1.2));
+
+        Assert.NotNull(result);
+        Assert.Equal(-36, result!.GridSteps);
+        Assert.Equal(-540.0, result.DiffMinutes, 3);
+        Assert.True(result.ResidualMinutes < CmTraceSkewTripwire.ResidualToleranceMinutes);
+    }
+
+    [Fact]
+    public void Fires_OnSingleGridStepWithBoundaryResidual()
+    {
+        // +15 min divergence with residual 1.9 — just inside the 2-min tolerance.
+        var result = CmTraceSkewTripwire.Evaluate(MakeScan(imeDeltaMinutes: 16.9, otherDeltaMinutes: 0.0));
+
+        Assert.NotNull(result);
+        Assert.Equal(1, result!.GridSteps);
+        Assert.Equal(1.9, result.ResidualMinutes, 3);
+    }
+
+    // ── Must stay silent ───────────────────────────────────────────────────
+
+    [Fact]
+    public void Silent_WhenResidualOffGrid()
+    {
+        // 17.5 min divergence: nearest grid step is 15, residual 2.5 ≥ tolerance — the replay
+        // signature (old log lines re-read late land anywhere, not on the zone grid).
+        Assert.Null(CmTraceSkewTripwire.Evaluate(MakeScan(imeDeltaMinutes: 17.5, otherDeltaMinutes: 0.0)));
+    }
+
+    [Fact]
+    public void Silent_WhenDivergenceBelowOneGridStep()
+    {
+        // 9 min rounds to 1 step but with residual 6 — and 7 min rounds to 0 steps. Both silent.
+        Assert.Null(CmTraceSkewTripwire.Evaluate(MakeScan(imeDeltaMinutes: 9.0, otherDeltaMinutes: 0.0)));
+        Assert.Null(CmTraceSkewTripwire.Evaluate(MakeScan(imeDeltaMinutes: 7.0, otherDeltaMinutes: 0.0)));
+    }
+
+    [Fact]
+    public void Silent_WhenImeSampleCountBelowMinimum()
+    {
+        var scan = MakeScan(imeDeltaMinutes: -540.0, otherDeltaMinutes: 0.0,
+            imeSamples: CmTraceSkewTripwire.MinSamplesPerSide - 1);
+        Assert.Null(CmTraceSkewTripwire.Evaluate(scan));
+    }
+
+    [Fact]
+    public void Silent_WhenDistinctBatchesBelowMinimum()
+    {
+        // A perfect grid divergence backed by only 2 upload batches on one side is a
+        // batch-composition artifact (ReceivedAt is stamped per batch, not per event).
+        var scan = MakeScan(imeDeltaMinutes: -540.0, otherDeltaMinutes: 0.0,
+            otherBatches: CmTraceSkewTripwire.MinDistinctBatchesPerSide - 1);
+        Assert.Null(CmTraceSkewTripwire.Evaluate(scan));
+    }
+
+    [Fact]
+    public void Silent_OnCommonModeSpoolLatency()
+    {
+        // Offline spool: BOTH sides uploaded 45 min late. The difference of medians is ~0 —
+        // shared latency must cancel, never read as skew.
+        Assert.Null(CmTraceSkewTripwire.Evaluate(MakeScan(imeDeltaMinutes: 45.3, otherDeltaMinutes: 45.1)));
+    }
+
+    [Fact]
+    public void Silent_OnNullOrEmptyScan()
+    {
+        Assert.Null(CmTraceSkewTripwire.Evaluate(null));
+        Assert.Null(CmTraceSkewTripwire.Evaluate(new SessionSkewScan()));
+    }
+
+    [Fact]
+    public void MedianIsRobustAgainstMinorityOutliers()
+    {
+        // A handful of replayed old lines (huge off-grid deltas) inside an otherwise healthy
+        // IME stream must not drag the median onto the grid.
+        var scan = MakeScan(imeDeltaMinutes: 0.5, otherDeltaMinutes: 0.4);
+        scan.ImeDeltaMinutes.Add(-1327.0);
+        scan.ImeDeltaMinutes.Add(-738.0);
+        Assert.Null(CmTraceSkewTripwire.Evaluate(scan));
+    }
+
+    // ── Bias suppression predicate ─────────────────────────────────────────
+
+    [Fact]
+    public void BiasDominated_WhenBiasIsHalfOrMore()
+    {
+        Assert.True(CmTraceSkewTripwire.IsBiasDominated(new Dictionary<string, int>
+        {
+            ["bias"] = 50,
+            ["line-anchored"] = 50,
+        }));
+        Assert.True(CmTraceSkewTripwire.IsBiasDominated(new Dictionary<string, int>
+        {
+            ["Bias"] = 3, // case-insensitive
+        }));
+    }
+
+    [Fact]
+    public void NotBiasDominated_WhenAnchoredMajorityOrNoData()
+    {
+        Assert.False(CmTraceSkewTripwire.IsBiasDominated(new Dictionary<string, int>
+        {
+            ["bias"] = 10,
+            ["line-anchored"] = 80,
+            ["reader-zone-fallback"] = 11,
+        }));
+        // Empty/missing histogram fails open toward reporting — a storage error must not
+        // silently swallow a genuine regression hit.
+        Assert.False(CmTraceSkewTripwire.IsBiasDominated(new Dictionary<string, int>()));
+        Assert.False(CmTraceSkewTripwire.IsBiasDominated(null));
+    }
+}

src/Backend/AutopilotMonitor.Functions.Tests/EventTimestampValidationTests.cs

@@ -379,20 +379,50 @@ public class EventTimestampValidationTests
     }
 
     [Fact]
-    public void RecalculateAppDurations_DownloadThenInstall_CorrectDownloadDuration()
+    public void DownloadThenInstall_AttemptScopedPairing_DownloadAndInstallDurations()
     {
+        // 2026-08 attempt-duration change: DownloadDurationSeconds pairs the latest download
+        // start with the NEXT install start at event-fold time (no first→first span math),
+        // and DurationSeconds anchors on the install attempt (download time is reported
+        // separately, not folded into the install duration).
         var downloadStart = new DateTime(2026, 3, 30, 10, 0, 0, DateTimeKind.Utc);
         var installStart = downloadStart.AddSeconds(30);
         var completed = installStart.AddSeconds(45);
 
+        var summaries = new Dictionary<string, AppInstallAggregationState>(StringComparer.OrdinalIgnoreCase);
+        foreach (var evt in new[]
+        {
+            AppInstallEvent("app_download_started", downloadStart),
+            AppInstallEvent("app_install_started", installStart),
+            AppInstallEvent("app_install_completed", completed, "Installed"),
+        })
+        {
+            EventIngestProcessor.AggregateAppInstallEvent(evt, "tenant", "session", summaries);
+        }
+
+        var summary = summaries["TestApp"].Summary;
+        Assert.Equal(30, summary.DownloadDurationSeconds); // download→install gap
+        Assert.Equal(45, summary.DurationSeconds);         // install attempt only
+        Assert.Equal(installStart, summary.LastAttemptStartedAt);
+        Assert.Equal(downloadStart, summary.StartedAt);    // first-seen anchor
+    }
+
+    [Fact]
+    public void RecalculateAppDurations_AttemptAnchor_BeatsFirstSeenSpan()
+    {
+        // With an observed attempt start, the duration is the attempt — never the span
+        // back to the first observation an hour earlier.
+        var firstSeen = new DateTime(2026, 3, 30, 10, 0, 0, DateTimeKind.Utc);
+        var attemptStart = firstSeen.AddMinutes(60);
+        var completed = attemptStart.AddSeconds(45);
+
         var state = new AppInstallAggregationState
         {
-            DownloadStartedAt = downloadStart,
-            InstallStartedAt = installStart,
             Summary = new AppInstallSummary
             {
                 AppName = "TestApp",
-                StartedAt = downloadStart,
+                StartedAt = firstSeen,
+                LastAttemptStartedAt = attemptStart,
                 CompletedAt = completed,
                 Status = "Succeeded"
             }
@@ -400,8 +430,46 @@ public class EventTimestampValidationTests
 
         EventIngestProcessor.RecalculateAppDurations(state);
 
-        Assert.Equal(30, state.Summary.DownloadDurationSeconds); // download→install gap
-        Assert.Equal(75, state.Summary.DurationSeconds);         // full duration
+        Assert.Equal(45, state.Summary.DurationSeconds);
+    }
+
+    [Fact]
+    public void RecalculateAppDurations_AttemptNewerThanCompletion_KeepsRecordedDuration()
+    {
+        // A fresh pass is in flight (start after the last terminal): CompletedAt belongs to
+        // the previous attempt — its recorded duration must stand.
+        var attempt1 = new DateTime(2026, 3, 30, 10, 0, 0, DateTimeKind.Utc);
+        var completed = attempt1.AddSeconds(40);
+        var attempt2 = completed.AddMinutes(30);
+
+        var state = new AppInstallAggregationState
+        {
+            Summary = new AppInstallSummary
+            {
+                AppName = "TestApp",
+                StartedAt = attempt1,
+                LastAttemptStartedAt = attempt2,
+                CompletedAt = completed,
+                DurationSeconds = 40,
+                Status = "Succeeded"
+            }
+        };
+
+        EventIngestProcessor.RecalculateAppDurations(state);
+
+        Assert.Equal(40, state.Summary.DurationSeconds);
+    }
+
+    private static EnrollmentEvent AppInstallEvent(string eventType, DateTime ts, string? state = null)
+    {
+        var evt = new EnrollmentEvent
+        {
+            EventType = eventType,
+            Timestamp = ts,
+            Data = new Dictionary<string, object> { ["appName"] = "TestApp" },
+        };
+        if (state != null) evt.Data["state"] = state;
+        return evt;
     }
 
     [Fact]

src/Backend/AutopilotMonitor.Functions.Tests/FleetHealthPayloadTests.cs

@@ -46,6 +46,8 @@ public class FleetHealthPayloadTests
         Assert.Equal(0, payload.Stats.Total);
         Assert.Equal(0d, payload.Stats.SuccessRate);
         Assert.Equal(0, payload.Stats.AvgDurationMinutes);
+        Assert.Equal(0, payload.Stats.MedianDurationMinutes);
+        Assert.Equal(0, payload.Stats.P90DurationMinutes);
         Assert.Empty(payload.FailureReasons);
         Assert.Empty(payload.ModelHealth);
         Assert.Empty(payload.SlowestModels);
@@ -109,6 +111,28 @@ public class FleetHealthPayloadTests
 
         // (600 + 1200) / 2 / 60 = 15 min.
         Assert.Equal(15, payload.Stats.AvgDurationMinutes);
+        // Same population feeds the percentile stats: sorted [600, 1200].
+        Assert.Equal(10, payload.Stats.MedianDurationMinutes);
+        Assert.Equal(20, payload.Stats.P90DurationMinutes);
+    }
+
+    [Fact]
+    public void MedianDuration_IsRobustAgainstOutliers_ThatDominateTheAverage()
+    {
+        // The card's raison d'être: 8 typical 10-min enrollments plus a 2 h and a 24 h
+        // outlier (overnight ESP / WhiteGlove late user phase). The mean explodes to ~2.7 h
+        // while the median still answers "how long does a typical enrollment take".
+        var sessions = new List<SessionSummary>();
+        for (int i = 0; i < 8; i++)
+            sessions.Add(S(SessionStatus.Succeeded, durationSeconds: 600));
+        sessions.Add(S(SessionStatus.Succeeded, durationSeconds: 7200));
+        sessions.Add(S(SessionStatus.Succeeded, durationSeconds: 86400));
+
+        var payload = MetricsMath.BuildFleetHealthPayload(sessions, days: 7);
+
+        Assert.Equal(164, payload.Stats.AvgDurationMinutes);   // (8*600 + 7200 + 86400) / 10 / 60
+        Assert.Equal(10, payload.Stats.MedianDurationMinutes); // unmoved by the tail
+        Assert.Equal(120, payload.Stats.P90DurationMinutes);   // tail stays visible
     }
 
     [Fact]

src/Backend/AutopilotMonitor.Functions.Tests/GraphFeatureCatalogSyncTests.cs

@@ -54,9 +54,13 @@ public class GraphFeatureCatalogSyncTests
             .Select(m => m.Groups["f"].Value)
             .ToArray();
 
+        // 'All' is a script-side meta-value that expands to every catalog feature — it is not
+        // (and must never become) a GraphFeatureCatalog entry, but the script must keep offering it.
+        Assert.Contains("All", scriptFeatures);
+
         Assert.Equal(
             GraphFeatureCatalog.Features.OrderBy(f => f, StringComparer.OrdinalIgnoreCase),
-            scriptFeatures.OrderBy(f => f, StringComparer.OrdinalIgnoreCase));
+            scriptFeatures.Where(f => f != "All").OrderBy(f => f, StringComparer.OrdinalIgnoreCase));
     }
 
     private static string ReadGrantScript()

src/Backend/AutopilotMonitor.Functions.Tests/IngestCriticalPathTests.cs

@@ -33,6 +33,31 @@ public class IngestCriticalPathTests
         Assert.All(events, evt => Assert.Equal(receivedAt, evt.ReceivedAt));
     }
 
+    [Fact]
+    public void StampServerFields_SetsSentAtOnAllEvents_AndOverridesAgentValues()
+    {
+        // P14: SentAt is request-level and server-stamped — a per-event value coming off the
+        // wire (agent bug, forged payload) must never survive.
+        var sentAt = DateTime.UtcNow.AddSeconds(-4);
+        var events = MakeEvents(3);
+        events[1].SentAt = DateTime.UtcNow.AddYears(1);
+
+        EventIngestProcessor.StampServerFields(events, ValidTenantId, ValidSessionId, DateTime.UtcNow, sentAt);
+
+        Assert.All(events, evt => Assert.Equal(sentAt, evt.SentAt));
+    }
+
+    [Fact]
+    public void StampServerFields_WithoutSendTimeHeader_LeavesSentAtNull()
+    {
+        var events = MakeEvents(2);
+        events[0].SentAt = DateTime.UtcNow; // forged per-event value must be cleared, not kept
+
+        EventIngestProcessor.StampServerFields(events, ValidTenantId, ValidSessionId, DateTime.UtcNow);
+
+        Assert.All(events, evt => Assert.Null(evt.SentAt));
+    }
+
     [Fact]
     public void StampServerFields_SetsTenantIdOnAllEvents()
     {

src/Backend/AutopilotMonitor.Functions.Tests/IngestTelemetryFunctionTests.cs

@@ -43,6 +43,45 @@ public class IngestTelemetryFunctionTests
         Assert.Equal(string.Empty, session);
     }
 
+    // ============================================================ X-Send-Time-Utc parsing (P14)
+
+    [Fact]
+    public void ParseSendTimeHeader_RoundTripUtc_ParsesToUtc()
+    {
+        var parsed = IngestTelemetryFunction.ParseSendTimeHeader("2026-08-21T10:15:30.1234567Z");
+
+        Assert.Equal(new DateTime(2026, 8, 21, 10, 15, 30, DateTimeKind.Utc).AddTicks(1234567), parsed);
+        Assert.Equal(DateTimeKind.Utc, parsed!.Value.Kind);
+    }
+
+    [Fact]
+    public void ParseSendTimeHeader_OffsetValue_NormalizedToUtc()
+    {
+        var parsed = IngestTelemetryFunction.ParseSendTimeHeader("2026-08-21T12:15:30+02:00");
+
+        Assert.Equal(new DateTime(2026, 8, 21, 10, 15, 30, DateTimeKind.Utc), parsed);
+    }
+
+    [Fact]
+    public void ParseSendTimeHeader_FutureDatedValue_KeptVerbatim()
+    {
+        // A future send time IS the device-clock-error measurement — no upper clamp.
+        var parsed = IngestTelemetryFunction.ParseSendTimeHeader("2027-01-01T00:00:00Z");
+
+        Assert.Equal(new DateTime(2027, 1, 1, 0, 0, 0, DateTimeKind.Utc), parsed);
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData("not-a-date")]
+    [InlineData("1999-12-31T23:59:59Z")] // pre-2000 can only be garbage (Table Storage floor guard)
+    public void ParseSendTimeHeader_AbsentOrGarbage_ReturnsNull(string? headerValue)
+    {
+        Assert.Null(IngestTelemetryFunction.ParseSendTimeHeader(headerValue));
+    }
+
     // ============================================================ Payload size-cap guard
 
     [Fact]

src/Backend/AutopilotMonitor.Functions.Tests/MaintenanceServerFrameLastContactTests.cs

