diff --git a/docs/backend/app-version-regression-radar.md b/docs/backend/app-version-regression-radar.md
new file mode 100644
index 00000000..c240b592
--- /dev/null
+++ b/docs/backend/app-version-regression-radar.md
@@ -0,0 +1,98 @@
+---
+type: Concept
+title: App Version Duration Regression Radar
+description: How the radar detects app versions whose median install duration regressed vs. the previous version (median lift ≥2x plus an absolute floor over first-seen-ordered versions), how alert episodes live in the appversionregression tracker keyspace, and which surfaces show them.
+resource: src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs
+tags:
+  - backend
+  - apps
+  - regression-radar
+  - insights
+timestamp: 2026-08-13T12:00:00+02:00
+---
+
+# App Version Duration Regression Radar
+
+Detects "version X made this app's installs much slower" — the concrete, quotable insight
+("median install duration rose from 11 to 29 min after version X") — from the per-(session,
+app) `AppInstallSummaries` rows. Duration only: failure-rate per version is already visible
+in the apps dashboard's `versionBreakdown`, and rate regressions belong to Wilson-interval
+statistics, not medians.
+
+# Schema
+
+## Signal & detection
+
+Per (tenant, app), the MEASURED install population is: `Status == "Succeeded"`, terminal
+state not Skipped/Postponed, `MetricsMath.HasMeasuredDuration` (1s..6h — 0s means the start
+was unobserved, above 6h means back-stamped batches), no `AppIdCollision`, non-empty
+`AppVersion`. Versions are ordered by FIRST-SEEN install time (min `StartedAt`), never by
+string comparison ("9.1" vs "2024.10" would lie). The comparison pair is always the newest
+version (the one with the most recent measured install) vs. the version with the latest
+first-seen strictly before it.
+
+MEDIANS, not means (nearest-rank, shared with the apps dashboard via
+`AppsAnalyticsHelper.Percentile`) — one back-stamped straggler must not fire a fleet alert.
+A regression fires only when ALL hold over the trailing 35-day horizon:
+
+1. both versions have ≥ 10 measured installs;
+2. current median ≥ 2× the previous version's median;
+3. absolute increase ≥ 300 s (a 20s→45s app is noise, not an incident).
+
+## Suppression & limits
+
+* Parallel ring rollouts can make "previous" a concurrently-deployed version — accepted in
+  v1; the episode key (app, current version) still caps it at one bell per version.
+* Platform kill switch: app setting `AppVersionRegressionRadarDisabled=true` skips the
+  radar (fail-open — it only notifies, never mutates data).
+* One cross-tenant install-summary read per pass (the same query the global apps dashboard
+  runs), grouped by tenant; per-tenant failures are non-fatal.
+
+## Alert episodes (tracker keyspace)
+
+An episode lives as `appversionregression|{app-lower}|{version-lower}` (table-key-sanitized;
+raw AppName/CurrentVersion live in columns, the mapper never parses the RowKey) in the
+notification-tracker table, next to the `ruleregression|` keyspace: the row IS the dedup
+(bell + ops event fire exactly once per episode) and the `versionRegressions[]` payload —
+both medians, both sample counts, lift. Numbers refresh on every radar pass while the
+episode stays active; `FirstNotifiedAt` never moves. The episode closes (dedup re-arms) when
+the alerted version drains under 10 measured installs in the horizon or its recomputed
+median falls back under 1.5× the previous version's median; the tracker's 30-day retention
+sweep also re-arms, so a month-old still-burning regression rings once more by design.
+
+## Notification chain (v1: bell + ops event)
+
+* Tenant bell `app_version_duration_regression` (audience: Admin), href
+  `/apps/detail?name={app}&days=35` (canonical `appDetailUrl` shape). Message carries the
+  full numbers so the admin can verify without a portal round-trip.
+* Ops event `AppVersionDurationRegression` (Tenant category, Warning) — dual-registered in
+  the web `OPS_EVENT_TYPES` catalog so operators can wire Telegram/Teams/Slack alert rules.
+
+## Surfaces
+
+* `apps/{appName}/analytics` (+ global twin with `?tenantId=`) responds with
+  `versionRegressions[]` (empty for the cross-tenant aggregate — episodes are per-tenant
+  rows), and `versionBreakdown[]` rows now carry `measuredInstalls` /
+  `medianDurationSeconds` / `p95DurationSeconds`.
+* Apps detail page: amber "↑ Duration regression" banner above the version cards and a
+  "Median Install Duration by Version" bar chart.
+
+# Examples
+
+A tenant ships Contoso VPN 2.4.0 after 2.3.9. 2.3.9 has 40 measured installs, median 660s;
+2.4.0 accumulates 12 measured installs with median 1740s. Lift 2.6×, absolute +1080s →
+episode `appversionregression|contoso vpn|2.4.0` opens, one bell + one ops event fire.
+Subsequent passes refresh the numbers only. When 2.4.1 replaces 2.4.0 and 2.4.0 drains
+below 10 measured installs in the horizon, the episode deletes and the dedup re-arms.
+
+# Citations
+
+* `src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs` — pure core
+  (gates, first-seen ordering, re-arm).
+* `src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.AppVersionRegression.cs`
+  — orchestration, kill switch, bell/ops-event emission, wording contract.
+* `src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs`
+  — episode keyspace, entity round-trip.
+* `src/Shared/AutopilotMonitor.Shared/Models/Metrics/AppVersionRegressionAlert.cs` — persisted
+  alert payload.
+* [Rule Regression Radar](rule-regression-radar.md) — the sibling pattern this radar mirrors.
diff --git a/docs/index.md b/docs/index.md
index 5f6e63a2..927676ea 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -39,6 +39,7 @@ https://docs.autopilotmonitor.com (separate repository).
 * [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.
 * [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.
 * [W365 Cloud PC Device Validation](backend/cloudpc-device-validation.md) - 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](backend/server-actions-on-demand-diagnostics.md) - 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.
diff --git a/docs/log.md b/docs/log.md
index bf225e70..b1a9a34f 100644
--- a/docs/log.md
+++ b/docs/log.md
@@ -1,5 +1,9 @@
 # Log
 
+## 2026-08-13 (later)
+
+* **Creation**: Added `backend/app-version-regression-radar.md` — app-version duration regression radar: per (tenant, app) the newest version's median measured install duration (nearest-rank; population Succeeded + non-skip + `HasMeasuredDuration` + no AppId collision + non-empty AppVersion) is compared against the previous version (first-seen ordering, never string sort); fires at median lift ≥2× AND ≥300s absolute with ≥10 measured installs on both sides. Episodes live as `appversionregression|{app}|{version}` tracker rows (one bell `app_version_duration_regression` + one `AppVersionDurationRegression` ops event per episode, refresh keeps `FirstNotifiedAt`, re-arm on drain/median-recovery/30d retention). Surfaces: `versionRegressions[]` + per-version `measuredInstalls`/`medianDurationSeconds`/`p95DurationSeconds` in the apps analytics responses, amber banner + duration-by-version chart on the apps detail page. Kill switch `AppVersionRegressionRadarDisabled`.
+
 ## 2026-08-13
 
