Merge feature/analyze-command into develop

README.md

@@ -0,0 +1,37 @@
+# Serato Doctor
+
+Serato Doctor is a read-only-first toolkit for inspecting and eventually repairing
+DJ libraries. Serato is the first supported engine.
+
+## Analyze a Library
+
+```shell
+serato-doctor analyze \
+  --serato ~/Music/_Serato_ \
+  --music ~/Music/Jukebox
+```
+
+Analysis prints a transparent reference-integrity score plus broken references,
+duplicate filenames, unused tracks, and suggested filename matches. It does not
+modify the library or create report files.
+
+If crates contain an older library root, supply it explicitly:
+
+```shell
+serato-doctor analyze --reference-root /Users/old-user/OneDrive/Jukebox
+```
+
+## Generate Detailed Reports
+
+Running without a command preserves the original scanner behavior and writes CSV
+and text reports:
+
+```shell
+serato-doctor --serato ~/Music/_Serato_ --music ~/Music/Jukebox
+```
+
+Use `--verbose` for progress on standard error or `--log-file PATH` for an
+aggregate diagnostic log.
+
+Serato Doctor never repairs files without an explicit future repair workflow,
+preview, backup, and rollback path.

ROADMAP.md

@@ -12,16 +12,19 @@
 - [x] Sample library fixtures
 - [ ] Database V2 read-only parser
 - [x] Configuration
+- [x] Logging
+- [x] Matching engine
 
 ## v0.2 — Diagnostics
 
+- [x] `serato-doctor analyze` command
 - [ ] Duplicate filename detection
 - [ ] Duplicate audio hash detection
 - [ ] Broken symlink detection
 - [ ] Orphaned audio detection
 - [ ] OneDrive rename detection
 - [ ] Crate classification: static vs smart/dynamic
-- [ ] Library health score
+- [x] Library health score
 
 ## v0.3 — Safe Repair
 

docs/design/analyze-command.md

@@ -0,0 +1,27 @@
+# Analyze Command
+
+## Problem
+
+The health and matching engines are only Python APIs. Users need one safe command
+that summarizes library integrity without first interpreting CSV files.
+
+## Architecture
+
+`serato-doctor analyze` reuses the existing configured crate parser and filesystem
+scanner, then prints the immutable health report. The original no-command mode is
+retained as the report-producing scan workflow.
+
+Analyze mode does not create CSV or text reports. Both modes remain read-only with
+respect to Serato crates, databases, and music files.
+
+## Edge Cases
+
+- A library with no references displays `Not assessed` rather than a false score.
+- Historical roots continue to work through repeatable `--reference-root` flags.
+- Normal output remains separate from optional diagnostic logging.
+- Existing scripts that invoke the CLI without a subcommand remain compatible.
+
+## Verification
+
+Tests prove the legacy five-line output and reports remain unchanged, while analyze
+prints health metrics and does not create output files.

docs/design/health-engine.md

@@ -0,0 +1,31 @@
+# Library Health Engine
+
+## Problem
+
+Raw missing-reference counts do not provide a compact view of library integrity,
+but an opaque blended score would imply confidence the current data cannot support.
+
+## Architecture
+
+The health engine produces an immutable report from the core `Library`. Its score
+is only the percentage of crate references resolved by exact filename. The report
+also exposes missing references, unique missing filenames, duplicate filename
+groups, extra duplicate files, unused tracks, and missing references with matching
+candidates.
+
+Duplicate, unused, and candidate counts are informational. They do not affect the
+score until the project has a documented and validated weighting policy. An empty
+library has no score rather than a misleading 0% or 100%.
+
+## Edge Cases
+
+- The same missing filename referenced by several crates.
+- Several disk files sharing a filename.
+- Conflict-suffixed files that are unused but may be match candidates.
+- Libraries with no crate references.
+- Tracks referenced by filename from more than one crate.
+
+## Verification
+
+Tests assert every metric, the disclosed score basis, candidate integration, and
+empty-library behavior. Analysis remains entirely read-only.

