"Get full history" on a channel page left the list on the cards the channel already had. The
count above it climbed into the thousands, the grid did not move, and only a browser F5 brought
the rest in.
The mechanism: the backfill runs in a BackgroundTask, so the PATCH that starts it returns before
a single row is written — and the mutation invalidates `qk.feed()` on that RESPONSE, which just
refetches the OLD catalogue. Nothing afterwards refetches it: the feed's infinite query has no
interval, and the app-wide defaults are `staleTime: 30s` + `refetchOnWindowFocus: false`. The job
emits no event either (the realtime layer only carries messages today), so the channel detail's
4s live poll is the only thing in the app that sees the job progress — and it refreshed only
`qk.channel`.
So the poll now drives the grid too: on a tick where the stored count moved (or the backfill
finished), it invalidates `qk.feed()` and the `qk.feedSummary()` behind the count pill. The window
is the poll's own (`deep_requested && !backfill_done` on the previous reading), so a detail
refetch caused by some other mutation — each of which invalidates the feed itself — cannot come
through here twice.
Measured on localdev against the real account, same instrument, `document.visibilityState`
forced visible (the poll deliberately pauses on a hidden tab, and a headless pane reads hidden —
without that the first measurement was about the harness, not the fix):
before — CASCADA 19 -> 176 stored: the header updated live to "162 normal", the grid and its
count pill sat on "5 items" for 50s.
after — fern 54 -> 139 stored: "54 items" -> "139 items" by ~12s, no reload.
6 vitest, mutation-checked against six mutations (no invalidation at all; grid only, count pill
forgotten; predicate ignored; no channel-identity guard; completion with an unchanged count
dropped; poll-window guard dropped) — each one red on exactly the test that names it.
peter
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