Dead File Cleaner: don't flag a whole library when paths just aren't reachable (#828)

macstainless: a Plex-on-macOS user running SoulSync in Docker had all 5,250
tracks flagged "dead" even though the files exist and play in Plex. Root cause:
the DB stores paths as Plex reported them (/Volumes/Core/Music/...), which don't
exist inside SoulSync's container. resolve_library_file_path() returns None for
"couldn't find it at any known base dir" — and for a mis-mounted library that's
EVERY track, not a deletion. The job treated None as "file deleted" and created
a finding per track.

Fix mirrors the existing transfer-folder abort: collect unresolvable tracks, and
if at least max_unresolved_fraction (default 0.5) of the library is unresolvable
once it's past min_tracks_for_guard (default 25), treat it as a path-mapping/
mount problem — abort with an actionable message (Docker mount / Settings →
Library → Music Paths) and create ZERO findings. A small fraction unresolvable
is still reported as genuine dead files, and tiny libraries (< min) report as
before. Both thresholds are configurable per the job's settings.

Tests: mass-unresolvable aborts with no findings; a lone dead file among real
ones is still reported; a small all-dead library still reports; thresholds
configurable. 54 repair tests pass.

core/repair_jobs/dead_file_cleaner.py

@@ -36,7 +36,17 @@ class DeadFileCleanerJob(RepairJob):
     icon = 'repair-icon-deadfile'
     default_enabled = True
     default_interval_hours = 24
-    default_settings = {}
+    default_settings = {
+        # Mass-false-positive guard: if at least this fraction of tracks resolve
+        # to no file on disk, treat it as a path-mapping/mount problem (SoulSync
+        # can't SEE the library — e.g. Docker, or library.music_paths unset for
+        # this environment) rather than thousands of individually-deleted files,
+        # and abort without creating findings. Mirrors the transfer-folder abort.
+        'max_unresolved_fraction': 0.5,
+        # ...but only once the library is at least this big — a small library can
+        # legitimately have a high dead fraction.
+        'min_tracks_for_guard': 25,
+    }
     auto_fix = False
 
     def scan(self, context: JobContext) -> JobResult:
@@ -87,9 +97,30 @@ class DeadFileCleanerJob(RepairJob):
         if context.config_manager:
             download_folder = context.config_manager.get('soulseek.download_path', '')
 
+        # Mass-false-positive guard thresholds (see default_settings).
+        max_unresolved_fraction = 0.5
+        min_tracks_for_guard = 25
+        if context.config_manager:
+            try:
+                max_unresolved_fraction = float(context.config_manager.get(
+                    self.get_config_key('max_unresolved_fraction'), 0.5))
+            except (TypeError, ValueError):
+                max_unresolved_fraction = 0.5
+            try:
+                min_tracks_for_guard = int(context.config_manager.get(
+                    self.get_config_key('min_tracks_for_guard'), 25))
+            except (TypeError, ValueError):
+                min_tracks_for_guard = 25
+
         if context.report_progress:
             context.report_progress(phase=f'Checking {total} tracks...', total=total)
 
+        # Collect unresolvable tracks first; decide whether they're genuine dead
+        # files or a systemic path problem AFTER the full pass (below). A "None"
+        # from the resolver means "couldn't find it at any known base dir" — which
+        # for a mis-mounted library is EVERY track, not a real deletion.
+        dead_rows = []
+
         for i, row in enumerate(tracks):
             if context.check_stop():
                 return result
@@ -112,7 +143,41 @@ class DeadFileCleanerJob(RepairJob):
                                            config_manager=context.config_manager)
 
             if resolved is None:
-                # File is truly missing — create finding
+                dead_rows.append(row)
+
+            if context.update_progress and (i + 1) % 100 == 0:
+                context.update_progress(i + 1, total)
+
+        # Mass-false-positive guard: a large fraction of unresolvable paths almost
+        # always means SoulSync can't SEE the library (Docker mount, or
+        # Settings → Library → Music Paths not set for this environment), NOT that
+        # thousands of files were individually deleted. Refuse to flag and say so
+        # — same principle as the transfer-folder abort above. (#828: a Plex-on-
+        # macOS user in Docker had all 5,250 tracks flagged because their stored
+        # /Volumes/... paths don't exist inside the container.)
+        if (dead_rows
+                and result.scanned >= min_tracks_for_guard
+                and len(dead_rows) >= result.scanned * max_unresolved_fraction):
+            logger.error(
+                "Dead file scan: %d/%d tracks unresolvable (>= %.0f%%) — aborting without "
+                "creating findings; this is a path-mapping/mount problem, not deleted files.",
+                len(dead_rows), result.scanned, max_unresolved_fraction * 100)
+            result.errors += 1
+            if context.report_progress:
+                context.report_progress(
+                    phase='Aborted — too many unreachable paths',
+                    log_line=(f"{len(dead_rows)} of {result.scanned} tracks point to paths SoulSync "
+                              f"can't reach — almost always a path-mapping issue (Docker mount, or "
+                              f"Settings → Library → Music Paths), not deleted files. No findings created."),
+                    log_type='error'
+                )
+            if context.update_progress:
+                context.update_progress(total, total)
+            return result
+
+        # A small fraction unresolvable — treat as genuine dead files and report.
+        for row in dead_rows:
+            track_id, title, artist_name, album_title, file_path, album_thumb, artist_thumb = row
             if context.report_progress:
                 context.report_progress(
                     log_line=f'Missing: {title or "Unknown"} — {os.path.basename(file_path)}',
@@ -147,9 +212,6 @@ class DeadFileCleanerJob(RepairJob):
                     logger.debug("Error creating dead file finding for track %s: %s", track_id, e)
                     result.errors += 1
 
