Cover Art Filler: write cover.jpg to the RESOLVED folder, not the raw DB path (Sokhi — the actual bug)

THE bug behind "embeds art but never writes cover.jpgs": _fix_missing_cover_art
passed `details['album_folder']` (= dirname of the raw DB path, e.g. Jellyfin's
/data/music/...) as the target folder. That path doesn't exist inside the
SoulSync container — only the resolved /app/... path does. So apply_art_to_album_
files' `os.path.isdir(target_dir)` was False and the ENTIRE cover.jpg block was
silently skipped: embedding still worked (it uses the resolved paths) and the DB
thumb updated, but the sidecar was never written. Exactly Sokhi's symptom + the
"Cover art already present — database thumbnail updated" toast (cover_written
stayed False).

Fix:
- _fix_missing_cover_art: derive the folder from the RESOLVED file
  (os.path.dirname(resolved[0])), never the raw album_folder.
- apply_art_to_album_files: bulletproof it — if the passed folder doesn't exist,
  fall back to the real directory of the files instead of silently skipping.

Tests: a non-existent folder still writes cover.jpg to the real file dir. 1348
cover/art/repair tests pass.

core/metadata/art_apply.py

@@ -198,8 +198,15 @@ def apply_art_to_album_files(
             logger.warning("Could not embed art into %s: %s", fp, exc)
             result["failed"] += 1
 
-    target_dir = folder or (os.path.dirname(paths[0]) if paths else None)
-    if target_dir and os.path.isdir(target_dir) and not folder_has_cover_sidecar(target_dir):
+    # Prefer the caller's folder, but if it doesn't actually exist (e.g. a raw
+    # DB path that isn't mounted in this container), fall back to the real
+    # directory of the files we just wrote to — never silently skip the sidecar
+    # because a passed-in folder was wrong (Sokhi: cover.jpg never written).
+    target_dir = folder if (folder and os.path.isdir(folder)) else None
+    if not target_dir and paths:
+        cand = os.path.dirname(paths[0])
+        target_dir = cand if os.path.isdir(cand) else None
+    if target_dir and not folder_has_cover_sidecar(target_dir):
         # Prefer the album's OWN embedded art for the cover.jpg sidecar: it's
         # always present once the files are arted (we may have just embedded it),
         # needs no API call, and the sidecar matches the files exactly

core/repair_worker.py

@@ -1394,7 +1394,14 @@ class RepairWorker:
             'album_name': album_title, 'album_image_url': artwork_url,
             'musicbrainz_release_id': mbid,
         }
-        folder = details.get('album_folder') or os.path.dirname(resolved[0])
+        # Use the RESOLVED file's directory — NOT details['album_folder'], which
+        # is the raw DB path (e.g. Jellyfin's /data/music) and frequently does
+        # NOT exist inside the SoulSync container (only the resolved /app/...
+        # path does). Passing the raw folder made os.path.isdir() fail in
+        # apply_art_to_album_files, silently skipping the cover.jpg write while
+        # embedding (which uses the resolved paths) still worked — Sokhi's
+        # "embeds art but never writes cover.jpgs".
+        folder = os.path.dirname(resolved[0])
         art_result = apply_art_to_album_files(resolved, metadata, album_info, folder=folder)
 
         embedded = art_result.get('embedded', 0)

tests/test_art_apply.py

@@ -314,3 +314,23 @@ def test_apply_skips_cover_when_sidecar_exists(tmp_path, monkeypatch):
     aa.apply_art_to_album_files([str(f)], {}, {}, folder=str(tmp_path))
     assert (tmp_path / 'cover.jpg').read_bytes() == b'EXISTING'   # untouched
     assert dl_called == []
+
+
+def test_apply_cover_falls_back_to_file_dir_when_folder_doesnt_exist(tmp_path, monkeypatch):
+    # The Sokhi bug: the caller passed the raw DB folder (e.g. Jellyfin's
+    # /data/music/...) which doesn't exist in the container, so the cover.jpg
+    # write was silently skipped. Now it falls back to the real directory of
+    # the files and writes there anyway.
+    real_dir = tmp_path / 'real'
+    real_dir.mkdir()
+    f = real_dir / '01.flac'; f.write_bytes(b'')
+    audio = SimpleNamespace(pictures=[SimpleNamespace(data=b'EMB')], tags=None, save=lambda: None)
+    monkeypatch.setattr(aa, 'get_mutagen_symbols', lambda: _fake_symbols(audio))
+    monkeypatch.setattr(aa, 'embed_album_art_metadata', lambda *a, **k: True)
+    monkeypatch.setattr(aa, 'download_cover_art', lambda *a, **k: None)
+
+    res = aa.apply_art_to_album_files([str(f)], {}, {},
+                                      folder='/data/music/does/not/exist/in/container')
+
+    assert (real_dir / 'cover.jpg').read_bytes() == b'EMB'   # written to the REAL dir
+    assert res['cover_written'] is True