[ajslater]

Summary

#910 pinned dynamic covers, custom covers and finish-on-last-page on, and read-RTL-in-reverse off. It kept their columns so the toggles could come back with a revert. This PR removes them for good.

• Migration 0057 removes SettingsBrowser.custom_covers / dynamic_covers and SettingsReader.finish_on_last_page / read_rtl_in_reverse with four RemoveField ops. All four shipped in 0038, so this has to be a new migration, not an edit to an old one. It is reversible: the browser columns have defaults and the reader columns are nullable. Historical migrations are untouched.
• Defaults, serializers, session payload: the keys are gone from BROWSER_DEFAULTS / READER_DEFAULTS, the reader, browser and session-defaults serializers, and get_reader_defaults (which now iterates READER_DEFAULTS). BrowserCoverInputSerializerBase is folded into BrowserSettingsSerializerBase.
• Telemetry and admin stats: the 3 sessions buckets and 8 per-user buckets are removed. The payload is still counts and closed enums only.
• User-data sidecar: the two columns are gone from the schema, the dump and the restore. SCHEMA_VERSION is unchanged because the store only adds columns and restore reads named columns. The legacy _browser_row restore fixture keeps both keys as a regression guard for restoring an old sidecar.
• Dead code removed:
  • the sort-name fuzzy cover match and parent_route in cover.py, plus the custom-cover early return;
  • the unused BrowserCoverInputSerializer;
  • the coverSettings getter and COVER_KEYS / DYNAMIC_COVER_KEYS;
  • setReadRTLInReverse;
  • the parked browser-settings-covers.vue;
  • every PENDING SCHEMA REMOVAL note.
• NEWS line under v2.5.5.

Test plan

• make fix, make lint, make ty: all clean
• make test: backend 1683 passed, 1 xfailed; frontend 994 passed (97 files)
• manage.py makemigrations --check --dry-run: no changes
• Grep for the four names (snake_case and camelCase), PENDING SCHEMA REMOVAL, parent_route and parentRoute: the only hits are 0038, 0057, the legacy restore fixture, and identifiers of the separate CustomCover upload feature
• Manual, on a copy of a dev DB:
  • migrate applies 0057, and migrate codex 0056 reverses it
  • the browse page shows collection and custom covers
  • a book is marked finished on its last page
  • an RTL book still reads right to left
  • the admin Stats tab renders without the removed rows
  • a user-data dump and restore works against a sidecar made before this change

Chronicle still charts dynamic_covers and tolerates the missing keys. Retiring that panel is a follow-up in that repo.

🤖 Generated with Claude Code