- A channel someone follows: the videos its exploration brings in (the list's
dialog, the channel page's explore) come in as the catalog's own, not
flagged via_explore, which subscribing would never clear and which kept
their watched marks waiting for good.
- The explore cleanup keeps the row of a channel a Takeout history shows
watched (it still reclaims the videos), so a looked-at channel no longer
drops off the list.
- The Shorts job takes up only users whose list still has lengths to ask or
channels to name, by each user's own follows, blocks and dismissals; a
naming that failed is tried again, and the list says it is not complete.
- The length lookups have a daily share of their own: a large history no
longer leaves the export's Watch later file waiting a day.
- Only a channel of the user's own history can be put out of the list.
- The dialog's videos have a query root of their own: the list's
invalidations no longer re-ask (and re-explore) under an open dialog.