Final lift in the web_server.py extraction effort. Pulls two route
handlers + one background worker out of `web_server.py` into new
focused packages:
- `core/streaming/prepare.py` — 258-line stream-prep worker that
downloads a track to the local Stream/ folder for the browser audio
player.
- `core/playlists/explorer.py` — 305-line route handler for
`POST /api/playlist-explorer/build-tree` that streams an NDJSON
discography tree from a mirrored playlist.
What `prepare_stream_task` does:
1. Reset stream state to 'loading' with the new track info.
2. Clear any prior file from Stream/ (only one stream lives there).
3. Spin up a fresh asyncio event loop and `soulseek_client.download()`.
4. Poll progress every 1.5s. Queue timeout 15s; overall 60s.
5. On succeeded + bytes-match: find the file with retry, move into
Stream/, signal slskd completion, mark state 'ready' with file_path.
6. On error/timeout/cancel: state goes to 'error' or 'stopped'.
7. Finally: tear down the event loop cleanly.
What `playlist_explorer_build_tree` does:
1. Validate request, load playlist + tracks from DB.
2. Pick active metadata source (Spotify if authed, else fallback).
3. Group tracks by artist using discovered matched_data when the
provider matches the active source.
4. Stream NDJSON: meta line → one artist line per group → complete line.
5. Per artist: cache check → resolve discography → tag releases with
`in_playlist` flag based on title-similarity match → filter by mode
(`albums` = only matches; `discographies` = full disco).
6. Mark playlist as explored on completion.
Strict 1:1 byte parity:
Both functions exposed their dependencies through proxy patterns
established in earlier lifts (PR4–PR8). For prepare_stream_task,
`stream_state` is a deps property; for the explorer, Flask `request` /
`jsonify` / `Response` are injected via deps so the lifted body keeps
its native syntax. Both lifts verified ZERO diff against the original
after `deps.X` → global X normalization.
258 lines orig = 258 lines lifted (prepare_stream_task).
305 lines orig = 305 lines lifted (explorer).
Bonus cleanup: web_server.py's module-level `import shutil` and
`import glob` were now unused (only `_prepare_stream_task` used them
at module scope; every other reference is via inline `import shutil`
in respective function bodies). Removed both module-level imports —
ruff caught the F811 redefinitions and confirmed they're truly
redundant.
Dependencies for `PrepareStreamDeps` (11 fields):
config_manager, soulseek_client, stream_lock, project_root,
docker_resolve_path, find_streaming_download_in_all_downloads,
find_downloaded_file, extract_filename, cleanup_empty_directories,
plus 2 stream_state property delegates.
Dependencies for `PlaylistExplorerDeps` (9 fields):
Flask request/Response/jsonify, spotify_client, get_database,
get_active_discovery_source, get_metadata_fallback_client,
get_metadata_fallback_source, get_metadata_cache.
Tests: 6 new under tests/streaming/test_prepare.py (state init,
Stream/ folder creation + clearing, download-init failure, completed
+ moved + ready state, partial-bytes incomplete-warning path) plus 9
new under tests/playlists/test_explorer.py (5 validation early-exit
paths, streaming response shape with meta/complete lines, mark-
explored side effect, discovered-artist grouping using matched_data,
provider mismatch falling back to raw artist name).
Full suite: 1355 passing (was 1340). Ruff clean.
End of the web_server.py extraction effort. Started at ~45,000 lines
across PR4–PR8 + this commit; finished around 35,000 lines with the
heavy worker + route logic now living in domain-cohesive packages
under core/. The remaining bulk in web_server.py is route handlers,
service initialization, and the deferred 1530-line
`_register_automation_handlers` (startup-only, marginal lift value).
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