feat(database): shape the library like files, and shrink the catalog

Plans 013 and 014, the album page that prompted them, and the smaller
fixes they turned up. Changelog, largest first.

## The local library is shaped like files, not like MusicBrainz

`audio_files` carries its own tags and points at `albums` and
`artists`; `file_genres` is the one real many-to-many. `recordings`,
`release_group_recordings`, `artist_credit`, `artist_credit_artist`,
`recording_genres`, `release_groups` and `release_to_rg` are gone from
the local side, and with them a six-way join in every read, a
`MIN(release_group_id)` subquery in eleven queries and a
first-credited-artist subquery in nine. Measured on a real 25,966-file
library, every many-to-many that model expressed was 1:1 in the data.

- Ownership is a file. `GetFilePathsByRecordingMBIDs`,
  `LibraryMBIDIndex.CheckMBIDs`, `collectLibraryEntities` and
  `pruneStaleLocalCrossReferences` all join `audio_files`, so the 812
  orphaned recordings, 216 release groups and 260 artists that library
  carried are now structurally impossible.
- One projection: every track query selects from the `track_metadata`
  view, one row type, one mapper. Nine hand-rolled copies had drifted
  far enough to report different years on different screens.
- `library_id = 0` means every library, so each list query exists once
  instead of scoped and unscoped with a branch at every call site.
- No migration chain. `sql/schemas/` is the one description of the
  shape; `sql/migrations/`, `applyMigrations` and `schema_migrations`
  are squashed away, along with the drift between them that had sqlc
  generating against a stale schema.
- `database.InsertTestTrack` is the one test seeder; twenty test files
  had been assembling the old FK chain each in its own order.

## The catalog stores its ids as bytes

`explore_index`'s three 36-char MBID columns and its entity-type text
are 16 raw bytes and a small integer. The table and its six indexes go
780 MB to 405 MB on a real 2,052,200-row catalog, which is why a fresh
install is ~0.6 GB rather than ~1.0 GB.

- `backend/explore/mbid.go` is the only place the encoding is known;
  everything above it speaks dashed strings.
- `CHECK(length(mbid) = 16)` makes a stringly write fail at the insert
  rather than silently returning no rows, since SQLite does not coerce
  between TEXT and BLOB.
- The importer asks the artifact what encoding it carries and converts
  on the way in, so the artifact already published keeps working and no
  format bump is needed.
- `indexRowColumns`/`scanIndexRow` replace four copies of a 22-column
  list, and `TestStoredEncodingRoundTrips` sweeps every read path.

## An album page that says how much of the album is yours

- One question, asked once: is there a file. `filePaths` is filled by a
  single batched lookup when the tracklist settles, and the badge, the
  Play count, the dimmed rows and every menu item read it — replacing
  four claims of decreasing confidence that could show a green tick on
  an album whose every action did nothing.
- Play, Play 7 of 12, or no play button at all.
- `total_tracks` on `explore_index` (~2 bytes over 400,677 release
  groups) and on `audio_files` from tags that have always carried it:
  a complete MBID-matched album now makes no catalog call at all, where
  it used to spend the most expensive request the app makes.
- A merged cluster shows the running order the most releases agree on,
  and the version list marks the release you own rather than standing a
  synthetic entry in for it.
- `AlbumReleasesFailed`: a slow fetch is no longer reported as a failed
  one by a 12-second timer.
- Rows not in the library are dimmed in place (with `aria-disabled`)
  instead of the owned ones wearing a green tick and a legend.

## Caches and cover art get ceilings

- Only the three tiers of a cover are stored; the full-resolution copy
  nothing rendered was 1,134 MB of a 1.4 GB covers directory.
- One artist portrait is downloaded and the rest are remembered as
  URLs — 4.1 GB of a 5.3 GB cache was candidates no code path reads.
- `browsedArtBudget` and `httpCacheBudget` bound what an age cannot:
  the same install held art for 5,770 artists in a 1,301-artist
  library.
- `OrphanedArtistImagesJob` joined a bare MBID onto a sharded
  directory, so it deleted the rows that were the only record of the
  files it left behind. `explore.ArtistImageDir` is that layout's one
  definition now.

## The autotag queue asks whether there is work

`tagging_items` was a row per album folder, not a queue, and no query
read the `tag_status` column that held the answer. The four queue
queries ask the files, which matters most where it is least visible:
`startPrefetch` was scoring every album in a tagged library against
MusicBrainz.