 * **Update**: `backend/session-annotations.md` — the `/annotations` portal overview page now carries the standard tenant switcher (GA/Reader: "All tenants" aggregate + per-tenant drill-down via `GET global/session-annotations`; delegated: managed subset), with a tenant column and tenant-qualified session deep links. The global list endpoint now derives `excludeGlobalAdminLane` from `HasGlobalScope`, so delegated-rescue callers on their managed `?tenantId=` path never receive the platform-internal `globaladmin` lane (endpoint-test-pinned).
diff --git a/src/Backend/AutopilotMonitor.Functions.Tests/AppVersionRegressionRadarTests.cs b/src/Backend/AutopilotMonitor.Functions.Tests/AppVersionRegressionRadarTests.cs
new file mode 100644
index 00000000..cdeaa17d
--- /dev/null
+++ b/src/Backend/AutopilotMonitor.Functions.Tests/AppVersionRegressionRadarTests.cs
@@ -0,0 +1,380 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.Json;
+using System.Threading.Tasks;
+using AutopilotMonitor.Functions.DataAccess.TableStorage;
+using AutopilotMonitor.Functions.Functions.Apps;
+using AutopilotMonitor.Functions.Helpers;
+using AutopilotMonitor.Functions.Services;
+using AutopilotMonitor.Shared.DataAccess;
+using AutopilotMonitor.Shared.Models;
+using Moq;
+using Xunit;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Pins the app-version duration regression radar (<see cref="AppVersionRegressionRadar"/>):
+/// detection gates (≥10 measured installs on both sides, median lift ≥2×, ≥300s absolute),
+/// first-seen version ordering (never string sort), the measured-population exclusions,
+/// re-arm semantics, the tracker keyspace round-trip, the wording contract, and the
+/// versionBreakdown duration fields on the analytics wire shape.
+/// </summary>
+public class AppVersionRegressionRadarTests
+{
+    private const string TenantA = "00000000-0000-0000-0000-0000000000a1";
+    private const string App = "Contoso VPN";
+    private static readonly DateTime Now = new(2026, 8, 13, 12, 0, 0, DateTimeKind.Utc);
+
+    private static int _sessionCounter;
+
+    private static AppInstallSummary Install(
+        string version,
+        int durationSeconds,
+        DateTime? startedAt = null,
+        string appName = App,
+        string status = "Succeeded",
+        string terminalState = "Installed",
+        bool collision = false)
+        => new()
+        {
+            TenantId = TenantA,
+            SessionId = $"s-{++_sessionCounter}",
+            AppName = appName,
+            AppVersion = version,
+            Status = status,
+            TerminalState = terminalState,
+            DurationSeconds = durationSeconds,
+            StartedAt = startedAt ?? Now.AddDays(-1),
+            AppIdCollision = collision,
+        };
+
+    /// <summary>n measured installs of one version, all with the same duration, spread over one day.</summary>
+    private static List<AppInstallSummary> Batch(string version, int count, int durationSeconds, DateTime firstSeen)
+        => Enumerable.Range(0, count)
+            .Select(i => Install(version, durationSeconds, firstSeen.AddMinutes(i)))
+            .ToList();
+
+    // ── detection gates ─────────────────────────────────────────────────────
+
+    [Theory]
+    // currentCount, previousCount, previousMedian, currentMedian, expectFire
+    [InlineData(10, 10, 300, 900, true)]    // lift 3×, +600s — fires
+    [InlineData(10, 10, 300, 600, true)]    // exactly 2× AND exactly +300s — boundary fires
+    [InlineData(9, 10, 300, 900, false)]    // current side below sample floor
+    [InlineData(10, 9, 300, 900, false)]    // previous side below sample floor
+    [InlineData(10, 10, 200, 499, false)]   // lift 2.5× but only +299s — absolute floor blocks
+    [InlineData(10, 10, 1000, 1900, false)] // +900s but lift 1.9× — lift gate blocks
+    public void Evaluate_Gates(int currentCount, int previousCount, int previousMedian, int currentMedian, bool expectFire)
+    {
+        var rows = Batch("1.0", previousCount, previousMedian, Now.AddDays(-20));
+        rows.AddRange(Batch("2.0", currentCount, currentMedian, Now.AddDays(-5)));
+
+        var findings = AppVersionRegressionRadar.Evaluate(rows);
+
+        if (!expectFire)
+        {
+            Assert.Empty(findings);
+            return;
+        }
+
+        var finding = Assert.Single(findings);
+        Assert.Equal(App, finding.AppName);
+        Assert.Equal("2.0", finding.CurrentVersion);
+        Assert.Equal("1.0", finding.PreviousVersion);
+        Assert.Equal(currentMedian, finding.CurrentMedianSeconds);
+        Assert.Equal(previousMedian, finding.PreviousMedianSeconds);
+        Assert.Equal(currentCount, finding.CurrentMeasuredCount);
+        Assert.Equal(previousCount, finding.PreviousMeasuredCount);
+        Assert.Equal(Math.Round((double)currentMedian / previousMedian, 1), finding.Lift);
+    }
+
+    [Fact]
+    public void Evaluate_MedianIsNearestRank_HandComputed()
+    {
+        // Even n: nearest-rank p50 takes the LOWER middle value (rank = ceil(0.5*4)-1 = 1).
+        var rows = new List<AppInstallSummary>();
+        foreach (var d in new[] { 100, 200, 300, 400 }) // median 200
+            rows.AddRange(Batch("1.0", 3, d, Now.AddDays(-20)));
+        foreach (var d in new[] { 500, 600, 700, 800 }) // median 600
+            rows.AddRange(Batch("2.0", 3, d, Now.AddDays(-5)));
+
+        var finding = Assert.Single(AppVersionRegressionRadar.Evaluate(rows));
+        Assert.Equal(600, finding.CurrentMedianSeconds);
+        Assert.Equal(200, finding.PreviousMedianSeconds);
+        Assert.Equal(3.0, finding.Lift);
+    }
+
+    // ── version ordering ────────────────────────────────────────────────────
+
+    [Fact]
+    public void Evaluate_VersionOrder_ByFirstSeen_NeverStringSort()
+    {
+        // Ordinally "9.1" > "2024.10", but "2024.10" is the NEWER version by first-seen.
+        // A string sort would flip current/previous and compare in the wrong direction.
+        var rows = Batch("9.1", 10, 300, Now.AddDays(-20));
+        rows.AddRange(Batch("2024.10", 10, 900, Now.AddDays(-5)));
+
+        var finding = Assert.Single(AppVersionRegressionRadar.Evaluate(rows));
+        Assert.Equal("2024.10", finding.CurrentVersion);
+        Assert.Equal("9.1", finding.PreviousVersion);
+    }
+
+    [Fact]
+    public void Evaluate_MultipleVersionsInFlight_PreviousIsLatestFirstSeenBeforeCurrent()
+    {
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-30));  // oldest
+        rows.AddRange(Batch("1.1", 10, 320, Now.AddDays(-18))); // the true predecessor
+        rows.AddRange(Batch("2.0", 10, 960, Now.AddDays(-4)));  // newest, regressed
+
+        var finding = Assert.Single(AppVersionRegressionRadar.Evaluate(rows));
+        Assert.Equal("2.0", finding.CurrentVersion);
+        Assert.Equal("1.1", finding.PreviousVersion); // not 1.0
+        Assert.Equal(320, finding.PreviousMedianSeconds);
+    }
+
+    [Fact]
+    public void Evaluate_SingleVersion_NeverFires()
+    {
+        var rows = Batch("1.0", 25, 900, Now.AddDays(-5));
+        Assert.Empty(AppVersionRegressionRadar.Evaluate(rows));
+    }
+
+    // ── measured-population exclusions ──────────────────────────────────────
+
+    [Fact]
+    public void Evaluate_ExcludedRows_DoNotCountTowardSamplesOrMedians()
+    {
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-20));
+        rows.AddRange(Batch("2.0", 10, 900, Now.AddDays(-5)));
+
+        // None of these may move the samples or medians:
+        rows.Add(Install("2.0", 0, Now.AddDays(-2)));                                  // unmeasured (start unobserved)
+        rows.Add(Install("2.0", 21601, Now.AddDays(-2)));                              // over the 6h plausibility cap
+        rows.Add(Install("2.0", 50, Now.AddDays(-2), terminalState: "Skipped"));       // skip — not an attempt
+        rows.Add(Install("2.0", 50, Now.AddDays(-2), terminalState: "Postponed"));     // skip — not an attempt
+        rows.Add(Install("2.0", 50, Now.AddDays(-2), status: "Failed"));               // failed — no duration signal
+        rows.Add(Install("2.0", 50, Now.AddDays(-2), collision: true));                // AppId collision — foreign outcomes
+        rows.Add(Install("", 50, Now.AddDays(-2)));                                    // no version
+        rows.Add(Install("2.0", 50, Now.AddDays(-2), appName: ""));                    // no app name
+
+        var finding = Assert.Single(AppVersionRegressionRadar.Evaluate(rows));
+        Assert.Equal(10, finding.CurrentMeasuredCount);
+        Assert.Equal(900, finding.CurrentMedianSeconds);
+    }
+
+    [Fact]
+    public void Evaluate_DeterministicOrdering_LiftDesc_ThenAppNameOrdinal()
+    {
+        var rows = new List<AppInstallSummary>();
+        rows.AddRange(Batch("1.0", 10, 300, Now.AddDays(-20)).Select(s => { s.AppName = "App B"; return s; }));
+        rows.AddRange(Batch("2.0", 10, 900, Now.AddDays(-5)).Select(s => { s.AppName = "App B"; return s; }));  // lift 3.0
+        rows.AddRange(Batch("1.0", 10, 300, Now.AddDays(-20)).Select(s => { s.AppName = "App A"; return s; }));
+        rows.AddRange(Batch("2.0", 10, 1500, Now.AddDays(-5)).Select(s => { s.AppName = "App A"; return s; })); // lift 5.0
+
+        var findings = AppVersionRegressionRadar.Evaluate(rows);
+        Assert.Equal(2, findings.Count);
+        Assert.Equal("App A", findings[0].AppName); // higher lift first
+        Assert.Equal("App B", findings[1].AppName);
+    }
+
+    // ── re-arm ──────────────────────────────────────────────────────────────
+
+    private static AppVersionRegressionAlert Alert(
+        string currentVersion = "2.0", string previousVersion = "1.0")
+        => new()
+        {
+            TenantId = TenantA,
+            AppName = App,
+            CurrentVersion = currentVersion,
+            PreviousVersion = previousVersion,
+            CurrentMedianSeconds = 900,
+            PreviousMedianSeconds = 300,
+            CurrentMeasuredCount = 10,
+            PreviousMeasuredCount = 10,
+            Lift = 3.0,
+            FirstNotifiedAt = Now.AddDays(-3),
+            LastEvaluatedAt = Now.AddDays(-1),
+        };
+
+    [Fact]
+    public void ShouldReArm_WhenCurrentVersionDrainedOutOfHorizon()
+    {
+        // Only the previous version still has measured installs — the alerted version is gone.
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-20));
+        Assert.True(AppVersionRegressionRadar.ShouldReArm(rows, Alert()));
+    }
+
+    [Fact]
+    public void ShouldReArm_WhenCurrentVersionBelowSampleFloor()
+    {
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-20));
+        rows.AddRange(Batch("2.0", 9, 900, Now.AddDays(-5)));
+        Assert.True(AppVersionRegressionRadar.ShouldReArm(rows, Alert()));
+    }
+
+    [Fact]
+    public void ShouldReArm_WhenMedianFellBackUnderReArmFactor()
+    {
+        // 400 < 1.5 × 300 — the regression recovered (e.g. CDN warmed up).
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-20));
+        rows.AddRange(Batch("2.0", 10, 400, Now.AddDays(-5)));
+        Assert.True(AppVersionRegressionRadar.ShouldReArm(rows, Alert()));
+    }
+
+    [Fact]
+    public void ShouldNotReArm_WhileMedianStaysElevated()
+    {
+        // 500 ≥ 1.5 × 300 — still elevated (even though below the 2× fire gate).
+        var rows = Batch("1.0", 10, 300, Now.AddDays(-20));
+        rows.AddRange(Batch("2.0", 10, 500, Now.AddDays(-5)));
+        Assert.False(AppVersionRegressionRadar.ShouldReArm(rows, Alert()));
+    }
+
+    [Fact]
+    public void ShouldNotReArm_WhenPreviousVersionDrained_NoComparisonBasis()
+    {
+        // The predecessor left the horizon; the episode is kept until the current
+        // version itself drains (fires-stopped-style re-arm only).
+        var rows = Batch("2.0", 10, 900, Now.AddDays(-5));
+        Assert.False(AppVersionRegressionRadar.ShouldReArm(rows, Alert()));
+    }
+
+    // ── tracker keyspace (round-trip + key shape) ───────────────────────────
+
+    [Fact]
+    public void AppVersionRegressionRowKey_PrefixedCaseFoldedAndSanitized()
+    {
+        Assert.Equal("appversionregression|contoso app_2|1.0_beta_",
+            TableHardwareRejectionNotificationTracker.BuildAppVersionRegressionRowKey(
+                "  Contoso App/2 ", " 1.0#Beta? "));
+    }
+
+    [Fact]
+    public void AppVersionRegressionRowKey_NoPrefixCollisionWithOtherKeyspaces()
+    {
+        var key = TableHardwareRejectionNotificationTracker.BuildAppVersionRegressionRowKey(App, "1.0");
+        Assert.StartsWith("appversionregression|", key, StringComparison.Ordinal);
+        // The prefix range [prefix, "appversionregression}") must not swallow the sibling
+        // keyspaces ("ruleregression|", "tpmpss|", "{mfr}|{model}").
+        Assert.True(string.CompareOrdinal("ruleregression|", "appversionregression}") > 0);
+        Assert.True(string.CompareOrdinal("tpmpss|", "appversionregression}") > 0);
+    }
+
+    [Fact]
+    public void AppVersionRegressionEntity_RoundTripsAllFields()
+    {
+        var alert = new AppVersionRegressionAlert
+        {
+            TenantId = TenantA,
+            AppName = App,
+            CurrentVersion = "2.4.0",
+            PreviousVersion = "2.3.9",
+            CurrentMedianSeconds = 1740,
+            PreviousMedianSeconds = 660,
+            CurrentMeasuredCount = 12,
+            PreviousMeasuredCount = 40,
+            Lift = 2.6,
+            FirstNotifiedAt = Now,
+            LastEvaluatedAt = Now.AddHours(2),
+        };
+
+        var entity = TableHardwareRejectionNotificationTracker.BuildAppVersionRegressionEntity(TenantA, alert);
+        Assert.Equal(TenantA.ToLowerInvariant(), entity.PartitionKey);
+        Assert.Equal("appversionregression|contoso vpn|2.4.0", entity.RowKey);
+
+        var mapped = TableHardwareRejectionNotificationTracker.MapToAppVersionRegressionAlert(entity);
+        Assert.Equal(TenantA, mapped.TenantId);
+        Assert.Equal(App, mapped.AppName);
+        Assert.Equal("2.4.0", mapped.CurrentVersion);
+        Assert.Equal("2.3.9", mapped.PreviousVersion);
+        Assert.Equal(1740, mapped.CurrentMedianSeconds);
+        Assert.Equal(660, mapped.PreviousMedianSeconds);
+        Assert.Equal(12, mapped.CurrentMeasuredCount);
+        Assert.Equal(40, mapped.PreviousMeasuredCount);
+        Assert.Equal(2.6, mapped.Lift);
+        Assert.Equal(Now, mapped.FirstNotifiedAt);
+        Assert.Equal(Now.AddHours(2), mapped.LastEvaluatedAt);
+    }
+
+    // ── wording contract ────────────────────────────────────────────────────
+
+    [Fact]
+    public void RegressionMessage_CarriesTheFullNumbers_MinutesOneDecimal()
+    {
+        var finding = new AppVersionDurationRegressionFinding
+        {
+            TenantId = TenantA,
+            AppName = App,
+            CurrentVersion = "2.4.0",
+            PreviousVersion = "2.3.9",
+            CurrentMedianSeconds = 1740,
+            PreviousMedianSeconds = 660,
+            CurrentMeasuredCount = 12,
+            PreviousMeasuredCount = 40,
+            Lift = 2.6,
+        };
+
+        Assert.Equal(
+            "Median install duration rose from 11 to 29 min after version 2.4.0 " +
+            "(12 measured installs vs 40 on version 2.3.9) — lift 2.6x over the last 35 days.",
+            MaintenanceService.BuildAppVersionRegressionMessage(finding));
+    }
+
+    // ── analytics wire shape (versionBreakdown duration fields) ─────────────
+
+    [Fact]
+    public async Task Analytics_VersionBreakdown_CarriesMeasuredDurationStats()
+    {
+        var sessionRepo = new Mock<ISessionRepository>();
+        sessionRepo.Setup(r => r.GetSessionAsync(It.IsAny<string>(), It.IsAny<string>()))
+            .ReturnsAsync((SessionSummary?)null);
+
+        var rows = new List<AppInstallSummary>
+        {
+            Install("1.0", 100), Install("1.0", 200), Install("1.0", 300), Install("1.0", 400),
+            Install("1.0", 0),                                  // unmeasured — excluded from stats
+            Install("1.0", 50, terminalState: "Skipped"),       // skip — excluded
+            Install("1.0", 50, status: "Failed"),               // failed — excluded from durations
+        };
+
+        var root = JsonSerializer.SerializeToElement(await AppsAnalyticsHelper.BuildAnalyticsResponseAsync(
+            rows, sessionRepo.Object, App, days: 30));
+
+        var version = root.GetProperty("versionBreakdown")[0];
+        Assert.Equal("1.0", version.GetProperty("appVersion").GetString());
+        Assert.Equal(7, version.GetProperty("installs").GetInt32());
+        Assert.Equal(4, version.GetProperty("measuredInstalls").GetInt32());
+        // Nearest-rank over [100, 200, 300, 400]: p50 = 200 (lower middle), p95 = 400.
+        Assert.Equal(200, version.GetProperty("medianDurationSeconds").GetInt32());
+        Assert.Equal(400, version.GetProperty("p95DurationSeconds").GetInt32());
+    }
+
+    [Fact]
+    public async Task Analytics_VersionRegressions_SerializedCamelCase_AndPresentWhenEmptyData()
+    {
+        var sessionRepo = new Mock<ISessionRepository>();
+        sessionRepo.Setup(r => r.GetSessionAsync(It.IsAny<string>(), It.IsAny<string>()))
+            .ReturnsAsync((SessionSummary?)null);
+
+        var alert = Alert();
+        // The Functions host serializes camelCase on the wire; mirror that here so the
+        // asserted property names match what the web client actually parses.
+        var wireOptions = new JsonSerializerOptions(JsonSerializerDefaults.Web);
+
+        // Empty-data early return still surfaces the block (episodes can outlive window data).
+        var emptyRoot = JsonSerializer.SerializeToElement(await AppsAnalyticsHelper.BuildAnalyticsResponseAsync(
+            new List<AppInstallSummary>(), sessionRepo.Object, App, days: 30,
+            new List<AppVersionRegressionAlert> { alert }), wireOptions);
+        Assert.Equal(1, emptyRoot.GetProperty("versionRegressions").GetArrayLength());
+
+        var root = JsonSerializer.SerializeToElement(await AppsAnalyticsHelper.BuildAnalyticsResponseAsync(
+            new List<AppInstallSummary> { Install("1.0", 100) }, sessionRepo.Object, App, days: 30,
+            new List<AppVersionRegressionAlert> { alert }), wireOptions);
+
+        var regression = root.GetProperty("versionRegressions")[0];
+        Assert.Equal("2.0", regression.GetProperty("currentVersion").GetString());
+        Assert.Equal(900, regression.GetProperty("currentMedianSeconds").GetInt32());
+    }
+}
diff --git a/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs b/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs
index 25bdbeb6..f43ed0f9 100644
--- a/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs
+++ b/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs
@@ -17,6 +17,8 @@ public class TenantNotificationAudienceCatalogTests
     [InlineData("sla_breach", NotificationAudience.Member)]
     [InlineData("sla_consecutive_failures", NotificationAudience.Member)]
     [InlineData("sla_resolved", NotificationAudience.Member)]
+    [InlineData("rule_frequency_regression", NotificationAudience.Admin)]
+    [InlineData("app_version_duration_regression", NotificationAudience.Admin)]
     public void Resolve_KnownTypes_ReturnsExpectedAudience(string type, NotificationAudience expected)
     {
         Assert.Equal(expected, TenantNotificationAudienceCatalog.Resolve(type));
diff --git a/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs b/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs
index e6a73915..c413939b 100644
--- a/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs
+++ b/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs
@@ -17,6 +17,9 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
     ///     cannot collide with a hardware key because no real manufacturer is named "tpmpss")
     ///   - F3 rule regression: "ruleregression|{ruleId-lower}" (trimmed; payload-carrying rows
     ///     that are refreshed while the episode is active and deleted on re-arm)
+    ///   - app-version duration regression: "appversionregression|{app-lower}|{version-lower}"
+    ///     (trimmed + table-key-sanitized; same payload-carrying episode semantics — raw
+    ///     AppName/CurrentVersion live in columns, the mapper never parses the RowKey)
     /// Race-safe via AddEntityAsync: Azure Table Storage returns 409 Conflict if the entity already exists.
     /// </summary>
     public class TableHardwareRejectionNotificationTracker : IHardwareRejectionNotificationTracker
@@ -251,6 +254,107 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
             return $"tpmpss|{sn}";
         }
 
