v1.4.37.1 — event-loop unblock on the read path

Hotfix on top of v1.4.37. The post-deploy verify caught
/api/analytics cold-mount hits of ~62 s and parallel /api/health
checks of ~58 s on the live instance, far above the v1.4.37
1.5-3 s perf claim. Root cause: the synchronous
ensureUserRollupsFresh(userId) call at the top of each heavy
read path folds the trailing 90-day DAY window when the rollup
watermark trails the newest measurement. On a power-user account
whose iOS step samples push the watermark every few minutes,
each cache miss synchronously paid the full refresh cost on a
Node worker that also serves the rest of the request fan-out
(including /api/health, /api/version, and concurrent iOS calls),
and the event loop was blocked for the duration of the
recompute.

Convert the three call sites (analytics route, comprehensive
aggregator, summaries slice) to fire-and-forget. The downstream
probeRollupCoverage gate falls back to live SQL on partial
coverage so correctness is preserved; the only user-observable
change is one cache window of staleness on the very first
request after a new measurement landed.

src/lib/analytics/summaries-slice.ts

@@ -179,11 +179,14 @@ export interface SummariesSlice {
 export async function computeSummariesSlice(
   userId: string,
 ): Promise<SummariesSlice> {
-  // Keep the persistent rollup table current before the bucket read
-  // fires. On a warm process this is a single watermark query; on a
-  // cold mount it folds the trailing 90-day window into the DAY
-  // rollup so the bucket read below has something to compose.
-  await ensureUserRollupsFresh(userId);
+  // v1.4.37.1 hotfix — fire-and-forget. See `src/app/api/analytics/route.ts`
+  // for the full rationale: awaiting this on the read path can stall
+  // the event loop for 30–60 s on power-user accounts whose iOS step
+  // samples keep the 90-day window slightly stale. The downstream
+  // coverage probe falls back to live SQL for uncovered types, so
+  // correctness is preserved; the read just doesn't block waiting
+  // for the background refresh.
+  void ensureUserRollupsFresh(userId);
 
   // v1.4.36 QA C1 — per-type coverage probe replaces the legacy global
   // COUNT. The previous gate returned true as soon as ANY type had at

src/lib/insights/comprehensive-aggregator.ts

@@ -233,12 +233,14 @@ export async function buildComprehensiveAggregate(
 ): Promise<ComprehensiveAggregate> {
   const ninetyDaysAgo = new Date(Date.now() - 90 * 24 * 60 * 60 * 1000);
 
-  // Keep the persistent rollup table current before any read fires.
-  // After this returns the DAY-granularity buckets for the trailing
-  // 90 days reflect every measurement that landed before this call
-  // (the per-write hook is synchronous on the DAY bucket, and
-  // `ensureUserRollupsFresh` covers cold-mount / process-restart).
-  await ensureUserRollupsFresh(userId);
+  // v1.4.37.1 hotfix — fire-and-forget. See `src/app/api/analytics/route.ts`
+  // for the full rationale: awaiting this on the read path can stall
+  // the event loop for 30–60 s on power-user accounts whose iOS step
+  // samples keep the 90-day window slightly stale. The downstream
+  // coverage probe falls back to live SQL for uncovered types, so
+  // correctness is preserved; the read just doesn't block waiting
+  // for the background refresh.
+  void ensureUserRollupsFresh(userId);
 
   // v1.4.36 QA C1 — per-type coverage probe. The legacy global COUNT
   // returned true as soon as any one type had a DAY bucket, which made