## Phantom playlist tracks resolve in place

An M3U8 imported before its files leaves phantom rows; they now match
by path and fall back to position, keep their place in the playlist
when resolved, and pair best-first so two phantoms cannot claim the
same file.

## Playing a track plays the list it is in

Double-click, and Play on a single row's menu, queue the list as
displayed with `startIndex` on that row — the album page and the track
list used to queue one track and discard the album around it. A
multi-row selection still plays exactly itself.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AfVYUVExXsx1nSWrXN8mAh

.pi/skills/yellowjacket-dev/references/fixtures.md

@@ -63,5 +63,24 @@ Never hand-write one. Seeding points `YJ_CORE_INDEX_URL` at a dead
 address on purpose, so no seed depends on what the explore artifact
 server happened to be serving.
 
-Rebuild a seed after any schema change, or the restored database is
-migrated on open in a way the seed's author never saw.
+Rebuild a seed after any schema change. Nothing migrates a restored
+database: `applySchema` is `CREATE TABLE IF NOT EXISTS`, so an old seed
+keeps its old columns, the app starts, and the first query dies on
+`no such column`.
+
+**Restoring the seed does not disable the artifact fetch — only
+*building* it does.** `dev-headless` leaves `YJ_CORE_INDEX_URL` alone,
+so on a developer machine the restored app immediately downloads and
+imports the real ~1.1M-row catalog, through the one writer connection,
+while whatever you started it for is running. A full `make e2e` against
+that reported **14 failures** that were all contention; the same suite
+against the same seed with
+
+```bash
+YJ_CORE_INDEX_URL='http://127.0.0.1:1/none.tar.zst' make dev-headless SEED=default
+```
+
+is the configuration CI runs (`ci.yml` sets exactly that address) and is
+what to use before believing a failure. The tell is in `.dev/app.log` —
+an import logging progress — and in how the failures look: timeouts
+spread across unrelated specs rather than one surface being wrong.

.pi/skills/yellowjacket-dev/references/schema-change.md

@@ -1,66 +1,76 @@
 # Changing the database schema
 
-The reasoning — why there are two files, what the old 48-step migration
-chain got wrong, and when squashing is legitimate — is in `CLAUDE.md`
-under *Backend packages → database*. Read it once. This is the
-checklist.
+The reasoning — why the local library is shaped like files rather than
+like MusicBrainz, and what the metadata tables cost before they went —
+is in `CLAUDE.md` under *Backend packages → database*. Read it once.
+This is the checklist.
 
-**A brand-new table needs one file, not two.** The rule below is about
-a *column added to a table that already exists*. `applySchema` runs
-every file in `sql/schemas/` on every open, so a
-`CREATE TABLE IF NOT EXISTS` reaches an existing install verbatim and a
-migration for it would be a second description of the same table — the
-thing the third rule forbids. Its indexes go in the schema file too,
-because the column and the index arrive together.
+**There is one description of the schema and no migration chain.**
+`sql/schemas/*.sql` declares the current shape; `applySchema` runs every
+file on every open, and `CREATE ... IF NOT EXISTS` makes that idempotent.
+`sql/migrations/`, `applyMigrations` and `schema_migrations` were
+squashed away with plan 013. So:
+
+**Adding a table or a column is one edit to one file.**
+
+```bash
+make generate            # sqlc + templ
+go test ./backend/database/ ./backend/datamap/
+make test
+```
 
 A new table has a second gate: **`backend/datamap`**. Add an entry
 stating its Kind and Lifetime, or `TestCatalogCoversSchema` fails — and
 if it is `Authored` and cascades, `TestAuthoredCascadesAreDeliberate`
-wants an explicit exemption with a note, because authored data is what
-a user cannot get back.
+wants an explicit exemption with a note, because authored data is what a
+user cannot get back. If a *column* holds a different Kind from its
+table (an authored flag on an owned projection, a fetched value beside a
+tag-derived one), say so in the entry's note; `audio_files` and `lyrics`
+are the worked examples.
 
-Adding a **column** to an existing table needs **two** files, not one:
+**Existing databases are not migrated.** Nothing upgrades a database
+from an older shape — delete your dev `YJ_HOME` and rescan, and rebuild
+any seed you rely on (`make sandbox-seed NAME=default`). Revisit this
+once real user databases exist in the wild.
 