+        public async Task<bool> TryRegisterAppVersionRegressionAsync(string tenantId, AppVersionRegressionAlert alert)
+        {
+            if (string.IsNullOrWhiteSpace(tenantId)
+                || string.IsNullOrWhiteSpace(alert?.AppName)
+                || string.IsNullOrWhiteSpace(alert?.CurrentVersion))
+            {
+                return false;
+            }
+
+            try
+            {
+                await _table.AddEntityAsync(BuildAppVersionRegressionEntity(tenantId, alert!));
+                _logger.LogInformation(
+                    "AppVersionRegression tracker registered: tenant={TenantId} app={AppName} version={Version}",
+                    tenantId, alert!.AppName, alert!.CurrentVersion);
+                return true;
+            }
+            catch (RequestFailedException ex) when (ex.Status == 409)
+            {
+                // Episode already active — one bell per (app, version) episode.
+                return false;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex,
+                    "AppVersionRegression tracker failed: tenant={TenantId} app={AppName} version={Version}",
+                    tenantId, alert!.AppName, alert!.CurrentVersion);
+                // Fail closed so we do not double-fire if the row was actually written.
+                return false;
+            }
+        }
+
+        public async Task RefreshAppVersionRegressionAsync(string tenantId, AppVersionRegressionAlert alert)
+        {
+            if (string.IsNullOrWhiteSpace(tenantId)
+                || string.IsNullOrWhiteSpace(alert?.AppName)
+                || string.IsNullOrWhiteSpace(alert?.CurrentVersion))
+            {
+                return;
+            }
+            try
+            {
+                // Replace-mode upsert with the FULL payload incl. the caller-carried
+                // FirstNotifiedAt — the retention sweep re-arms on the ORIGINAL age, so a
+                // refresh must never rejuvenate the row.
+                await _table.UpsertEntityAsync(BuildAppVersionRegressionEntity(tenantId, alert!), TableUpdateMode.Replace);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex,
+                    "AppVersionRegression tracker refresh failed: tenant={TenantId} app={AppName} version={Version} (stale numbers remain)",
+                    tenantId, alert!.AppName, alert!.CurrentVersion);
+            }
+        }
+
+        public async Task DeleteAppVersionRegressionAsync(string tenantId, string appName, string currentVersion)
+        {
+            if (string.IsNullOrWhiteSpace(tenantId)
+                || string.IsNullOrWhiteSpace(appName)
+                || string.IsNullOrWhiteSpace(currentVersion))
+            {
+                return;
+            }
+            try
+            {
+                await _table.DeleteEntityAsync(
+                    tenantId.ToLowerInvariant(), BuildAppVersionRegressionRowKey(appName, currentVersion));
+            }
+            catch (RequestFailedException ex) when (ex.Status == 404)
+            {
+                // Already gone (retention sweep or concurrent pass) — idempotent.
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex,
+                    "AppVersionRegression tracker delete failed: tenant={TenantId} app={AppName} version={Version} (episode stays until retention)",
+                    tenantId, appName, currentVersion);
+            }
+        }
+
+        public async Task<List<AppVersionRegressionAlert>> GetAppVersionRegressionsAsync(string tenantId)
+        {
+            var results = new List<AppVersionRegressionAlert>();
+            if (string.IsNullOrWhiteSpace(tenantId)) return results;
+            try
+            {
+                var partitionKey = tenantId.ToLowerInvariant();
+                // '}' (0x7D) sorts directly after '|' (0x7C) — prefix range over "appversionregression|…".
+                var filter = $"PartitionKey eq '{partitionKey}' and RowKey ge '{AppVersionRegressionRowKeyPrefix}' and RowKey lt 'appversionregression}}'";
+                await foreach (var entity in _table.QueryAsync<TableEntity>(filter: filter))
+                {
+                    results.Add(MapToAppVersionRegressionAlert(entity));
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "AppVersionRegression tracker list failed for tenant {TenantId}", tenantId);
+            }
+            return results;
+        }
+
         internal const string RuleRegressionRowKeyPrefix = "ruleregression|";
 
