AutopilotMonitor/docs/index.md

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Autopilot Monitor — Technical Knowledge Bundle

Contributor-facing technical documentation for Autopilot Monitor, organized as an Open Knowledge Format (OKF) knowledge bundle. Customer-facing product documentation lives at https://docs.autopilotmonitor.com (separate repository).

Architecture

• Architecture Guide - High-level architecture overview and solution layout for contributors.
• Version Contract - One version shape for agent, backend and MCP: the ETag-CAS counter blob that mints build numbers, and the manifests published only after a deploy is verified live.
• Customer Script Publishing - How the customer-facing PowerShell scripts reach download.autopilotmonitor.com/agent/, why publishing is decoupled from agent releases, and the guards keeping the published copy, the version badge and the portal's version oracle in agreement.
• URL Registry - Every well-known host lives in one registry file per component (Constants.cs / utils/config.ts / src/config.ts), enforced by guard tests; includes the agent-download migration to the download alias and its deploy-order constraint.
• Drift Guards - The 2026-08 fragility-audit follow-up contracts: SignalR message-name catalog (typed on both ends), the inverted-tick RowKey codec, tombstone table tagging, the shrink-only OkAsync baseline, per-section config PATCH with the section field map, and the web's scoped-endpoint builders + sidebar visibility matrix.

Agent

• V2 Agent - How the on-device agent works: runtime overview, decision engine (reducer, signals, completion arms), logs & persistence (signal log, snapshot, crash recovery), diagnostics package (built-in section catalog shared with the portal, RealmJoin/Device Preparation collection gates, handle-validated reads against the junction race, caps, manifest), Hello wizard un-skip (why a single "WHfB disabled" read never decides completion), Autopilot ZTD diagnostics (event IDs, diagnostic registry, endpoints, error-code map).
• Build Counter Blob - How agent build numbers are minted: shared counter blob with ETag-CAS so local and CI builds never collide; CI additionally attests build provenance (Sigstore).
• Agent Endpoint Migration - How the backend re-homes agents to a new API base URL via the config channel (backend move or per-tenant region move): live-fetch-only, allowlist-validated on both sides, one hop, kill wins.
• Gather Rule Debug Log - EnableGatherRuleDebugLog (ConfigVersion 36): the per-tenant local trace file that explains every gather-rule evaluation decision — scope skips, on_change suppression, empty collector results, logparser position/parse-mode outcomes — for rules that produce no timeline events.
• MDM Reboot Coalescing - Attributing the mid-ESP coalesced reboot ("second sign-in") to the device-assigned policy URIs that forced it: aggregated DM-Enterprise 2800 observations (neutral, flush-time watermark) + the ANALYZE-ESP-005 advisory gated on an actually-observed reboot.
• ESP Completion Starvation — the sits-d Cloud-PC complex - 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).
• Zero User-Targeted Apps — the starved user-phase completion gate - Why a device with no user-targeted Intune apps could never satisfy the IME user-session gate — IME skips its "Completed user session" line entirely in the zero-app branch — turning the 30-minute completion backstop into esp_exit_without_completion_evidence on a third of one tenant's enrollments, with the user at the desktop and RealmJoin still installing. The two fixes: read the line IME does write (IME-USER-SESSION-ZERO-APPS), and never fail a session while a completion gate with its own armed deadline is deliberately holding it.
• Secure Boot CA-2023 Detection - 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 - 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 - 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; plus the linear-cost CMTrace line parser (first open / last parseable trailer, timeout-backed) and the agent multiline caps.
• IME Pattern Health — the pattern-drift loop - How a Microsoft change to IME log wording becomes visible before it breaks timelines: tracker health counters in agent_metrics_snapshot, the one-shot ime_tracker_degraded Warning, the session-end ime_pattern_hits histogram folded into the global per-IME-version ImePatternStats table, the data-driven drift alarm (ImePatternDriftSuspected: an expected pattern — ≥80 % on the fleet baseline — matched in none of ≥25 sessions on a newer version), the Global Admin → Metrics → IME Pattern Health matrix and the get_ime_pattern_health MCP tool.
• IME Log Tracker — Anchored Patterns and the Bounded Read Loop - The IME Logs folder is user-writable, so the SYSTEM tracker must stay linear on hostile input: every shipped pattern starts with ^ (a non-match is O(prefix)), no chained unbounded scans, a byte-bounded line reader (32 MB — real Get policies lines reach 5.6 MB) with exact bookmarks, a 2 s per-line matching budget, held-back unterminated tails, and one Warning per pass instead of silent Debug timeouts.
• Registry App-State Second Pillar - 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 - 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.
• IME Process Watcher — Identity Before Attach, Re-Arm After Exit - ime_process_exited comes only from a process that runs in session 0 with its image under the IME install root (QueryFullProcessImageName, cross-bitness) — a process name is not an identity (CWE-807: a standard user can start a renamed binary during AccountSetup); the oldest trusted candidate wins, untrusted matches are logged once per PID and never attached, and a reported exit re-arms discovery so an IME restart and a later crash are both seen.
• Local Admin Analyzer - What local_admin_analysis asserts at enrollment start/end: every local account inventoried, disabled ones included (a /active:no backdoor is dormant at both scans), Administrators membership read from the SAM by well-known SID (NetLocalGroupGetMembers, WMI-independent), unexpected admin members scored +40, built-ins matched by well-known RID (localized Guest/Administrator never flagged), shutdown-time dynamic allowance never covers a local SAM account (CWE-807), junctions and $GUID folders are not profiles, non-local members (Entra role SIDs) listed but never flagged, built-in Administrator enabled-state reported but not scored.
• Power-State Watcher - 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 - 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 - 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 - 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.
• WiFi SSID and the Windows 24H2 Location Gate - Why wifi_signal_info vanished on Windows 11 24H2+: WlanQueryInterface(wlan_intf_opcode_current_connection) is gated behind precise-location consent, the prompt only fires in a user context outside System32, and SYSTEM in session 0 falls back to the device-level ConsentStore value - so netsh (same gate) could never cover for it. The tiered WifiInfoProvider (native, then ungated WinRT GetConnectedSsid, then netsh), SSID-only semantics on tier 2, and the Warning-level rc=5 diagnostic that names the gate.

