The calendar pulled every airing show in the library regardless of whether you
follow it. Now it's scoped to the EFFECTIVE watchlist by default — explicit show
follows ∪ airing library shows (not muted), same logic as the Shows watchlist tab —
so it tracks what you actually care about, and you can mute a show off it. A
'Watchlist / All library' toggle on the calendar lets you flip to everything you
own (remembered in localStorage).
- calendar_upcoming(watchlist_only=) adds the watchlist filter; /calendar takes
?scope=watchlist|all (default watchlist).
- Calendar page gets a scope toggle (defaults watchlist, persists, refetches on
change).
Tests: DB scope (followed-only / airing-default / mute drops out / all-library sees
all) + frontend wiring. node --check clean.
