Final extraction in the download orchestrator series. Lifts the 586-line
master worker that drives the entire missing-tracks pipeline from
`web_server.py` into `core/downloads/master.py`. Pure 1:1 lift — wrappers
keep the original entry-point name so the three callers
(`missing_download_executor.submit(_run_full_missing_tracks_process, ...)`)
continue to work without changes.
What the master worker does:
1. PHASE 1 ANALYSIS — per-track DB ownership check with album fast path
(lookup album by name+artist, match tracks within it) plus a
MusicBrainz release-cache preflight so per-track post-processing all
uses the same release MBID (prevents Navidrome album splits).
2. Wishlist removal for tracks already in the library.
3. Explicit-content filter.
4. PHASE 2 transition — if nothing missing, mark batch complete, update
per-source playlist phases, kick auto-wishlist completion handler.
5. Soulseek album pre-flight — search for a complete album folder before
falling back to track-by-track search, cache the source for reuse.
6. Wishlist album grouping — derive per-album disc counts and resolve ONE
artist context per album so collab albums don't fold-split.
7. Task creation with explicit album/artist context injection +
playlist-folder-mode flag propagation.
8. Hand off to download_monitor + start_next_batch_of_downloads.
9. Error handler — phase=error, reset YouTube playlist phase to
'discovered', reset auto-wishlist globals on auto-initiated batches.
Dependencies injected via `MasterDeps` (21 fields) — wide surface
covering config, MB caches/locks, soulseek client, source-page state
dicts, multiple callbacks (wishlist removal, explicit filter, executor
+ auto-completion fn, monitor, start_next_batch). The only behaviour
difference from a pure paste is `import traceback` hoisted to module
scope (was inline in the except block) — same behaviour. Trailing
whitespace on two blank lines also got normalized away by the editor;
neither has any runtime effect.
`reset_wishlist_auto_processing` callback wraps the
`global wishlist_auto_processing, wishlist_auto_processing_timestamp`
write + `wishlist_timer_lock` since `global` can't reach back into
web_server.py from a separate module.
Tests: 21 new under tests/downloads/test_downloads_master.py covering
analysis-phase state, force_download_all, found-track wishlist removal,
explicit filter, no-missing complete + per-source state updates, auto
wishlist completion submit, album fast path (direct + fallthrough),
MB preflight (caches both keys, no-mb-worker no-op), task creation
(queue + tasks dict, explicit context for albums, wishlist album
grouping consistency, playlist folder mode), monitor + next-batch
handoff, multi-disc total_discs computation, error handler (phase set,
youtube reset, auto wishlist reset), and batch-removed-mid-flight
defensive path.
Full suite: 1050 passing (was 1029). Ruff clean.
End of the PR4 series — `web_server.py` lost ~590 lines on this commit
alone; total trim across PR4a–PR4h is ~2900 lines of orchestrator code
moved into focused `core/downloads/*.py` modules.
fa29ee2195