Add broken symlink diagnostics

ROADMAP.md

@@ -20,7 +20,7 @@
 - [x] `serato-doctor analyze` command
 - [x] Duplicate filename detection
 - [ ] Duplicate audio hash detection
-- [ ] Broken symlink detection
+- [x] Broken symlink detection
 - [ ] Orphaned audio detection
 - [ ] OneDrive rename detection
 - [x] Crate classification: static vs smart/dynamic

docs/design/broken-symlinks.md

@@ -0,0 +1,27 @@
+# Broken Symlink Detection
+
+## Problem
+
+Library migrations may leave symbolic links pointing to files or folders that no
+longer exist. The filesystem scanner previously skipped those links silently.
+
+## Architecture
+
+One read-only filesystem traversal now returns audio tracks and broken symbolic
+links. Each finding preserves the link path and its raw target when the operating
+system can read it. The library and health report retain only immutable findings.
+
+Broken links are reported separately and do not affect the reference-integrity
+score. The detector does not follow, recreate, remove, or rewrite any link.
+
+## Edge Cases
+
+- Relative and absolute link targets.
+- Links to missing files and missing directories.
+- Link targets that cannot be read due to an operating-system error.
+- Valid symlinks, which remain eligible for ordinary audio scanning.
+
+## Verification
+
+Tests create synthetic valid and broken links in temporary directories, verify the
+raw target, and confirm health integration. Existing scanner behavior is preserved.

serato_doctor/cli.py

@@ -6,7 +6,7 @@ from serato_doctor.crate_parser import load_library_crates
 from serato_doctor.health import analyze_health
 from serato_doctor.logging import configure_logging
 from serato_doctor.models.library import Library
-from serato_doctor.scanner import scan_audio
+from serato_doctor.scanner import scan_filesystem
 from serato_doctor.report import write_csv, write_missing_report
 
 
@@ -56,9 +56,11 @@ def main():
     logger.debug("Music directory: %s", config.music)
 
     crates = load_library_crates(config.serato, config.reference_roots)
+    filesystem = scan_filesystem(config.music)
     library = Library.from_crates(
         crates=crates,
-        tracks=scan_audio(config.music),
+        tracks=filesystem.tracks,
+        broken_symlinks=filesystem.broken_symlinks,
     )
     results = library.reconcile_by_filename()
     missing_count = sum(1 for result in results if not result.exists_by_filename)
@@ -90,6 +92,7 @@ def main():
         )
         print(f"Unused Tracks: {health.unused_tracks}")
         print(f"Suggested Matches: {health.suggested_matches}")
+        print(f"Broken Symlinks: {health.broken_symlinks}")
         print(f"Static Crates: {health.static_crates}")
         print(f"Smart Crates: {health.smart_crates}")
         print(

serato_doctor/health.py

@@ -62,6 +62,7 @@ def analyze_health(library: Library) -> HealthReport:
         ),
         unused_tracks=unused_count,
         suggested_matches=suggested_count,
+        broken_symlinks=len(library.broken_symlinks),
         static_crates=sum(
             crate.kind is CrateKind.STATIC for crate in library.crates
         ),

serato_doctor/models/__init__.py

@@ -1,5 +1,6 @@
 from serato_doctor.models.crate import Crate, CrateKind
 from serato_doctor.models.duplicate import DuplicateGroup, DuplicateKind
+from serato_doctor.models.filesystem import BrokenSymlink, FilesystemScan
 from serato_doctor.models.health import HealthReport
 from serato_doctor.models.library import Library
 from serato_doctor.models.match import MatchEvidence, TrackMatch
@@ -12,6 +13,8 @@ __all__ = [
     "DiskTrack",
     "DuplicateGroup",
     "DuplicateKind",
+    "BrokenSymlink",
+    "FilesystemScan",
     "HealthReport",
     "Library",
     "MatchEvidence",

serato_doctor/models/filesystem.py

@@ -0,0 +1,21 @@
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Optional, Tuple
+
+from serato_doctor.models.track import DiskTrack
+
+
+@dataclass(frozen=True)
+class BrokenSymlink:
+    """A symbolic link whose target cannot be resolved."""
+
+    path: Path
+    target: Optional[Path]
+
+
+@dataclass(frozen=True)
+class FilesystemScan:
+    """Read-only findings from one traversal of a music folder."""
+
+    tracks: Tuple[DiskTrack, ...]
+    broken_symlinks: Tuple[BrokenSymlink, ...]

serato_doctor/models/health.py

@@ -19,6 +19,7 @@ class HealthReport:
     suspected_cloud_conflict_files: int
     unused_tracks: int
     suggested_matches: int
+    broken_symlinks: int
     static_crates: int
     smart_crates: int
     unknown_crates: int

serato_doctor/models/library.py

@@ -2,6 +2,7 @@ from dataclasses import dataclass
 from typing import Iterable, Tuple
 
 from serato_doctor.models.crate import Crate
+from serato_doctor.models.filesystem import BrokenSymlink
 from serato_doctor.models.reference import ReferenceResult, TrackReference
 from serato_doctor.models.track import DiskTrack
 
@@ -13,18 +14,27 @@ class Library:
     references: Tuple[TrackReference, ...]
     tracks: Tuple[DiskTrack, ...]
     crates: Tuple[Crate, ...] = ()
+    broken_symlinks: Tuple[BrokenSymlink, ...] = ()
 