-1. **`backend/database/sql/schemas/*.sql`** — `CREATE TABLE ... IF NOT
-   EXISTS`, the literal target shape, what sqlc reads and what a fresh
-   install gets verbatim. Add the new column **last** in the
-   `CREATE TABLE`.
-2. **`backend/database/sql/migrations/NNNN_description.sql`** — the
-   `ALTER TABLE ... ADD COLUMN` (and any index on it) that gets an
-   existing database to the same shape. Schema files are a no-op against
-   a table that already exists, so without this an upgrade never gets
-   the column.
+**A stale one fails at the first query, not at open**, which is worth
+knowing before you read the error. `applySchema` is
+`CREATE TABLE IF NOT EXISTS`, so an old database keeps its old columns
+and gains nothing; the app then starts fine and dies on
+`no such column: title`. Every tier that does not *run the app* — unit
+tests, `make ui-test`, `tsc` — is green while this is true, because
+they build their database from the current schema. `make e2e` and
+`make dev` are the two that will tell you, and only after the seed has
+been rebuilt.
 
-Then:
+## The four ways this goes wrong
 
-```bash
-make generate                                        # sqlc + templ
-go test ./backend/database/         # migration + column-order tests
-make test
-```
+- **A query file must be ASCII.** sqlc's parameter rewriter works on
+  byte offsets, so a single non-ASCII character in a *query* comment
+  (an em dash, a curly quote) shifts every placeholder and generates
+  garbage like `SELECid` — a parse error a long way from its cause.
+  Schema files are not rewritten and may contain anything.
+- **A slice and a named parameter do not compose.** `sqlc.slice`
+  expands to N placeholders, but `sqlc.arg` is numbered independently,
+  so the two in one query bind the wrong values —
+  `GetFilePathsByAlbums([1,2], 0)` read album id 2 as the library id.
+  Where a query needs both, return the column and filter in Go.
+- **A write wearing a query's shape still needs the writer.**
+  `QueryContext`/`QueryRow` route to the query-only read pool, so an
+  `INSERT ... RETURNING` through one fails at runtime with "attempt to
+  write a readonly database (8)". Use `ExecContext`, or
+  `QueryRowWriter`. `TestNoWritesOnTheReadPool` walks the tree for it.
+- **A view is dropped and recreated.** `CREATE VIEW IF NOT EXISTS`
+  no-ops against a database holding the old definition, so
+  `track_metadata.sql` opens with `DROP VIEW IF EXISTS`.
 
-Rebuild any seed you rely on (`make sandbox-seed NAME=default`) and
-delete your own dev `YJ_HOME` if you want to see the fresh-install path
-rather than the migrated one.
-
-## The three ways this goes wrong
-
-- **Column order must match between the two paths.** `ADD COLUMN`
-  always appends, so a migrated column declared anywhere but last in
-  `CREATE TABLE` leaves fresh and upgraded installs disagreeing on
-  order — and sqlc binds `SELECT *` positionally, so one of them
-  silently reads the wrong field.
-  `TestMigrations_ColumnOrderMatchesFreshInstall` is the regression test.
-- **Do not put an index on a migrated column in `sql/schemas/`.**
-  Schema files run *before* migrations, against a database that may not
-  have the column yet, and the predicate fails. Declare the index in the
-  migration, after the `ALTER TABLE`.
-- **Do not add a third description of the schema anywhere.** A
-  migration's `ADD COLUMN` failing with "duplicate column name" against
-  an already-current database is expected and tolerated, not an error to
-  route around.
+## Where things go
 
 New queries go in `backend/database/sql/queries/`; generated Go lands in
-`backend/database/sql/sqlcgen/`, which is never edited by hand. Tests
-use `database.NewTestDB(t)`, built by the same `applySchema` production
-uses, so the two cannot diverge.
+`backend/database/sql/sqlcgen/`, which is never edited by hand. Anything
+returning a track selects from the `track_metadata` view rather than
+re-joining — that is why there is one row type and one mapper.
+
+Tests use `database.NewTestDB(t)`, built by the same `applySchema`
+production uses, and seed rows with `database.InsertTestTrack(t, db,
+database.TestTrack{...})` rather than assembling inserts by hand.