An event carries what a consumer needs so it never has to invalidate.
- `library-store` answers `TrackPlayCountChanged` by patching one
track, replacing the tracks array (consumers key memoized caches on
its identity) while sharing every unchanged Track — instead of
discarding four collections and refetching 25 MB per song.
- `playlist-store` answers `PlaylistTracksChanged` by refetching the
one playlist the event names, plus the summaries, since `UpdatedAt`
is a sort key. 2 668 kB and 172 ms for one heart, against 2.0 kB. It
falls back to a full invalidate only where a patch cannot be shown
to be equivalent: no id, a cold cache, an unknown id, or a fetch
already in flight. And a store with no subscriber fetches nothing —
the singleton's constructor used to put every track of every
playlist on the path to first paint for a view the user might never
open.
- `library-store` guards every fetch with a cache generation and holds
the request itself instead of deriving a promise from subscriber
notifications, which fixes the library-filter race and the
never-settling waiter together: they are the same bug seen from
either end.
- `explore-cache`'s two art caches are bounded, sharing one exported
cap constant — the artist photo's data URL is held by both, so
capping either alone frees nothing at all and reads as a fix that
did not work.
- `search-store` deliberately does *not* coalesce its notify: deferring
makes a subscriber that unsubscribes synchronously after a `setTerm`
miss the notification entirely, which is a semantic change rather
than an optimisation, and this is the store on the keystroke path.
- `selection-controller` retains its keys across a refetch rather than
clearing them, since they are file paths and those survive one, and
`getSelectedKeysOrdered()` gains an early exit. It stays a walk of
the list: an index goes stale on any re-sort, re-filter or refetch
while a file path survives all three, and 3 ms does not buy a
silently mis-ordered queue insert.
logan
7d9e0bf2fb