     @classmethod
     def build(
         cls,
         references: Iterable[TrackReference],
         tracks: Iterable[DiskTrack],
+        broken_symlinks: Iterable[BrokenSymlink] = (),
     ) -> "Library":
-        return cls(tuple(references), tuple(tracks))
+        return cls(
+            tuple(references),
+            tuple(tracks),
+            broken_symlinks=tuple(broken_symlinks),
+        )
 
     @classmethod
     def from_crates(
-        cls, crates: Iterable[Crate], tracks: Iterable[DiskTrack]
+        cls,
+        crates: Iterable[Crate],
+        tracks: Iterable[DiskTrack],
+        broken_symlinks: Iterable[BrokenSymlink] = (),
     ) -> "Library":
         crate_tuple = tuple(crates)
         references = tuple(
@@ -32,7 +42,12 @@ class Library:
             for crate in crate_tuple
             for reference in crate.references
         )
-        return cls(references, tuple(tracks), crate_tuple)
+        return cls(
+            references,
+            tuple(tracks),
+            crate_tuple,
+            tuple(broken_symlinks),
+        )
 
     def reconcile_by_filename(self) -> Tuple[ReferenceResult, ...]:
         disk_names = {track.filename for track in self.tracks}

serato_doctor/scanner.py

@@ -1,14 +1,23 @@
 from pathlib import Path
 
+from serato_doctor.models.filesystem import BrokenSymlink, FilesystemScan
 from serato_doctor.models.track import DiskTrack
 
 AUDIO_SUFFIXES = {".mp3", ".m4a", ".wav", ".aif", ".aiff", ".flac"}
 
 
-def scan_audio(folder: Path) -> list[DiskTrack]:
+def scan_filesystem(folder: Path) -> FilesystemScan:
     tracks = []
+    broken_symlinks = []
 
     for path in folder.rglob("*"):
+        if path.is_symlink() and not path.exists():
+            try:
+                target = path.readlink()
+            except OSError:
+                target = None
+            broken_symlinks.append(BrokenSymlink(path=path, target=target))
+            continue
         if not path.is_file():
             continue
         if path.suffix.lower() not in AUDIO_SUFFIXES:
@@ -28,4 +37,13 @@ def scan_audio(folder: Path) -> list[DiskTrack]:
             )
         )
 
-    return tracks
+    return FilesystemScan(
+        tracks=tuple(tracks),
+        broken_symlinks=tuple(broken_symlinks),
+    )
+
+
+def scan_audio(folder: Path) -> list[DiskTrack]:
+    """Scan audio files while preserving the prototype API."""
+
+    return list(scan_filesystem(folder).tracks)

tests/test_health.py

@@ -2,6 +2,7 @@ from pathlib import Path
 
 from serato_doctor.health import analyze_health
 from serato_doctor.models.crate import Crate, CrateKind
+from serato_doctor.models.filesystem import BrokenSymlink
 from serato_doctor.models.library import Library
 from serato_doctor.models.reference import TrackReference
 from serato_doctor.models.track import DiskTrack
@@ -104,3 +105,16 @@ def test_health_reports_cloud_conflicts_separately_from_exact_duplicates():
     assert report.duplicate_files == 1
     assert report.suspected_cloud_conflict_groups == 1
     assert report.suspected_cloud_conflict_files == 1
+
+
+def test_health_reports_broken_symlinks_without_changing_score():
+    library = Library.build(
+        [reference("Found.mp3")],
+        [track("Found.mp3")],
+        [BrokenSymlink(Path("/music/Broken.mp3"), Path("missing.mp3"))],
+    )
+
+    report = analyze_health(library)
+
+    assert report.score == 100.0
+    assert report.broken_symlinks == 1

tests/test_scanner.py

@@ -1,4 +1,6 @@
-from serato_doctor.scanner import scan_audio
+from pathlib import Path
+
+from serato_doctor.scanner import scan_audio, scan_filesystem
 
 
 def test_scan_audio_finds_supported_files(tmp_path):
@@ -15,3 +17,34 @@ def test_scan_audio_finds_supported_files(tmp_path):
     first = next(track for track in tracks if track.filename == "First.MP3")
     assert first.suffix == ".mp3"
     assert first.size == len(b"synthetic audio")
+
+
+def test_scan_filesystem_reports_broken_symlink(tmp_path):
+    music = tmp_path / "music"
+    music.mkdir()
+    link = music / "Missing.mp3"
+    link.symlink_to("not-there.mp3")
+
+    result = scan_filesystem(music)
+
+    assert result.tracks == ()
+    assert len(result.broken_symlinks) == 1
+    assert result.broken_symlinks[0].path == link
+    assert result.broken_symlinks[0].target == Path("not-there.mp3")
+
+
+def test_valid_audio_symlink_is_scanned_normally(tmp_path):
+    music = tmp_path / "music"
+    music.mkdir()
+    target = music / "Target.mp3"
+    target.write_bytes(b"synthetic audio")
+    link = music / "Linked.mp3"
+    link.symlink_to(target)
+
+    result = scan_filesystem(music)
+
+    assert {track.filename for track in result.tracks} == {
+        "Linked.mp3",
+        "Target.mp3",
+    }
+    assert result.broken_symlinks == ()