feat(node): Music app node-side — indexing, MusicBrainz enrichment, protocol

Implements the node half of docs/musicbay.md against MNP 0.8:

- IndexEntry gains artist/album/track_no (reuses duration/thumb_hash/
  display_title, already generic). New musicbrainz_config/_enabled and
  music_meta_req/_resp message pairs, mirroring the TMDB shape.
- title_parse.parse_track_filename: track-number-prefix + title parsing,
  fallback-only (embedded tags are the primary source, unlike Videos).
- indexer.enrich_audio.AudioEnricher: mutagen-based tag/embedded-cover
  extraction through its own bounded pool (asyncio.to_thread, no
  subprocess — no ffmpeg-shaped deadlock risk). Gated on "music" in a
  group's enabled_apps rather than a video_root-style scoped folder.
- musicbrainz.py: MusicBrainzClient — no API key (unlike TMDB), just a
  self-imposed ~1 req/s pace and a configurable, non-default User-Agent
  contact string; inert (no calls at all) when no contact is configured,
  never sends an unidentified client.
- media_cache.py: file_mbid/mbid_meta tables alongside the existing TMDB
  ones, cover art reusing the thumbs table via a synthetic
  musicbrainz:{mbid} id, pruned on file deletion.
- roster.py/ops.py/webrtc_server.py: musicbrainz_contact (node-wide) and
  musicbrainz_enabled (per-group, from the start) as signed operator
  settings, ALLOWED_APPS gains "music", _do_music_meta_request resolves
  and caches a release-level MusicBrainz match per (artist, album).
- daemon.py: AudioEnricher/MusicBrainzClient wired alongside the video
  ones; a group's existing library is swept when "music" is newly
  enabled (no video_root equivalent — see musicbay.md §2.1).

41 new tests (musicbrainz.py against a mocked transport, admin-op policy
for both new settings, media_cache round-trip/pruning, enrich_audio
end-to-end against real ffmpeg-generated MP3s). Full suite (common +
node + hub): 1116 passed, no regressions.

Client-side (music-app.js, persistent player bar) not started yet.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KBi7ALLGfwcjBXt57yNMcy

