diff --git a/CHANGELOG.md b/CHANGELOG.md
index aaf417289..9cf8c4eea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,41 @@
 # Changelog
 
+## [1.4.38.7] — 2026-05-18 — Rollup recompute observability + admin trigger
+
+The v1.4.38.5 / v1.4.38.6 chain promised a fast-path recovery for
+power-user accounts but gave the operator no way to confirm whether
+the boot-time discovery had actually found a stranded user — the
+success log only fired when `enqueued > 0 || skipped > 0`, so the
+silent "found nothing" case looked identical to the silent "boot hook
+never ran" case. And once the worker was up there was no way to
+re-trigger discovery short of bouncing the container.
+
+### Added
+
+- **`POST /api/admin/rollups/recompute`** — operator-triggered ad-hoc
+  rollup recompute. Body `{ userId: string }` synchronously folds
+  one user (`recomputeUserRollups` awaited inside the request). Body
+  `{}` re-runs `enqueueBootTimeRollupBackfill()` to kick the
+  boot-discovery loop across every user. Admin gate via
+  `requireAdmin()` (cookie-only, never Bearer).
+- **`fallback_reason` + `missing_types` annotate** on the
+  `slim_summaries` live-fallback path. When the rollup-fast-path
+  declines, the wide-event now reports exactly which measurement
+  types are missing DAY-bucket coverage so the operator can match
+  a slow `/api/analytics` cold-mount to the responsible type without
+  touching the DB.
+
+### Changed
+
+- **Boot-backfill discovery now logs every result, including the
+  silent "no users to backfill" case.** The line cost is one row per
+  worker boot; the operator gain is the ability to tell discovery
+  ran cleanly from discovery silently no-op'd.
+
+### Operator notes
+
+- No new migration. No env-var change.
+
 ## [1.4.38.6] — 2026-05-18 — Boot-backfill discovery SQL fix
 
