Add episodeCacheMode/count/days preferences (default: date, 60 days).
Apply the bound when reading instead of writing, so a preference change
takes effect without a refetch; the full parse cache stays intact so
fetch-more can page beyond the bound. Thread the window through
load/saveFeedsToFile and update tests and task docs.
Persisted feeds keep only episodes from the last 30 days (plus completed
downloads); older episodes live in volatile memory and survive refreshes
via union merge, with per-feed in-memory caches capped at 500. Refresh
batches run at FETCH_CONCURRENCY=4 with per-feed incremental apply (no
Promise.all barrier), config.json writes are trailing-edge debounced
(250ms, immediate flushPendingSave for unsubscribes), and cold
fetch-more refetches abort at FETCH_TIMEOUT_MS. A shared activity store
powers a global top-right indicator covering refresh, fetch-more,
subscribe, search, and downloads.
Also includes the in-flight incremental RSS parsing (chunked with
event-loop yields) and refresh spinner work this tree already carried.
Self-rescheduling refresh timer (default 30 min, configurable via a
Preferences item, re-read on every tick, skips in-flight refreshes).
fetchEpisodes returns null on network failure/timeout so a failed
refresh can never wipe a feed's episodes (addFeed/refreshFeed/
refreshAllFeeds all treat null as unchanged); feeds still refresh on
launch.
Two fixes to refresh order stability (My Shows / Feed sort by
lastUpdated):
- A refresh that fetches identical episodes no longer bumps
lastUpdated (id-set comparison via sameEpisodes), so unchanged
feeds keep their position instead of reordering every cycle.
- refreshAllFeeds now fetches in parallel and applies ONE atomic
update instead of a per-feed setFeeds, which re-sorted the list
once per completion and made order flap until the batch finished.
Adds feed-refresh regression tests with mocked clock.