@@ -0,0 +1,75 @@
+using System;
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.Models;
+using Xunit;
+
+namespace AutopilotMonitor.Functions.Tests
+{
+    /// <summary>
+    /// Pins the clock-frame contract of the agent-silence sweep.
+    ///
+    /// <para>
+    /// <c>LastEventAt</c> is the maximum AGENT-supplied event timestamp and therefore lives in the
+    /// device clock frame — it carries the device's clock error and, for CMTrace-derived events,
+    /// the writing process's timezone belief. Field measurement over 11k sessions found skews from
+    /// -17 h to +1 h. Comparing that against a server-derived silence cutoff marked live agents
+    /// Stalled ("Agent silent for 1020min") and left genuinely silent ones undetected for the
+    /// duration of the skew. <c>LastIngestAt</c> is stamped from the server clock on every ingest
+    /// and is the only value such a comparison may use.
+    /// </para>
+    /// </summary>
+    public class MaintenanceServerFrameLastContactTests
+    {
+        private static readonly DateTime Now = new(2026, 08, 20, 12, 00, 00, DateTimeKind.Utc);
+
+        private static SessionSummary Session(DateTime? lastIngestAt, DateTime? lastEventAt, DateTime startedAt)
+            => new() { LastIngestAt = lastIngestAt, LastEventAt = lastEventAt, StartedAt = startedAt };
+
+        [Fact]
+        public void PrefersServerFrameIngestStamp_OverDeviceFrameEventStamp()
+        {
+            var s = Session(lastIngestAt: Now.AddMinutes(-1), lastEventAt: Now.AddHours(-17), startedAt: Now.AddHours(-2));
+            Assert.Equal(Now.AddMinutes(-1), MaintenanceService.ServerFrameLastContact(s));
+        }
+
+        [Fact]
+        public void NegativeSkew_DoesNotLookSilent_WhenIngestIsFresh()
+        {
+            // The exact field shape: IME-derived events landed 17 h in the past, so LastEventAt is
+            // far behind the 2 h silence cutoff while the agent is demonstrably still reporting.
+            var silenceCutoff = Now.AddHours(-2);
+            var s = Session(lastIngestAt: Now.AddSeconds(-30), lastEventAt: Now.AddHours(-17), startedAt: Now.AddHours(-1));
+
+            Assert.True(MaintenanceService.ServerFrameLastContact(s) > silenceCutoff,
+                "a session whose ingest stamp is 30 s old must never be classified as agent-silent");
+        }
+
+        [Fact]
+        public void PositiveSkew_DoesNotMaskSilence_WhenIngestIsStale()
+        {
+            // Mirror case: a +1 h skew pushes LastEventAt into the future, which previously made the
+            // sweep blind for an hour. The server frame still sees the silence.
+            var silenceCutoff = Now.AddHours(-2);
+            var s = Session(lastIngestAt: Now.AddHours(-3), lastEventAt: Now.AddHours(1), startedAt: Now.AddHours(-4));
+
+            Assert.True(MaintenanceService.ServerFrameLastContact(s) < silenceCutoff,
+                "a session with no ingest for 3 h must be detected as silent regardless of a future-dated event stamp");
+        }
+
+        [Fact]
+        public void FallsBackToEventStamp_OnRowsPredatingTheIngestStamp()
+        {
+            // Rollout safety: rows written before LastIngestAt existed must keep the old behaviour
+            // rather than dropping out of the sweep entirely.
+            var s = Session(lastIngestAt: null, lastEventAt: Now.AddHours(-3), startedAt: Now.AddHours(-5));
+            Assert.Equal(Now.AddHours(-3), MaintenanceService.ServerFrameLastContact(s));
+        }
+
+        [Fact]
+        public void FallsBackToStartedAt_WhenNoEventStampExists()
+        {
+            var s = Session(lastIngestAt: null, lastEventAt: null, startedAt: Now.AddHours(-4));
+            Assert.Equal(Now.AddHours(-4), MaintenanceService.ServerFrameLastContact(s));
+        }
+    }
+}

src/Backend/AutopilotMonitor.Functions.Tests/PowerStateRuleTests.cs

@@ -0,0 +1,222 @@
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.DataAccess;
+using AutopilotMonitor.Shared.Models;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Power watcher analyze rules — pins the firing behaviour of the built-ins that consume the
+/// agent's live <c>power_state_change</c> events (PowerStateWatcherHost):
+///   - ANALYZE-DEV-009 (high): battery crossed the 15% threshold while enrolling on battery.
+///   - ANALYZE-DEV-010 (warning): the device switched from AC to battery mid-enrollment.
+/// Both rules are deliberately single-required-condition: event_data conditions scan events
+/// INDEPENDENTLY (no same-instance join), so a two-condition rule could false-positive across
+/// two different power events. DEV-009 matches the agent-stamped thresholdPercent (only present
+/// on threshold events, value pins the ladder level); DEV-010 matches transition=ac_to_battery.
+/// Also pins that the rule's string "15" compares equal against the agent's numeric payload.
+/// </summary>
+public class PowerStateRuleTests
+{
+    private const string TenantId  = "a1b2c3d4-e5f6-7890-abcd-ef1234567890";
+    private const string SessionId = "11111111-2222-3333-4444-555555555555";
+
+    [Fact]
+    public async Task ANALYZE_DEV_009_fires_high_on_the_15_percent_threshold_event()
+    {
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-009");
+        Assert.True(rule.Enabled);
+        Assert.Equal("high", rule.Severity);
+        Assert.False(rule.MarkSessionAsFailedDefault); // environment risk, not a KO verdict
+
+        var events = new List<EnrollmentEvent>
+        {
+            ThresholdCrossed(thresholdPercent: 15, batteryPercent: 13),
+        };
+
+        var outcome = await RunAsync(rule, events);
+
+        var result = Assert.Single(outcome.Results);
+        Assert.Equal("ANALYZE-DEV-009", result.RuleId);
+        Assert.Equal("high", result.Severity);
+
+        // The numeric payload (int 15) must satisfy the rule's string value "15"; field/value on
+        // the matched condition feed the {{thresholdPercent}} interpolation token.
+        var matched = AsDict(result.MatchedConditions["battery_threshold_15"]);
+        Assert.Equal("thresholdPercent", AsString(matched["field"]));
+        Assert.Equal("15", AsString(matched["value"]));
+    }
+
+    [Theory]
+    [InlineData(50)]
+    [InlineData(30)]
+    public async Task ANALYZE_DEV_009_does_not_fire_on_higher_threshold_levels(int level)
+    {
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-009");
+
+        var events = new List<EnrollmentEvent>
+        {
+            ThresholdCrossed(thresholdPercent: level, batteryPercent: level - 2),
+        };
+
+        var outcome = await RunAsync(rule, events);
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ANALYZE_DEV_009_does_not_fire_on_a_low_battery_transition_event()
+    {
+        // An ac_to_battery event at 13% carries batteryPercent but NO thresholdPercent — the
+        // agent emits the separate threshold event for that; the rule must not fire early here.
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-009");
+
+        var events = new List<EnrollmentEvent>
+        {
+            Transition("ac_to_battery", onAcPower: false, batteryPercent: 13),
+        };
+
+        var outcome = await RunAsync(rule, events);
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ANALYZE_DEV_010_fires_warning_on_ac_to_battery()
+    {
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-010");
+        Assert.True(rule.Enabled);
+        Assert.Equal("warning", rule.Severity);
+        Assert.False(rule.MarkSessionAsFailedDefault);
+
+        var events = new List<EnrollmentEvent>
+        {
+            Transition("ac_to_battery", onAcPower: false, batteryPercent: 63),
+        };
+
+        var outcome = await RunAsync(rule, events);
+
+        var result = Assert.Single(outcome.Results);
+        Assert.Equal("ANALYZE-DEV-010", result.RuleId);
+        Assert.Equal("warning", result.Severity);
+
+        var matched = AsDict(result.MatchedConditions["switched_to_battery"]);
+        Assert.Equal("transition", AsString(matched["field"]));
+        Assert.Equal("ac_to_battery", AsString(matched["value"]));
+    }
+
+    [Theory]
+    [InlineData("battery_to_ac")]
+    [InlineData("threshold_crossed")]
+    public async Task ANALYZE_DEV_010_does_not_fire_on_other_transitions(string transition)
+    {
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-010");
+
+        var events = new List<EnrollmentEvent>
+        {
+            Transition(transition, onAcPower: transition == "battery_to_ac", batteryPercent: 40),
+        };
+
+        var outcome = await RunAsync(rule, events);
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task Neither_rule_fires_on_the_startup_power_state_check()
+    {
+        // The one-shot startup probe event (power_state_check) is a different event type and must
+        // not satisfy either rule, even when it reports a low battery on DC power.
+        var rules = BuiltInAnalyzeRules.GetAll()
+            .Where(r => r.RuleId is "ANALYZE-DEV-009" or "ANALYZE-DEV-010").ToList();
+        Assert.Equal(2, rules.Count);
+
+        var events = new List<EnrollmentEvent>
+        {
+            new()
+            {
+                EventId = Guid.NewGuid().ToString(),
+                TenantId = TenantId,
+                SessionId = SessionId,
+                EventType = "power_state_check",
+                Timestamp = DateTime.UtcNow,
+                Sequence = 5,
+                Data = new Dictionary<string, object>
+                {
+                    ["onAcPower"] = false,
+                    ["hasBattery"] = true,
+                    ["batteryPercent"] = 12,
+                    ["isCharging"] = false,
+                },
+            },
+        };
+
+        foreach (var rule in rules)
+        {
+            var outcome = await RunAsync(rule, events);
+            Assert.Empty(outcome.Results);
+        }
+    }
+
+    // ===== Event builders — mirror the PowerStateWatcherHost emit shape =====
+
+    private static EnrollmentEvent ThresholdCrossed(int thresholdPercent, int batteryPercent) => new()
+    {
+        EventId = Guid.NewGuid().ToString(),
+        TenantId = TenantId,
+        SessionId = SessionId,
+        EventType = "power_state_change",
+        Timestamp = DateTime.UtcNow,
+        Sequence = 42,
+        Data = new Dictionary<string, object>
+        {
+            ["transition"] = "threshold_crossed",
+            ["thresholdPercent"] = thresholdPercent,
+            ["onAcPower"] = false,
+            ["batteryPercent"] = batteryPercent,
+            ["isCharging"] = false,
+            ["batteryLifeMinutes"] = 25,
+        }
+    };
+
+    private static EnrollmentEvent Transition(string transition, bool onAcPower, int batteryPercent) => new()
+    {
+        EventId = Guid.NewGuid().ToString(),
+        TenantId = TenantId,
+        SessionId = SessionId,
+        EventType = "power_state_change",
+        Timestamp = DateTime.UtcNow,
+        Sequence = 43,
+        Data = new Dictionary<string, object>
+        {
+            ["transition"] = transition,
+            ["onAcPower"] = onAcPower,
+            ["batteryPercent"] = batteryPercent,
+            ["isCharging"] = onAcPower,
+            ["batteryLifeMinutes"] = 120,
+        }
+    };
+
+    private static Dictionary<string, object> AsDict(object o)
+    {
+        if (o is Dictionary<string, object> d) return d;
+        throw new InvalidOperationException($"Expected Dictionary<string,object>, got {o?.GetType().Name ?? "null"}");
+    }
+
+    private static string AsString(object o) => o?.ToString() ?? string.Empty;
+
+    private static async Task<AnalysisOutcome> RunAsync(AnalyzeRule rule, List<EnrollmentEvent> events)
+    {
+        var ruleRepo = new Mock<IRuleRepository>();
+        ruleRepo.Setup(r => r.GetAnalyzeRulesAsync("global")).ReturnsAsync(new List<AnalyzeRule> { rule });
+        ruleRepo.Setup(r => r.GetAnalyzeRulesAsync(TenantId)).ReturnsAsync(new List<AnalyzeRule>());
+        ruleRepo.Setup(r => r.GetRuleStatesAsync(It.IsAny<string>())).ReturnsAsync(new Dictionary<string, RuleState>());
+        ruleRepo.Setup(r => r.GetRuleResultsAsync(It.IsAny<string>(), It.IsAny<string>())).ReturnsAsync(new List<RuleResult>());
+
+        var sessionRepo = new Mock<ISessionRepository>();
+        sessionRepo.Setup(s => s.GetSessionEventsStrictAsync(TenantId, SessionId, It.IsAny<int>())).ReturnsAsync(events);
+
+        var ruleService = new AnalyzeRuleService(ruleRepo.Object, NullLogger<AnalyzeRuleService>.Instance);
+        var engine = new RuleEngine(ruleService, ruleRepo.Object, sessionRepo.Object, NullLogger<PowerStateRuleTests>.Instance);
+
+        return await engine.AnalyzeSessionAsync(TenantId, SessionId);
+    }
+}

src/Backend/AutopilotMonitor.Functions.Tests/ReportAgentErrorFunctionTests.cs

@@ -200,4 +200,120 @@ public class ReportAgentErrorFunctionTests
 
         Assert.Empty(h.OpsEvents);
     }
+
+    // =========================================================================
+    // MaterializeIntegrityMismatchAsync — an IntegrityCheckFailed report becomes an
+    // AgentBinaryIntegrityMismatch ops event, UNLESS it is the known release race
+    // (agents comparing against hash snapshots that don't belong to their own binary;
+    // AdminConfig cache TTL 5 min). e9753578 proved the race: a genuine 1410 exe was
+    // compared against the cached 1409 hash and reported a "mismatch" that cost a day
+    // of mis-attributed root-causing while sitting invisible in App Insights.
+    // =========================================================================
+
+    private const string RunningExeSha = "5fca975e43fa5fca975e43fa5fca975e43fa5fca975e43fa5fca975e43fa0000";
+    private const string PublishedExeSha = "8ebaa060ad348ebaa060ad348ebaa060ad348ebaa060ad348ebaa060ad340000";
+
+    private static AgentErrorReport IntegrityReport(
+        string? sessionId = SessionId, string agentVersion = "2.0.1410", string? actualSha = null) => new()
+    {
+        SessionId = sessionId!,
+        TenantId = TenantId,
+        ErrorType = AgentErrorType.IntegrityCheckFailed,
+        Message = $"Running exe SHA-256 differs from backend-advertised hash. actual={actualSha ?? RunningExeSha}, expected={PublishedExeSha}",
+        AgentVersion = agentVersion,
+        Timestamp = Now,
+    };
+
+    private static Task RunIntegrityAsync(
+        Harness h, AgentErrorReport report,
+        string? latestVersion = "2.0.1410", string? latestExeSha = PublishedExeSha)
+        => ReportAgentErrorFunction.MaterializeIntegrityMismatchAsync(
+            report, TenantId, h.OpsService, latestVersion, latestExeSha,
+            NullLogger<ReportAgentErrorFunction>.Instance);
+
+    [Fact]
+    public async Task SameVersion_with_unknown_binary_records_ops_event()
+    {
+        // The real signal: an agent claiming the LATEST version whose running exe is NOT
+        // the published one — tamper, stale blob, or a build outside the release pipeline.
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, IntegrityReport());
+
+        var ops = Assert.Single(h.OpsEvents);
+        Assert.Equal("AgentBinaryIntegrityMismatch", ops.EventType);
+        Assert.Equal(TenantId, ops.TenantId);
+        Assert.Contains("actual=5fca", ops.Message);
+        Assert.Contains("2.0.1410", ops.Message);
+    }
+
+    [Fact]
+    public async Task RunningHash_equal_to_published_exe_is_suppressed_as_stale_expectation()
+    {
+        // e9753578's exact shape: the device RUNS the published binary; only its cached
+        // expectation was the previous release's hash. Self-heals — must not alert.
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, IntegrityReport(actualSha: PublishedExeSha));
+
+        Assert.Empty(h.OpsEvents);
+    }
+
+    [Fact]
+    public async Task Older_agent_version_than_latest_is_suppressed_as_update_race()
+    {
+        // The long-known direction: version N agent sees version N+1's hash right after a
+        // release; the forced self-update heals it.
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, IntegrityReport(agentVersion: "2.0.1409+d43cfe2b"), latestVersion: "2.0.1410");
+
+        Assert.Empty(h.OpsEvents);
+    }
+
+    [Fact]
+    public async Task Version_with_commit_suffix_matches_latest_without_suffix()
+    {
+        // Agent versions carry "+<commit>", AdminConfiguration does not — the comparison
+        // must normalize, otherwise every genuine mismatch would look like a version race.
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, IntegrityReport(agentVersion: "2.0.1410+3b59dab2df6c"));
+
+        Assert.Single(h.OpsEvents);
+    }
+
+    [Fact]
+    public async Task Missing_latest_config_fails_open_to_recording()
+    {
+        // No published-version info available → visibility wins over suppression.
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, IntegrityReport(), latestVersion: null, latestExeSha: null);
+
+        Assert.Single(h.OpsEvents);
+    }
+
+    [Fact]
+    public async Task Integrity_mismatch_without_session_id_still_records_ops_event()
+    {
+        // The report can arrive before session registration — the binary evidence must
+        // never be dropped for lack of a session.
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, IntegrityReport(sessionId: null));
+
+        var ops = Assert.Single(h.OpsEvents);
+        Assert.Equal("AgentBinaryIntegrityMismatch", ops.EventType);
+    }
+
+    [Fact]
+    public async Task Other_error_types_do_not_record_integrity_ops_event()
+    {
+        var h = new Harness();
+
+        await RunIntegrityAsync(h, Report(Now));
+
+        Assert.Empty(h.OpsEvents);
+    }
 }