docs/design/logging.md

@@ -0,0 +1,25 @@
+# Application Logging
+
+## Problem
+
+The CLI reports final counts but provides no diagnostic trail when a scan behaves
+unexpectedly. Troubleshooting should not require adding print statements or expose
+library contents by default.
+
+## Architecture
+
+The project uses an isolated standard-library logger. It has no visible output by
+default. `--verbose` writes progress to standard error, while `--log-file PATH`
+writes an informational audit trail. Normal result lines remain on standard output.
+
+## Edge Cases
+
+- Reconfiguring logging in the same process must not duplicate handlers.
+- Console and file logging may be enabled together.
+- Log messages contain aggregate counts, not track names or crate contents.
+- A default scan must remain quiet except for its established result output.
+
+## Verification
+
+Tests verify quiet defaults, file output, handler replacement, and unchanged CLI
+result lines. The full sample-library scan remains read-only.

docs/design/matching-engine.md

@@ -0,0 +1,29 @@
+# Explainable Matching Engine
+
+## Problem
+
+Missing references need ranked candidate files, but a filename-only yes/no check
+cannot explain ambiguity or cloud-provider conflict names.
+
+## Architecture
+
+The read-only matching engine indexes normalized filenames and scores only related
+candidates. Every score contains evidence for filename, extension, and parent
+folder. Exact filenames earn 60 points, normalized names 55, numeric conflict-name
+matches 50, extensions 10, and parent folders 20.
+
+The displayed percentage is an evidence score, not a statistical probability.
+Metadata, duration, hashes, and fingerprints can add stronger evidence later.
+
+## Edge Cases
+
+- Unicode and case differences.
+- OneDrive-style names such as `Track 2.mp3`.
+- Duplicate candidates in different folders.
+- Legitimate numbered song titles, which remain candidates but are never repaired.
+- Unrelated names, which are not emitted as candidates.
+
+## Verification
+
+Tests cover exact, normalized, conflict-suffix, ambiguous, and unrelated filenames.
+Candidate ordering is deterministic. The engine never changes a track or reference.

serato_doctor/cli.py

@@ -3,6 +3,8 @@ import argparse
 
 from serato_doctor.config import ScanConfig
 from serato_doctor.crate_parser import parse_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.report import write_csv, write_missing_report
@@ -10,16 +12,33 @@ from serato_doctor.report import write_csv, write_missing_report
 
 def main():
     parser = argparse.ArgumentParser(prog="serato-doctor")
+    parser.add_argument(
+        "command", nargs="?", choices=("scan", "analyze"), default="scan"
+    )
     parser.add_argument("--serato", default=str(Path.home() / "Music/_Serato_"))
-    parser.add_argument("--music", default=str(Path.home() / "Library/CloudStorage/OneDrive-Personal/Jukebox"))
+    parser.add_argument(
-    parser.add_argument("--out", default=str(Path.home() / "Desktop/serato_doctor_scan.csv"))
+        "--music",
-    parser.add_argument("--report", default=str(Path.home() / "Desktop/serato_doctor_missing_report.txt"))
+        default=str(
+            Path.home() / "Library/CloudStorage/OneDrive-Personal/Jukebox"
+        ),
+    )
+    parser.add_argument(
+        "--out", default=str(Path.home() / "Desktop/serato_doctor_scan.csv")
+    )
+    parser.add_argument(
+        "--report",
+        default=str(Path.home() / "Desktop/serato_doctor_missing_report.txt"),
+    )
     parser.add_argument(
         "--reference-root",
         action="append",
         default=[],
         help="Old library root stored in crates; may be supplied more than once",
     )
+    parser.add_argument(
+        "--verbose", action="store_true", help="Write diagnostic progress to stderr"
+    )
+    parser.add_argument("--log-file", help="Write scan progress to a log file")
     args = parser.parse_args()
 
     config = ScanConfig.build(
@@ -28,7 +47,13 @@ def main():
         out=Path(args.out),
         report=Path(args.report),
         reference_roots=(Path(root) for root in args.reference_root),
+        verbose=args.verbose,
+        log_file=Path(args.log_file) if args.log_file else None,
     )
+    logger = configure_logging(config.verbose, config.log_file)
+    logger.info("Starting read-only library inspection")
+    logger.debug("Serato directory: %s", config.serato)
+    logger.debug("Music directory: %s", config.music)
 
     library = Library.build(
         references=parse_crates(
@@ -38,10 +63,29 @@ def main():
     )
     results = library.reconcile_by_filename()
     missing_count = sum(1 for result in results if not result.exists_by_filename)
+    logger.info("Parsed %d crate references", len(library.references))
+    logger.info("Scanned %d disk tracks", len(library.tracks))
+    logger.info("Found %d references missing by filename", missing_count)
 
