The compiler auto-memoises, which is the point: it infers what the app's
112 `useCallback` and 48 `useMemo` call sites were hand-written for and
applies the equivalent itself. It is on repo-wide with no opt-out list —
it bails on anything it cannot prove safe, and says so through the lint
rules. Verified in the built bundle rather than assumed: 369
`react.memo_cache_sentinel` markers across 35 of the 76 chunks.
ONE transform, shared by vite.config.ts and vitest.config.ts through
reactPlugin.ts. Not two `react()` calls: if the compiler ran only in the
production build, every vitest run would exercise code the user never
receives and a compiler-induced change would ship green — the same
gate-vs-image split 0.93.2 was released to fix. The plugin is imported
rather than named by the usual string, because a string is invisible to
knip and, worse, a typo in it is a silent no-op that ships an uncompiled
bundle, while a bad import is a tsc error.
eslint-plugin-react-hooks 5 -> 7 brings the whole compiler rule set: 283
findings, triaged rather than bulk-suppressed, because the two halves
needed different answers.
react-hooks/refs (217) is OFF. 153 of those 217 are this app's popover
architecture, not its history: 79 are @floating-ui/react's documented
`pop.refs.setReference` / `getReferenceProps` callback-ref setters, and
74 more are passing the popover handle down as a prop, which is what
components/ui's popover engine is for. Suppressing them would not help
the next popover anyone writes. The remaining ~64 are genuine
render-phase `ref.current = x` writes and are real, but the rule cannot
tell them apart here; they are E27 S2's work.
The other 66 go into eslint-suppressions.json as a ratchet — new
violations fail the gate, and `--prune-suppressions` makes a fixed one
fail too until it is removed. 45 of them are `set-state-in-effect`,
which IS E27 S2's subject, so that sprint now has a measured worklist.
react-i18next deliberately stays on 14. It never declared a React-19
peer — every version from 14 to 17 asks only for `react >= 16.8.0` — and
what the newer lines actually require is i18next 25/26 against our 23.
That is an i18n runtime migration wearing a React hat, and it buys this
sprint nothing.
Two React 19 type changes: `useRef<T>(null)` is now `RefObject<T | null>`
(the honest shape — the element is null until it mounts), so
PlexPlayerSettings' prop follows; and reactPlugin.ts joins
tsconfig.node.json's include.
The compiler skips memoising VirtualGrid and reports it: TanStack
Virtual's `useVirtualizer()` returns functions that cannot be memoised
without going stale. That is the right trade for a component whose cost
is its row window, and it is the one such site in the app, so it carries
a targeted disable with the reason — a second incompatible library
anywhere else must still stop the gate.
Nine lanes green, vitest 1558. Browser UAT on the dev server against the
still-running React 18 build as a control: boot, feed (virtualized grid,
popover menu, a filter change that moved the list 195,187 -> 64 items
with the URL mirrored, so no stale memoised UI), command palette, player
modal — no console errors on any of it.