-            if context.update_progress and (i + 1) % 100 == 0:
-                context.update_progress(i + 1, total)
-
         if context.update_progress:
             context.update_progress(total, total)
 

tests/test_dead_file_cleaner_guard.py

@@ -0,0 +1,135 @@
+"""Dead File Cleaner — mass-false-positive guard (#828).
+
+macstainless: a Plex-on-macOS user running SoulSync in Docker had all 5,250
+tracks flagged "dead" because their stored /Volumes/... paths don't exist inside
+the container. The resolver returning None means "couldn't find it at any known
+base dir" — for a mis-mounted library that's EVERY track, not a real deletion.
+The job now refuses to flag when a large fraction is unresolvable (a path-mapping
+problem) and reports it as such, mirroring the existing transfer-folder abort.
+"""
+
+from __future__ import annotations
+
+from core.repair_jobs.base import JobContext
+from core.repair_jobs.dead_file_cleaner import DeadFileCleanerJob
+
+
+class _Cur:
+    def __init__(self, rows):
+        self._rows = rows
+
+    def execute(self, *a, **k):
+        pass
+
+    def fetchall(self):
+        return self._rows
+
+    def fetchone(self):
+        return [len(self._rows)]
+
+    def close(self):
+        pass
+
+
+class _Conn:
+    def __init__(self, rows):
+        self._rows = rows
+
+    def cursor(self):
+        return _Cur(self._rows)
+
+    def close(self):
+        pass
+
+
+class _Db:
+    def __init__(self, rows):
+        self._rows = rows
+
+    def _get_connection(self):
+        return _Conn(self._rows)
+
+
+class _Cfg:
+    def __init__(self, overrides=None):
+        self._o = overrides or {}
+
+    def get(self, key, default=None):
+        return self._o.get(key, default)
+
+
+def _row(i, path):
+    # (track_id, title, artist, album, file_path, album_thumb, artist_thumb)
+    return (i, f"Track {i}", "Yellowcard", "Ocean Avenue", path, None, None)
+
+
+def _run(rows, transfer_folder, cfg_overrides=None):
+    findings = []
+    cfg = _Cfg({'soulseek.download_path': '', **(cfg_overrides or {})})
+    ctx = JobContext(
+        db=_Db(rows),
+        transfer_folder=str(transfer_folder),
+        config_manager=cfg,
+        create_finding=lambda **kw: (findings.append(kw) or True),
+    )
+    res = DeadFileCleanerJob().scan(ctx)
+    return res, findings
+
+
+def test_mass_unresolvable_aborts_without_findings(tmp_path):
+    # 30 tracks all pointing to a /Volumes path that doesn't exist in this env
+    # -> systemic path problem -> abort, zero findings, one error.
+    rows = [_row(i, f"/Volumes/Core/Music/Plex/Yellowcard/{i}.mp3") for i in range(30)]
+    res, findings = _run(rows, tmp_path)
+    assert findings == []
+    assert res.findings_created == 0
+    assert res.errors >= 1
+    assert res.scanned == 30
+
+
+def test_few_unresolvable_creates_findings(tmp_path):
+    # 4 real (resolvable) files + 1 genuinely missing -> fraction 0.2 < 0.5 ->
+    # the one dead file IS reported.
+    rows = []
+    for i in range(4):
+        f = tmp_path / f"real_{i}.mp3"
+        f.write_text("x")
+        rows.append(_row(i, str(f)))
+    rows.append(_row(99, "/no/such/path/dead.mp3"))
+    res, findings = _run(rows, tmp_path,
+                         {'repair.jobs.dead_file_cleaner.min_tracks_for_guard': 4})
+    assert res.findings_created == 1
+    assert len(findings) == 1
+    assert findings[0]['entity_id'] == '99'
+    assert res.errors == 0
+
+
+def test_small_library_all_dead_still_reports(tmp_path):
+    # 3 dead tracks, below the default min_tracks_for_guard (25) -> guard doesn't
+    # apply -> all 3 reported (a tiny library can legitimately be all-dead).
+    rows = [_row(i, f"/no/such/{i}.mp3") for i in range(3)]
+    res, findings = _run(rows, tmp_path)
+    assert res.findings_created == 3
+
+
+def test_guard_thresholds_configurable(tmp_path):
+    # Lower min to 4; all 4 dead -> fraction 1.0 >= 0.5 -> abort.
+    rows = [_row(i, f"/no/such/{i}.mp3") for i in range(4)]
+    res, findings = _run(rows, tmp_path,
+                         {'repair.jobs.dead_file_cleaner.min_tracks_for_guard': 4})
+    assert res.findings_created == 0
+    assert res.errors >= 1
+
+
+def test_healthy_library_no_abort_no_findings(tmp_path):
+    # 30 fully-resolvable tracks -> 0 dead -> neither aborts nor flags anything.
+    rows = []
+    for i in range(30):
+        f = tmp_path / f"ok_{i}.mp3"
+        f.write_text("x")
+        rows.append(_row(i, str(f)))
+    res, findings = _run(rows, tmp_path)
+    assert res.findings_created == 0
+    assert res.errors == 0
+    assert res.scanned == 30
+    assert findings == []