src/Backend/AutopilotMonitor.Functions.Tests/RuleEngineClockSkewTests.cs

@@ -0,0 +1,450 @@
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.DataAccess;
+using AutopilotMonitor.Shared.Models;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Pins the clock_skew condition source (EvaluateClockSkewCondition) behind ANALYZE-DEV-008.
+/// The evaluator measures d = Timestamp − ReceivedAt per event, reduces to per-upload-batch
+/// medians (wide-spread batches = spool backlogs are dropped), then detects either a persistent
+/// mid-session step between two flat plateaus (clock_jump) or a stable whole-session offset
+/// (sustained_offset). IME-log-derived events are excluded so a CMTrace anchoring regression
+/// (the e9753578 field incident) can never fire this customer-facing rule — that failure mode
+/// belongs to the operator-side CmTraceSkewTripwire.
+/// </summary>
+public class RuleEngineClockSkewTests
+{
+    private const string TenantId  = "a1b2c3d4-e5f6-7890-abcd-ef1234567890";
+    private const string SessionId = "b2c3d4e5-f6a7-8901-bcde-f12345678901";
+
+    private static readonly DateTime T0 = new(2026, 8, 20, 10, 0, 0, DateTimeKind.Utc);
+
+    // ── clock_jump: must fire ──────────────────────────────────────────────
+
+    [Fact]
+    public async Task ClockJump_ForwardStepBetweenStableFrames_Fires()
+    {
+        // 4 batches on frame 0, then 4 batches on frame +1800 s (+30 min) that hold to
+        // session end — the canonical "clock corrected forward mid-session".
+        var events = Batches(offsetsSeconds: new double[] { 0, 0, 0, 0, 1800, 1800, 1800, 1800 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["clock_jump"]);
+        Assert.Equal("forward", evidence["direction"]);
+        Assert.Equal(1800, Convert.ToDouble(evidence["jumpSeconds"]), 0);
+        Assert.Equal("skewSummary", evidence["field"]);
+    }
+
+    [Fact]
+    public async Task ClockJump_BackwardStep_Fires()
+    {
+        var events = Batches(new double[] { 0, 0, 0, -1200, -1200, -1200 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["clock_jump"]);
+        Assert.Equal("backward", evidence["direction"]);
+    }
+
+    [Fact]
+    public async Task ClockJump_WrongClockCorrectedMidSession_Fires()
+    {
+        // Device started 30 min behind, time sync fixed it: the CORRECTED frame is the
+        // persistent change, so this must fire (direction forward).
+        var events = Batches(new double[] { -1800, -1800, -1800, 0, 0, 0 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["clock_jump"]);
+        Assert.Equal("forward", evidence["direction"]);
+    }
+
+    // ── clock_jump: must stay silent ───────────────────────────────────────
+
+    [Fact]
+    public async Task ClockJump_ImeDerivedSkew_ExcludedFromMeasurement_Silent()
+    {
+        // e9753578 replica: IME-derived events carry grid-multiple wrong timestamps (−7 h /
+        // +2 h writer eras) while the agent's own events are healthy. The IME events must be
+        // excluded up front — a CMTrace anchoring regression may NEVER fire the customer rule.
+        var events = Batches(new double[] { 0, 0, 0, 0, 0, 0 });
+        var seq = 1000;
+        foreach (var imeOffset in new double[] { -25200, -25200, 7200, 7200, -25200, 7200 })
+            events.Add(MakeEvent(seq++, T0.AddMinutes(seq % 7), imeOffset, source: "ImeLogTracker"));
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_WideSpreadSpoolBatch_DroppedAndSilent()
+    {
+        // One upload batch whose events span 30 min of emission time (offline spool flushed
+        // in a single request) — the internal spread disqualifies the batch entirely.
+        var events = Batches(new double[] { 0, 0, 0, 0, 0, 0 });
+        var flushReceivedAt = T0.AddMinutes(90);
+        for (int i = 0; i < 20; i++)
+            events.Add(MakeEvent(2000 + i, flushReceivedAt, offsetSeconds: -1800 + i * 90));
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_GradualBacklogDrainRamp_Silent()
+    {
+        // A chunked spool drain produces a RAMP of batch medians walking back to the live
+        // frame. No flat pre/post plateau pair exists, so the step detector must reject every
+        // candidate — this is a delivery artifact, not a clock change.
+        var events = Batches(new double[] { -1800, -1500, -1200, -900, -600, -300, 0, 0 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_TransientExcursionReturnsToFrame_Silent()
+    {
+        // Frame dips for two batches and returns — whatever it was, it is not a SUSTAINED
+        // clock change (end-state persistence fails).
+        var events = Batches(new double[] { 0, 0, 0, -1800, -1800, 0, 0, 0 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_BelowThreshold_Silent()
+    {
+        var events = Batches(new double[] { 0, 0, 0, 240, 240, 240 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_TooFewBatches_Silent()
+    {
+        // 5 batches < 2×ConfirmBatches — not enough for two comparison windows.
+        var events = Batches(new double[] { 0, 0, 1800, 1800, 1800 });
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_LegacyEventsWithoutReceivedAt_Silent()
+    {
+        var events = Batches(new double[] { 0, 0, 0, 1800, 1800, 1800 });
+        foreach (var e in events)
+            e.ReceivedAt = null;
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ClockJump_ClampedEventsExcluded_Silent()
+    {
+        // The jumped frame exists only on clamped events (their OccurredUtc is already
+        // server-substituted in production) — excluding them leaves a single stable frame.
+        var events = Batches(new double[] { 0, 0, 0, 0, 0, 0 });
+        var seq = 3000;
+        foreach (var offset in new double[] { 1800, 1800, 1800 })
+        {
+            var evt = MakeEvent(seq, T0.AddMinutes(120 + seq % 5), offset);
+            evt.TimestampClamped = true;
+            events.Add(evt);
+            seq++;
+        }
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    // ── sustained_offset ───────────────────────────────────────────────────
+
+    [Fact]
+    public async Task SustainedOffset_ClockBehindWholeSession_Fires()
+    {
+        var events = Batches(new double[] { -1800, -1795, -1805, -1800, -1798 });
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["sustained_offset"]);
+        Assert.Equal("behind", evidence["direction"]);
+        Assert.Equal(-30.0, Convert.ToDouble(evidence["offsetMinutes"]), 1);
+    }
+
+    [Fact]
+    public async Task SustainedOffset_HealthyUploadLatencyBaseline_Silent()
+    {
+        // Healthy devices sit a few seconds NEGATIVE (upload latency) — far below threshold.
+        var events = Batches(new double[] { -3, -5, -2, -4, -6 });
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task SustainedOffset_UnstableBatchOffsets_Silent()
+    {
+        // Medians all over the place: no honest single-offset statement exists, even though
+        // the overall median magnitude clears the threshold.
+        var events = Batches(new double[] { -2400, 900, -1800, 300, -3600, -600 });
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    // ── P14: SentAt direct measurement (X-Send-Time-Utc batches) ───────────
+
+    [Fact]
+    public async Task SentAt_SpoolFlushWithWideEventSpread_JumpStillMeasured_Fires()
+    {
+        // Every batch is a spool flush spanning 30 min of emission time — the legacy path
+        // drops ALL of them via the spread cap and stays blind. SentAt measures the frame
+        // crossing directly, so the +30 min step must fire regardless of event-timestamp
+        // spread, and every batch counts as a SentAt batch.
+        static double[] Wide(int _) => new double[] { -1800, -1350, -900, -450, 0 };
+        var events = SentAtBatches(new double[] { 0, 0, 0, 0, 1800, 1800, 1800, 1800 }, Wide);
+
+        var outcome = await RunAsync(MakeRule("clock_jump", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["clock_jump"]);
+        Assert.Equal("forward", evidence["direction"]);
+        Assert.Equal(8, Convert.ToInt32(evidence["sentAtBatchCount"]));
+    }
+
+    [Fact]
+    public async Task SentAt_UniformBacklogBatches_ReadAsHealthy_Silent()
+    {
+        // EXACTLY the event shape of SustainedOffset_ClockBehindWholeSession_Fires (tight
+        // −30 min Timestamp−ReceivedAt deltas), but the batches carry SentAt ≈ ReceivedAt:
+        // the device clock is fine, the events are merely OLD (uniform spool backlog).
+        // The legacy median cannot tell those apart — SentAt can, and must stay silent.
+        static double[] Backlog(int b) => new double[] { -1800, -1795, -1805, -1800, -1798 };
+        var events = SentAtBatches(new double[] { -3, -5, -2, -4, -6 }, Backlog);
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task SentAt_SustainedOffset_MeasuredFromSendTime_Fires()
+    {
+        var events = SentAtBatches(new double[] { -1800, -1795, -1805, -1800, -1798 });
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["sustained_offset"]);
+        Assert.Equal("behind", evidence["direction"]);
+        Assert.Equal(-30.0, Convert.ToDouble(evidence["offsetMinutes"]), 1);
+        Assert.Equal(5, Convert.ToInt32(evidence["sentAtBatchCount"]));
+    }
+
+    [Fact]
+    public async Task SentAt_ImeOnlyBatches_MeasurableViaSendTime_Fires()
+    {
+        // IME-source events are excluded from the LEGACY measurement (writer timezone
+        // belief), but a SentAt batch never reads event timestamps — the device clock is
+        // measured from the send moment, so IME-only sessions become measurable.
+        var events = SentAtBatches(
+            new double[] { -1800, -1800, -1800, -1800, -1800 }, source: "ImeLogTracker");
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["sustained_offset"]);
+        Assert.Equal("behind", evidence["direction"]);
+    }
+
+    [Fact]
+    public async Task SentAt_HealthyUploadLatencyBaseline_Silent()
+    {
+        var events = SentAtBatches(new double[] { -3, -5, -2, -4, -6 });
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task SentAt_MixedWithLegacyBatches_ConsistentFrame_Fires()
+    {
+        // Mid-session agent update: first half legacy (event-median), second half SentAt.
+        // Both measure the same physical quantity, so a consistent −30 min frame across the
+        // mix must still produce a sustained-offset verdict.
+        var events = Batches(new double[] { -1800, -1795, -1805 });
+        long seq = 1000;
+        for (int b = 0; b < 3; b++)
+        {
+            var receivedAt = T0.AddMinutes(60 + b * 5);
+            var sentAt = receivedAt.AddSeconds(-1800);
+            for (int i = 0; i < 5; i++)
+            {
+                var evt = MakeEvent(seq++, receivedAt, -1800 + (i - 2));
+                evt.SentAt = sentAt;
+                events.Add(evt);
+            }
+        }
+
+        var outcome = await RunAsync(MakeRule("sustained_offset", "300"), events);
+
+        var result = Assert.Single(outcome.Results);
+        var evidence = Assert.IsAssignableFrom<IDictionary<string, object>>(result.MatchedConditions["sustained_offset"]);
+        Assert.Equal(-30.0, Convert.ToDouble(evidence["offsetMinutes"]), 1);
+        Assert.Equal(3, Convert.ToInt32(evidence["sentAtBatchCount"]));
+        Assert.Equal(6, Convert.ToInt32(evidence["batchCount"]));
+    }
+
+    // ── ANALYZE-DEV-008 shape: two optional conditions ─────────────────────
+
+    [Fact]
+    public async Task Dev008Shape_JumpOnlySession_FiresWithSingleMatchedCondition()
+    {
+        // Mirrors the shipped rule: both conditions required:false, baseConfidence 60,
+        // threshold 50 — one matching metric must be enough to fire.
+        var rule = MakeRule("clock_jump", "300");
+        rule.Conditions[0].Required = false;
+        rule.Conditions.Add(new RuleCondition
+        {
+            Signal = "sustained_offset",
+            Source = "clock_skew",
+            SkewMetric = "sustained_offset",
+            Operator = "gte",
+            Value = "300",
+            Required = false,
+        });
+
+        var events = Batches(new double[] { 0, 0, 0, 0, 1800, 1800, 1800, 1800 });
+
+        var outcome = await RunAsync(rule, events);
+
+        var result = Assert.Single(outcome.Results);
+        Assert.True(result.MatchedConditions.ContainsKey("clock_jump"));
+    }
+
+    // ===== Helpers =====
+
+    private static AnalyzeRule MakeRule(string skewMetric, string thresholdSeconds) => new()
+    {
+        RuleId = "ANALYZE-TST-CLK",
+        Title = "clock_skew test rule",
+        Severity = "warning",
+        Category = "device",
+        Enabled = true,
+        IsBuiltIn = false,
+        BaseConfidence = 60,
+        ConfidenceThreshold = 50,
+        Conditions = new List<RuleCondition>
+        {
+            new()
+            {
+                Signal = skewMetric,
+                Source = "clock_skew",
+                SkewMetric = skewMetric,
+                Operator = "gte",
+                Value = thresholdSeconds,
+                Required = true,
+            }
+        },
+        Explanation = "test {{skewSummary}}",
+    };
+
+    /// <summary>
+    /// One upload batch per entry: 5 events sharing the batch's ReceivedAt, each with
+    /// Timestamp = ReceivedAt + offsetSeconds (±2 s in-batch jitter, well under the spread cap).
+    /// </summary>
+    private static List<EnrollmentEvent> Batches(double[] offsetsSeconds)
+    {
+        var events = new List<EnrollmentEvent>();
+        long seq = 1;
+        for (int b = 0; b < offsetsSeconds.Length; b++)
+        {
+            var receivedAt = T0.AddMinutes(b * 5);
+            for (int i = 0; i < 5; i++)
+                events.Add(MakeEvent(seq++, receivedAt, offsetsSeconds[b] + (i - 2)));
+        }
+        return events;
+    }
+
+    /// <summary>
+    /// One SentAt-carrying upload batch per frame offset: SentAt = ReceivedAt + frameOffset
+    /// (the P14 direct measurement), event timestamps default to healthy in-batch jitter but
+    /// can be overridden per batch to simulate spool spreads or backlogs.
+    /// </summary>
+    private static List<EnrollmentEvent> SentAtBatches(
+        double[] frameOffsetsSeconds,
+        Func<int, double[]>? eventOffsetsForBatch = null,
+        string source = "DecisionEngine")
+    {
+        var events = new List<EnrollmentEvent>();
+        long seq = 1;
+        for (int b = 0; b < frameOffsetsSeconds.Length; b++)
+        {
+            var receivedAt = T0.AddMinutes(b * 5);
+            var sentAt = receivedAt.AddSeconds(frameOffsetsSeconds[b]);
+            var offsets = eventOffsetsForBatch?.Invoke(b) ?? new double[] { -2, -1, 0, 1, 2 };
+            foreach (var offset in offsets)
+            {
+                var evt = MakeEvent(seq++, receivedAt, offset, source);
+                evt.SentAt = sentAt;
+                events.Add(evt);
+            }
+        }
+        return events;
+    }
+
+    private static EnrollmentEvent MakeEvent(long sequence, DateTime receivedAt, double offsetSeconds,
+        string source = "DecisionEngine") => new()
+    {
+        EventId = Guid.NewGuid().ToString(),
+        TenantId = TenantId,
+        SessionId = SessionId,
+        EventType = "status_update",
+        Source = source,
+        Timestamp = receivedAt.AddSeconds(offsetSeconds),
+        ReceivedAt = receivedAt,
+        Sequence = sequence,
+        Data = new Dictionary<string, object>(),
+    };
+
+    private static async Task<AnalysisOutcome> RunAsync(AnalyzeRule rule, List<EnrollmentEvent> events)
+    {
+        var ruleRepo = new Mock<IRuleRepository>();
+        ruleRepo.Setup(r => r.GetAnalyzeRulesAsync("global")).ReturnsAsync(new List<AnalyzeRule> { rule });
+        ruleRepo.Setup(r => r.GetAnalyzeRulesAsync(TenantId)).ReturnsAsync(new List<AnalyzeRule>());
+        ruleRepo.Setup(r => r.GetRuleStatesAsync(It.IsAny<string>())).ReturnsAsync(new Dictionary<string, RuleState>());
+        ruleRepo.Setup(r => r.GetRuleResultsAsync(It.IsAny<string>(), It.IsAny<string>())).ReturnsAsync(new List<RuleResult>());
+
+        var sessionRepo = new Mock<ISessionRepository>();
+        sessionRepo.Setup(s => s.GetSessionEventsStrictAsync(TenantId, SessionId, It.IsAny<int>())).ReturnsAsync(events);
+
+        var ruleService = new AnalyzeRuleService(ruleRepo.Object, NullLogger<AnalyzeRuleService>.Instance);
+        var engine = new RuleEngine(ruleService, ruleRepo.Object, sessionRepo.Object, NullLogger<RuleEngineClockSkewTests>.Instance);
+
+        return await engine.AnalyzeSessionAsync(TenantId, SessionId);
+    }
+}

src/Backend/AutopilotMonitor.Functions.Tests/RuleEngineDryRunTests.cs

@@ -270,6 +270,59 @@ public class RuleEngineDryRunTests
         Assert.Contains(DryRunAnalyzeRuleFunction.ValidateDraftRule(rule), e => e.Contains("joinField"));
     }
 
