`commit`'s success handler writes the dragged list into the detail cache — round 6's fix, so a
re-entry inside the 30s staleTime renders the accepted order without a request — but then invalidated
only the LIST key, while the YouTube sibling it cites invalidates both. `next` is the membership of
the render that started the drag, and `reorder_playlist` only touches the rating_keys it is handed,
so it never ratifies that list: anything that landed meanwhile was clobbered by the write with
nothing scheduled to correct it. `commit` sets no busy flag either, so a removal really can complete
while a reorder is in flight, and with staleTime 30s and refetchOnWindowFocus off the phantom row
stayed on screen for as long as the view was mounted — and the next drag persisted an order built
from it.
Round 6's test had to be re-pointed, because it was written in a world with no refetch: its mock
answered the pre-reorder order forever, which a server that just accepted the write cannot do. It now
holds the refetch open instead, so it still pins what round 6 actually fixed — the cache is right
WITHOUT waiting for a request — and would fail if the write were deleted. Both halves are
mutation-checked against each other.
The YouTube list got this rule in round 5 — one accepted write, one cache entry
that matches it — and the Plex list got only the rollback half of that fix. Its
success path invalidated `qk.plexPlaylists()`, a disjoint key root, and never
touched `qk.plexPlaylist(id)`: the key `putBack` rolls back to, and the one a
re-entry renders from without refetching.
So after an accepted drag the detail cache still held the pre-reorder order.
Leaving the playlist and coming back inside the 30 s staleTime showed the
reorder undone, and the next drag from there persisted that — silently undoing
an order the server had taken. Measured in jsdom: server 2,1,3, cache 1,2,3, no
refetch.
1 test, mutation-checked.
peter