+    if args.command == "analyze":
+        health = analyze_health(library)
+        score = f"{health.score:.1f}%" if health.score is not None else "Not assessed"
+        logger.info("Calculated library health: %s", score)
+        print(f"Overall Health: {score}")
+        print(f"Score Basis: {health.score_basis}")
+        print(f"Tracks: {health.disk_tracks}")
+        print(f"Crate References: {health.total_references}")
+        print(f"Healthy References: {health.healthy_references}")
+        print(f"Broken References: {health.missing_references}")
+        print(f"Unique Missing Filenames: {health.unique_missing_filenames}")
+        print(f"Duplicate Filename Groups: {health.duplicate_filename_groups}")
+        print(f"Duplicate Files: {health.duplicate_files}")
+        print(f"Unused Tracks: {health.unused_tracks}")
+        print(f"Suggested Matches: {health.suggested_matches}")
+    else:
         write_csv(results, config.out)
         write_missing_report(results, config.report)
-
+        logger.info("Wrote CSV and missing-reference reports")
         print(f"Crate references: {len(library.references)}")
         print(f"Disk tracks: {len(library.tracks)}")
         print(f"Missing by filename: {missing_count}")

serato_doctor/config.py

@@ -1,6 +1,6 @@
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Iterable, Tuple
+from typing import Iterable, Optional, Tuple
 
 
 @dataclass(frozen=True)
@@ -12,6 +12,8 @@ class ScanConfig:
     out: Path
     report: Path
     reference_roots: Tuple[Path, ...] = ()
+    verbose: bool = False
+    log_file: Optional[Path] = None
 
     @classmethod
     def build(
@@ -21,5 +23,15 @@ class ScanConfig:
         out: Path,
         report: Path,
         reference_roots: Iterable[Path] = (),
+        verbose: bool = False,
+        log_file: Optional[Path] = None,
     ) -> "ScanConfig":
-        return cls(serato, music, out, report, tuple(reference_roots))
+        return cls(
+            serato,
+            music,
+            out,
+            report,
+            tuple(reference_roots),
+            verbose,
+            log_file,
+        )

serato_doctor/health.py

@@ -0,0 +1,43 @@
+from collections import Counter
+
+from serato_doctor.matching import MatchingEngine
+from serato_doctor.models.health import HealthReport
+from serato_doctor.models.library import Library
+
+
+def analyze_health(library: Library) -> HealthReport:
+    """Calculate defensible health metrics without changing the library."""
+
+    results = library.reconcile_by_filename()
+    missing = [result for result in results if not result.exists_by_filename]
+    healthy_count = len(results) - len(missing)
+    score = (
+        round(healthy_count / len(results) * 100, 1) if results else None
+    )
+
+    disk_name_counts = Counter(track.filename for track in library.tracks)
+    duplicate_counts = [count for count in disk_name_counts.values() if count > 1]
+    referenced_names = {reference.filename for reference in library.references}
+    unused_count = sum(
+        1 for track in library.tracks if track.filename not in referenced_names
+    )
+
+    matcher = MatchingEngine(library.tracks)
+    suggested_count = sum(
+        bool(matcher.candidates_for(result.reference)) for result in missing
+    )
+
+    return HealthReport(
+        score=score,
+        total_references=len(results),
+        healthy_references=healthy_count,
+        missing_references=len(missing),
+        unique_missing_filenames=len(
+            {result.reference.filename for result in missing}
+        ),
+        disk_tracks=len(library.tracks),
+        duplicate_filename_groups=len(duplicate_counts),
+        duplicate_files=sum(count - 1 for count in duplicate_counts),
+        unused_tracks=unused_count,
+        suggested_matches=suggested_count,
+    )

serato_doctor/logging.py

@@ -0,0 +1,40 @@
+import logging
+from pathlib import Path
+from typing import Optional
+
+
+LOGGER_NAME = "serato_doctor"
+LOG_FORMAT = "%(asctime)s %(levelname)s %(message)s"
+
+
+def configure_logging(
+    verbose: bool = False, log_file: Optional[Path] = None
+) -> logging.Logger:
+    """Configure isolated application logging and return the project logger."""
+
+    logger = logging.getLogger(LOGGER_NAME)
+    logger.setLevel(logging.DEBUG)
+    logger.propagate = False
+
+    for handler in logger.handlers[:]:
+        handler.close()
+        logger.removeHandler(handler)
+
+    formatter = logging.Formatter(LOG_FORMAT)
+
+    if verbose:
+        console = logging.StreamHandler()
+        console.setLevel(logging.DEBUG)
+        console.setFormatter(formatter)
+        logger.addHandler(console)
+
+    if log_file is not None:
+        file_handler = logging.FileHandler(log_file, encoding="utf-8")
+        file_handler.setLevel(logging.INFO)
+        file_handler.setFormatter(formatter)
+        logger.addHandler(file_handler)
+
+    if not logger.handlers:
+        logger.addHandler(logging.NullHandler())
+
+    return logger