1 files changed, 150 insertions, 0 deletions

diff --git a/packages/meshbay-node/tests/test_enrich_audio.py b/packages/meshbay-node/tests/test_enrich_audio.py
new file mode 100644
index 0000000..62d0a0a
--- /dev/null
+++ b/packages/meshbay-node/tests/test_enrich_audio.py
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+"""Tests for indexer/enrich_audio.py — tag/cover extraction and the end-to-end pool."""
+
+import asyncio
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+from meshbay_common.protocol import IndexEntry
+from meshbay_node.indexer.enrich_audio import (
+    AudioEnricher, _artist_album_from_ancestors, _extract_cover,
+)
+from meshbay_node.indexer.title_parse import parse_track_filename
+from meshbay_node.media_cache import MediaCache
+
+_HAVE_FFMPEG = shutil.which("ffmpeg") and shutil.which("ffprobe")
+
+
+# ── pure helpers, no ffmpeg/mutagen file needed ──────────────────────────────
+
+def test_parse_track_filename_splits_leading_track_number():
+    parsed = parse_track_filename("01 - Venus As A Boy (Edited Lp Version).mp3")
+    assert parsed.track_no == 1
+    assert parsed.title == "Venus As A Boy (Edited Lp Version)"
+
+
+def test_parse_track_filename_handles_dot_separated():
+    parsed = parse_track_filename("03. Human Behaviour.mp3")
+    assert parsed.track_no == 3
+    assert parsed.title == "Human Behaviour"
+
+
+def test_parse_track_filename_handles_underscore_separated():
+    parsed = parse_track_filename("12_Some_Title.mp3")
+    assert parsed.track_no == 12
+    assert parsed.title == "Some Title"
+
+
+def test_parse_track_filename_no_prefix_leaves_track_no_none():
+    parsed = parse_track_filename("Some Title.mp3")
+    assert parsed.track_no is None
+    assert parsed.title == "Some Title"
+
+
+def test_parse_track_filename_does_not_mistake_a_leading_year_for_a_track_number():
+    parsed = parse_track_filename("1999 - Some Title.mp3")
+    assert parsed.track_no is None, "a 4-digit prefix is capped out, not read as track 199"
+
+
+def test_artist_album_from_ancestors_reads_artist_album_track_layout(tmp_path):
+    folder = tmp_path / "Some Artist" / "Some Album"
+    folder.mkdir(parents=True)
+    track = folder / "01 - A Track.mp3"
+    track.touch()
+
+    artist, album = _artist_album_from_ancestors(track)
+
+    assert artist == "Some Artist"
+    assert album == "Some Album"
+
+
+# ── end-to-end against a real (tiny, synthetic) MP3 file ────────────────────
+
+pytestmark_ffmpeg = pytest.mark.skipif(not _HAVE_FFMPEG, reason="ffmpeg/ffprobe not installed")
+
+
+def _make_clip(path: Path, *, title=None, artist=None, album=None, track=None) -> None:
+    subprocess.run(
+        ["ffmpeg", "-hide_banner", "-loglevel", "error", "-y",
+         "-f", "lavfi", "-i", "sine=frequency=440:duration=1",
+         "-c:a", "libmp3lame", "-b:a", "64k",
+         *(["-metadata", f"title={title}"] if title else []),
+         *(["-metadata", f"artist={artist}"] if artist else []),
+         *(["-metadata", f"album={album}"] if album else []),
+         *(["-metadata", f"track={track}"] if track else []),
+         str(path)],
+        check=True, capture_output=True,
+    )
+
+
+@pytest.fixture
+async def media_cache(tmp_path):
+    c = MediaCache(db_path=tmp_path / "media_cache.db")
+    await c.open()
+    yield c
+    await c.close()
+
+
+@pytestmark_ffmpeg
+@pytest.mark.asyncio
+async def test_enricher_prefers_tags_over_filename_parse(tmp_path, media_cache):
+    clip = tmp_path / "99 - wrong title.mp3"
+    _make_clip(clip, title="Real Title", artist="Real Artist", album="Real Album", track=3)
+    entry = IndexEntry(id="fileid1", name=clip.name, path=clip.name,
+                        size=clip.stat().st_size, type="audio", added_at=0)
+
+    enricher = AudioEnricher(media_cache)
+    done = asyncio.get_event_loop().create_future()
+
+    async def on_done(file_id, fields):
+        done.set_result((file_id, fields))
+
+    enricher.spawn(entry, clip, on_done)
+    file_id, fields = await asyncio.wait_for(done, timeout=30)
+
+    assert file_id == "fileid1"
+    assert fields["display_title"] == "Real Title"
+    assert fields["artist"] == "Real Artist"
+    assert fields["album"] == "Real Album"
+    assert fields["track_no"] == 3
+    assert fields["duration"] == 1
+    assert fields.get("thumb_hash") is None, "no embedded cover was written in this clip"
+
+
+@pytestmark_ffmpeg
+@pytest.mark.asyncio
+async def test_enricher_falls_back_to_filename_and_folder_when_tags_absent(tmp_path, media_cache):
+    folder = tmp_path / "Folder Artist" / "Folder Album"
+    folder.mkdir(parents=True)
+    clip = folder / "05 - Filename Title.mp3"
+    _make_clip(clip)   # no metadata tags at all
+    entry = IndexEntry(id="fileid2", name=clip.name,
+                        path=str(clip.relative_to(tmp_path)),
+                        size=clip.stat().st_size, type="audio", added_at=0)
+
+    enricher = AudioEnricher(media_cache)
+    done = asyncio.get_event_loop().create_future()
+
+    async def on_done(file_id, fields):
+        done.set_result((file_id, fields))
+
+    enricher.spawn(entry, clip, on_done)
+    _, fields = await asyncio.wait_for(done, timeout=30)
+
+    assert fields["display_title"] == "Filename Title"
+    assert fields["track_no"] == 5
+    assert fields["artist"] == "Folder Artist"
+    assert fields["album"] == "Folder Album"
+
+
+@pytestmark_ffmpeg
+def test_extract_cover_returns_none_when_no_apic_frame(tmp_path):
+    from mutagen import File as MutagenFile
+
+    clip = tmp_path / "plain.mp3"
+    _make_clip(clip)
+
+    mf = MutagenFile(str(clip))
+    assert _extract_cover(mf) is None