+    [Fact]
+    public void Validate_ClockSkewMissingOrUnknownMetric_Error()
+    {
+        var rule = MakeRule();
+        rule.Conditions[0].Source = "clock_skew";
+        rule.Conditions[0].SkewMetric = null;
+        rule.Conditions[0].Operator = "gte";
+        rule.Conditions[0].Value = "300";
+        Assert.Contains(DryRunAnalyzeRuleFunction.ValidateDraftRule(rule), e => e.Contains("skewMetric"));
+
+        rule.Conditions[0].SkewMetric = "drift"; // not a known metric
+        Assert.Contains(DryRunAnalyzeRuleFunction.ValidateDraftRule(rule), e => e.Contains("skewMetric"));
+    }
+
+    [Theory]
+    [InlineData("lt")]
+    [InlineData("equals")]
+    public void Validate_ClockSkewUnsupportedOperator_Error(string op)
+    {
+        var rule = MakeRule();
+        rule.Conditions[0].Source = "clock_skew";
+        rule.Conditions[0].SkewMetric = "clock_jump";
+        rule.Conditions[0].Operator = op;
+        rule.Conditions[0].Value = "300";
+        Assert.Contains(DryRunAnalyzeRuleFunction.ValidateDraftRule(rule), e => e.Contains("only gt/gte"));
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("abc")]
+    [InlineData("-300")]
+    [InlineData("0")]
+    public void Validate_ClockSkewNonPositiveThreshold_Error(string value)
+    {
+        var rule = MakeRule();
+        rule.Conditions[0].Source = "clock_skew";
+        rule.Conditions[0].SkewMetric = "sustained_offset";
+        rule.Conditions[0].Operator = "gte";
+        rule.Conditions[0].Value = value;
+        Assert.Contains(DryRunAnalyzeRuleFunction.ValidateDraftRule(rule), e => e.Contains("positive numeric value"));
+    }
+
+    [Fact]
+    public void Validate_ClockSkewValidCondition_NoErrors()
+    {
+        var rule = MakeRule();
+        rule.Conditions[0].Source = "clock_skew";
+        rule.Conditions[0].SkewMetric = "clock_jump";
+        rule.Conditions[0].Operator = "gte";
+        rule.Conditions[0].Value = "300";
+        Assert.Empty(DryRunAnalyzeRuleFunction.ValidateDraftRule(rule));
+    }
+
     [Fact]
     public void Validate_InvalidRegex_Error()
     {

src/Backend/AutopilotMonitor.Functions.Tests/SessionIndexFieldManifestTests.cs

@@ -90,6 +90,7 @@ public class SessionIndexFieldManifestTests
         ["DiagnosticsBlobName"] = "diag-0001.zip",
         ["DiagnosticsBlobDestination"] = "Hosted",
         ["LastEventAt"] = new DateTimeOffset(StartedAt.AddMinutes(44)),
+        ["LastIngestAt"] = new DateTimeOffset(StartedAt.AddMinutes(46)),
         ["ResumedAt"] = new DateTimeOffset(StartedAt.AddMinutes(10)),
         ["StalledAt"] = new DateTimeOffset(StartedAt.AddMinutes(20)),
         ["AvgApiLatencyMs"] = 513.5,

src/Backend/AutopilotMonitor.Functions.Tests/SessionStatsAggregationTests.cs

@@ -36,6 +36,8 @@ public class SessionStatsAggregationTests
         Assert.Equal(0, stats.FailedLastNDays);
         Assert.Equal(0, stats.SuccessRatePct);
         Assert.Equal(0, stats.AvgDurationMinutes);
+        Assert.Equal(0, stats.MedianDurationMinutes);
+        Assert.Equal(0, stats.P90DurationMinutes);
         Assert.Equal(0, stats.TotalToday);
         Assert.Equal(0, stats.FailedToday);
     }
@@ -116,6 +118,29 @@ public class SessionStatsAggregationTests
 
         // (30 + 10) / 2 = 20 minutes
         Assert.Equal(20, stats.AvgDurationMinutes);
+        // Same Succeeded population feeds the percentile stats: sorted [600, 1800].
+        Assert.Equal(10, stats.MedianDurationMinutes);
+        Assert.Equal(30, stats.P90DurationMinutes);
+    }
+
+    [Fact]
+    public void Median_duration_is_robust_against_outliers_that_dominate_the_average()
+    {
+        // 8 typical 10-min enrollments plus a 2 h and a 24 h outlier: the mean explodes
+        // to ~2.7 h while the median still answers "how long does a typical enrollment
+        // take" — the reason the dashboard card leads with the median.
+        var now = DateTime.UtcNow;
+        var sessions = new List<SessionSummary>();
+        for (int i = 0; i < 8; i++)
+            sessions.Add(MakeSession(SessionStatus.Succeeded, now.AddHours(-1), 600));
+        sessions.Add(MakeSession(SessionStatus.Succeeded, now.AddHours(-2), 7200));
+        sessions.Add(MakeSession(SessionStatus.Succeeded, now.AddHours(-3), 86400));
+
+        var stats = TableStorageService.AggregateSessionStats(sessions, days: 7);
+
+        Assert.Equal(164, stats.AvgDurationMinutes);   // (8*600 + 7200 + 86400) / 10 / 60
+        Assert.Equal(10, stats.MedianDurationMinutes); // unmoved by the tail
+        Assert.Equal(120, stats.P90DurationMinutes);   // tail stays visible
     }
 
     [Fact]

src/Backend/AutopilotMonitor.Functions.Tests/SessionStatsProjectionEquivalenceTests.cs

@@ -172,7 +172,9 @@ public class SessionStatsProjectionEquivalenceTests
         Assert.Equal(full.SucceededLastNDays, projected.SucceededLastNDays);
         Assert.Equal(full.FailedLastNDays, projected.FailedLastNDays);
         Assert.Equal(full.SuccessRatePct, projected.SuccessRatePct);
-        Assert.Equal(full.AvgDurationMinutes, projected.AvgDurationMinutes); // the duration-sensitive card
+        Assert.Equal(full.AvgDurationMinutes, projected.AvgDurationMinutes); // duration-sensitive
+        Assert.Equal(full.MedianDurationMinutes, projected.MedianDurationMinutes); // the headline card
+        Assert.Equal(full.P90DurationMinutes, projected.P90DurationMinutes);
         Assert.Equal(full.TotalToday, projected.TotalToday);
         Assert.Equal(full.FailedToday, projected.FailedToday);
     }

src/Backend/AutopilotMonitor.Functions.Tests/SleepEpisodeRuleTests.cs

@@ -0,0 +1,137 @@
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.DataAccess;
+using AutopilotMonitor.Shared.Models;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// ANALYZE-DEV-012 — pins the firing behaviour of the built-in that consumes the agent's
+/// <c>system_sleep_episode</c> events (SystemTimelineWatcherHost): informational, fires once
+/// (trigger single) when a completed sleep/hibernate/Modern-Standby episode of at least
+/// 5 minutes is observed. Single-required-condition on durationSeconds so the match is pinned
+/// to one event instance and the interpolated duration is the matched value. Also pins that the
+/// agent's numeric payload (long) satisfies the rule's string "300" via numeric gte.
+/// </summary>
+public class SleepEpisodeRuleTests
+{
+    private const string TenantId  = "a1b2c3d4-e5f6-7890-abcd-ef1234567890";
+    private const string SessionId = "66666666-7777-8888-9999-aaaaaaaaaaaa";
+
+    [Fact]
+    public async Task ANALYZE_DEV_012_fires_info_on_a_five_minute_episode()
+    {
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-012");
+        Assert.True(rule.Enabled);
+        Assert.Equal("info", rule.Severity);
+        Assert.False(rule.MarkSessionAsFailedDefault); // environment observation, never a KO verdict
+
+        var events = new List<EnrollmentEvent>
+        {
+            SleepEpisode(durationSeconds: 300, kind: "modern_standby"),
+        };
+
+        var outcome = await RunAsync(rule, events);
+
+        var result = Assert.Single(outcome.Results);
+        Assert.Equal("ANALYZE-DEV-012", result.RuleId);
+        Assert.Equal("info", result.Severity);
+
+        // durationSeconds is the matched condition's dataField, so {{durationSeconds}} in the
+        // explanation interpolates the matched value (the DEV-009 whitelist lesson).
+        var matched = AsDict(result.MatchedConditions["slept_during_enrollment"]);
+        Assert.Equal("durationSeconds", AsString(matched["field"]));
+    }
+
+    [Theory]
+    [InlineData(60)]   // real but short episode — below the rule's 5-minute floor
+    [InlineData(299)]  // boundary: gte 300 must not fire at 299
+    public async Task ANALYZE_DEV_012_does_not_fire_below_the_five_minute_floor(long durationSeconds)
+    {
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-012");
+
+        var events = new List<EnrollmentEvent>
+        {
+            SleepEpisode(durationSeconds, kind: "sleep"),
+        };
+
+        var outcome = await RunAsync(rule, events);
+        Assert.Empty(outcome.Results);
+    }
+
+    [Fact]
+    public async Task ANALYZE_DEV_012_does_not_fire_on_a_clock_change_event()
+    {
+        // The sibling watcher event carries a large timeDeltaMs but is a different event type —
+        // the rule must key on system_sleep_episode only.
+        var rule = BuiltInAnalyzeRules.GetAll().First(r => r.RuleId == "ANALYZE-DEV-012");
+
+        var events = new List<EnrollmentEvent>
+        {
+            new()
+            {
+                EventId = Guid.NewGuid().ToString(),
+                TenantId = TenantId,
+                SessionId = SessionId,
+                EventType = "system_clock_changed",
+                Timestamp = DateTime.UtcNow,
+                Sequence = 7,
+                Data = new Dictionary<string, object>
+                {
+                    ["timeDeltaMs"] = 7_200_000L,
+                    ["durationSeconds"] = 900L, // adversarial: same field name on the wrong type
+                    ["reason"] = 1,
+                },
+            },
+        };
+
+        var outcome = await RunAsync(rule, events);
+        Assert.Empty(outcome.Results);
+    }
+
+    // ===== Event builder — mirrors the SystemTimelineTracker emit shape =====
+
+    private static EnrollmentEvent SleepEpisode(long durationSeconds, string kind) => new()
+    {
+        EventId = Guid.NewGuid().ToString(),
+        TenantId = TenantId,
+        SessionId = SessionId,
+        EventType = "system_sleep_episode",
+        Timestamp = DateTime.UtcNow,
+        Sequence = 42,
+        Data = new Dictionary<string, object>
+        {
+            ["kind"] = kind,
+            ["enteredAt"] = DateTime.UtcNow.AddSeconds(-durationSeconds).ToString("o"),
+            ["exitedAt"] = DateTime.UtcNow.ToString("o"),
+            ["durationSeconds"] = durationSeconds,
+            ["backfilled"] = false,
+        }
+    };
+
+    private static Dictionary<string, object> AsDict(object o)
+    {
+        if (o is Dictionary<string, object> d) return d;
+        throw new InvalidOperationException($"Expected Dictionary<string,object>, got {o?.GetType().Name ?? "null"}");
+    }
+
+    private static string AsString(object o) => o?.ToString() ?? string.Empty;
+
+    private static async Task<AnalysisOutcome> RunAsync(AnalyzeRule rule, List<EnrollmentEvent> events)
+    {
+        var ruleRepo = new Mock<IRuleRepository>();
+        ruleRepo.Setup(r => r.GetAnalyzeRulesAsync("global")).ReturnsAsync(new List<AnalyzeRule> { rule });
+        ruleRepo.Setup(r => r.GetAnalyzeRulesAsync(TenantId)).ReturnsAsync(new List<AnalyzeRule>());
+        ruleRepo.Setup(r => r.GetRuleStatesAsync(It.IsAny<string>())).ReturnsAsync(new Dictionary<string, RuleState>());
+        ruleRepo.Setup(r => r.GetRuleResultsAsync(It.IsAny<string>(), It.IsAny<string>())).ReturnsAsync(new List<RuleResult>());
+
+        var sessionRepo = new Mock<ISessionRepository>();
+        sessionRepo.Setup(s => s.GetSessionEventsStrictAsync(TenantId, SessionId, It.IsAny<int>())).ReturnsAsync(events);
+
+        var ruleService = new AnalyzeRuleService(ruleRepo.Object, NullLogger<AnalyzeRuleService>.Instance);
+        var engine = new RuleEngine(ruleService, ruleRepo.Object, sessionRepo.Object, NullLogger<SleepEpisodeRuleTests>.Instance);
+
+        return await engine.AnalyzeSessionAsync(TenantId, SessionId);
+    }
+}

src/Backend/AutopilotMonitor.Functions.Tests/TenantConfigTableSerializationTests.cs

@@ -120,6 +120,31 @@ public class TenantConfigTableSerializationTests
         Assert.Null(mapped.AbsoluteMaxSessionHours);
     }
 
+    [Fact]
+    public void Roundtrip_EnableDoGroupIdAutoSet_SurvivesStoreAndMap()
+    {
+        var config = new TenantConfiguration
+        {
+            TenantId = TenantId,
+            DomainName = "contoso.com",
+            UpdatedBy = "admin@contoso.com",
+            EnableDoGroupIdAutoSet = true
+        };
+
+        var mapped = TableConfigRepository.ConvertFromTenantTableEntity(
+            TableConfigRepository.ConvertToTenantTableEntity(config));
+
+        Assert.True(mapped.EnableDoGroupIdAutoSet);
+    }
+
+    [Fact]
+    public void Map_LegacyRow_WithoutDoGroupIdColumn_ReadsNull()
+    {
+        // null = "not set" → GetAgentConfigFunction serves the agent default (false).
+        var entity = new TableEntity(TenantId, "config") { { "DomainName", "fabrikam.com" } };
+        Assert.Null(TableConfigRepository.ConvertFromTenantTableEntity(entity).EnableDoGroupIdAutoSet);
+    }
+
     [Fact]
     public void Roundtrip_NotificationChannelsJson_SurvivesStoreAndMap()
     {

src/Backend/AutopilotMonitor.Functions.Tests/TimeAttributionCalculatorTests.cs

@@ -404,10 +404,12 @@ public class TimeAttributionCalculatorTests
         Assert.Equal(0, b.BlockingAppCount);
     }
 
-    // ── retry: occupancy spans to the LAST terminal event (audit Q1) ────────
+    // ── retry: every ATTEMPT counts as active time, idle gaps between them don't ──
+    // (2026-08 attempt-duration change: per-pass segment pairing replaced the old
+    // first-start → last-terminal hull.)
 
     [Fact]
-    public void Retry_IntervalRunsFromFirstStart_ToLastTerminalEvent()
+    public void Retry_ActiveSegmentsSummed_GapBetweenAttemptsExcluded()
     {
         var events = new List<EnrollmentEvent>
         {
@@ -426,10 +428,41 @@ public class TimeAttributionCalculatorTests
 
         AssertExactPartition(b);
         var interval = Assert.Single(b.BlockingApps);
-        // First started (+6m) → LAST terminal (+12m) = 360 s. The payload timing would have
-        // frozen at the first failure (+8m) — event timestamps are the only valid source.
-        Assert.Equal(360, interval.Seconds);
-        Assert.Equal(360, b.EspAppsOccupancySeconds);
+        // Failed attempt (+6m→+8m = 120 s) + retry (+9m→+12m = 180 s) = 300 s active; the
+        // idle minute between the attempts is not this app's time. The failed attempt still
+        // counts — the payload timing would have frozen at the first failure (audit Q1).
+        Assert.Equal(300, interval.Seconds);
+        // Hull endpoints stay first-start → last-terminal for display/what-if.
+        Assert.Equal(T0.AddMinutes(6), interval.StartUtc);
+        Assert.Equal(T0.AddMinutes(12), interval.EndUtc);
+        Assert.Equal(300, b.EspAppsOccupancySeconds);
+    }
+
+    [Fact]
+    public void TwoPasses_OccupancyCountsActiveSegments_NotTheInterPassGap()
+    {
+        // Field case 44862cd3 ("Set TimeZone"): evaluation pass ends Skipped, the real
+        // install runs much later. The app occupies the critical path only while the IME
+        // actively processes it — the gap belongs to whatever installed in between.
+        var events = new List<EnrollmentEvent>
+        {
+            Evt(T0, "agent_started", EnrollmentPhase.DeviceSetup),
+            Evt(T0.AddMinutes(1), "esp_config_detected", data: EspLists(win32Ids: new[] { AppA })),
+            Evt(T0.AddMinutes(2), "esp_phase_changed", EnrollmentPhase.AppsDevice),
+            Evt(T0.AddMinutes(6), "app_install_started", data: AppData(AppA, "App A")),
+            Evt(T0.AddMinutes(7), "app_install_completed", data: AppData(AppA, "App A", "Skipped")),
+            Evt(T0.AddMinutes(40), "app_install_started", data: AppData(AppA, "App A")),  // real install pass
+            Evt(T0.AddMinutes(41), "app_install_completed", data: AppData(AppA, "App A", "Installed")),
+            Evt(T0.AddMinutes(45), "enrollment_complete"),
+        };
+
+        var b = TimeAttributionCalculator.Compute(
+            Input(events, completedAt: T0.AddMinutes(45), durationSeconds: 2700))!;
+
+        AssertExactPartition(b);
+        var interval = Assert.Single(b.BlockingApps);
+        Assert.Equal(120, interval.Seconds);              // 60 s eval + 60 s install — not 2100 s hull
+        Assert.Equal(120, b.EspAppsOccupancySeconds);     // gap not on the critical path either
     }
 
     // ── reboots: spans from event gaps, never the detection event's stamp ───
@@ -466,6 +499,136 @@ public class TimeAttributionCalculatorTests
         Assert.Equal(1200 - 300, b.GetSegmentTotals()[TimeAttributionSegments.EspApps]);
     }
 