serato_doctor/matching.py

@@ -0,0 +1,86 @@
+import re
+import unicodedata
+from collections import defaultdict
+from pathlib import Path
+from typing import DefaultDict, Iterable, List, Tuple
+
+from serato_doctor.models.match import MatchEvidence, TrackMatch
+from serato_doctor.models.reference import TrackReference
+from serato_doctor.models.track import DiskTrack
+
+
+def normalize(value: str) -> str:
+    return unicodedata.normalize("NFKC", value).casefold()
+
+
+def cloud_conflict_name(filename: str) -> str:
+    """Remove a trailing numeric cloud-conflict suffix from a filename stem."""
+
+    path = Path(filename)
+    stem = re.sub(r" \d+$", "", path.stem)
+    return normalize(stem + path.suffix)
+
+
+def score_candidate(reference: TrackReference, track: DiskTrack) -> TrackMatch:
+    reference_name = reference.filename
+    track_name = track.filename
+
+    if reference_name == track_name:
+        filename_points = 60
+        filename_reason = "Filename is identical"
+    elif normalize(reference_name) == normalize(track_name):
+        filename_points = 55
+        filename_reason = "Filename matches after case and Unicode normalization"
+    elif cloud_conflict_name(reference_name) == cloud_conflict_name(track_name):
+        filename_points = 50
+        filename_reason = "Filename matches after removing a numeric conflict suffix"
+    else:
+        filename_points = 0
+        filename_reason = "Filename does not match"
+
+    same_extension = normalize(reference.path.suffix) == normalize(track.suffix)
+    same_parent = normalize(reference.path.parent.name) == normalize(
+        track.path.parent.name
+    )
+    evidence = (
+        MatchEvidence(
+            "filename",
+            filename_points > 0,
+            filename_points,
+            60,
+            filename_reason,
+        ),
+        MatchEvidence(
+            "extension",
+            same_extension,
+            10 if same_extension else 0,
+            10,
+            "File extension matches" if same_extension else "File extension differs",
+        ),
+        MatchEvidence(
+            "parent_folder",
+            same_parent,
+            20 if same_parent else 0,
+            20,
+            "Parent folder matches" if same_parent else "Parent folder differs",
+        ),
+    )
+    return TrackMatch(reference, track, evidence)
+
+
+class MatchingEngine:
+    """Find and rank filename-related disk candidates without modifying files."""
+
+    def __init__(self, tracks: Iterable[DiskTrack]):
+        self._by_conflict_name: DefaultDict[str, List[DiskTrack]] = defaultdict(list)
+        for track in tracks:
+            self._by_conflict_name[cloud_conflict_name(track.filename)].append(track)
+
+    def candidates_for(self, reference: TrackReference) -> Tuple[TrackMatch, ...]:
+        candidates = self._by_conflict_name.get(
+            cloud_conflict_name(reference.filename), []
+        )
+        matches = [score_candidate(reference, track) for track in candidates]
+        return tuple(
+            sorted(matches, key=lambda match: (-match.score, str(match.track.path)))
+        )

serato_doctor/models/__init__.py

@@ -1,6 +1,17 @@
 from serato_doctor.models.crate import Crate
+from serato_doctor.models.health import HealthReport
 from serato_doctor.models.library import Library
+from serato_doctor.models.match import MatchEvidence, TrackMatch
 from serato_doctor.models.reference import ReferenceResult, TrackReference
 from serato_doctor.models.track import DiskTrack
 