Rules

• Gather Rule Phase Scoping, One-Shot Triggers & Emit-on-Change - 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 - 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 - 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 - 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 - 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

• Telemetry Ingest Shaping - One canonical App Insights request record (worker copy with tenant context, per-item sampling bypass; host HTTP duplicate dropped by a workspace transformation DCR), expected storage outcomes 404/412/409 and successful SignalR REST calls filtered in the worker, and the count()/sum(itemCount) query rules that follow.
• Table Schema Sentinel - Startup no longer issues one CreateTableIfNotExists per table: a SHA-256 over TableNames.All in AdminConfiguration gates the full pass (derived, never hand-maintained), the SessionsIndex backfill runs only after a full pass behind a conditional-insert claim, and daily maintenance repairs out-of-band deletions.
• Business Timestamps - 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 - 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 - 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.
• Silent-Session Classification - How a session whose agent went silent gets its honest status: the two-stage maintenance sweep (2h Stalled marker with the WhiteGlove Part-2 AwaitingUser gate and the self-deploying Succeeded gate, 5h timeout classification), the EnrollmentTimeoutClassifier rule order (explicit failure → WG Part 2 → self-deploying → completion evidence → emergency break → desktop+Hello → Device Setup/grace), the ingest paths sharing it (max-lifetime, late-telemetry heal, stall probe) and the admin retro-reconcile modes incl. self_deploying_silent.
• Device Journeys & First-Time-Right - 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 - 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 - 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 - 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.
• Verdict Calibration - How every session status write declares its VerdictPath (origin:detail vocabulary incl. classifier rule ids), how overriding a verdict preserves PriorStatus/PriorVerdictPath as the correction stream, the daily per-path calibration aggregate with the 7-day re-enrollment proxy and read-side legacy derivation, the GA endpoint / MCP tool / admin matrix, and the drift radar (share, silence-share, r6 evidence gap) with its operator-only ops events.
• App Version Duration Regression Radar - 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.
• Session Owner Binding - Agent endpoints authenticate per tenant but write per caller-supplied session id; each Sessions row is now bound to the device identity that created it (cert thumbprint + Intune device id from the CN, or bootstrap code + serial), the rule matrix that keeps restart / WhiteGlove Part 2 / bootstrap→cert handoff / cert re-issue working, the shadow telemetry (SessionOwnerBinding request dimension, AgentSessionOwnerBinding warning, SessionOwnerMismatch ops event), and the enforcement contract where a 403 session_owner_mismatch makes the agent rotate its session id instead of counting an auth failure.
• Plan Downgrade Policy & the Retention Grace Period - What happens when a tenant loses Pro: every entitlement gates read-time and reversibly ("gate, don't destroy"), except retention — a 30-day grace keeps the Pro cap before the Community cap starts hard-deleting; the ProDowngradedUtc/trial-expiry anchor model, the TenantPlanDowngraded/RetentionGrace* ops events, and the deliberate non-grace of everything else.
• Tenant Activation & the Once-Only Welcome Mail - 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.
• W365 Cloud PC Device Validation - Why Cloud PCs can never pass the Autopilot serial lookup, and the cert-CN-bound CloudPc fallback validator: Subject CN (= Intune device id) matched against the tenant's Graph virtualEndpoint/cloudPCs inventory — admits exactly the service-provisioned Cloud PCs, nothing else.
• ServerActions & On-Demand Diagnostics - The queue-on-session, deliver-on-ingest action channel, the TenantAdminOrOperator tier with in-function per-type re-gating, the portal's Collect Logs flow (quick-config orders rotate_config before request_diagnostics), and the hosted-prefix sweep in the offboarding cascade.
• Session Annotations - Role-separated human verdicts on sessions (operator / tenantadmin / globaladmin lanes, one row each): the per-lane write matrix with own-tenant binding, the platform-internal GA lane, the fired-rule-id snapshot that makes annotations rule-quality labels, and the portal card + MCP list/annotate surfaces.
• Lifecycle Manifests & Session Scope Resolution - The fragility-audit P5/P6 completeness nets: every table classified into a deletion lifecycle (offboarding buckets incl. the RowKey-anchored SafeWipe Variant D, per-session cascade, kept-by-design), the SessionsIndex field manifest with bidirectional builder/reader pinning, the single ResolveSessionScopeAsync helper backed by the SessionTenantLookup point-read, and the server-side dashboard free-text search (q=) with its page-backfill loop.