+    // ── sleep spans: payload instants are authoritative, annotation not partition ─────────
+
+    [Fact]
+    public void SleepSpan_ComesFromPayloadInstants_NotFromEventTimestamp()
+    {
+        var enteredAt = T0.AddMinutes(8);
+        var exitedAt = T0.AddMinutes(14);
+        var events = new List<EnrollmentEvent>
+        {
+            Evt(T0, "agent_started", EnrollmentPhase.DeviceSetup),
+            Evt(T0.AddMinutes(5), "esp_phase_changed", EnrollmentPhase.AppsDevice),
+            // Emitted at wake (its Timestamp is the wake moment, possibly clamped) — only the
+            // payload carries the true episode bounds.
+            Evt(T0.AddMinutes(14.2), "system_sleep_episode", data: new Dictionary<string, object>
+            {
+                ["kind"] = "modern_standby",
+                ["enteredAt"] = enteredAt.ToString("o"),
+                ["exitedAt"] = exitedAt.ToString("o"),
+                ["durationSeconds"] = 360L,
+            }),
+            Evt(T0.AddMinutes(20), "enrollment_complete"),
+        };
+
+        var b = TimeAttributionCalculator.Compute(
+            Input(events, completedAt: T0.AddMinutes(20), durationSeconds: 1200))!;
+
+        AssertExactPartition(b); // sleep is an annotation — the wall-clock partition is untouched
+        var span = Assert.Single(b.SleepSpans);
+        Assert.Equal(enteredAt, span.StartUtc);
+        Assert.Equal(exitedAt, span.EndUtc);
+        Assert.Equal(360, span.Seconds);
+        Assert.Equal(360, b.SleepSeconds);
+        Assert.Equal("modern_standby", span.Kind);
+        Assert.Equal(TimeAttributionSegments.EspApps, span.SegmentKey);
+    }
+
+    [Fact]
+    public void SleepSpan_DuplicateEpisode_NotDoubleCounted()
+    {
+        var enteredAt = T0.AddMinutes(8);
+        var exitedAt = T0.AddMinutes(10);
+        Dictionary<string, object> Episode() => new Dictionary<string, object>
+        {
+            ["kind"] = "sleep",
+            ["enteredAt"] = enteredAt.ToString("o"),
+            ["exitedAt"] = exitedAt.ToString("o"),
+        };
+        var events = new List<EnrollmentEvent>
+        {
+            Evt(T0, "agent_started", EnrollmentPhase.DeviceSetup),
+            // Same episode observed twice (e.g. backfilled again after an agent restart from a
+            // different event-log record).
+            Evt(T0.AddMinutes(10.1), "system_sleep_episode", data: Episode()),
+            Evt(T0.AddMinutes(12), "system_sleep_episode", data: Episode()),
+            Evt(T0.AddMinutes(20), "enrollment_complete"),
+        };
+
+        var b = TimeAttributionCalculator.Compute(
+            Input(events, completedAt: T0.AddMinutes(20), durationSeconds: 1200))!;
+
+        Assert.Single(b.SleepSpans);
+        Assert.Equal(120, b.SleepSeconds);
+    }
+
+    [Fact]
+    public void SleepSpan_MissingOrUnparseablePayload_Ignored()
+    {
+        var events = new List<EnrollmentEvent>
+        {
+            Evt(T0, "agent_started", EnrollmentPhase.DeviceSetup),
+            Evt(T0.AddMinutes(5), "system_sleep_episode", data: new Dictionary<string, object>
+            {
+                ["kind"] = "sleep",
+                ["enteredAt"] = "not-a-timestamp",
+                ["exitedAt"] = T0.AddMinutes(5).ToString("o"),
+            }),
+            Evt(T0.AddMinutes(6), "system_sleep_episode", data: new Dictionary<string, object>
+            {
+                ["kind"] = "sleep", // bounds missing entirely
+            }),
+            // exitedAt <= enteredAt — pathological, no claim.
+            Evt(T0.AddMinutes(7), "system_sleep_episode", data: new Dictionary<string, object>
+            {
+                ["kind"] = "sleep",
+                ["enteredAt"] = T0.AddMinutes(7).ToString("o"),
+                ["exitedAt"] = T0.AddMinutes(6).ToString("o"),
+            }),
+            Evt(T0.AddMinutes(20), "enrollment_complete"),
+        };
+
+        var b = TimeAttributionCalculator.Compute(
+            Input(events, completedAt: T0.AddMinutes(20), durationSeconds: 1200))!;
+
+        Assert.Empty(b.SleepSpans);
+        Assert.Equal(0, b.SleepSeconds);
+    }
+
+    [Fact]
+    public void WhiteGlove_SleepAcrossPause_CountsOnlyInWindowFlanks()
+    {
+        var part1End = T0.AddMinutes(20);
+        var resumedAt = T0.AddDays(2);
+        var completedAt = resumedAt.AddMinutes(10);
+
+        var events = new List<EnrollmentEvent>
+        {
+            Evt(T0, "agent_started", EnrollmentPhase.DeviceSetup),
+            Evt(T0.AddMinutes(2), "esp_phase_changed", EnrollmentPhase.AppsDevice),
+            Evt(part1End, "whiteglove_part1_complete"),
+            // Sealed device slept through the pause: episode starts 1 min before the seal and
+            // ends 30 s into part 2 — only the in-window flanks may count (90 s), never the
+            // ~2-day pause (RebootSpan precedent).
+            Evt(resumedAt.AddSeconds(35), "system_sleep_episode", data: new Dictionary<string, object>
+            {
+                ["kind"] = "hibernate",
+                ["enteredAt"] = part1End.AddMinutes(-1).ToString("o"),
+                ["exitedAt"] = resumedAt.AddSeconds(30).ToString("o"),
+            }),
+            Evt(completedAt, "enrollment_complete"),
+        };
+
+        var b = TimeAttributionCalculator.Compute(
+            Input(events, completedAt, durationSeconds: 1800, wg: true, resumedAt: resumedAt))!;
+
+        AssertExactPartition(b);
+        var span = Assert.Single(b.SleepSpans);
+        Assert.Equal(90, span.Seconds);
+        Assert.Equal(90, b.SleepSeconds);
+    }
+
     // ── WhiteGlove pause vs. intervals/reboots (Codex review P1): the pause lies INSIDE
     // the windows' hull, so hull-clamping alone would count it — a reboot bracketing the
     // pause must contribute only its in-window flanks, never the pause itself ─────────────

src/Backend/AutopilotMonitor.Functions.Tests/TimeAttributionPersistenceAndAggregationTests.cs

@@ -46,6 +46,11 @@ public class TimeAttributionPersistenceAndAggregationTests
             {
                 new() { StartUtc = T0.AddMinutes(10), EndUtc = T0.AddMinutes(14), Seconds = 240, SegmentKey = TimeAttributionSegments.EspApps },
             },
+            SleepSeconds = 360,
+            SleepSpans = new List<SleepSpan>
+            {
+                new() { StartUtc = T0.AddMinutes(20), EndUtc = T0.AddMinutes(26), Seconds = 360, SegmentKey = TimeAttributionSegments.EspApps, Kind = "modern_standby" },
+            },
             BlockingApps = new List<BlockingAppInterval>
             {
                 new() { AppId = AppX, AppName = "App X", StartUtc = T0.AddMinutes(6), EndUtc = T0.AddMinutes(16), Seconds = 600 },
@@ -77,6 +82,13 @@ public class TimeAttributionPersistenceAndAggregationTests
         Assert.Equal(TimeAttributionSegments.EspApps, reboot.SegmentKey);
         Assert.Equal(240, reboot.Seconds);
 
+        Assert.Equal(360, mapped.SleepSeconds);
+        var sleep = Assert.Single(mapped.SleepSpans);
+        Assert.Equal("modern_standby", sleep.Kind);
+        Assert.Equal(TimeAttributionSegments.EspApps, sleep.SegmentKey);
+        Assert.Equal(T0.AddMinutes(20), sleep.StartUtc);
+        Assert.Equal(360, sleep.Seconds);
+
         var app = Assert.Single(mapped.BlockingApps);
         Assert.Equal(AppX, app.AppId);
         Assert.Equal("App X", app.AppName);

src/Backend/AutopilotMonitor.Functions.Tests/VulnerabilityReportEventSequenceTests.cs

@@ -0,0 +1,138 @@
+using AutopilotMonitor.Functions.Services.Vulnerability;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Pins <see cref="VulnerabilityCorrelateHandler.BuildVulnerabilityReportEvent"/> — the
+/// backend-materialized <c>vulnerability_report</c> event. The load-bearing logic is the
+/// Sequence assignment: the correlation runs async off a queue, so without one the event
+/// defaulted to Sequence 0 and sorted to the TOP of the timeline (a −13m time-jump badge
+/// on a report that actually arrived last). Default is max+1 (sorts LAST, same contract as
+/// BuildSessionTimeoutEvent / BuildAgentEmergencyBreakEvent); WhiteGlove Part 1 instead
+/// anchors at the Part-1 terminal markers so a late Part-1 report can never cross the
+/// web timeline's sequence-based Pre-Provisioning / User Enrollment split and render as
+/// the start of User Enrollment.
+/// </summary>
+public class VulnerabilityReportEventSequenceTests
+{
+    private const string TenantId  = "a1b2c3d4-e5f6-7890-abcd-ef1234567890";
+    private const string SessionId = "b2c3d4e5-f6a7-8901-bcde-f12345678901";
+
+    private static readonly DateTime NowUtc = new(2026, 8, 21, 13, 25, 46, DateTimeKind.Utc);
+
+    private static Dictionary<string, object> Report(string risk = "high") => new()
+    {
+        ["scan_summary"] = new Dictionary<string, object> { ["overall_risk"] = risk },
+        ["findings"] = new List<Dictionary<string, object>>(),
+    };
+
+    private static EnrollmentEvent Build(
+        string? phaseLabel, IReadOnlyList<EnrollmentEvent> existing, Dictionary<string, object>? report = null)
+        => VulnerabilityCorrelateHandler.BuildVulnerabilityReportEvent(
+            TenantId, SessionId, report ?? Report(), phaseLabel, existing, NowUtc);
+
+    [Fact]
+    public void NonWhiteGlove_SortsOnePastTheSessionMax()
+    {
+        var existing = new List<EnrollmentEvent>
+        {
+            new() { Sequence = 3 },
+            new() { Sequence = 41 }, // max — even though out of array order
+            new() { Sequence = 17 },
+        };
+
+        Assert.Equal(42, Build(phaseLabel: null, existing).Sequence);
+    }
+
+    [Fact]
+    public void Sequence_IsOne_WhenNoPriorEvents()
+    {
+        Assert.Equal(1, Build(null, new List<EnrollmentEvent>()).Sequence);
+        Assert.Equal(1, Build(null, null!).Sequence);
+    }
+
+    [Fact]
+    public void WhiteGlovePart1_AnchorsAtPart1Markers_NotPastThePart2Boot()
+    {
+        // Part 2 already running when the async Part-1 scan lands. The web split is
+        // agent_started(50) - 1 = 49; max+1 would be 61 and cross it.
+        var existing = new List<EnrollmentEvent>
+        {
+            new() { Sequence = 10, EventType = "esp_phase_changed" },
+            new() { Sequence = 20, EventType = "whiteglove_complete" },
+            new() { Sequence = 30, EventType = "software_inventory_analysis" },
+            new() { Sequence = 40, EventType = "whiteglove_part1_complete" },
+            new() { Sequence = 50, EventType = "agent_started" },        // Part-2 boot
+            new() { Sequence = 60, EventType = "whiteglove_resumed" },
+        };
+
+        var evt = Build("device_setup", existing);
+
+        // Anchored at the highest Part-1 terminal marker; the timestamp tie-break in the
+        // web sort places it right behind that marker, still inside Pre-Provisioning.
+        Assert.Equal(40, evt.Sequence);
+    }
+
+    [Fact]
+    public void WhiteGlovePart1_UsesWhiteGloveComplete_WhenPart1CompleteMarkerMissing()
+    {
+        var existing = new List<EnrollmentEvent>
+        {
+            new() { Sequence = 20, EventType = "whiteglove_complete" },
+            new() { Sequence = 50, EventType = "agent_started" },
+        };
+
+        Assert.Equal(20, Build("device_setup", existing).Sequence);
+    }
+
+    [Fact]
+    public void WhiteGlovePart1_FallsBackToMaxPlusOne_WithoutAnyMarker()
+    {
+        // No marker ⇒ the web derives no split either, so sorting last is safe.
+        var existing = new List<EnrollmentEvent> { new() { Sequence = 7, EventType = "agent_started" } };
+
+        Assert.Equal(8, Build("device_setup", existing).Sequence);
+    }
+
+    [Fact]
+    public void WhiteGlovePart2_SortsOnePastTheSessionMax()
+    {
+        var existing = new List<EnrollmentEvent>
+        {
+            new() { Sequence = 40, EventType = "whiteglove_part1_complete" },
+            new() { Sequence = 90, EventType = "esp_phase_changed" },
+        };
+
+        Assert.Equal(91, Build("user_enrollment", existing).Sequence);
+    }
+
+    [Fact]
+    public void Shape_IsUnchangedByTheSequenceFix()
+    {
+        var evt = Build(null, new List<EnrollmentEvent>());
+
+        Assert.Equal("vulnerability_report", evt.EventType);
+        Assert.Equal(AutopilotMonitor.Shared.Constants.EventTypes.VulnerabilityReport, evt.EventType);
+        Assert.Equal("VulnerabilityCorrelationService", evt.Source);
+        Assert.Equal(EventSeverity.Error, evt.Severity); // risk=high → Error
+        // Non-phase event: must stay Unknown so the UI timeline doesn't render a phantom phase boundary.
+        Assert.Equal(EnrollmentPhase.Unknown, evt.Phase);
+        Assert.Equal(NowUtc, evt.Timestamp);
+        Assert.Equal(TenantId, evt.TenantId);
+        Assert.Equal(SessionId, evt.SessionId);
+        Assert.Equal("Vulnerability scan complete (risk=high).", evt.Message);
+        Assert.Equal(true, evt.Data["reportAvailable"]);
+        Assert.Equal("single", evt.Data["phase"]);
+        Assert.IsType<Dictionary<string, object>>(evt.Data["scan_summary"]);
+    }
+
+    [Fact]
+    public void Data_Phase_CarriesTheLabel()
+    {
+        var existing = new List<EnrollmentEvent> { new() { Sequence = 20, EventType = "whiteglove_complete" } };
+
+        Assert.Equal("device_setup", Build("device_setup", existing).Data["phase"]);
+        Assert.Equal("user_enrollment", Build("user_enrollment", existing).Data["phase"]);
+    }
+}

src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableConfigRepository.cs

@@ -620,6 +620,7 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
                 { "RebootDelaySeconds", config.RebootDelaySeconds },
                 { "EnableGeoLocation", config.EnableGeoLocation },
                 { "EnableTimezoneAutoSet", config.EnableTimezoneAutoSet },
+                { "EnableDoGroupIdAutoSet", config.EnableDoGroupIdAutoSet },
                 { "NtpServer", config.NtpServer },
                 { "EnableImeMatchLog", config.EnableImeMatchLog },
                 { "EnableGatherRuleDebugLog", config.EnableGatherRuleDebugLog },
@@ -727,6 +728,7 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
                 RebootDelaySeconds = entity.GetInt32("RebootDelaySeconds"),
                 EnableGeoLocation = entity.GetBoolean("EnableGeoLocation"),
                 EnableTimezoneAutoSet = entity.GetBoolean("EnableTimezoneAutoSet"),
+                EnableDoGroupIdAutoSet = entity.GetBoolean("EnableDoGroupIdAutoSet"),
                 NtpServer = string.IsNullOrWhiteSpace(entity.GetString("NtpServer")) ? "time.windows.com" : entity.GetString("NtpServer"),
                 EnableImeMatchLog = entity.GetBoolean("EnableImeMatchLog"),
                 EnableGatherRuleDebugLog = entity.GetBoolean("EnableGatherRuleDebugLog"),

src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableSessionRepository.cs

@@ -131,9 +131,12 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
                 earliestEventTimestamp, latestEventTimestamp, currentPhase,
                 platformScriptIncrement, remediationScriptIncrement, rebootIncrement);
 
-        public Task ReconcileSessionCountersAsync(string tenantId, string sessionId)
+        public Task<SessionSkewScan?> ReconcileSessionCountersAsync(string tenantId, string sessionId)
             => _storage.ReconcileSessionCountersAsync(tenantId, sessionId);
 
+        public Task<Dictionary<string, int>> GetImeOffsetOriginHistogramAsync(string tenantId, string sessionId, int maxRows = 500)
+            => _storage.GetImeOffsetOriginHistogramAsync(tenantId, sessionId, maxRows);
+
         public Task UpdateSessionDiagnosticsBlobAsync(
             string tenantId, string sessionId, string blobName, string? destination = null)
             => _storage.UpdateSessionDiagnosticsBlobAsync(tenantId, sessionId, blobName, destination);

src/Backend/AutopilotMonitor.Functions/Functions/Admin/ReseedFromGitHubFunction.cs

