placeholderData keeps the previous range painted while a health-chart
range switch fetches, paired with its truth condition: the container
dims and goes inert while isPlaceholderData is true, so the old range
cannot masquerade as the new one. The mood chart needs no pairing — its
range is a client-side slice over one static-key query and never drops
to a skeleton.
/checkups and /mood gain the dashboard-template RSC prefetch: the
primary list read moves into a shared lib read (route + wrapper consume
one query, so filter/order/wire shape cannot drift), the wrapper honours
the DASHBOARD_SSR_PREFETCH kill-switch, resolves identity through
getUnswitchedSession, JSON-round-trips the dehydrated state, and fails
soft to the bare client on every error path. Page-prefetch unit tests
pin the seeded keys and the fail-soft arms; the SSR hydration spec
gains an assertion per page.
The achievement-unlock poll drops to five minutes (in-app writes already
invalidate the cell; the poll only covers out-of-band ingest), and the
plan-proposal poll gains the advisor-style bounded attempt ceiling so an
open thread stops polling after its budget.
`/` runs its reads server-side and hands them to TanStack through a
HydrationBoundary, so the first HTML already carries real tiles. React threw
that away on every cold load. The app shell hydrates first and its mount
answers `/api/auth/me`; the dashboard sits below `loading.tsx`, hydrates later,
and its first client render therefore read an account the server never had.
That disagreed with the streamed HTML, React reported #418 and re-rendered the
whole page. The prefetch paid for its queries and delivered none of its paint.
The account payload is now withheld from the hydration render wherever it is
only rendered. `useAccountOnceMounted()` answers null until the component has
mounted, which is what the server rendered, and hands the payload over on the
next render. The dashboard page, the caregiver card, the getting-started
checklist, the achievements tile and the unit labels read it that way. `useAuth`
itself still reads the cache, because the document vault redirects off
`user.modules` and a first render claiming "no account" bounces it to `/`.
Two tiles disagreed without any account involved. A query reports `isLoading`
true on the client's first render and false on the server, so both now gate on
whether the cell holds an answer.
Nothing in CI ran the shipped configuration: the suite's server turns the
prefetch off so route mocks keep governing the dashboard. A second server runs
it on, and one spec asserts that no hydration error is reported and that the
tile node the server streamed is still the node in the DOM once the page
settles.
Measured over nine cold loads with the CPU throttled 4x: seven bailouts before
and none after, median LCP 869 ms before and 145 ms after. FCP and the time to
the first tile in the DOM are unchanged, because the streamed paint was never
the problem. Keeping it was.
Marc-André Bombeck