         internal static string BuildRuleRegressionRowKey(string ruleId)
@@ -317,5 +421,69 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
                 LastEvaluatedAt = entity.GetDateTimeOffset("LastEvaluatedAt")?.UtcDateTime ?? DateTime.MinValue,
             };
         }
+
+        internal const string AppVersionRegressionRowKeyPrefix = "appversionregression|";
+
+        /// <summary>
+        /// App names and versions are free-form agent payloads — they can contain characters
+        /// Azure Table keys reject ('/', '\', '#', '?'). Sanitized for the KEY only (worst case
+        /// two apps share an episode row — tolerable); the raw values live in columns and the
+        /// mapper reads them, never the RowKey.
+        /// </summary>
+        internal static string BuildAppVersionRegressionRowKey(string appName, string version)
+        {
+            var app = SanitizeTableKey((appName ?? string.Empty).Trim().ToLowerInvariant());
+            var ver = SanitizeTableKey((version ?? string.Empty).Trim().ToLowerInvariant());
+            return $"{AppVersionRegressionRowKeyPrefix}{app}|{ver}";
+        }
+
+        /// <summary>Replace characters not allowed in Azure Table Storage keys (/, \, #, ?).</summary>
+        private static string SanitizeTableKey(string key)
+        {
+            return key
+                .Replace("/", "_")
+                .Replace("\\", "_")
+                .Replace("#", "_")
+                .Replace("?", "_");
+        }
+
+        // internal static: entity builder + mapper are pinned by round-trip unit tests
+        // (table-storage-serialization rule — every property must survive Store→Map).
+        internal static TableEntity BuildAppVersionRegressionEntity(string tenantId, AppVersionRegressionAlert alert)
+        {
+            return new TableEntity(
+                tenantId.ToLowerInvariant(), BuildAppVersionRegressionRowKey(alert.AppName, alert.CurrentVersion))
+            {
+                ["TenantId"] = tenantId,
+                ["AppName"] = alert.AppName,
+                ["CurrentVersion"] = alert.CurrentVersion,
+                ["PreviousVersion"] = alert.PreviousVersion ?? string.Empty,
+                ["CurrentMedianSeconds"] = alert.CurrentMedianSeconds,
+                ["PreviousMedianSeconds"] = alert.PreviousMedianSeconds,
+                ["CurrentMeasuredCount"] = alert.CurrentMeasuredCount,
+                ["PreviousMeasuredCount"] = alert.PreviousMeasuredCount,
+                ["Lift"] = alert.Lift,
+                ["FirstNotifiedAt"] = alert.FirstNotifiedAt,
+                ["LastEvaluatedAt"] = alert.LastEvaluatedAt,
+            };
+        }
+
+        internal static AppVersionRegressionAlert MapToAppVersionRegressionAlert(TableEntity entity)
+        {
+            return new AppVersionRegressionAlert
+            {
+                TenantId = entity.GetString("TenantId") ?? entity.PartitionKey,
+                AppName = entity.GetString("AppName") ?? string.Empty,
+                CurrentVersion = entity.GetString("CurrentVersion") ?? string.Empty,
+                PreviousVersion = entity.GetString("PreviousVersion") ?? string.Empty,
+                CurrentMedianSeconds = entity.GetInt32("CurrentMedianSeconds") ?? 0,
+                PreviousMedianSeconds = entity.GetInt32("PreviousMedianSeconds") ?? 0,
+                CurrentMeasuredCount = entity.GetInt32("CurrentMeasuredCount") ?? 0,
+                PreviousMeasuredCount = entity.GetInt32("PreviousMeasuredCount") ?? 0,
+                Lift = entity.GetDouble("Lift") ?? 0,
+                FirstNotifiedAt = entity.GetDateTimeOffset("FirstNotifiedAt")?.UtcDateTime ?? DateTime.MinValue,
+                LastEvaluatedAt = entity.GetDateTimeOffset("LastEvaluatedAt")?.UtcDateTime ?? DateTime.MinValue,
+            };
+        }
     }
 }
diff --git a/src/Backend/AutopilotMonitor.Functions/Functions/Apps/AppsAnalyticsHelper.cs b/src/Backend/AutopilotMonitor.Functions/Functions/Apps/AppsAnalyticsHelper.cs
index 4fca336b..b5e46ba5 100644
--- a/src/Backend/AutopilotMonitor.Functions/Functions/Apps/AppsAnalyticsHelper.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Functions/Apps/AppsAnalyticsHelper.cs
@@ -229,8 +229,13 @@ namespace AutopilotMonitor.Functions.Functions.Apps
             List<AppInstallSummary> allSummaries,
             ISessionRepository sessionRepo,
             string appName,
-            int days)
+            int days,
+            IReadOnlyList<AppVersionRegressionAlert>? versionRegressions = null)
         {
+            // Active duration-regression episodes for THIS app (tracker rows; models serialize
+            // camelCase on the wire like the rule-stats regressions[] block).
+            var appVersionRegressions = versionRegressions ?? Array.Empty<AppVersionRegressionAlert>();
+
             var now = DateTime.UtcNow;
             var cutoff = now.AddDays(-days);
             var midpoint = now.AddDays(-days / 2.0);
@@ -275,7 +280,10 @@ namespace AutopilotMonitor.Functions.Functions.Apps
                     installerPhaseBreakdown = Array.Empty<object>(),
                     topFailureCodes = Array.Empty<object>(),
                     detectionLiesCount = 0,
-                    deviceModelBreakdown = Array.Empty<object>()
+                    deviceModelBreakdown = Array.Empty<object>(),
+                    // Lockstep with the full response: episodes can outlive the window's data
+                    // (e.g. a shrunk days= selection), so the block is still surfaced here.
+                    versionRegressions = appVersionRegressions
                 };
             }
 
@@ -313,12 +321,23 @@ namespace AutopilotMonitor.Functions.Functions.Apps
                     var vFailed = g.Count(s => s.Status == "Failed");
                     // Same PR0 convention as the top-level rate: skips are not attempts.
                     var vSucceeded = g.Count(s => s.Status == "Succeeded" && !MetricsMath.IsSkipTerminalState(s));
+                    // Same measured population as the top-level duration stats: succeeded,
+                    // non-skip, and a plausible observed duration (0s = start unobserved,
+                    // >6h = back-stamped batch — both excluded, never averaged in).
+                    var vDurations = g
+                        .Where(s => s.Status == "Succeeded" && !MetricsMath.IsSkipTerminalState(s))
+                        .Where(MetricsMath.HasMeasuredDuration)
+                        .Select(s => s.DurationSeconds)
+                        .ToList();
                     return new
                     {
                         appVersion = g.Key,
                         installs = vTotal,
                         failed = vFailed,
-                        failureRate = MetricsMath.TerminalFailureRatePct(vFailed, vSucceeded)
+                        failureRate = MetricsMath.TerminalFailureRatePct(vFailed, vSucceeded),
+                        measuredInstalls = vDurations.Count,
+                        medianDurationSeconds = Percentile(vDurations, 0.50),
+                        p95DurationSeconds = Percentile(vDurations, 0.95)
                     };
                 })
                 .OrderByDescending(v => v.installs)
@@ -421,7 +440,8 @@ namespace AutopilotMonitor.Functions.Functions.Apps
                 installerPhaseBreakdown,
                 topFailureCodes,
                 detectionLiesCount,
-                deviceModelBreakdown
+                deviceModelBreakdown,
+                versionRegressions = appVersionRegressions
             };
         }
 
@@ -586,7 +606,9 @@ namespace AutopilotMonitor.Functions.Functions.Apps
             return date.AddDays(-diff);
         }
 