@@ -137,6 +137,18 @@ namespace AutopilotMonitor.Functions.Functions.Admin
 
         private async Task<(int deleted, int written, int orphanStatesGcd, int sunsetSkipped)> ReseedGatherAsync(List<AutopilotMonitor.Shared.Models.GatherRule> rules)
         {
+            // Global-partition rules must stay inside the reserved built-in namespace — an ID
+            // outside it (e.g. GATHER-CUSTOM-*) would silently shadow every tenant's same-ID
+            // custom rule at merge time (global wins). Reject instead of import.
+            var rejectedGather = rules.Where(r => !AutopilotMonitor.Shared.Models.RuleIdPolicy.IsReservedBuiltInId(r.RuleId)).ToList();
+            if (rejectedGather.Count > 0)
+            {
+                _logger.LogError(
+                    "GitHub reseed gather: rejected {Count} rule(s) outside the reserved built-in namespace: {Ids}",
+                    rejectedGather.Count, string.Join(", ", rejectedGather.Select(r => r.RuleId)));
+                rules = rules.Except(rejectedGather).ToList();
+            }
+
             var existing = await _ruleRepo.GetGatherRulesAsync("global");
             var newCatalogIds = rules.Select(r => r.RuleId).ToHashSet(System.StringComparer.Ordinal);
             // A rule the deployed binary already ships IDENTICALLY is embedded-provenance; one whose
@@ -199,6 +211,18 @@ namespace AutopilotMonitor.Functions.Functions.Admin
 
         private async Task<(int deleted, int written, int orphanStatesGcd, int sunsetSkipped)> ReseedAnalyzeAsync(List<AutopilotMonitor.Shared.Models.AnalyzeRule> rules)
         {
+            // Global-partition rules must stay inside the reserved built-in namespace — an ID
+            // outside it (e.g. ANALYZE-CUSTOM-*) would silently shadow every tenant's same-ID
+            // custom rule at merge time (global wins). Reject instead of import.
+            var rejectedAnalyze = rules.Where(r => !AutopilotMonitor.Shared.Models.RuleIdPolicy.IsReservedBuiltInId(r.RuleId)).ToList();
+            if (rejectedAnalyze.Count > 0)
+            {
+                _logger.LogError(
+                    "GitHub reseed analyze: rejected {Count} rule(s) outside the reserved built-in namespace: {Ids}",
+                    rejectedAnalyze.Count, string.Join(", ", rejectedAnalyze.Select(r => r.RuleId)));
+                rules = rules.Except(rejectedAnalyze).ToList();
+            }
+
             var existing = await _ruleRepo.GetAnalyzeRulesAsync("global");
             var newCatalogIds = rules.Select(r => r.RuleId).ToHashSet(System.StringComparer.Ordinal);
             // A rule the deployed binary already ships IDENTICALLY is embedded-provenance; one whose

src/Backend/AutopilotMonitor.Functions/Functions/Apps/AppsAnalyticsHelper.cs

@@ -513,7 +513,10 @@ namespace AutopilotMonitor.Functions.Functions.Apps
                     exitCode = s.ExitCode,
                     attemptNumber = s.AttemptNumber,
                     startedAt = s.StartedAt,
-                    durationSeconds = s.DurationSeconds
+                    durationSeconds = s.DurationSeconds,
+                    // 2+ = the IME processed this app in multiple passes (device-ESP
+                    // evaluation + real install) — explains a completion far after startedAt.
+                    installPassCount = s.InstallPassCount
                 };
             }).ToList();
 
@@ -606,16 +609,14 @@ namespace AutopilotMonitor.Functions.Functions.Apps
             return date.AddDays(-diff);
         }
 
-        // Internal so AppVersionRegressionRadar shares the same nearest-rank convention
-        // (a third percentile implementation would invite subtle median drift).
+        // Internal so AppVersionRegressionRadar shares the same nearest-rank convention.
+        // Thin delegation onto the single shared implementation (PercentileMath) — parallel
+        // implementations would invite subtle median drift.
         internal static int Percentile(List<int> values, double percentile)
         {
             if (values.Count == 0) return 0;
-            var sorted = values.OrderBy(v => v).ToList();
-            var rank = (int)Math.Ceiling(percentile * sorted.Count) - 1;
-            if (rank < 0) rank = 0;
-            if (rank >= sorted.Count) rank = sorted.Count - 1;
-            return sorted[rank];
+            var sorted = values.Select(v => (double)v).OrderBy(v => v).ToList();
+            return (int)Helpers.PercentileMath.Percentile(sorted, percentile);
         }
     }
 }

src/Backend/AutopilotMonitor.Functions/Functions/Config/GetAgentConfigFunction.cs

@@ -274,7 +274,7 @@ namespace AutopilotMonitor.Functions.Functions.Config
             var response = req.CreateResponse(HttpStatusCode.OK);
             await response.WriteAsJsonAsync(new AgentConfigResponse
             {
-                ConfigVersion = 37, // EnableEspContinueAnywayObservation (Continue-Anyway observation mode)
+                ConfigVersion = 40, // EnableDoGroupIdAutoSet (Delivery Optimization group ID from network fingerprint)
                 UploadIntervalSeconds = Shared.Constants.DefaultUploadIntervalSeconds,
                 SelfDestructOnComplete = tenantConfig.SelfDestructOnComplete ?? true,
                 KeepLogFile = tenantConfig.KeepLogFile ?? false,
@@ -312,6 +312,7 @@ namespace AutopilotMonitor.Functions.Functions.Config
                 AllowAgentDowngrade = adminConfig.AllowAgentDowngrade,
                 NtpServer = string.IsNullOrEmpty(tenantConfig.NtpServer) ? "time.windows.com" : tenantConfig.NtpServer,
                 EnableTimezoneAutoSet = tenantConfig.EnableTimezoneAutoSet ?? false,
+                EnableDoGroupIdAutoSet = tenantConfig.EnableDoGroupIdAutoSet ?? false,
                 SendTraceEvents = tenantConfig.SendTraceEvents,
                 UnrestrictedMode = TenantEntitlementService.IsUnrestrictedModeActive(tenantConfig, DateTime.UtcNow),
                 GatherRules = gatherRules,

src/Backend/AutopilotMonitor.Functions/Functions/Ingest/IngestTelemetryFunction.cs

@@ -221,10 +221,17 @@ namespace AutopilotMonitor.Functions.Functions.Ingest
                 // EventIngestProcessor, saving one Sessions point-read per batch.
                 var preFetchedStatus = TryReadSessionStatus(guardSessionRow);
 
+                // P14: device-clock send time of this upload (one value per request). Separates
+                // spool delay from device-vs-server clock offset downstream; absent/garbage → null.
+                var sentAtHeader = req.Headers.Contains("X-Send-Time-Utc")
+                    ? req.Headers.GetValues("X-Send-Time-Utc").FirstOrDefault()
+                    : null;
+                var sentAt = ParseSendTimeHeader(sentAtHeader);
+
                 // Partition + persist. Events are routed through EventIngestProcessor which runs the
                 // full pipeline (rule engine / app-install aggregation / SignalR / webhooks / ...);
                 // Signal + Transition go straight to their repositories.
-                var outcome = await PersistItemsAsync(items, bodyTenantId, sessionId, validation, preFetchedStatus);
+                var outcome = await PersistItemsAsync(items, bodyTenantId, sessionId, validation, preFetchedStatus, sentAt);
 
                 _logger.LogInformation(
                     "IngestTelemetry: tenant={Tenant} session={Session} events={E} signals={S} transitions={T} unknown={U}",
@@ -349,7 +356,8 @@ namespace AutopilotMonitor.Functions.Functions.Ingest
             string tenantId,
             string sessionId,
             SecurityValidationResult validation,
-            SessionStatus? preFetchedStatus)
+            SessionStatus? preFetchedStatus,
+            DateTime? sentAt)
         {
             var events      = new List<EnrollmentEvent>();
             var signals     = new List<SignalRecord>();
@@ -435,6 +443,7 @@ namespace AutopilotMonitor.Functions.Functions.Ingest
                     SessionId = sessionId,
                     TenantId  = tenantId,
                     Events    = events,
+                    SentAt    = sentAt,
                 };
                 var processed = await _eventProcessor.ProcessEventsAsync(eventRequest, validation, preFetchedStatus);
 
@@ -570,6 +579,29 @@ namespace AutopilotMonitor.Functions.Functions.Ingest
             return false;
         }
 
+        /// <summary>
+        /// Parses the <c>X-Send-Time-Utc</c> header (agent device-clock send time, ISO-8601
+        /// round-trip). Returns null for absent/unparseable values and for anything before
+        /// year 2000 — Table Storage rejects pre-1601 DateTimes outright, and a sub-2000
+        /// value can only be garbage, never a measurable clock offset. Deliberately NO upper
+        /// clamp: a future-dated send time IS the device-clock-error measurement this field
+        /// exists to capture.
+        /// </summary>
+        internal static DateTime? ParseSendTimeHeader(string? headerValue)
+        {
+            if (string.IsNullOrWhiteSpace(headerValue)) return null;
+
+            if (!DateTimeOffset.TryParse(
+                    headerValue,
+                    System.Globalization.CultureInfo.InvariantCulture,
+                    System.Globalization.DateTimeStyles.RoundtripKind,
+                    out var parsed))
+                return null;
+
+            var utc = parsed.UtcDateTime;
+            return utc.Year >= 2000 ? utc : (DateTime?)null;
+        }
+
         /// <summary>
         /// PartitionKey convention is <c>{tenantId}_{sessionId}</c> — both GUIDs with dashes, so
         /// splitting on the single underscore between them is unambiguous. Returns false for any

src/Backend/AutopilotMonitor.Functions/Functions/Ingest/ReportAgentErrorFunction.cs

@@ -178,9 +178,90 @@ namespace AutopilotMonitor.Functions.Functions.Ingest
 
             await MaterializeEmergencyBreakArtifactsAsync(report, tenantId, _sessionRepo, _opsEventService, _logger);
 
+            var adminConfig = await _adminConfigService.GetConfigurationAsync();
+            await MaterializeIntegrityMismatchAsync(
+                report, tenantId, _opsEventService,
+                adminConfig?.LatestAgentV2Version, adminConfig?.LatestAgentV2ExeSha256, _logger);
+
             return req.CreateResponse(HttpStatusCode.OK);
         }
 
+        /// <summary>
+        /// Regex over OUR OWN report format (AgentRuntimeConfig.VerifyBinaryIntegrity):
+        /// "... actual=&lt;sha256&gt;, expected=&lt;sha256&gt;". Parsed leniently — an unparseable
+        /// message records rather than suppresses.
+        /// </summary>
+        private static readonly System.Text.RegularExpressions.Regex ActualHashRegex =
+            new(@"actual=([0-9a-fA-F]{64})", System.Text.RegularExpressions.RegexOptions.Compiled);
+
+        /// <summary>
+        /// Surfaces an <c>IntegrityCheckFailed</c> report as an <c>AgentBinaryIntegrityMismatch</c>
+        /// ops event. Before 2026-08-20 this report went to App Insights only — session e9753578's
+        /// agent reported a hash mismatch and no product surface showed it, which cost a day of
+        /// mis-attributed root-causing.
+        ///
+        /// <para>
+        /// KNOWN, ACCEPTED RACE (must not spam the ops feed): around every release, agents compare
+        /// against a hash snapshot that does not belong to their own binary — a freshly installed
+        /// latest agent can receive the PREVIOUS release's hashes from the 5-minute
+        /// AdminConfiguration cache (e9753578: genuine 1410 exe vs cached 1409 hash), and an
+        /// older agent's next config fetch sees the NEW release's hash. Both self-heal via the
+        /// forced self-update. Suppression, evaluated against the CURRENT config at receive time:
+        /// the reported RUNNING hash equals the published exe (stale expectation), or the
+        /// reporting agent's version is not the latest (update in flight). What remains — an agent
+        /// claiming the latest version whose binary is NOT the published one — is the real signal:
+        /// tamper, stale blob, or a build that never came from the release pipeline.
+        /// </para>
+        ///
+        /// <para>
+        /// Ops event only, no timeline event: the report is about the BINARY, not the enrollment,
+        /// and may arrive before the session is registered. No idempotency read: the agent-side
+        /// trigger is single-shot per process. Best-effort — a failure here must never turn the
+        /// always-200 channel into a retry loop.
+        /// </para>
+        /// </summary>
+        internal static async Task MaterializeIntegrityMismatchAsync(
+            AgentErrorReport report,
+            string tenantId,
+            OpsEventService opsEventService,
+            string? latestAgentVersion,
+            string? latestAgentExeSha256,
+            ILogger logger)
+        {
+            if (report.ErrorType != AgentErrorType.IntegrityCheckFailed)
+            {
+                return;
+            }
+
+            try
+            {
+                // "2.0.1410+3b59dab2..." → "2.0.1410" (the manifest/AdminConfig carry no +commit).
+                var reportedVersion = (report.AgentVersion ?? string.Empty).Split('+')[0];
+                if (!string.IsNullOrEmpty(latestAgentVersion)
+                    && !string.IsNullOrEmpty(reportedVersion)
+                    && !string.Equals(reportedVersion, latestAgentVersion, StringComparison.OrdinalIgnoreCase))
+                {
+                    return; // older agent vs newer release — the forced self-update heals this.
+                }
+
+                var actualMatch = ActualHashRegex.Match(report.Message ?? string.Empty);
+                if (actualMatch.Success
+                    && !string.IsNullOrEmpty(latestAgentExeSha256)
+                    && string.Equals(actualMatch.Groups[1].Value, latestAgentExeSha256, StringComparison.OrdinalIgnoreCase))
+                {
+                    return; // the running binary IS the published one — the agent's expectation was stale.
+                }
+
+                await opsEventService.RecordAgentBinaryIntegrityMismatchAsync(
+                    tenantId, report.SessionId, report.AgentVersion, report.Message ?? string.Empty);
+            }
+            catch (Exception ex)
+            {
+                logger.LogWarning(ex,
+                    "ReportAgentError: failed to record AgentBinaryIntegrityMismatch ops event for session {SessionId}", report.SessionId);
+            }
+        }
+
         /// <summary>
         /// Materializes the agent's silent 48h emergency break as (1) a timeline event so it shows
         /// in the session and the timeout classifier can see it, (2) the cross-session EventType

src/Backend/AutopilotMonitor.Functions/Functions/Rules/DryRunAnalyzeRuleFunction.cs

@@ -128,7 +128,12 @@ namespace AutopilotMonitor.Functions.Functions.Rules
         internal static readonly HashSet<string> KnownSources = new(StringComparer.Ordinal)
         {
             "event_type", "event_data", "event_data_array", "event_count",
-            "phase_duration", "app_install_duration", "event_correlation",
+            "phase_duration", "app_install_duration", "event_correlation", "clock_skew",
+        };
+
+        internal static readonly HashSet<string> KnownSkewMetrics = new(StringComparer.Ordinal)
+        {
+            "clock_jump", "sustained_offset",
         };
 
         internal static readonly HashSet<string> KnownOperators = new(StringComparer.OrdinalIgnoreCase)
@@ -196,6 +201,18 @@ namespace AutopilotMonitor.Functions.Functions.Rules
                         errors.Add($"{label}: event_correlation requires joinField");
                 }
 