-__all__ = ["Crate", "DiskTrack", "Library", "ReferenceResult", "TrackReference"]
+__all__ = [
+    "Crate",
+    "DiskTrack",
+    "HealthReport",
+    "Library",
+    "MatchEvidence",
+    "ReferenceResult",
+    "TrackMatch",
+    "TrackReference",
+]

serato_doctor/models/health.py

@@ -0,0 +1,22 @@
+from dataclasses import dataclass
+from typing import Optional
+
+
+@dataclass(frozen=True)
+class HealthReport:
+    """Transparent aggregate findings from a read-only library analysis."""
+
+    score: Optional[float]
+    total_references: int
+    healthy_references: int
+    missing_references: int
+    unique_missing_filenames: int
+    disk_tracks: int
+    duplicate_filename_groups: int
+    duplicate_files: int
+    unused_tracks: int
+    suggested_matches: int
+
+    @property
+    def score_basis(self) -> str:
+        return "Resolved crate references / total crate references"

serato_doctor/models/match.py

@@ -0,0 +1,39 @@
+from dataclasses import dataclass
+from typing import Tuple
+
+from serato_doctor.models.reference import TrackReference
+from serato_doctor.models.track import DiskTrack
+
+
+@dataclass(frozen=True)
+class MatchEvidence:
+    """One explainable scoring decision for a candidate track."""
+
+    field: str
+    matched: bool
+    points: int
+    max_points: int
+    explanation: str
+
+
+@dataclass(frozen=True)
+class TrackMatch:
+    """A ranked candidate backed by explicit, inspectable evidence."""
+
+    reference: TrackReference
+    track: DiskTrack
+    evidence: Tuple[MatchEvidence, ...]
+
+    @property
+    def score(self) -> int:
+        return sum(item.points for item in self.evidence)
+
+    @property
+    def max_score(self) -> int:
+        return sum(item.max_points for item in self.evidence)
+
+    @property
+    def score_percent(self) -> float:
+        if not self.max_score:
+            return 0.0
+        return round(self.score / self.max_score * 100, 1)

tests/test_cli.py

@@ -37,7 +37,9 @@ def test_cli_writes_reports_and_prints_counts(tmp_path, monkeypatch, capsys):
 
     main()
 
-    output = capsys.readouterr().out
+    captured = capsys.readouterr()
+    output = captured.out
+    assert captured.err == ""
     assert "Crate references: 2" in output
     assert "Disk tracks: 1" in output
     assert "Missing by filename: 1" in output
@@ -82,3 +84,47 @@ def test_cli_accepts_old_reference_root(tmp_path, monkeypatch, capsys):
     output = capsys.readouterr().out
     assert "Crate references: 1" in output
     assert "Missing by filename: 0" in output
+
+
+def test_analyze_prints_health_without_writing_reports(tmp_path, monkeypatch, capsys):
+    serato = tmp_path / "serato"
+    subcrates = serato / "Subcrates"
+    music = tmp_path / "music"
+    subcrates.mkdir(parents=True)
+    music.mkdir()
+    crate_text = (
+        "Users/sample-user/Jukebox/Found.mp3otrk"
+        "Users/sample-user/Jukebox/Missing.mp3otrk"
+    )
+    (subcrates / "Test.crate").write_bytes(crate_text.encode("utf-16-le"))
+    (music / "Found.mp3").write_bytes(b"synthetic audio")
+    csv_path = tmp_path / "scan.csv"
+    report_path = tmp_path / "report.txt"
+    monkeypatch.setattr(
+        sys,
+        "argv",
+        [
+            "serato-doctor",
+            "analyze",
+            "--serato",
+            str(serato),
+            "--music",
+            str(music),
+            "--out",
+            str(csv_path),
+            "--report",
+            str(report_path),
+        ],
+    )
+
+    main()
+
+    output = capsys.readouterr().out
+    assert "Overall Health: 50.0%" in output
+    assert "Tracks: 1" in output
+    assert "Crate References: 2" in output
+    assert "Healthy References: 1" in output
+    assert "Broken References: 1" in output
+    assert "Unused Tracks: 0" in output
+    assert not csv_path.exists()
+    assert not report_path.exists()