-        private static int Percentile(List<int> values, double percentile)
+        // Internal so AppVersionRegressionRadar shares the same nearest-rank convention
+        // (a third percentile implementation 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();
diff --git a/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetAppAnalyticsFunction.cs b/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetAppAnalyticsFunction.cs
index bdb4106f..28e17849 100644
--- a/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetAppAnalyticsFunction.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetAppAnalyticsFunction.cs
@@ -17,15 +17,18 @@ namespace AutopilotMonitor.Functions.Functions.Apps
         private readonly ILogger<GetAppAnalyticsFunction> _logger;
         private readonly IMetricsRepository _metricsRepo;
         private readonly ISessionRepository _sessionRepo;
+        private readonly IHardwareRejectionNotificationTracker _notificationTracker;
 
         public GetAppAnalyticsFunction(
             ILogger<GetAppAnalyticsFunction> logger,
             IMetricsRepository metricsRepo,
-            ISessionRepository sessionRepo)
+            ISessionRepository sessionRepo,
+            IHardwareRejectionNotificationTracker notificationTracker)
         {
             _logger = logger;
             _metricsRepo = metricsRepo;
             _sessionRepo = sessionRepo;
+            _notificationTracker = notificationTracker;
         }
 
         [Function("GetAppAnalytics")]
@@ -51,8 +54,12 @@ namespace AutopilotMonitor.Functions.Functions.Apps
                     days = parsedDays;
 
                 var summaries = await AppsAnalyticsHelper.LoadSummariesAsync(_metricsRepo, tenantId, days);
+                // Active duration-regression episodes for this app (fail-soft: empty on error).
+                var versionRegressions = (await _notificationTracker.GetAppVersionRegressionsAsync(tenantId))
+                    .Where(a => string.Equals(a.AppName, decodedAppName, StringComparison.OrdinalIgnoreCase))
+                    .ToList();
                 var body = await AppsAnalyticsHelper.BuildAnalyticsResponseAsync(
-                    summaries, _sessionRepo, decodedAppName, days);
+                    summaries, _sessionRepo, decodedAppName, days, versionRegressions);
 
                 var response = req.CreateResponse(HttpStatusCode.OK);
                 await response.WriteAsJsonAsync(body);
diff --git a/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetGlobalAppAnalyticsFunction.cs b/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetGlobalAppAnalyticsFunction.cs
index d67ec325..7e25b4e7 100644
--- a/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetGlobalAppAnalyticsFunction.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Functions/Apps/GetGlobalAppAnalyticsFunction.cs
@@ -1,6 +1,7 @@
 using System.Net;
 using AutopilotMonitor.Functions.Helpers;
 using AutopilotMonitor.Shared.DataAccess;
+using AutopilotMonitor.Shared.Models;
 using Microsoft.Azure.Functions.Worker;
 using Microsoft.Azure.Functions.Worker.Http;
 using Microsoft.Extensions.Logging;
@@ -17,15 +18,18 @@ namespace AutopilotMonitor.Functions.Functions.Apps
         private readonly ILogger<GetGlobalAppAnalyticsFunction> _logger;
         private readonly IMetricsRepository _metricsRepo;
         private readonly ISessionRepository _sessionRepo;
+        private readonly IHardwareRejectionNotificationTracker _notificationTracker;
 
         public GetGlobalAppAnalyticsFunction(
             ILogger<GetGlobalAppAnalyticsFunction> logger,
             IMetricsRepository metricsRepo,
-            ISessionRepository sessionRepo)
+            ISessionRepository sessionRepo,
+            IHardwareRejectionNotificationTracker notificationTracker)
         {
             _logger = logger;
             _metricsRepo = metricsRepo;
             _sessionRepo = sessionRepo;
+            _notificationTracker = notificationTracker;
         }
 
         [Function("GetGlobalAppAnalytics")]
@@ -61,8 +65,15 @@ namespace AutopilotMonitor.Functions.Functions.Apps
                     decodedAppName, userEmail, scopedTenantId ?? "<all>", days);
 
                 var summaries = await AppsAnalyticsHelper.LoadSummariesAsync(_metricsRepo, scopedTenantId, days);
+                // Episodes are per-tenant tracker rows; without a tenant scope the aggregated
+                // cross-tenant view carries none (mirrors the rule-stats global route).
+                var versionRegressions = string.IsNullOrEmpty(scopedTenantId)
+                    ? new List<AppVersionRegressionAlert>()
+                    : (await _notificationTracker.GetAppVersionRegressionsAsync(scopedTenantId!))
+                        .Where(a => string.Equals(a.AppName, decodedAppName, StringComparison.OrdinalIgnoreCase))
+                        .ToList();
                 var body = await AppsAnalyticsHelper.BuildAnalyticsResponseAsync(
-                    summaries, _sessionRepo, decodedAppName, days);
+                    summaries, _sessionRepo, decodedAppName, days, versionRegressions);
 