+                if (string.Equals(c.Source, "clock_skew", StringComparison.Ordinal))
+                {
+                    if (string.IsNullOrWhiteSpace(c.SkewMetric) || !KnownSkewMetrics.Contains(c.SkewMetric))
+                        errors.Add($"{label}: clock_skew requires skewMetric (one of: {string.Join(", ", KnownSkewMetrics)})");
+                    if (!string.Equals(c.Operator, "gt", StringComparison.OrdinalIgnoreCase)
+                        && !string.Equals(c.Operator, "gte", StringComparison.OrdinalIgnoreCase))
+                        errors.Add($"{label}: clock_skew supports only gt/gte (magnitude vs threshold)");
+                    if (!double.TryParse(c.Value, System.Globalization.NumberStyles.Float,
+                            System.Globalization.CultureInfo.InvariantCulture, out var skewThreshold) || skewThreshold <= 0)
+                        errors.Add($"{label}: clock_skew requires a positive numeric value (threshold in seconds)");
+                }
+
                 if ((string.Equals(c.Operator, "regex", StringComparison.OrdinalIgnoreCase)
                         || string.Equals(c.Operator, "not_regex", StringComparison.OrdinalIgnoreCase))
                     && !string.IsNullOrEmpty(c.Value))

src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs

@@ -35,7 +35,12 @@ public sealed class AppVersionDurationRegressionFinding
 /// </list>
 /// Measured population: Succeeded, non-skip terminal state, plausible observed duration
 /// (<see cref="MetricsMath.HasMeasuredDuration"/>), no AppId collision, non-empty
-/// AppVersion. Version ORDER comes from first-seen install time (min StartedAt) — version
+/// AppVersion, and — cutover gate of the 2026-08 attempt-duration change — an
+/// attempt-anchored duration (<c>LastAttemptStartedAt</c> present). Rows from before the
+/// change carry the old full-span semantics; a median over a mixed population would both
+/// mask real regressions (inflated previous vs. attempt-short current) and falsely re-arm
+/// active episodes, so pre-cutover rows are excluded on BOTH sides of every comparison.
+/// Version ORDER comes from first-seen install time (min StartedAt) — version
 /// strings are never sorted lexically ("9.1" vs "2024.10" would lie). "Previous" is the
 /// version with the latest first-seen strictly before the current version's first-seen;
 /// with parallel ring rollouts that can be a concurrently-deployed version — accepted for
@@ -149,6 +154,9 @@ public static class AppVersionRegressionRadar
             if (summary.Status != "Succeeded") continue;
             if (MetricsMath.IsSkipTerminalState(summary)) continue;
             if (!MetricsMath.HasMeasuredDuration(summary)) continue;
+            // Attempt-semantics cutover gate (see class doc): only attempt-anchored rows
+            // enter the duration population, on both sides of every comparison.
+            if (!summary.LastAttemptStartedAt.HasValue) continue;
 
             if (!groups.TryGetValue(summary.AppName, out var list))
             {

src/Backend/AutopilotMonitor.Functions/Helpers/EventFieldProjection.cs

@@ -63,7 +63,7 @@ namespace AutopilotMonitor.Functions.Helpers
         private static readonly HashSet<string> KnownFieldKeys = new(StringComparer.OrdinalIgnoreCase)
         {
             "eventId", "sessionId", "tenantId", "eventType", "severity", "source", "phase",
-            "phaseName", "timestamp", "receivedAt", "message", "sequence", "rowKey",
+            "phaseName", "timestamp", "receivedAt", "sentAt", "message", "sequence", "rowKey",
             "originalTimestamp", "timestampClamped", "causedByTransitionStepIndex",
             "causedBySignalOrdinal", "data",
         };
@@ -86,6 +86,7 @@ namespace AutopilotMonitor.Functions.Helpers
             if (fields.Contains("phaseName")) dict["phaseName"] = e.PhaseName;
             if (fields.Contains("timestamp")) dict["timestamp"] = e.Timestamp;
             if (fields.Contains("receivedAt")) dict["receivedAt"] = e.ReceivedAt;
+            if (fields.Contains("sentAt")) dict["sentAt"] = e.SentAt;
             if (fields.Contains("message")) dict["message"] = e.Message;
             if (fields.Contains("sequence")) dict["sequence"] = e.Sequence;
             if (fields.Contains("rowKey")) dict["rowKey"] = e.RowKey;

src/Backend/AutopilotMonitor.Functions/Helpers/MetricsMath.cs

@@ -35,11 +35,14 @@ public static class MetricsMath
     /// <summary>
     /// Upper plausibility bound for an observed install duration: 6 h, the agent's default
     /// max observation lifetime (AgentMaxLifetimeMinutes = 360) — nothing longer can have
-    /// been continuously watched. Rows above it are emission artifacts, not slow installs:
-    /// a batch emission at session end pins CompletedAt far past the real finish (verified
-    /// in production 2026-07-27: app rows carrying 60 175 s in a session whose own wall
-    /// clock was 2 697 s; 490 rows &gt; 6 h overall, worst 117 days — dominating the
-    /// slowest-apps ranking with six-figure averages).
+    /// been continuously watched. Historically this mostly caught full-span pathologies
+    /// (pre-2026-08 rows measured first observation → last terminal across all install
+    /// passes; verified in production 2026-07-27: app rows carrying 60 175 s in a session
+    /// whose own wall clock was 2 697 s; 490 rows &gt; 6 h overall, worst 117 days). Since
+    /// the 2026-08 attempt-duration change DurationSeconds measures the last attempt, so
+    /// far fewer rows trip this bound — it remains as the guard against back-stamped
+    /// completions, where a single ATTEMPT longer than the agent's own lifetime is still
+    /// impossible to have observed.
     /// </summary>
     public const int MaxPlausibleInstallDurationSeconds = 6 * 3600;
 
@@ -168,14 +171,15 @@ public static class MetricsMath
     /// drained up to 200k raw sessions into the browser and ran these aggregations on the main
     /// thread. Success rate follows the SLA convention: Succeeded / (Succeeded + Failed) — finished
     /// enrollments only, so in-flight sessions and Incomplete (terminal, non-failure) never dilute
-    /// it. Average duration counts every non-in-progress session that carries a positive duration
-    /// (failures included).
+    /// it. Duration stats (average, median, P90) count every non-in-progress session that carries a
+    /// positive duration (failures included); the cards lead with the median because enrollment
+    /// durations are heavily right-skewed and a handful of multi-hour outliers make the mean
+    /// meaningless as a "typical enrollment" answer.
     /// </summary>
     public static FleetHealthMetrics BuildFleetHealthPayload(IReadOnlyList<SessionSummary> sessions, int days)
     {
         int succeeded = 0, failed = 0, inProgress = 0, incomplete = 0;
-        long completedDurationSeconds = 0;
-        int completedWithDurationCount = 0;
+        var completedDurationSeconds = new List<double>();
 
         foreach (var s in sessions)
         {
@@ -188,12 +192,10 @@ public static class MetricsMath
             }
 
             if (s.Status != SessionStatus.InProgress && s.DurationSeconds is int d && d > 0)
-            {
-                completedDurationSeconds += d;
-                completedWithDurationCount++;
-            }
+                completedDurationSeconds.Add(d);
         }
 
+        completedDurationSeconds.Sort(); // Percentile() expects ascending order
         int total = sessions.Count;
         int finished = succeeded + failed;
         var stats = new FleetHealthStats
@@ -204,9 +206,11 @@ public static class MetricsMath
             InProgress = inProgress,
             Incomplete = incomplete,
             SuccessRate = finished > 0 ? Math.Round((double)succeeded / finished * 100, 1) : 0,
-            AvgDurationMinutes = completedWithDurationCount > 0
-                ? (int)Math.Round((double)completedDurationSeconds / completedWithDurationCount / 60.0, MidpointRounding.AwayFromZero)
+            AvgDurationMinutes = completedDurationSeconds.Count > 0
+                ? (int)Math.Round(completedDurationSeconds.Average() / 60.0, MidpointRounding.AwayFromZero)
                 : 0,
+            MedianDurationMinutes = SecondsToMinutes(Percentile(completedDurationSeconds, 50)),
+            P90DurationMinutes = SecondsToMinutes(Percentile(completedDurationSeconds, 90)),
         };
 
         return new FleetHealthMetrics
@@ -369,6 +373,10 @@ public static class MetricsMath
     /// rounded to one decimal place. Callers MUST pass values pre-sorted ascending.
     /// Returns 0 for an empty list.
     /// </summary>
+    /// <summary>Rounds a duration in seconds to whole minutes (away from zero, matching the avg).</summary>
+    public static int SecondsToMinutes(double seconds)
+        => (int)Math.Round(seconds / 60.0, MidpointRounding.AwayFromZero);
+
     public static double Percentile(List<double> sortedValues, int percentile)
     {
         if (sortedValues.Count == 0) return 0;

src/Backend/AutopilotMonitor.Functions/Helpers/PercentileMath.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace AutopilotMonitor.Functions.Helpers
+{
+    /// <summary>
+    /// The single nearest-rank percentile implementation (rank = ceil(p·n) − 1, clamped).
+    /// AppsAnalyticsHelper.Percentile and PlatformMetricsService.Percentile delegate here;
+    /// keep it that way — parallel implementations invite subtle median drift between
+    /// surfaces that report the "same" statistic.
+    /// </summary>
+    internal static class PercentileMath
+    {
+        /// <summary>Nearest-rank percentile over an ascending-sorted list.</summary>
+        internal static double Percentile(IReadOnlyList<double> sortedValues, double percentile)
+        {
+            if (sortedValues.Count == 0) return 0;
+            var rank = (int)Math.Ceiling(percentile * sortedValues.Count) - 1;
+            return sortedValues[Math.Max(0, Math.Min(rank, sortedValues.Count - 1))];
+        }
+
+        /// <summary>Median (p50) over unsorted values.</summary>
+        internal static double Median(IEnumerable<double> values)
+        {
+            var sorted = values.OrderBy(v => v).ToList();
+            return Percentile(sorted, 0.50);
+        }
+    }
+}

src/Backend/AutopilotMonitor.Functions/Helpers/TimeAttributionCalculator.cs

@@ -72,7 +72,9 @@ public static class TimeAttributionCalculator
     /// <summary>Bump on any semantic change so aggregates never mix definitions (truthfulness rule 8).</summary>
     // v2: PriorEnrollmentResidue flag — sessions whose phase anchors are distorted by
     // pre-enrollment state on disk are now flagged and excluded from fleet segment stats.
-    public const int CurrentVersion = 2;
+    // v3: SleepSpans — completed sleep/standby episodes (system_sleep_episode) as cross-cutting
+    // annotations mirroring RebootSpans; the maintenance sweep recomputes older rows.
+    public const int CurrentVersion = 3;
 
     /// <summary>
     /// Enrollment class for fleet aggregation — classes are NEVER mixed in one aggregate (a
@@ -111,6 +113,10 @@ public static class TimeAttributionCalculator
         public string AppName = string.Empty;
         public DateTime? FirstStart;
         public DateTime? LastTerminal;
+        /// <summary>Start of the currently open activity segment (start seen, terminal pending).</summary>
+        public DateTime? OpenStart;
+        /// <summary>Closed activity segments: one per fully-observed install pass/attempt (start → terminal).</summary>
+        public List<(DateTime Start, DateTime End)> Segments = new();
     }
 
     /// <summary>
@@ -152,16 +158,19 @@ public static class TimeAttributionCalculator
         else if (blockingSets.IsTruncated)
             flags |= TimeAttributionFlags.BlockingSetTruncated;
 
-        var (blockingApps, blockingAppCount) = BuildBlockingAppIntervals(events, blockingSets, windows, ref flags);
+        var (blockingApps, blockingAppCount, blockingAppSegments) = BuildBlockingAppIntervals(events, blockingSets, windows, ref flags);
 
         int? occupancy = null;
         if (blockingSets != null && blockingSets.ListedCount > 0)
         {
             var espAppsSpans = spans.Where(s => s.SegmentKey == TimeAttributionSegments.EspApps).ToList();
-            occupancy = ComputeOccupancySeconds(blockingApps, espAppsSpans);
+            // Occupancy merges the per-pass SEGMENTS, not the per-app hulls — a hull spans
+            // the idle gap between install passes, which is not occupied by this app.
+            occupancy = ComputeOccupancySeconds(blockingAppSegments, espAppsSpans);
         }
 
         var rebootSpans = BuildRebootSpans(events, windows, spans);
+        var sleepSpans = BuildSleepSpans(events, windows, spans);
 
         if (events.Any(e => e.EventType == Constants.EventTypes.AgentLateStart))
             flags |= TimeAttributionFlags.PartialObservation;
@@ -185,6 +194,8 @@ public static class TimeAttributionCalculator
             UnattributedSeconds = unattributed,
             RebootSeconds = rebootSpans.Sum(r => r.Seconds),
             RebootSpans = rebootSpans,
+            SleepSeconds = sleepSpans.Sum(s => s.Seconds),
+            SleepSpans = sleepSpans,
             BlockingApps = blockingApps
                 .OrderByDescending(a => a.Seconds)
                 .ThenBy(a => a.AppName, StringComparer.OrdinalIgnoreCase)
@@ -403,12 +414,12 @@ public static class TimeAttributionCalculator
 
     // ── blocking-app intervals + occupancy ──────────────────────────────────
 
-    private static (List<BlockingAppInterval> Intervals, int MatchedCount) BuildBlockingAppIntervals(
+    private static (List<BlockingAppInterval> Intervals, int MatchedCount, List<BlockingAppInterval> OccupancySegments) BuildBlockingAppIntervals(
         List<EnrollmentEvent> events, EspBlockingSets? sets, List<Window> windows, ref TimeAttributionFlags flags)
     {
         var intervals = new List<BlockingAppInterval>();
         if (sets == null || sets.ListedCount == 0)
-            return (intervals, 0);
+            return (intervals, 0, intervals);
 
         // Fold per-app activity from EVENT timestamps (never payload timing — audit Q1).
         var apps = new Dictionary<string, AppActivity>(StringComparer.OrdinalIgnoreCase);
@@ -436,36 +447,75 @@ public static class TimeAttributionCalculator
                 activity.AppName = nameObj?.ToString()?.Trim() ?? string.Empty;
             }
 
-            if (isStart && (!activity.FirstStart.HasValue || evt.Timestamp < activity.FirstStart.Value))
-                activity.FirstStart = evt.Timestamp;
-            // LAST terminal wins — an IME retry (Error → retry → Installed) extends the
-            // occupancy to the final outcome instead of freezing at the first failure.
-            if (isTerminal && (!activity.LastTerminal.HasValue || evt.Timestamp > activity.LastTerminal.Value))
-                activity.LastTerminal = evt.Timestamp;
+            if (isStart)
+            {
+                if (!activity.FirstStart.HasValue || evt.Timestamp < activity.FirstStart.Value)
+                    activity.FirstStart = evt.Timestamp;
+                // A download start followed by an install start is ONE active window —
+                // the earliest open start survives until a terminal closes the segment.
+                activity.OpenStart ??= evt.Timestamp;
+            }
+            if (isTerminal)
+            {
+                if (!activity.LastTerminal.HasValue || evt.Timestamp > activity.LastTerminal.Value)
+                    activity.LastTerminal = evt.Timestamp;
+                // Segment pairing (2026-08 attempt-duration change): each fully-observed
+                // pass/attempt (start → terminal, sequence-ordered) is its own activity
+                // segment. The IME processes the app list in multiple passes; the idle gap
+                // between passes belongs to the apps actually running then, not to this one.
+                // A failed attempt still counts as active time — the retry opens a new
+                // segment, so the old "LAST terminal wins" retry intent is preserved.
+                if (activity.OpenStart.HasValue)
+                {
+                    if (evt.Timestamp >= activity.OpenStart.Value)
+                        activity.Segments.Add((activity.OpenStart.Value, evt.Timestamp));
+                    else
+                        flags |= TimeAttributionFlags.ClockSkewDropped;
+                    activity.OpenStart = null;
+                }
+                // Terminal without an observed start: no segment claim (attach window,
+                // audit §0.5) — same rule as before.
+            }
         }
 
         var matched = 0;
+        var occupancySegments = new List<BlockingAppInterval>();
         foreach (var activity in apps.Values)
         {
             if (!sets.Contains(activity.AppId)) continue; // absent ⇒ unknown, never "not blocking"
             matched++;
 
-            if (!activity.FirstStart.HasValue || !activity.LastTerminal.HasValue)
-                continue; // unobserved endpoint → no interval claim (attach window, audit §0.5)
-            if (activity.LastTerminal.Value < activity.FirstStart.Value)
-            {
-                flags |= TimeAttributionFlags.ClockSkewDropped;
-                continue;
-            }
+            if (activity.Segments.Count == 0)
+                continue; // no fully-observed attempt → no interval claim (attach window, audit §0.5)
 
-            var clamped = ClampToWindows(activity.FirstStart.Value, activity.LastTerminal.Value, windows);
-            if (!clamped.HasValue)
+            // Clamp each segment; the persisted per-app interval is the hull of the clamped
+            // segments with Seconds = the SUM of in-window active time (not the hull span —
+            // the inter-pass idle gap is not this app's time).
+            var total = 0;
+            DateTime? hullStart = null, hullEnd = null;
+            foreach (var segment in activity.Segments)
             {
-                // Outside the hull entirely → pathological timestamps (flagged, as before).
-                // Inside the hull but touching no window (wholly inside the WhiteGlove pause):
-                // no in-window observation → no interval claim, and nothing wrong with clocks.
-                if (activity.LastTerminal.Value < windows[0].Start ||
-                    activity.FirstStart.Value > windows[windows.Count - 1].End)
+                var clamped = ClampToWindows(segment.Start, segment.End, windows);
+                if (!clamped.HasValue) continue;
+                total += clamped.Value.Seconds;
+                if (hullStart == null || clamped.Value.Start < hullStart.Value) hullStart = clamped.Value.Start;
+                if (hullEnd == null || clamped.Value.End > hullEnd.Value) hullEnd = clamped.Value.End;
+                occupancySegments.Add(new BlockingAppInterval
+                {
+                    AppId = activity.AppId,
+                    AppName = activity.AppName,
+                    StartUtc = clamped.Value.Start,
+                    EndUtc = clamped.Value.End,
+                    Seconds = clamped.Value.Seconds,
+                });
+            }
+            if (hullStart == null || hullEnd == null)
+            {
+                // No segment overlapped any window. Outside the hull entirely →
+                // pathological timestamps (flagged, as before). Wholly inside the
+                // WhiteGlove pause → no in-window observation, nothing wrong with clocks.
+                if (activity.LastTerminal!.Value < windows[0].Start ||
+                    activity.FirstStart!.Value > windows[windows.Count - 1].End)
                 {
                     flags |= TimeAttributionFlags.ClockSkewDropped;
                 }
@@ -476,14 +526,13 @@ public static class TimeAttributionCalculator
             {
                 AppId = activity.AppId,
                 AppName = activity.AppName,
-                StartUtc = clamped.Value.Start,
-                EndUtc = clamped.Value.End,
-                // In-window seconds — a WG-pause-straddling interval never counts the pause.
-                Seconds = clamped.Value.Seconds,
+                StartUtc = hullStart.Value,
+                EndUtc = hullEnd.Value,
+                Seconds = total,
             });
         }
 
