A related list's cursor cost nothing, and a cursor is a free string: a replayed one read and
enriched without end. Every request now takes a slot of the user's daily cap — taken under a lock
before the work (`quota.claim_action`), so requests sent together cannot all pass the last free
one, and given back when the request fails outright (`quota.refund_action`). The live search's
scrape source takes its slots the same way.
A limit of 0 turns the feature off: a distinct 409 `related_disabled` / `search_disabled`, and
`/api/me` says `related_enabled` / `search_enabled` so the UI can leave it out.
A videos.list that fails no longer reads as an empty page: `ingest_candidates` raises, and the
search and the related list answer the refusal (the shared budget spent says "quota") instead of
"no results". The two routes' page loops are one (`_gather`).
`clear` deletes only what the caller found: a related list's rows carry no find, and any user
could name them.
The player shows what YouTube lists beside the video, without what the
user has watched or hidden. Wide, a Related tab beside the description;
stacked, a button beside the info opens them in a drawer. A row plays in
the same player (Back returns) and the list stays the opened video's.
A switch picks on-topic or Hungarian-trending lists, kept on the account.
Each related row says whether the user follows its channel; the row is
the video card's narrow form with its whole menu. VideoMenu moves to
features/video, where the player can reach it.
GET /api/search/related/{video_id} reads the list YouTube shows beside a
video from the website's InnerTube "next" endpoint (no quota), and brings
it into the catalog the way live-search results come in. It leaves out
what the user watched or hid, here or in their Takeout history (unless
taken back to "new" since), blocked channels and the video itself, and
pages on until 20 are gathered (at most 4 pages). region=topical|hu picks
the locale the list is filled in. Its own per-user daily cap
(related_daily_limit_per_user, one event per opened list); a failed
scrape answers 422 youtube/unavailable.
The InnerTube request (live key, consent cookie, errors) moves into
youtube/innertube.py, shared by the search scrape and the related one.
peter