                 var response = req.CreateResponse(HttpStatusCode.OK);
                 await response.WriteAsJsonAsync(body);
diff --git a/src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs b/src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs
new file mode 100644
index 00000000..ee57d36f
--- /dev/null
+++ b/src/Backend/AutopilotMonitor.Functions/Helpers/AppVersionRegressionRadar.cs
@@ -0,0 +1,208 @@
+using AutopilotMonitor.Functions.Functions.Apps;
+using AutopilotMonitor.Shared.Models;
+
+namespace AutopilotMonitor.Functions.Helpers;
+
+/// <summary>One fired duration regression: an app whose newest version installs much slower than its predecessor (see <see cref="AppVersionRegressionRadar"/>).</summary>
+public sealed class AppVersionDurationRegressionFinding
+{
+    public string TenantId { get; init; } = string.Empty;
+    public string AppName { get; init; } = string.Empty;
+    public string CurrentVersion { get; init; } = string.Empty;
+    public string PreviousVersion { get; init; } = string.Empty;
+
+    public int CurrentMedianSeconds { get; init; }
+    public int PreviousMedianSeconds { get; init; }
+    public int CurrentMeasuredCount { get; init; }
+    public int PreviousMeasuredCount { get; init; }
+
+    /// <summary>Current median ÷ previous median, one decimal. Never null — measured durations are ≥1s, so the previous median cannot be 0.</summary>
+    public double Lift { get; init; }
+}
+
+/// <summary>
+/// Deterministic, I/O-free core of the app-version duration regression radar. Detects
+/// "version X made this app's installs much slower" from the per-(session, app) install
+/// summaries: per (tenant, app), the newest version's MEDIAN measured install duration is
+/// compared against the previous version's median. Medians (nearest-rank, shared with the
+/// apps dashboard via <see cref="AppsAnalyticsHelper.Percentile"/>) rather than means —
+/// a single back-stamped straggler must not fire a fleet alert. A regression fires only
+/// when ALL hold:
+/// <list type="number">
+/// <item>both versions have ≥ 10 measured installs inside the horizon;</item>
+/// <item>current median ≥ 2× the previous version's median;</item>
+/// <item>absolute increase ≥ 300 s — a 20s→45s app is noise, not an incident.</item>
+/// </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
+/// 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
+/// v1, the episode key (app, current version) still caps it at one bell per version.
+/// </summary>
+public static class AppVersionRegressionRadar
+{
+    /// <summary>Days of install summaries the radar loads and reasons over (mirrors the rule radar's 7+28 horizon).</summary>
+    public const int HorizonDays = 35;
+    public const int MinMeasuredInstalls = 10;
+    public const double MinMedianLift = 2.0;
+    public const int MinAbsoluteIncreaseSeconds = 300;
+
+    /// <summary>An active alert re-arms once the current median falls back under 1.5× the previous version's median.</summary>
+    public const double ReArmLiftFactor = 1.5;
+
+    /// <summary>Per-version duration stats inside the horizon (see <see cref="ComputeVersionStats"/>).</summary>
+    public sealed class VersionStats
+    {
+        public string Version { get; init; } = string.Empty;
+        public DateTime FirstSeen { get; init; }
+        public DateTime LastSeen { get; init; }
+        public int MeasuredCount { get; init; }
+        public int MedianSeconds { get; init; }
+    }
+
+    /// <summary>
+    /// Evaluates one tenant's install summaries (loaded for the last <see cref="HorizonDays"/>
+    /// days). Returns at most one finding per app — the newest version vs. its predecessor;
+    /// older version pairs are yesterday's news, not an alert. Deterministic ordering:
+    /// lift descending, then app name ordinal.
+    /// </summary>
+    public static List<AppVersionDurationRegressionFinding> Evaluate(IReadOnlyList<AppInstallSummary> tenantSummaries)
+    {
+        var findings = new List<AppVersionDurationRegressionFinding>();
+        foreach (var app in MeasuredAppGroups(tenantSummaries))
+        {
+            var stats = ComputeVersionStats(app.Value);
+            var (current, previous) = SelectComparisonPair(stats);
+            if (current == null || previous == null) continue;
+
+            if (current.MeasuredCount < MinMeasuredInstalls) continue;
+            if (previous.MeasuredCount < MinMeasuredInstalls) continue;
+            if (current.MedianSeconds < MinMedianLift * previous.MedianSeconds) continue;
+            if (current.MedianSeconds - previous.MedianSeconds < MinAbsoluteIncreaseSeconds) continue;
+
+            findings.Add(new AppVersionDurationRegressionFinding
+            {
+                TenantId = app.Value[0].TenantId,
+                AppName = app.Key,
+                CurrentVersion = current.Version,
+                PreviousVersion = previous.Version,
+                CurrentMedianSeconds = current.MedianSeconds,
+                PreviousMedianSeconds = previous.MedianSeconds,
+                CurrentMeasuredCount = current.MeasuredCount,
+                PreviousMeasuredCount = previous.MeasuredCount,
+                Lift = Math.Round((double)current.MedianSeconds / previous.MedianSeconds, 1),
+            });
+        }
+        return findings
+            .OrderByDescending(f => f.Lift)
+            .ThenBy(f => f.AppName, StringComparer.Ordinal)
+            .ToList();
+    }
+
+    /// <summary>
+    /// True when an ACTIVE alert may re-arm: the alerted version has drained out of the
+    /// horizon (fewer than <see cref="MinMeasuredInstalls"/> measured installs left — it was
+    /// superseded or pulled), or its recomputed median fell back under
+    /// <see cref="ReArmLiftFactor"/>× the previous version's recomputed median. When the
+    /// previous version itself has drained there is no comparison basis anymore — the
+    /// episode is kept until the current version drains (fires-stopped-style re-arm only).
+    /// </summary>
+    public static bool ShouldReArm(IReadOnlyList<AppInstallSummary> tenantSummaries, AppVersionRegressionAlert alert)
+    {
+        var stats = ComputeVersionStatsForApp(tenantSummaries, alert.AppName);
+        var current = stats.FirstOrDefault(s => string.Equals(s.Version, alert.CurrentVersion, StringComparison.Ordinal));
+        if (current == null || current.MeasuredCount < MinMeasuredInstalls) return true;
+
+        var previous = stats.FirstOrDefault(s => string.Equals(s.Version, alert.PreviousVersion, StringComparison.Ordinal));
+        if (previous == null || previous.MeasuredCount < MinMeasuredInstalls) return false;
+
+        return current.MedianSeconds < ReArmLiftFactor * previous.MedianSeconds;
+    }
+
+    /// <summary>Per-version stats for one app (measured rows only), or empty when the app has none.</summary>
+    public static List<VersionStats> ComputeVersionStatsForApp(IReadOnlyList<AppInstallSummary> tenantSummaries, string appName)
+    {
+        foreach (var app in MeasuredAppGroups(tenantSummaries))
+        {
+            if (string.Equals(app.Key, appName, StringComparison.OrdinalIgnoreCase))
+                return ComputeVersionStats(app.Value);
+        }
+        return new List<VersionStats>();
+    }
+
+    /// <summary>
+    /// Groups the MEASURED rows by app name: succeeded, non-skip, plausible duration,
+    /// no AppId collision (a second app's outcomes must not fire this app's alert),
+    /// non-empty version. Rate/failure signals are deliberately out of scope — this
+    /// radar alerts on duration only.
+    /// </summary>
+    internal static Dictionary<string, List<AppInstallSummary>> MeasuredAppGroups(IReadOnlyList<AppInstallSummary> summaries)
+    {
+        var groups = new Dictionary<string, List<AppInstallSummary>>(StringComparer.OrdinalIgnoreCase);
+        foreach (var summary in summaries)
+        {
+            if (string.IsNullOrEmpty(summary.AppName)) continue;
+            if (string.IsNullOrEmpty(summary.AppVersion)) continue;
+            if (summary.AppIdCollision) continue;
+            if (summary.Status != "Succeeded") continue;
+            if (MetricsMath.IsSkipTerminalState(summary)) continue;
+            if (!MetricsMath.HasMeasuredDuration(summary)) continue;
+
+            if (!groups.TryGetValue(summary.AppName, out var list))
+            {
+                list = new List<AppInstallSummary>();
+                groups[summary.AppName] = list;
+            }
+            list.Add(summary);
+        }
+        return groups;
+    }
+
+    /// <summary>Per-version first/last-seen and nearest-rank median over one app's measured rows.</summary>
+    internal static List<VersionStats> ComputeVersionStats(IReadOnlyList<AppInstallSummary> measuredAppRows)
+    {
+        return measuredAppRows
+            .GroupBy(s => s.AppVersion, StringComparer.Ordinal)
+            .Select(g =>
+            {
+                var durations = g.Select(s => s.DurationSeconds).ToList();
+                return new VersionStats
+                {
+                    Version = g.Key,
+                    FirstSeen = g.Min(s => s.StartedAt),
+                    LastSeen = g.Max(s => s.StartedAt),
+                    MeasuredCount = durations.Count,
+                    MedianSeconds = AppsAnalyticsHelper.Percentile(durations, 0.50),
+                };
+            })
+            .ToList();
+    }
+
+    /// <summary>
+    /// Current = the version of the most recent measured install (ties broken by later
+    /// first-seen, then version ordinal — deterministic); previous = the version with the
+    /// latest first-seen strictly before the current version's first-seen (same tie-break).
+    /// Either is null when the app has fewer than two versions in the horizon.
+    /// </summary>
+    internal static (VersionStats? Current, VersionStats? Previous) SelectComparisonPair(IReadOnlyList<VersionStats> stats)
+    {
+        if (stats.Count < 2) return (null, null);
+
+        var current = stats
+            .OrderByDescending(s => s.LastSeen)
+            .ThenByDescending(s => s.FirstSeen)
+            .ThenByDescending(s => s.Version, StringComparer.Ordinal)
+            .First();
+
+        var previous = stats
+            .Where(s => s.FirstSeen < current.FirstSeen)
+            .OrderByDescending(s => s.FirstSeen)
+            .ThenByDescending(s => s.LastSeen)
+            .ThenByDescending(s => s.Version, StringComparer.Ordinal)
+            .FirstOrDefault();
+
+        return (current, previous);
+    }
+}
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.AppVersionRegression.cs b/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.AppVersionRegression.cs
new file mode 100644
index 00000000..b9fa26e1
--- /dev/null
+++ b/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.AppVersionRegression.cs
@@ -0,0 +1,212 @@
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading.Tasks;
+using AutopilotMonitor.Functions.Helpers;
+using AutopilotMonitor.Shared.Models;
+using Microsoft.Extensions.Logging;
+
+namespace AutopilotMonitor.Functions.Services
+{
+    /// <summary>
+    /// Partial: app-version duration regression radar (sibling of the F3 rule radar).
+    /// </summary>
+    public partial class MaintenanceService
+    {
+        /// <summary>App setting kill switch: set to "true" to skip the radar entirely. Fail-open — the radar only notifies, it never mutates data.</summary>
+        internal const string AppVersionRadarKillSwitchSetting = "AppVersionRegressionRadarDisabled";
+
+        /// <summary>
+        /// Detects per-tenant apps whose newest version's median install duration regressed
+        /// (≥2× and ≥5 min over the previous version — <see cref="AppVersionRegressionRadar"/>)
+        /// and reconciles the alert episodes in the notification tracker:
+        /// new finding → tracker row + tenant bell + AppVersionDurationRegression ops event,
+        /// exactly once per (app, version) episode; still-regressed → numbers refreshed
+        /// (FirstNotifiedAt untouched); no longer regressed → re-arm check (version drained,
+        /// or median back under 1.5×) deletes the row so a future regression rings again.
+        /// The tracker's 30d retention sweep re-arms long-burning episodes by design.
+        /// <para>
+        /// One cross-tenant install-summary read over the trailing
+        /// <see cref="AppVersionRegressionRadar.HorizonDays"/> days (the same query the global
+        /// apps dashboard runs), then grouped by tenant — mirrors the rule radar's enumeration.
+        /// Idempotent per pass via the tracker dedup. Fail-soft per tenant and overall.
+        /// </para>
+        /// </summary>
+        private async Task RunAppVersionRegressionRadarAsync()
+        {
+            try
+            {
+                if (string.Equals(_configuration[AppVersionRadarKillSwitchSetting], "true", StringComparison.OrdinalIgnoreCase))
+                {
+                    _logger.LogInformation("App-version regression radar skipped ({Setting}=true)", AppVersionRadarKillSwitchSetting);
+                    return;
+                }
+
+                var sw = Stopwatch.StartNew();
+                var sinceUtc = DateTime.UtcNow.AddDays(-AppVersionRegressionRadar.HorizonDays);
+                var summaries = await _metricsRepo.GetAppsDashboardSummariesAsync(sinceUtc, tenantId: null);
+
+                var byTenant = summaries
+                    .Where(s => !string.IsNullOrEmpty(s.TenantId))
+                    .GroupBy(s => s.TenantId, StringComparer.OrdinalIgnoreCase);
+
+                int fired = 0, refreshed = 0, rearmed = 0, tenants = 0;
+                foreach (var tenantGroup in byTenant)
+                {
+                    tenants++;
+                    try
+                    {
+                        var (f, r, a) = await EvaluateTenantAppVersionRegressionsAsync(tenantGroup.Key, tenantGroup.ToList());
+                        fired += f;
+                        refreshed += r;
+                        rearmed += a;
+                    }
+                    catch (Exception tenantEx)
+                    {
+                        _logger.LogWarning(tenantEx, "App-version regression radar failed for tenant {TenantId} (non-fatal)", tenantGroup.Key);
+                    }
+                }
+
+                sw.Stop();
+                _logger.LogInformation(
+                    "App-version regression radar: {Tenants} tenants over {Rows} install summaries — {Fired} fired, {Refreshed} refreshed, {Rearmed} re-armed in {Ms}ms",
+                    tenants, summaries.Count, fired, refreshed, rearmed, sw.ElapsedMilliseconds);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "App-version regression radar failed (non-fatal)");
+            }
+        }
+
+        private async Task<(int Fired, int Refreshed, int Rearmed)> EvaluateTenantAppVersionRegressionsAsync(
+            string tenantId, System.Collections.Generic.List<AppInstallSummary> tenantSummaries)
+        {
+            var findings = AppVersionRegressionRadar.Evaluate(tenantSummaries);
+            var active = await _hardwareRejectionTracker.GetAppVersionRegressionsAsync(tenantId);
+            var activeByKey = active.ToDictionary(
+                a => AppVersionEpisodeKey(a.AppName, a.CurrentVersion), StringComparer.OrdinalIgnoreCase);
+
+            int fired = 0, refreshed = 0, rearmed = 0;
+            var firedKeys = new System.Collections.Generic.HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+            foreach (var finding in findings)
+            {
+                var key = AppVersionEpisodeKey(finding.AppName, finding.CurrentVersion);
+                firedKeys.Add(key);
+
+                if (activeByKey.TryGetValue(key, out var existing))
+                {
+                    // Episode still burning: refresh numbers for the versionRegressions[] block;
+                    // FirstNotifiedAt never moves (retention re-arm counts from the bell).
+                    await _hardwareRejectionTracker.RefreshAppVersionRegressionAsync(
+                        tenantId, BuildAppVersionAlert(finding, existing.FirstNotifiedAt));
+                    refreshed++;
+                    continue;
+                }
+
+                var alert = BuildAppVersionAlert(finding, DateTime.UtcNow);
+                if (!await _hardwareRejectionTracker.TryRegisterAppVersionRegressionAsync(tenantId, alert))
+                    continue; // a concurrent pass won the episode — its bell suffices
+
+                fired++;
+                await _tenantNotificationService.CreateNotificationAsync(
+                    tenantId,
+                    type: "app_version_duration_regression",
+                    title: $"Install duration regressed: {finding.AppName}",
+                    message: BuildAppVersionRegressionMessage(finding),
+                    // Canonical appDetailUrl shape (lib/routes.ts) with the radar's horizon window.
+                    href: $"/apps/detail?name={Uri.EscapeDataString(finding.AppName)}&days={AppVersionRegressionRadar.HorizonDays}");
+                await _opsEventService.RecordAppVersionDurationRegressionAsync(
+                    tenantId, finding.AppName, finding.CurrentVersion, finding.PreviousVersion,
+                    finding.CurrentMedianSeconds, finding.PreviousMedianSeconds,
+                    finding.CurrentMeasuredCount, finding.PreviousMeasuredCount, finding.Lift);
+            }
+
+            foreach (var alert in active)
+            {
+                if (firedKeys.Contains(AppVersionEpisodeKey(alert.AppName, alert.CurrentVersion)))
+                    continue;
+
+                if (AppVersionRegressionRadar.ShouldReArm(tenantSummaries, alert))
+                {
+                    await _hardwareRejectionTracker.DeleteAppVersionRegressionAsync(tenantId, alert.AppName, alert.CurrentVersion);
+                    rearmed++;
+                }
+                else
+                {
+                    // Elevated but below the fire gates (between 1.5× and 2×, or the absolute
+                    // delta shrank): keep the episode, refresh the numbers so the
+                    // versionRegressions[] block stays honest.
+                    var refreshedAlert = TryBuildOngoingAppVersionAlert(tenantSummaries, alert);
+                    if (refreshedAlert != null)
+                    {
+                        await _hardwareRejectionTracker.RefreshAppVersionRegressionAsync(tenantId, refreshedAlert);
+                        refreshed++;
+                    }
+                }
+            }
+
+            return (fired, refreshed, rearmed);
+        }
+
+        private static string AppVersionEpisodeKey(string appName, string version)
+            => $"{appName}\n{version}";
+
+        private static AppVersionRegressionAlert BuildAppVersionAlert(
+            AppVersionDurationRegressionFinding finding, DateTime firstNotifiedAt)
+            => new()
+            {
+                TenantId = finding.TenantId,
+                AppName = finding.AppName,
+                CurrentVersion = finding.CurrentVersion,
+                PreviousVersion = finding.PreviousVersion,
+                CurrentMedianSeconds = finding.CurrentMedianSeconds,
+                PreviousMedianSeconds = finding.PreviousMedianSeconds,
+                CurrentMeasuredCount = finding.CurrentMeasuredCount,
+                PreviousMeasuredCount = finding.PreviousMeasuredCount,
+                Lift = finding.Lift,
+                FirstNotifiedAt = firstNotifiedAt,
+                LastEvaluatedAt = DateTime.UtcNow,
+            };
+
+        /// <summary>
+        /// Refresh payload for a still-open episode below the fire gates: recomputed medians
+        /// against the SAME version pair, everything identifying carried over. Null when either
+        /// version has left the horizon — the stale numbers then remain until re-arm/retention.
+        /// </summary>
+        private static AppVersionRegressionAlert? TryBuildOngoingAppVersionAlert(
+            System.Collections.Generic.IReadOnlyList<AppInstallSummary> tenantSummaries, AppVersionRegressionAlert existing)
+        {
+            var stats = AppVersionRegressionRadar.ComputeVersionStatsForApp(tenantSummaries, existing.AppName);
+            var current = stats.FirstOrDefault(s => string.Equals(s.Version, existing.CurrentVersion, StringComparison.Ordinal));
+            var previous = stats.FirstOrDefault(s => string.Equals(s.Version, existing.PreviousVersion, StringComparison.Ordinal));
+            if (current == null || previous == null || previous.MedianSeconds <= 0)
+                return null;
+
+            return new AppVersionRegressionAlert
+            {
+                TenantId = existing.TenantId,
+                AppName = existing.AppName,
+                CurrentVersion = existing.CurrentVersion,
+                PreviousVersion = existing.PreviousVersion,
+                CurrentMedianSeconds = current.MedianSeconds,
+                PreviousMedianSeconds = previous.MedianSeconds,
+                CurrentMeasuredCount = current.MeasuredCount,
+                PreviousMeasuredCount = previous.MeasuredCount,
+                Lift = Math.Round((double)current.MedianSeconds / previous.MedianSeconds, 1),
+                FirstNotifiedAt = existing.FirstNotifiedAt,
+                LastEvaluatedAt = DateTime.UtcNow,
+            };
+        }
+
+        /// <summary>Bell message with the full numbers (the admin can verify without a portal round-trip). Minutes, one decimal.</summary>
+        internal static string BuildAppVersionRegressionMessage(AppVersionDurationRegressionFinding finding)
+        {
+            var fromMin = Math.Round(finding.PreviousMedianSeconds / 60.0, 1);
+            var toMin = Math.Round(finding.CurrentMedianSeconds / 60.0, 1);
+            return $"Median install duration rose from {fromMin} to {toMin} min after version {finding.CurrentVersion} " +
+                   $"({finding.CurrentMeasuredCount} measured installs vs {finding.PreviousMeasuredCount} on version {finding.PreviousVersion}) " +
+                   $"— lift {finding.Lift}x over the last {AppVersionRegressionRadar.HorizonDays} days.";
+        }
+    }
+}
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.cs b/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.cs
index c6590f6e..a36d02bf 100644
--- a/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Services/MaintenanceService.cs
@@ -148,6 +148,9 @@ namespace AutopilotMonitor.Functions.Services
                 // aggregation so the window rows are fresh. Anchored on YESTERDAY — whole
                 // days only, a partial today would understate the window rate. Fail-soft.
                 await RunRuleRegressionRadarAsync(DateTime.UtcNow.Date.AddDays(-1));
+                // App-version duration regression radar: same episode/tracker pattern over the
+                // install summaries (trailing 35d horizon loaded internally). Fail-soft.
+                await RunAppVersionRegressionRadarAsync();
                 // F1 PR2: rolling 30d breakdown backfill + daily attribution aggregates. Owns
                 // its own window (NOT the snapshot-gated catch-up above) so late-terminating
                 // sessions still reach their StartedAt-date's aggregate. Fail-soft internally.
@@ -222,6 +225,7 @@ namespace AutopilotMonitor.Functions.Services
                 // Timer-path parity: radar re-runs are idempotent (tracker dedup), so a manual
                 // aggregation also re-evaluates regressions anchored on the aggregated date.
                 await RunRuleRegressionRadarAsync(dateToAggregate);
+                await RunAppVersionRegressionRadarAsync();
 