-        return (intervals, matched);
+        return (intervals, matched, occupancySegments);
     }
 
     /// <summary>
@@ -665,6 +714,63 @@ public static class TimeAttributionCalculator
         return result;
     }
 
+    // ── sleep spans ─────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// One span per completed sleep episode (<c>system_sleep_episode</c>). The payload's
+    /// <c>enteredAt</c>/<c>exitedAt</c> are the authoritative instants — the event's own
+    /// timestamp is stamped at wake and may have been clamped server-side. Structural clone of
+    /// <see cref="BuildRebootSpans"/>: spans are clipped to the observation hull (a WhiteGlove
+    /// pause episode contributes nothing), dedup'd on the enter instant (an episode straddling
+    /// an agent restart can be backfilled twice from different records), and annotate the
+    /// segment they started in — they are never a slice of the wall-clock partition.
+    /// </summary>
+    private static List<SleepSpan> BuildSleepSpans(
+        List<EnrollmentEvent> events, List<Window> windows, List<TimeAttributionSpan> spans)
+    {
+        var result = new List<SleepSpan>();
+        var seenEpisodes = new HashSet<DateTime>();
+
+        foreach (var evt in events)
+        {
+            if (evt.EventType != Constants.EventTypes.SystemSleepEpisode || evt.Data == null) continue;
+
+            var enteredAt = ParseUtcInstant(evt.Data, "enteredAt");
+            var exitedAt = ParseUtcInstant(evt.Data, "exitedAt");
+            if (!enteredAt.HasValue || !exitedAt.HasValue || exitedAt.Value <= enteredAt.Value) continue;
+            if (!seenEpisodes.Add(enteredAt.Value)) continue; // duplicate observation of the same episode
+
+            var clamped = ClampToWindows(enteredAt.Value, exitedAt.Value, windows);
+            if (!clamped.HasValue) continue;
+            var seconds = clamped.Value.Seconds;
+            if (seconds <= 0) continue;
+
+            var kind = evt.Data.TryGetValue("kind", out var kindObj) ? kindObj?.ToString() ?? string.Empty : string.Empty;
+
+            result.Add(new SleepSpan
+            {
+                StartUtc = clamped.Value.Start,
+                EndUtc = clamped.Value.End,
+                Seconds = seconds,
+                SegmentKey = SegmentAt(spans, clamped.Value.Start),
+                Kind = kind,
+            });
+        }
+
+        return result.OrderBy(s => s.StartUtc).ToList();
+    }
+
+    private static DateTime? ParseUtcInstant(Dictionary<string, object> data, string key)
+    {
+        if (!data.TryGetValue(key, out var raw)) return null;
+        var text = raw?.ToString();
+        if (string.IsNullOrEmpty(text)) return null;
+        return DateTime.TryParse(text, CultureInfo.InvariantCulture,
+            DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out var parsed)
+            ? parsed
+            : (DateTime?)null;
+    }
+
     private static string SegmentAt(List<TimeAttributionSpan> spans, DateTime ts)
     {
         foreach (var span in spans)

src/Backend/AutopilotMonitor.Functions/Services/Analyze/AnalyzeOnEnrollmentEndHandler.cs

@@ -289,10 +289,16 @@ namespace AutopilotMonitor.Functions.Services.Analyze
                         rule.Title, rule.Category, rule.Severity,
                         fired, confidence).ConfigureAwait(false);
 
-                    await _metricsRepo.IncrementRuleStatAsync(
-                        today, "global", rule.RuleId, "analyze",
-                        rule.Title, rule.Category, rule.Severity,
-                        fired, confidence).ConfigureAwait(false);
+                    // Global aggregate row is catalog-only: custom-rule IDs are tenant-chosen
+                    // and not unique across tenants, so a shared "global_{ruleId}" row would
+                    // sum unrelated tenants' counters (title/severity last-writer-wins).
+                    if (rule.IsBuiltIn || rule.IsCommunity)
+                    {
+                        await _metricsRepo.IncrementRuleStatAsync(
+                            today, "global", rule.RuleId, "analyze",
+                            rule.Title, rule.Category, rule.Severity,
+                            fired, confidence).ConfigureAwait(false);
+                    }
                 }
             }
             catch (Exception ex)

src/Backend/AutopilotMonitor.Functions/Services/CmTraceSkewTripwire.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Collections.Generic;
+using AutopilotMonitor.Functions.Helpers;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Functions.Services
+{
+    /// <summary>
+    /// Regression tripwire for the agent's CMTrace time resolution (per-line self-anchoring,
+    /// docs/agent/cmtrace-time-resolution.md). Runs once per session on the terminal ingest
+    /// batch, over samples the counter reconcile collected in its existing partition scan.
+    ///
+    /// Detection: diff = median(Δ_IME) − median(Δ_other), where Δ = ReceivedAt − OccurredUtc.
+    /// Shared upload/spool latency is common-mode and cancels in the difference; a timezone
+    /// mis-conversion shifts only the IME side and lands on the 15-minute offset grid.
+    /// Replayed old log lines produce large OFF-grid deltas — the grid-residual test is what
+    /// separates the two (field measurement 2026-08-20: without it, 48 instead of 26 true hits).
+    ///
+    /// Goal state: this never fires. Any hit is either a case the per-line anchoring does not
+    /// cover or a detector bug — both are actionable findings, never noise to tune away.
+    /// </summary>
+    internal static class CmTraceSkewTripwire
+    {
+        // Same grid the agent anchors on and the same residual tolerance as its own grid
+        // guard (docs/agent/cmtrace-time-resolution.md) — keep these in lockstep with the
+        // agent so a future anchoring change stays traceable to this detector.
+        internal const int GridMinutes = 15;
+        internal const double ResidualToleranceMinutes = 2.0;
+        internal const int MinSamplesPerSide = 20;
+        // ReceivedAt is stamped per upload batch, not per event; a side backed by fewer
+        // distinct batches yields a batch-composition artifact, not a session property.
+        internal const int MinDistinctBatchesPerSide = 3;
+
+        internal sealed class Result
+        {
+            public double MedianImeDeltaMinutes { get; set; }
+            public double MedianOtherDeltaMinutes { get; set; }
+            public double DiffMinutes { get; set; }
+            public int GridSteps { get; set; }
+            public double ResidualMinutes { get; set; }
+            public int ImeSampleCount { get; set; }
+            public int OtherSampleCount { get; set; }
+            public int ImeBatchCount { get; set; }
+            public int OtherBatchCount { get; set; }
+        }
+
+        /// <summary>
+        /// Pure detector: non-null exactly when the session shows a grid-aligned divergence
+        /// between IME-derived and other event timestamps. All suppression inputs live in the
+        /// scan itself so the decision is fully unit-testable.
+        /// </summary>
+        internal static Result? Evaluate(SessionSkewScan? scan)
+        {
+            if (scan == null)
+                return null;
+            if (scan.ImeDeltaMinutes.Count < MinSamplesPerSide || scan.OtherDeltaMinutes.Count < MinSamplesPerSide)
+                return null;
+            if (scan.ImeDistinctBatchCount < MinDistinctBatchesPerSide || scan.OtherDistinctBatchCount < MinDistinctBatchesPerSide)
+                return null;
+
+            var medianIme = PercentileMath.Median(scan.ImeDeltaMinutes);
+            var medianOther = PercentileMath.Median(scan.OtherDeltaMinutes);
+            var diff = medianIme - medianOther;
+            var steps = (int)Math.Round(diff / GridMinutes, MidpointRounding.AwayFromZero);
+            var residual = Math.Abs(diff - steps * (double)GridMinutes);
+
+            if (Math.Abs(steps) < 1 || residual >= ResidualToleranceMinutes)
+                return null;
+
+            return new Result
+            {
+                MedianImeDeltaMinutes = medianIme,
+                MedianOtherDeltaMinutes = medianOther,
+                DiffMinutes = diff,
+                GridSteps = steps,
+                ResidualMinutes = residual,
+                ImeSampleCount = scan.ImeDeltaMinutes.Count,
+                OtherSampleCount = scan.OtherDeltaMinutes.Count,
+                ImeBatchCount = scan.ImeDistinctBatchCount,
+                OtherBatchCount = scan.OtherDistinctBatchCount,
+            };
+        }
+
+        /// <summary>
+        /// True when the session's IME events are dominated by writer-declared ("bias")
+        /// offsets — a bias offset comes verbatim from the log line's own zone marker and
+        /// cannot be an anchoring regression, so a grid hit there is not ours to alarm on.
+        /// measuredWriterOffsetMinutes is deliberately NOT consulted: the per-file
+        /// observation sticks to a stale value after an era flip-back (monotonicity guard),
+        /// making it non-authoritative for exactly the sessions this tripwire inspects.
+        /// </summary>
+        internal static bool IsBiasDominated(IReadOnlyDictionary<string, int>? originHistogram)
+        {
+            if (originHistogram == null || originHistogram.Count == 0)
+                return false;
+
+            int total = 0, bias = 0;
+            foreach (var kv in originHistogram)
+            {
+                total += kv.Value;
+                if (string.Equals(kv.Key, "bias", StringComparison.OrdinalIgnoreCase))
+                    bias += kv.Value;
+            }
+            return total > 0 && bias * 2 >= total;
+        }
+    }
+}

src/Backend/AutopilotMonitor.Functions/Services/EventIngestProcessor.AppInstall.cs

@@ -112,6 +112,22 @@ namespace AutopilotMonitor.Functions.Services
                 case "app_install_start":
                     if (!state.InstallStartedAt.HasValue || evt.Timestamp < state.InstallStartedAt.Value)
                         state.InstallStartedAt = evt.Timestamp;
+                    // Attempt anchor: the LATEST start wins (max-fold). DurationSeconds
+                    // measures the status-defining attempt, not the session-wide span — the
+                    // IME processes the app list in multiple passes (device-ESP evaluation,
+                    // user-context install, retries), often an hour apart.
+                    if (!summary.LastAttemptStartedAt.HasValue || evt.Timestamp > summary.LastAttemptStartedAt.Value)
+                        summary.LastAttemptStartedAt = evt.Timestamp;
+                    summary.InstallPassCount++;
+                    // Attempt-scoped download pairing: a pending download start is consumed
+                    // by the next install start of the same app.
+                    if (state.PendingDownloadStartedAt.HasValue && evt.Timestamp >= state.PendingDownloadStartedAt.Value)
+                    {
+                        var pairedDl = EventTimestampValidator.SafeDurationSeconds(state.PendingDownloadStartedAt.Value, evt.Timestamp);
+                        if (pairedDl > 0)
+                            summary.DownloadDurationSeconds = pairedDl;
+                        state.PendingDownloadStartedAt = null;
+                    }
                     if (summary.Status == "InProgress" || summary.Status == string.Empty)
                         summary.Status = "InProgress";
                     break;
@@ -119,34 +135,48 @@ namespace AutopilotMonitor.Functions.Services
                 case "app_download_started":
                     if (!state.DownloadStartedAt.HasValue || evt.Timestamp < state.DownloadStartedAt.Value)
                         state.DownloadStartedAt = evt.Timestamp;
+                    // Latest unconsumed download start — pairs with the NEXT install start.
+                    if (!state.PendingDownloadStartedAt.HasValue || evt.Timestamp > state.PendingDownloadStartedAt.Value)
+                        state.PendingDownloadStartedAt = evt.Timestamp;
                     if (summary.Status == "InProgress" || summary.Status == string.Empty)
                         summary.Status = "InProgress";
                     break;
 
                 case "app_install_completed":
                 case "app_install_complete":
+                    // A weaker terminal (Skipped/Postponed re-evaluation pass) never overrides
+                    // an Installed/Error already observed — mirrors the app_install_skipped
+                    // guard below. It must not move CompletedAt/DurationSeconds either: the
+                    // row keeps describing the attempt that produced the surviving terminal.
+                    var incomingTerminalState = evt.Data?.ContainsKey("state") == true
+                        ? evt.Data["state"]?.ToString() : null;
+                    if ((summary.TerminalState == "Installed" || summary.TerminalState == "Error") &&
+                        (incomingTerminalState == "Skipped" || incomingTerminalState == "Postponed"))
+                        break;
                     summary.Status = "Succeeded";
                     summary.CompletedAt = evt.Timestamp;
-                    if (summary.StartedAt != DateTime.MinValue)
-                        summary.DurationSeconds = Math.Max(1, EventTimestampValidator.SafeDurationSeconds(summary.StartedAt, evt.Timestamp));
+                    var attemptStart = summary.LastAttemptStartedAt
+                        ?? (summary.StartedAt != DateTime.MinValue ? summary.StartedAt : (DateTime?)null);
+                    if (attemptStart.HasValue)
+                        summary.DurationSeconds = Math.Max(1, EventTimestampValidator.SafeDurationSeconds(attemptStart.Value, evt.Timestamp));
                     // PR0 (2026-07-26): the agent emits app_install_completed for EVERY terminal
                     // transition — including Skipped/Postponed (V1 wire parity). The payload's
                     // `state` field is the only way to tell a real install apart from a no-op
                     // (e.g. WinGet "Update for X" policies that were not applicable). Persist it
                     // so metrics can exclude skips from durations and rates. Unknown/absent state
                     // leaves the sentinel empty — never guessed.
-                    var terminalStateRaw = evt.Data?.ContainsKey("state") == true
-                        ? evt.Data["state"]?.ToString() : null;
-                    if (terminalStateRaw == "Installed" || terminalStateRaw == "Skipped" || terminalStateRaw == "Postponed")
-                        summary.TerminalState = terminalStateRaw;
+                    if (incomingTerminalState == "Installed" || incomingTerminalState == "Skipped" || incomingTerminalState == "Postponed")
+                        summary.TerminalState = incomingTerminalState;
                     break;
 
                 case "app_install_failed":
                     summary.Status = "Failed";
                     summary.TerminalState = "Error";
                     summary.CompletedAt = evt.Timestamp;
-                    if (summary.StartedAt != DateTime.MinValue)
-                        summary.DurationSeconds = Math.Max(1, EventTimestampValidator.SafeDurationSeconds(summary.StartedAt, evt.Timestamp));
+                    var failedAttemptStart = summary.LastAttemptStartedAt
+                        ?? (summary.StartedAt != DateTime.MinValue ? summary.StartedAt : (DateTime?)null);
+                    if (failedAttemptStart.HasValue)
+                        summary.DurationSeconds = Math.Max(1, EventTimestampValidator.SafeDurationSeconds(failedAttemptStart.Value, evt.Timestamp));
                     // FailureCode preference: canonical `failureType` > raw `errorCode` > empty.
                     // c117946b debrief (2026-05-12): the V2 termination handler tags promoted
                     // "likely stuck" apps with failureType=esp_apps_timeout so the UI can
@@ -310,20 +340,30 @@ namespace AutopilotMonitor.Functions.Services
                 summary.StartedAt = effectiveStart;
             }
 
-            // Download duration: from first download start to first install start.
-            if (state.DownloadStartedAt.HasValue && state.InstallStartedAt.HasValue &&
-                state.InstallStartedAt.Value >= state.DownloadStartedAt.Value)
-            {
-                summary.DownloadDurationSeconds = EventTimestampValidator.SafeDurationSeconds(
-                    state.DownloadStartedAt.Value, state.InstallStartedAt.Value);
-            }
+            // Download duration is paired attempt-scoped at the app_install_started event
+            // (latest download start → next install start) — no span computation here.
 
-            // Full duration: from effective start to completion/failure.
-            if (summary.CompletedAt.HasValue && summary.StartedAt != DateTime.MinValue &&
-                summary.CompletedAt.Value >= summary.StartedAt)
+            // Full duration: the status-defining attempt. CompletedAt pairs with the latest
+            // attempt start at or before it. A LastAttemptStartedAt NEWER than CompletedAt
+            // means a fresh pass is in flight — the recorded duration of the completed
+            // attempt stands. Rows without any observed start (legacy agents, terminal-only
+            // batches) keep the historical StartedAt (span) fallback.
+            if (summary.CompletedAt.HasValue)
             {
-                summary.DurationSeconds = EventTimestampValidator.SafeDurationSeconds(
-                    summary.StartedAt, summary.CompletedAt.Value);
+                if (summary.LastAttemptStartedAt.HasValue)
+                {
+                    if (summary.LastAttemptStartedAt.Value <= summary.CompletedAt.Value)
+                    {
+                        summary.DurationSeconds = EventTimestampValidator.SafeDurationSeconds(
+                            summary.LastAttemptStartedAt.Value, summary.CompletedAt.Value);
+                    }
+                }
+                else if (summary.StartedAt != DateTime.MinValue &&
+                         summary.CompletedAt.Value >= summary.StartedAt)
+                {
+                    summary.DurationSeconds = EventTimestampValidator.SafeDurationSeconds(
+                        summary.StartedAt, summary.CompletedAt.Value);
+                }
             }
         }
     }
@@ -333,5 +373,7 @@ namespace AutopilotMonitor.Functions.Services
         public AppInstallSummary Summary { get; set; } = new();
         public DateTime? DownloadStartedAt { get; set; }
         public DateTime? InstallStartedAt { get; set; }
+        /// <summary>Latest download start not yet consumed by an install start (attempt-scoped download-duration pairing).</summary>
+        public DateTime? PendingDownloadStartedAt { get; set; }
     }
 }