Add torrent usenet PR notes and test updates

Adds the PR description for the torrent/usenet release-staging feature and updates drifted tests for the new plugin registry entries and search exclude_sources signature.

Verified with the focused pytest command covering cancellation and default registry source registration.

pr_description.md

@@ -0,0 +1,76 @@
+## Summary
+
+Adds torrent and usenet as release-oriented download sources backed by Prowlarr and the configured downloader clients. These sources can download full releases, stage the resulting audio files, and let SoulSync match/import the requested tracks through the existing post-processing pipeline.
+
+This PR also improves the torrent/usenet user experience with clearer release-download progress, source-aware service labels, library history provenance, and safer staged-release matching for album files that include featured-artist or bonus-track filename noise.
+
+## Scope
+
+- Adds torrent and usenet plugin support for release downloads.
+- Adds album-bundle staging for single-source torrent/usenet album downloads.
+- Keeps hybrid album downloads on per-track-capable sources by excluding torrent/usenet from hybrid album per-track searches.
+- Allows torrent/usenet in hybrid for non-album track downloads, such as playlist singles and wishlist tracks.
+- Selects the requested audio file from completed release folders instead of importing the first audio file blindly.
+- Reports live album-bundle progress to the Downloads page and download modal.
+- Records torrent/usenet provenance in library history.
+- Adds UI polish for release-first download states.
+
+## Behavior Gates
+
+- Users who do not select torrent or usenet as a download source should not hit the new download paths.
+- Single-source `torrent` / `usenet` album downloads use the release staging flow.
+- Hybrid album downloads skip torrent/usenet and continue through the existing per-track source chain.
+- Hybrid non-album downloads may use torrent/usenet when they are included in the hybrid order.
+
+## Notable Implementation Details
+
+- Torrent/usenet release downloads use private per-batch staging folders under the configured album-bundle staging root.
+- Post-processing receives the real source label (`torrent` / `usenet`) so library history no longer falls back to `Soulseek`.
+- Staging matching strips only conservative noise like `(feat. Artist)` and `(Bonus Track)` while preserving meaningful version text like `remix`, `extended`, `live`, and `acoustic`.
+- When a staged release does not contain a requested track, the task is marked not found instead of repeatedly searching/downloading the same release.
+- Completed release downloads expose all discovered audio files so post-processing can choose the best matching track.
+
+## Testing
+
+Manually tested:
+
+- Torrent-only album download for `good kid, m.A.A.d city (Deluxe)`.
+- Torrent playlist/single-track flow.
+- Album-bundle progress in the download modal and Downloads page.
+- Torrent source labeling in library history for new imports.
+- Staging match behavior for featured-artist filenames and bonus-track labels.
+- Quarantine behavior for wrong-version matches.
+
+Automated tests run during development:
+
+```bash
+.venv/bin/python -m pytest \
+  tests/downloads/test_downloads_status.py \
+  tests/test_album_bundle_dispatch.py \
+  tests/downloads/test_downloads_staging.py \
+  tests/test_torrent_usenet_plugins.py
+```
+
+```bash
+.venv/bin/python -m pytest \
+  tests/downloads/test_downloads_validation.py \
+  tests/test_manual_pick_no_auto_retry.py \
+  tests/downloads/test_downloads_post_processing.py \
+  tests/downloads/test_downloads_task_worker.py \
+  tests/imports/test_import_side_effects.py
+```
+
+Focused checks also passed for:
+
+- staged release feature suffix matching
+- bonus-track title matching
+- wrong-version separation
+- private torrent album staging miss handling
+- torrent/usenet history source labels
+
+## Reviewer Notes
+
+- This is intentionally gated behind torrent/usenet source selection, but it is still a new release-oriented download path and should be considered beta/experimental for first release.
+- Remote downloader setups need SoulSync to be able to read the downloader save path. Local/all-in-one setups should be the easiest path.
+- Existing library history rows that were previously recorded as `Soulseek` are not backfilled by this PR.
+- Release matching is naturally fuzzier than track-native sources, so reviewer focus should stay on false positives, version handling, and staged-file selection.

tests/downloads/test_downloads_task_worker.py

@@ -319,7 +319,7 @@ def test_cancellation_mid_query_returns_without_completion():
     _seed_task()
     rec = _Recorder()
 
-    def _cancel_during_search(query, timeout=30):
+    def _cancel_during_search(query, timeout=30, exclude_sources=None):
         download_tasks['t1']['status'] = 'cancelled'
 
         async def _empty():

tests/test_download_plugin_conformance.py

@@ -85,6 +85,7 @@ def test_default_registry_registers_all_sources():
     expected = {
         'soulseek', 'youtube', 'tidal', 'qobuz',
         'hifi', 'deezer', 'lidarr', 'soundcloud', 'amazon',
+        'torrent', 'usenet',
     }
     assert set(registry.names()) == expected