MCP Server

• MCP Protocol Eras & Client ID Metadata Documents - One per-request factory serving the 2026-07-28 stateless revision (server/discover, ttlMs/cacheScope, Mcp-Method routing) and 2025-era initialize clients side by side, why the legacy leg stays a hand-wired JSON+gzip transport, the never-public cache-hint contract, and the CIMD client-registration path (SSRF-gated document fetch, same redirect allowlist) next to the deprecated dynamic registration.
• MCP Docs Corpus - How the published customer documentation becomes the search_docs corpus: CRLF-safe heading chunking, build-time embedding as a third precomputed section, and why a docs edit needs an MCP redeploy.
• MCP Tool Telemetry - The three telemetry layers for judging tool quality: backend App Insights via X-MCP-Tool-Name, the per-user usage table, and the MCP_TOOL_LOGGING stderr lines (soft errors, result size vs. cap, zero-hit searches, Zod rejections).

Web Portal

• Portal Navigation Prefetch & the SWA Runtime Bottleneck - Why every navigation Link sets prefetch={false}: the App Router's viewport prefetch fans out one RSC request per visible link and the Static Web Apps SSR runtime queues them server-side into a multi-minute tail. Records the follow-up measurement (the Standard plan changed nothing; the prefetch storm was an accidental keep-alive), where browser telemetry actually lives, and why this curl build cannot be trusted for HTTP versions.

Security & Identity

• MCP OAuth Flow - Who authenticates where when connecting an AI client to the MCP server; two identities, three parties plus Entra ID.
• Vulnerability Correlation Sources - How the software inventory becomes CVE findings from four cached primaries (NVD per-CPE cache with budget and TTLs, CISA KEV, MSRC, FIRST EPSS stored on the cached CVE and re-scored nightly), the NVD throttle contract (a refused answer is never cached as "0 CVEs"; bounded process-wide cooldown honouring Retry-After), the persisted CVSS vector, and the act/attend/track priority that keeps severity and likelihood as two visible signals instead of one composite score.
• Client-Certificate Tenant Binding - Why a chain-valid Intune MDM certificate only proves "issued to some tenant", which extension actually carries the Entra tenant id (…5.14) versus the two that look like it (…5.6 Intune Account id, …5.4 device id, different encodings), why the Entra join certificate is not part of the auth path, the shadow-then-enforce rollout with its volume-controlled telemetry, and why X-ARR-ClientCert is the only certificate transport (TLS handshake = proof of possession; bootstrap routes token-only, fail-closed).
• Admin Identity Binding - Why a GlobalAdmins / DelegatedAdmins row keyed on a UPN string must never confer access by itself in an API that accepts tokens from every Entra tenant (domain re-registration, UPN recycling), the AdminIdentityBindings table pinning each cross-tenant-role UPN to its immutable home tid + oid, the fail-closed resolution order in both role services (row → binding → entitlement), the first-sign-in object-id pin with its race semantics, the 409 on grant-time conflicts, and the explicit GET/PUT/DELETE rebind surface.
• IME Installer Archive - How every fleet-observed IME build is archived as its MSI: the ime_agent_version sighting that queues the job (first sighting, or a later sighting with a version-authoritative CSP URL after a 24 h backoff), the primary/secondary/hotfix candidate walk, the managed MSI ProductVersion check that keeps another ring's build out of the version folder (Failed:VersionMismatch), provenance with the full candidate walk, the skill-side overwrite path for corrections, and the trust boundary of a device-reported version (plausibility guard, one sighting per session, second-tenant corroboration, fleet-confirmed tenant view).

Conventions for this bundle

• Every concept document is a markdown file with YAML frontmatter; type is mandatory, title, description, resource, tags, and timestamp are recommended.
• Use standard relative markdown links between documents (e.g. agent/overview.md, ../architecture.md). Do NOT use the spec's /-prefixed bundle-absolute form — GitHub resolves those against the repo root (missing /docs) and navigation breaks.
• Record notable additions and changes in log.md.
• index.md and log.md are reserved names — never use them for concept documents.