Send order let a refetch read before an unanswered mark committed and drop it. A reset's position 0 is written again after a refetch that set out before the server took the reset. The player-session refetch also waits for the player's closing checkpoint, which the player now tracks (progressFlushes); refetched first, the list put the older position back.
Deep-review R4. 1630a3df wrote the YT player's stored position into the react-query cache so a
reopen could not rewind it — but only the feed actually read it back:
- Playlists renders from its own undoable copy of the list, re-seeded only when the SET of ids
changes, so the patched position never reached it: close a video at 830 s, reopen it from the
playlist, and it resumed at the old spot and the next checkpoint wrote that over the 830. A detail
with the same membership now rebases its fresh rows into every snapshot, keeping order and undo
history. (The ids-only guard is older than this round; the write that depended on it was new.)
- Live YouTube search results carry the same per-user position and open the same player, but their
cache was never patched. It is now — patched only, never invalidated, since refetching an
API-sourced search page spends 100 quota units.
Tests for what had none: a Playlists harness (PlayerModal stubbed to record its launch props) and a
PlayerModal harness with a fake IFrame API that records where each item is started — the latter pins
that stepping back to an item watched earlier in the same session resumes at THIS session's position.
3 mutations, each red on its assertion.
The player checkpointed every 5s and the server stored it, but nothing wrote the new
position back into react-query: the close path only marked qk.feed() stale with
refetchType "none", and nothing refetches the feed until it remounts (staleTime 30s,
refetchOnWindowFocus off). So the resume read the position the cache had been FETCHED
with, and the next checkpoint then persisted that older value over the newer one.
Measured on localdev: played to 830s, closed (server had 830), reopened the same card
without a reload -> the row was back to 751s. 79 seconds of progress destroyed by a
reopen, and the card's progress bar never moved either.
The Plex player already solved this for its detail query, with a comment describing the
identical failure; this is the feed-side twin that was missed in that sweep. patchCachedProgress
writes the position the SERVER stored (the endpoint clears trivially-early and near-finished
checkpoints to 0, so mirroring our own reading would disagree with the row) into every cached
feed page and playlist detail, keeping array identity where nothing changed. A session map
covers the second half: the launch queue is frozen at mount, so stepping next->prev back to an
item played earlier in the same session resumed from that snapshot.
Verified in the browser: 811 -> close 816 -> reopen 825, and the card now shows Continue/Restart.
peter