                 // Timer-path parity: manual maintenance also refreshes the attribution
                 // breakdowns + daily aggregates and the device-history/FTR rollups
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/OpsEventService.cs b/src/Backend/AutopilotMonitor.Functions/Services/OpsEventService.cs
index a7334954..b4905171 100644
--- a/src/Backend/AutopilotMonitor.Functions/Services/OpsEventService.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Services/OpsEventService.cs
@@ -542,6 +542,35 @@ namespace AutopilotMonitor.Functions.Services
                     lift,
                 });
 
+        /// <summary>
+        /// App-version duration regression radar: an app's newest version installs with a median
+        /// duration ≥2× (and ≥5 min absolute) over the previous version's median. Fired ONCE per
+        /// (app, version) episode (the notification-tracker row is the dedup); the message
+        /// carries the full numbers so the event is verifiable without a portal round-trip.
+        /// Dual-registered in the web OPS_EVENT_TYPES catalog
+        /// (memory: feedback_ops_event_types_dual_register).
+        /// </summary>
+        public Task RecordAppVersionDurationRegressionAsync(
+            string tenantId, string appName, string currentVersion, string previousVersion,
+            int currentMedianSeconds, int previousMedianSeconds,
+            int currentMeasuredCount, int previousMeasuredCount, double lift)
+            => WriteAsync(OpsEventCategory.Tenant, "AppVersionDurationRegression", OpsEventSeverity.Warning,
+                $"App '{appName}' median install duration rose from {Math.Round(previousMedianSeconds / 60.0, 1)} to " +
+                $"{Math.Round(currentMedianSeconds / 60.0, 1)} min after version {currentVersion} " +
+                $"({currentMeasuredCount} measured installs vs {previousMeasuredCount} on {previousVersion}) — lift {lift}x",
+                tenantId, "System.Maintenance",
+                new
+                {
+                    appName,
+                    currentVersion,
+                    previousVersion,
+                    currentMedianSeconds,
+                    previousMedianSeconds,
+                    currentMeasuredCount,
+                    previousMeasuredCount,
+                    lift,
+                });
+
         // ── Agent ──────────────────────────────────────────────────────────────
 
         public Task RecordSessionTimeoutsAsync(string tenantId, int sessionCount, int timeoutHours)
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs b/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs
index 0e6bdf72..116dcd21 100644
--- a/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs
@@ -33,6 +33,8 @@ public static class TenantNotificationAudienceCatalog
         // F3 regression radar: rule-tuning is an admin concern (the alert deep-links into the
         // analyze-rules page, which members cannot act on).
         ["rule_frequency_regression"] = NotificationAudience.Admin,
+        // App-version duration regression radar: packaging/rollout is an admin concern.
+        ["app_version_duration_regression"] = NotificationAudience.Admin,
     };
 
     public static NotificationAudience Resolve(string? type)
diff --git a/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs b/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs
index 74fc77a7..38038bc3 100644
--- a/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs
+++ b/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs
@@ -8,9 +8,10 @@ namespace AutopilotMonitor.Shared.DataAccess
     /// <summary>
     /// Notification dedup store (one table, RowKey-prefixed key spaces). Subjects:
     /// hardware rejections per (tenant, manufacturer, model), TPM PSS incompatibilities per
-    /// (tenant, serial number) — both lifetime insert-once — and F3 rule-frequency
-    /// regressions per (tenant, ruleId), whose rows additionally carry the alert payload,
-    /// are refreshed while the episode stays active, and are deleted when the rate re-arms.
+    /// (tenant, serial number) — both lifetime insert-once — F3 rule-frequency
+    /// regressions per (tenant, ruleId), and app-version duration regressions per
+    /// (tenant, app, version). The regression key spaces additionally carry the alert
+    /// payload, are refreshed while the episode stays active, and are deleted on re-arm.
     /// </summary>
     public interface IHardwareRejectionNotificationTracker
     {
@@ -54,6 +55,30 @@ namespace AutopilotMonitor.Shared.DataAccess
         /// <summary>Active regression episodes of one tenant (RowKey-prefix scan; empty on failure — fail-soft reads).</summary>
         Task<List<RuleRegressionAlert>> GetRuleRegressionsAsync(string tenantId);
 
