The measured first-load gap on / was never the server: FCP painted the
SSR shell at ~1.8 s but LCP landed at ~5.5 s (mobile-throttled) because
the tiles waited for JS download + hydrate + a CLIENT-side snapshot
fetch — while /api/dashboard/snapshot answers in ~8 ms server-side.
src/app/page.tsx is now a thin RSC wrapper: it runs the same cached
snapshot read the API route uses (extracted to
src/lib/dashboard/snapshot-read.ts, one shared SWR cell for both
readers) and hands the result to TanStack via HydrationBoundary +
dehydrate, so the first HTML carries real tile data and the mounted
cell starts warm (staleTime 60 s, refetchOnMount false — no double
fetch). Query keys come only from the central factory
(dashboardSnapshot(locale) + the dashboardWidgets seed the client cell
already performs); the payload is JSON-round-tripped so the hydrated
shape is byte-equal to the wire shape. Fail-soft: no session or any
builder error renders the page exactly as before. The 1,727-line client
page moves unchanged to src/app/page-client.tsx; no component-tree
rewrite.
Companion: the documented bundle tooling was dead on Turbopack
(ANALYZE=1 silent no-op, bundle-report read a webpack-only JSON), so
H2/H3-class regressions shipped invisibly. scripts/check-bundle-budget.mjs
derives per-route gzip totals from the Turbopack client-reference
manifests + rootMainFiles, prints the report (pnpm bundle-report), and
enforces bundle-budget.json (pnpm bundle-check): per-route caps,
total-client-JS cap, a recharts-duplication guard (fingerprint count
must stay 1), and a catalog guard (no message catalog referenced by any
route manifest). Wired into the existing e2e workflow after next build.
H4
The client bundle carries only the active locale — resolved on the
server and handed to the provider with no hydration flash, halving the
dashboard route to under a megabyte parsed (288 KiB gzip). The auth
shell renders the app chrome immediately instead of a spinner while the
session resolves in parallel, the widgets request folds into the
snapshot it duplicated, and insight pills prefetch their sub-pages —
a first visit to a sub-page lands in about ninety milliseconds instead
of nearly a second.
v1.4.39.1 wired the rollup write hook into the Withings sync, /api/import,
and admin-restore paths and widened the boot-time backfill discovery to
per-(user, type, day). Two follow-ups Marc surfaced from the post-deploy
trace remained: the dashboard chart still painted its `< 3 daily points`
empty-state on the 30-point range for accounts whose historic rollup
partition had not yet been folded, and the cold-mount UX waterfall left
every per-type tile waiting on the heavy /api/analytics envelope.
### Fixed
- GET /api/measurements?source=rollup now reconciles the rollup table
against the live measurements table when the read returns suspiciously
few rows. A request that lands while the boot backfill is still folding
the historic partition would previously short-circuit on the sparse
rollup (`rollupRows.length > 0`) and never reconcile with the live
table. The route now probes
`COUNT(DISTINCT date_trunc('day', measured_at))` against measurements
for the requested window when the rollup carries fewer than three
rows on a window of at least seven days; if the live table holds more
distinct days than the rollup, the route folds the
(user, type, DAY, [from, to]) partition inline via
`recomputeUserRollups` and re-reads. The chart paints the full window
on the same request without paying the cost on subsequent requests.
The probe is gated on rollup sparsity so covered-tenant hot paths
stay single-read.
### Changed
- Dashboard analytics fan-out split across two parallel queries. The
per-type tile strip now reads from the slim `?slice=summaries`
branch and paints as soon as the slim slice resolves; the
BD-Zielbereich and glucose tiles stream in from the thick branch
afterwards. Pre-fix the single thick-slice query blocked every
per-type tile until the heavy fan-out resolved, so the mood and
medication tiles (separate routes) painted first and every other
tile arrived as one delayed burst. Both queries share the
`caches.analytics` 60 s LRU server-side so warm hits stay free.
### Notes
- No schema migration. Runtime-only fix on top of the v1.4.39.1
write-path hooks.
- pnpm test --run green at 4654 / 4655 (1 long-standing skip);
targeted suites (src/app/api/measurements, src/lib/measurements,
src/app/__tests__) all clean.
- The inline rollup fold cost is bounded by the requested window and
one measurement type. For the dashboard chart's 30-day BP_SYS window
that is a single 30-row upsert against the composite primary key —
well inside the request budget.
Marc-André Bombeck