Review round on the E2 stack (S1-S5). No correctness bugs; the surviving
low/medium findings addressed:
- altitude (#1): extract the shared `tags_by_category` helper used by BOTH
filtered_query (SQL tag WHERE) and feed_summary (Python facet/count), removing
the category-grouping duplication, and add bidirectional "keep in lockstep —
equivalence-tested by test_feed_summary_matches_count_plus_facets" comments so
the SQL<->Python tag rule can't silently drift.
- test-coverage (#2): the /feed/summary equivalence test seeded only system tags,
leaving the `ChannelTag.user_id == user.id` visibility branch untested. Add a
user-owned Tag + link + two combos; the suite is now 346 (was 344) and the new
cases pass (feed_summary agrees with /feed/count + /facets on user-visible tags).
- dead-code (#3): annotate get_feed_count, get_facets, and the FE api.feedCount/
facets as "SUPERSEDED by /feed/summary — kept only as the equivalence oracle;
retire together" so the intentionally-retained surface reads as deliberate.
Not changed (confirmed no-op): the search channel-name resolve (#4) is
once-per-request on a 633-row table and a deliberate pre-resolve for PERF-12's
BitmapOr plan; the facet loop (#5) already computes passes() once per
(channel, category) with a distinct exclude each, so there is no recomputation.
Gate green: ruff + 346 pytest; frontend tsc/knip/prettier (FE change is a comment).
The FE fired /feed/count (1 pass) + /facets (3 passes) on every filter change =
4 full scans of the subscribed set. New /api/feed/summary does ONE grouped query
(the base filter with tags stripped, GROUP BY channel_id -> per-channel video
counts) and derives the total count + every tag's distinct-channel facet count in
Python on the ~few-hundred-row channel map, faithfully mirroring filtered_query's
channel-based tag logic + the /facets drill-down (own category dropped, unless a
conjunctive topic-AND). Returns {count, facets} — the same numbers the two old
endpoints returned.
FE: a single shared query (Feed reads .count, Sidebar reads .facets); same key +
filters, so React Query dedupes to ONE request. Invalidations repointed to
qk.feedSummary. The old /feed/count + /facets endpoints (and their now-unused FE
api/qk) are kept as the equivalence-test oracle + safety net; a later cleanup can
drop them.
New equivalence test (test_feed_views, 8 filter combos incl. cross-category,
disjunctive/conjunctive topic modes, search): /feed/summary count == /feed/count
and facets == /facets, byte-identical. Structural win: 2 requests / 4-6 queries
-> 1 request / 2-3 queries (the review measured 530 -> 144 ms). Gate green:
344 pytest, frontend tsc/eslint/knip/prettier/222 vitest.
Move feed, channels, sync, playlists, tags, notifications, saved-views and
quota out of the lib/api.ts god object into per-domain slice modules, each
owning its own types + method slice and spread into the façade. The `api`
object shape and all 54 call sites are unchanged; account/auth/setup/admin
stay inline until S2.
Reunites the interleaved tags read/CRUD that motivated the epic.
peter