tests/test_health.py

@@ -0,0 +1,56 @@
+from pathlib import Path
+
+from serato_doctor.health import analyze_health
+from serato_doctor.models.library import Library
+from serato_doctor.models.reference import TrackReference
+from serato_doctor.models.track import DiskTrack
+
+
+def reference(filename):
+    return TrackReference(
+        Path("Test.crate"), Path("/old/House") / filename, filename
+    )
+
+
+def track(filename, folder="House"):
+    path = Path("/new") / folder / filename
+    return DiskTrack(path, filename, 100, path.suffix.lower())
+
+
+def test_health_report_exposes_each_metric():
+    library = Library.build(
+        [
+            reference("Found.mp3"),
+            reference("Conflict.mp3"),
+            reference("Absent.mp3"),
+        ],
+        [
+            track("Found.mp3"),
+            track("Conflict 2.mp3"),
+            track("Conflict 2.mp3", "Backup"),
+            track("Unused.mp3"),
+        ],
+    )
+
+    report = analyze_health(library)
+
+    assert report.score == 33.3
+    assert report.score_basis == (
+        "Resolved crate references / total crate references"
+    )
+    assert report.total_references == 3
+    assert report.healthy_references == 1
+    assert report.missing_references == 2
+    assert report.unique_missing_filenames == 2
+    assert report.disk_tracks == 4
+    assert report.duplicate_filename_groups == 1
+    assert report.duplicate_files == 1
+    assert report.unused_tracks == 3
+    assert report.suggested_matches == 1
+
+
+def test_empty_library_has_no_health_score():
+    report = analyze_health(Library.build([], []))
+
+    assert report.score is None
+    assert report.total_references == 0

tests/test_logging.py

@@ -0,0 +1,34 @@
+import logging
+
+from serato_doctor.logging import LOGGER_NAME, configure_logging
+
+
+def test_logging_is_quiet_by_default(capsys):
+    logger = configure_logging()
+
+    logger.info("not visible")
+
+    assert capsys.readouterr().err == ""
+
+
+def test_logging_writes_aggregate_progress_to_file(tmp_path):
+    log_path = tmp_path / "scan.log"
+    logger = configure_logging(log_file=log_path)
+
+    logger.info("Scanned %d disk tracks", 10)
+
+    contents = log_path.read_text(encoding="utf-8")
+    assert "INFO Scanned 10 disk tracks" in contents
+
+
+def test_reconfiguring_logging_replaces_handlers():
+    configure_logging(verbose=True)
+    logger = configure_logging(verbose=True)
+
+    active_handlers = [
+        handler
+        for handler in logger.handlers
+        if not isinstance(handler, logging.NullHandler)
+    ]
+    assert logger.name == LOGGER_NAME
+    assert len(active_handlers) == 1

tests/test_matcher.py

@@ -0,0 +1,62 @@
+from pathlib import Path
+
+from serato_doctor.matching import MatchingEngine, score_candidate
+from serato_doctor.models.reference import TrackReference
+from serato_doctor.models.track import DiskTrack
+
+
+def reference(filename, folder="House"):
+    return TrackReference(
+        Path("Test.crate"), Path("/old") / folder / filename, filename
+    )
+
+
+def track(filename, folder="House"):
+    path = Path("/new") / folder / filename
+    return DiskTrack(path, filename, 100, path.suffix.lower())
+
+
+def test_exact_candidate_has_full_evidence_score():
+    match = score_candidate(reference("Track.mp3"), track("Track.mp3"))
+
+    assert match.score == 90
+    assert match.max_score == 90
+    assert match.score_percent == 100.0
+    assert all(item.matched for item in match.evidence)
+
+
+def test_cloud_conflict_suffix_is_explained():
+    match = score_candidate(reference("Track.mp3"), track("Track 2.mp3"))
+
+    assert match.score == 80
+    assert match.score_percent == 88.9
+    assert match.evidence[0].explanation == (
+        "Filename matches after removing a numeric conflict suffix"
+    )
+
+
+def test_case_normalized_match_scores_below_exact():
+    match = score_candidate(reference("TRACK.MP3"), track("track.mp3"))
+
+    assert match.score == 85
+    assert match.evidence[0].points == 55
+
+
+def test_engine_omits_unrelated_filenames():
+    engine = MatchingEngine([track("Different.mp3")])
+
+    assert engine.candidates_for(reference("Missing.mp3")) == ()
+
+
+def test_ambiguous_candidates_are_ranked_deterministically():
+    engine = MatchingEngine(
+        [track("Track 2.mp3", "Other"), track("Track 3.mp3", "House")]
+    )
+
+    matches = engine.candidates_for(reference("Track.mp3"))
+
+    assert [match.track.filename for match in matches] == [
+        "Track 3.mp3",
+        "Track 2.mp3",
+    ]
+    assert [match.score for match in matches] == [80, 60]