+        // --- App-version duration regressions (RowKey "appversionregression|{app}|{version}") ---
+
+        /// <summary>
+        /// Atomically opens a duration-regression episode for (tenantId, alert.AppName,
+        /// alert.CurrentVersion). Returns true when this pass owns the episode (caller fires
+        /// bell + ops event exactly once), false when an episode is already active or on
+        /// failure (fail-closed — never double-fire).
+        /// </summary>
+        Task<bool> TryRegisterAppVersionRegressionAsync(string tenantId, AppVersionRegressionAlert alert);
+
+        /// <summary>
+        /// Refreshes an active episode's numbers (medians, counts, LastEvaluatedAt) so the
+        /// versionRegressions[] block stays current. FirstNotifiedAt is carried from the alert
+        /// unchanged — the retention sweep re-arms on the ORIGINAL notification age.
+        /// Fail-soft; never fires notifications.
+        /// </summary>
+        Task RefreshAppVersionRegressionAsync(string tenantId, AppVersionRegressionAlert alert);
+
+        /// <summary>Closes an episode (median re-armed or the version drained out of the horizon). 404-tolerant.</summary>
+        Task DeleteAppVersionRegressionAsync(string tenantId, string appName, string currentVersion);
+
+        /// <summary>Active app-version regression episodes of one tenant (RowKey-prefix scan; empty on failure — fail-soft reads).</summary>
+        Task<List<AppVersionRegressionAlert>> GetAppVersionRegressionsAsync(string tenantId);
+
         /// <summary>
         /// Retention cleanup: deletes tracker rows whose FirstNotifiedAt is older than
         /// <paramref name="cutoffUtc"/>. Every key space lives in one table, so pruning re-arms
diff --git a/src/Shared/AutopilotMonitor.Shared/Models/Metrics/AppVersionRegressionAlert.cs b/src/Shared/AutopilotMonitor.Shared/Models/Metrics/AppVersionRegressionAlert.cs
new file mode 100644
index 00000000..9cd30762
--- /dev/null
+++ b/src/Shared/AutopilotMonitor.Shared/Models/Metrics/AppVersionRegressionAlert.cs
@@ -0,0 +1,43 @@
+using System;
+
+namespace AutopilotMonitor.Shared.Models
+{
+    /// <summary>
+    /// One ACTIVE app-version duration regression: an app whose newest version's median
+    /// install duration rose ≥2× (and ≥5 minutes absolute) over the previous version's
+    /// median, both sides with enough measured installs. Persisted as the
+    /// <c>appversionregression|{app}|{version}</c> keyspace of the notification tracker
+    /// table — the row IS the dedup (one bell per episode), and the
+    /// <c>versionRegressions[]</c> payload on the app-analytics response. Deleted when the
+    /// episode re-arms (median falls back under 1.5× or the version drains out of the
+    /// horizon) or by the tracker's 30-day retention sweep. Numbers refresh on every radar
+    /// pass while the episode stays active; <see cref="FirstNotifiedAt"/> never moves.
+    /// </summary>
+    public class AppVersionRegressionAlert
+    {
+        public string TenantId { get; set; } = string.Empty;
+        public string AppName { get; set; } = string.Empty;
+
+        /// <summary>The regressed (newer) version — episode key together with the app.</summary>
+        public string CurrentVersion { get; set; } = string.Empty;
+
+        /// <summary>The comparison version: latest first-seen strictly before the current version's first-seen.</summary>
+        public string PreviousVersion { get; set; } = string.Empty;
+
+        public int CurrentMedianSeconds { get; set; }
+        public int PreviousMedianSeconds { get; set; }
+
+        /// <summary>Measured installs backing each median (gate: both ≥10).</summary>
+        public int CurrentMeasuredCount { get; set; }
+        public int PreviousMeasuredCount { get; set; }
+
+        /// <summary>Current median ÷ previous median (gate: ≥2.0; previous median is never 0 — measured durations are ≥1s).</summary>
+        public double Lift { get; set; }
+
+        /// <summary>When the episode first fired (bell + ops event moment). Never moves on refresh; drives the 30d retention re-arm.</summary>
+        public DateTime FirstNotifiedAt { get; set; }
+
+        /// <summary>Last radar pass that re-confirmed/refreshed this episode.</summary>
+        public DateTime LastEvaluatedAt { get; set; }
+    }
+}
diff --git a/src/Web/autopilot-monitor-web/app/admin/components/OpsAlertRulesSection.tsx b/src/Web/autopilot-monitor-web/app/admin/components/OpsAlertRulesSection.tsx
index 53e87de2..8f15a6bc 100644
--- a/src/Web/autopilot-monitor-web/app/admin/components/OpsAlertRulesSection.tsx
+++ b/src/Web/autopilot-monitor-web/app/admin/components/OpsAlertRulesSection.tsx
@@ -108,6 +108,11 @@ const OPS_EVENT_TYPES: Record<string, string[]> = {
     // (Wilson-separated). Warning-tier, once per episode (tracker-deduped). Dual-register
     // per memory feedback_ops_event_types_dual_register.
     "RuleFrequencyRegression",
+    // App-version duration regression radar: an app's newest version installs with a median
+    // duration ≥2× (and ≥5 min absolute) over the previous version. Warning-tier, once per
+    // (app, version) episode (tracker-deduped). Dual-register per memory
+    // feedback_ops_event_types_dual_register.
+    "AppVersionDurationRegression",
     // Auto-activation audit: the tenant-auto-approve worker activated a new signup
     // (AutoApproveNewTenants enabled). Info-tier. Dual-register per memory
     // feedback_ops_event_types_dual_register.
diff --git a/src/Web/autopilot-monitor-web/app/apps/detail/page.tsx b/src/Web/autopilot-monitor-web/app/apps/detail/page.tsx
index d7e92418..69c80598 100644
--- a/src/Web/autopilot-monitor-web/app/apps/detail/page.tsx
+++ b/src/Web/autopilot-monitor-web/app/apps/detail/page.tsx
@@ -51,6 +51,25 @@ interface VersionRow {
   installs: number;
   failed: number;
   failureRate: number;
+  /** Succeeded installs with a plausible observed duration — the basis of the median/p95 below. */
+  measuredInstalls: number;
+  medianDurationSeconds: number;
+  p95DurationSeconds: number;
+}
+
+/** Active duration-regression episode from the radar (tracker row, camelCase on the wire). */
+interface AppVersionRegressionRow {
+  tenantId: string;
+  appName: string;
+  currentVersion: string;
+  previousVersion: string;
+  currentMedianSeconds: number;
+  previousMedianSeconds: number;
+  currentMeasuredCount: number;
+  previousMeasuredCount: number;
+  lift: number;
+  firstNotifiedAt: string;
+  lastEvaluatedAt: string;
 }
 
 interface PhaseRow {
@@ -102,6 +121,7 @@ interface AnalyticsResponse {
   topFailureCodes: FailureCodeRow[];
   detectionLiesCount: number;
   deviceModelBreakdown: DeviceModelRow[];
+  versionRegressions: AppVersionRegressionRow[];
 }
 
 interface SessionRow {
@@ -527,6 +547,23 @@ function AppDetailContent() {
                 </Card>
               </div>
 
+              {/* Duration regression banner: active radar episodes for this app (bell-deduped
+                  server-side; this is the durable badge while the episode burns). */}
+              {(analytics.versionRegressions ?? []).length > 0 && (
+                <div className="rounded-lg border border-amber-300 bg-amber-50 px-4 py-3 space-y-1">
+                  {analytics.versionRegressions.map((reg) => (
+                    <p key={`${reg.appName}|${reg.currentVersion}`} className="text-sm text-amber-800">
+                      <span className="font-semibold">↑ Duration regression:</span>{" "}
+                      median install duration rose from {(reg.previousMedianSeconds / 60).toFixed(1)} to{" "}
+                      {(reg.currentMedianSeconds / 60).toFixed(1)} min after version{" "}
+                      <span className="font-mono">{reg.currentVersion}</span>{" "}
+                      ({reg.currentMeasuredCount} measured installs vs {reg.previousMeasuredCount} on{" "}
+                      <span className="font-mono">{reg.previousVersion}</span> — lift {reg.lift}x)
+                    </p>
+                  ))}
+                </div>
+              )}
+
               {/* Charts row 2: version breakdown + phase breakdown.
                   Each card is hidden when empty so the row collapses gracefully:
                   - Version: will appear once new agents emit AppVersion data
@@ -547,6 +584,17 @@ function AppDetailContent() {
                       />
                     </Card>
                   )}
+                  {analytics.versionBreakdown.some((v) => v.measuredInstalls > 0) && (
+                    <Card title="Median Install Duration by Version">
+                      <AppBarChart
+                        data={analytics.versionBreakdown.filter((v) => v.measuredInstalls > 0) as unknown as Array<Record<string, unknown>>}
+                        categoryKey="appVersion"
+                        valueKey="medianDurationSeconds"
+                        valueFormatter={(v) => formatDuration(Number(v))}
+                        barColor={chartColors.primary}
+                      />
+                    </Card>
+                  )}
                   {analytics.installerPhaseBreakdown.length > 0 && (
                     <Card title="Installer Phase (failures only)">
                       <AppBarChart