 The v1.4.38.5 discovery rewrite filtered the LEFT JOIN with
diff --git a/package.json b/package.json
index 45536d17b..18a978ffe 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "healthlog",
-  "version": "1.4.38.6",
+  "version": "1.4.38.7",
   "description": "Self-hosted personal-health-tracking PWA with Withings integration, AI insights, and doctor-report PDF export.",
   "license": "AGPL-3.0-only",
   "homepage": "https://healthlog.dev",
diff --git a/src/app/api/admin/rollups/recompute/route.ts b/src/app/api/admin/rollups/recompute/route.ts
new file mode 100644
index 000000000..3b4fee9b1
--- /dev/null
+++ b/src/app/api/admin/rollups/recompute/route.ts
@@ -0,0 +1,111 @@
+/**
+ * `POST /api/admin/rollups/recompute` — operator-triggered ad-hoc
+ * rollup recompute.
+ *
+ * Surface added in v1.4.38.7 after the boot-time backfill could not
+ * be re-triggered without a deploy. A power-user account whose
+ * `isFullyCovered(coverage)` probe returned `false` (typically
+ * because a brand-new measurement type landed between the last fold
+ * and the next analytics read) gets stranded on the live SQL
+ * aggregator until the next worker boot. This endpoint lets the
+ * operator force a fold for one user or kick the boot-discovery loop
+ * across every user without bouncing the worker container.
+ *
+ * Body:
+ *   { userId?: string }
+ *
+ *   - `userId` — single user mode. Synchronously calls
+ *     `recomputeUserRollups(userId)` and returns the row count when
+ *     the fold completes. The call is awaited inside the request, so
+ *     the operator sees the duration in the response.
+ *   - `userId` omitted — calls `enqueueBootTimeRollupBackfill()` to
+ *     re-run the worker-boot discovery (`{ enqueued, skipped }` shape).
+ *
+ * Admin gate via `requireAdmin()` (cookie-only — Bearer never elevates
+ * to admin per the v1.4.25 security boundary).
+ */
+import type { NextRequest } from "next/server";
+
+import { apiHandler, requireAdmin } from "@/lib/api-handler";
+import { auditLog } from "@/lib/auth/audit";
+import {
+  apiError,
+  apiSuccess,
+  getClientIp,
+  safeJson,
+} from "@/lib/api-response";
+import { annotate } from "@/lib/logging/context";
+import {
+  enqueueBootTimeRollupBackfill,
+  recomputeUserRollups,
+} from "@/lib/measurements/rollups";
+
+interface RecomputeBody {
+  userId?: string;
+}
+
+export const POST = apiHandler(async (request: NextRequest) => {
+  const { user } = await requireAdmin();
+  annotate({ action: { name: "admin.rollups.recompute" } });
+
+  const { data: rawBody, error: jsonError } =
+    await safeJson<RecomputeBody>(request);
+  if (jsonError) return jsonError;
+
+  const body: RecomputeBody =
+    rawBody && typeof rawBody === "object" ? rawBody : {};
+  const userId =
+    typeof body.userId === "string" && body.userId.length > 0
+      ? body.userId
+      : undefined;
+
+  if (userId) {
+    await auditLog("admin.rollups.recompute.start", {
+      userId: user.id,
+      ipAddress: getClientIp(request),
+      details: { targetUserId: userId, mode: "single" },
+    });
+
+    let result: Awaited<ReturnType<typeof recomputeUserRollups>>;
+    try {
+      result = await recomputeUserRollups(userId);
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err);
+      return apiError(message, 500);
+    }
+
+    await auditLog("admin.rollups.recompute.complete", {
+      userId: user.id,
+      ipAddress: getClientIp(request),
+      details: { targetUserId: userId, ...result },
+    });
+
+    return apiSuccess({
+      mode: "single",
+      targetUserId: userId,
+      rowsUpserted: result.rowsUpserted,
+      durationMs: result.durationMs,
+    });
+  }
+
+  await auditLog("admin.rollups.recompute.start", {
+    userId: user.id,
+    ipAddress: getClientIp(request),
+    details: { mode: "boot-discovery" },
+  });
+
+  const discovery = await enqueueBootTimeRollupBackfill();
+
+  await auditLog("admin.rollups.recompute.complete", {
+    userId: user.id,
+    ipAddress: getClientIp(request),
+    details: { mode: "boot-discovery", ...discovery },
+  });
+
+  return apiSuccess({
+    mode: "boot-discovery",
+    enqueued: discovery.enqueued,
+    skipped: discovery.skipped,
+    error: discovery.error,
+  });
+});
diff --git a/src/lib/analytics/summaries-slice.ts b/src/lib/analytics/summaries-slice.ts
index d1e15bcfa..20015e50d 100644
--- a/src/lib/analytics/summaries-slice.ts
+++ b/src/lib/analytics/summaries-slice.ts
@@ -217,6 +217,26 @@ export async function computeSummariesSlice(
   if (isFullyCovered(coverage)) {
     return computeFromRollups(userId);
   }
+  // v1.4.38.7 — annotate the live fallback with the per-type
+  // coverage map so the operator can see WHICH type stranded the
+  // request on the live aggregator. Without this the wide-event only
+  // says `path:"live"`, and "why" requires shell access to the DB.
+  const missing: string[] = [];
+  for (const [type, hasBuckets] of coverage.entries()) {
+    if (!hasBuckets) missing.push(type);
+  }
+  annotate({
+    meta: {
+      analytics: {
+        slim_summaries: {
+          fallback_reason: "partial_rollup_coverage",
+          missing_types: missing,
+          covered_count: coverage.size - missing.length,
+          total_types: coverage.size,
+        },
+      },
+    },
+  });
   return computeFromLiveAggregate(userId);
 }
 
diff --git a/src/lib/jobs/reminder-worker.ts b/src/lib/jobs/reminder-worker.ts
index a8f77f234..c763421be 100644
--- a/src/lib/jobs/reminder-worker.ts
+++ b/src/lib/jobs/reminder-worker.ts
@@ -1960,7 +1960,13 @@ export async function startReminderWorker() {
         "error",
         `[rollup-full-backfill] boot discovery failed: ${error}`,
       );
-    } else if (enqueued > 0 || skipped > 0) {
+    } else {
+      // v1.4.38.7 — log the discovery result on every boot, including
+      // the silent `enqueued=0 skipped=0` case. Without this, an
+      // operator chasing "analytics is slow" cannot tell whether the
+      // discovery query ran successfully (and found nothing to fold)
+      // vs. silently no-op'd. The line is one row per worker boot, so
+      // the log cost is negligible.
       workerLog(
         "info",
         `[rollup-full-backfill] boot discovery: enqueued=${enqueued} skipped=${skipped}`,