From fa29ee2195cc60d778db53410cc78d7b72be9fd0 Mon Sep 17 00:00:00 2001
From: Broque Thomas <26755000+Nezreka@users.noreply.github.com>
Date: Tue, 28 Apr 2026 10:34:13 -0700
Subject: [PATCH] PR4h: lift _run_full_missing_tracks_process to
 core/downloads/master.py
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Final extraction in the download orchestrator series. Lifts the 586-line
master worker that drives the entire missing-tracks pipeline from
`web_server.py` into `core/downloads/master.py`. Pure 1:1 lift — wrappers
keep the original entry-point name so the three callers
(`missing_download_executor.submit(_run_full_missing_tracks_process, ...)`)
continue to work without changes.

What the master worker does:
1. PHASE 1 ANALYSIS — per-track DB ownership check with album fast path
   (lookup album by name+artist, match tracks within it) plus a
   MusicBrainz release-cache preflight so per-track post-processing all
   uses the same release MBID (prevents Navidrome album splits).
2. Wishlist removal for tracks already in the library.
3. Explicit-content filter.
4. PHASE 2 transition — if nothing missing, mark batch complete, update
   per-source playlist phases, kick auto-wishlist completion handler.
5. Soulseek album pre-flight — search for a complete album folder before
   falling back to track-by-track search, cache the source for reuse.
6. Wishlist album grouping — derive per-album disc counts and resolve ONE
   artist context per album so collab albums don't fold-split.
7. Task creation with explicit album/artist context injection +
   playlist-folder-mode flag propagation.
8. Hand off to download_monitor + start_next_batch_of_downloads.
9. Error handler — phase=error, reset YouTube playlist phase to
   'discovered', reset auto-wishlist globals on auto-initiated batches.

Dependencies injected via `MasterDeps` (21 fields) — wide surface
covering config, MB caches/locks, soulseek client, source-page state
dicts, multiple callbacks (wishlist removal, explicit filter, executor
+ auto-completion fn, monitor, start_next_batch). The only behaviour
difference from a pure paste is `import traceback` hoisted to module
scope (was inline in the except block) — same behaviour. Trailing
whitespace on two blank lines also got normalized away by the editor;
neither has any runtime effect.

`reset_wishlist_auto_processing` callback wraps the
`global wishlist_auto_processing, wishlist_auto_processing_timestamp`
write + `wishlist_timer_lock` since `global` can't reach back into
web_server.py from a separate module.

Tests: 21 new under tests/downloads/test_downloads_master.py covering
analysis-phase state, force_download_all, found-track wishlist removal,
explicit filter, no-missing complete + per-source state updates, auto
wishlist completion submit, album fast path (direct + fallthrough),
MB preflight (caches both keys, no-mb-worker no-op), task creation
(queue + tasks dict, explicit context for albums, wishlist album
grouping consistency, playlist folder mode), monitor + next-batch
handoff, multi-disc total_discs computation, error handler (phase set,
youtube reset, auto wishlist reset), and batch-removed-mid-flight
defensive path.

Full suite: 1050 passing (was 1029). Ruff clean.

End of the PR4 series — `web_server.py` lost ~590 lines on this commit
alone; total trim across PR4a–PR4h is ~2900 lines of orchestrator code
moved into focused `core/downloads/*.py` modules.
---
 core/downloads/master.py                 | 648 +++++++++++++++++++++
 tests/downloads/test_downloads_master.py | 684 +++++++++++++++++++++++
 web_server.py                            | 623 ++-------------------
 3 files changed, 1372 insertions(+), 583 deletions(-)
 create mode 100644 core/downloads/master.py
 create mode 100644 tests/downloads/test_downloads_master.py

diff --git a/core/downloads/master.py b/core/downloads/master.py
new file mode 100644
index 00000000..9a449b9c
--- /dev/null
+++ b/core/downloads/master.py
@@ -0,0 +1,648 @@
+"""Master worker for the missing-tracks download workflow.
+
+`run_full_missing_tracks_process(batch_id, playlist_id, tracks_json, deps)` is
+the single 580-line worker that orchestrates the entire pipeline:
+
+  1. PHASE 1 — Analysis: per-track DB ownership check, with album fast path
+     (lookup album by name+artist, match tracks within it) plus a
+     MusicBrainz release-cache preflight so per-track post-processing all
+     uses the same release MBID (prevents Navidrome album splits).
+  2. Wishlist removal for tracks already in the library.
+  3. Explicit-content filter.
+  4. PHASE 2 transition — if nothing missing, mark batch complete, update
+     per-source playlist phases, kick auto-wishlist completion handler.
+  5. Soulseek album pre-flight — search for a complete album folder before
+     falling back to track-by-track search, cache the source for reuse.
+  6. Wishlist album grouping — derive per-album disc counts and resolve
+     ONE artist context per album so collab albums don't fold-split.
+  7. Task creation with explicit album/artist context injection.
+  8. Hand off to download monitor + start_next_batch_of_downloads.
+
+Lifted verbatim from web_server.py. Wide dependency surface (config, MB
+caches, Soulseek client, source-page state dicts, multiple helper funcs)
+all injected via `MasterDeps`.
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+import re
+import time
+import traceback
+import uuid
+from dataclasses import dataclass
+from typing import Any, Callable
+
+from core.runtime_state import download_batches, download_tasks, tasks_lock
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class MasterDeps:
+    """Bundle of cross-cutting deps the master worker needs."""
+    config_manager: Any
+    soulseek_client: Any
+    run_async: Callable[..., Any]
+    mb_worker: Any
+    mb_release_cache: dict
+    mb_release_cache_lock: Any
+    mb_release_detail_cache: dict
+    mb_release_detail_cache_lock: Any
+    normalize_album_cache_key: Callable[[str], str]
+    check_and_remove_track_from_wishlist_by_metadata: Callable
+    is_explicit_blocked: Callable
+    youtube_playlist_states: dict
+    tidal_discovery_states: dict
+    deezer_discovery_states: dict
+    spotify_public_discovery_states: dict
+    missing_download_executor: Any
+    process_failed_tracks_to_wishlist_exact_with_auto_completion: Callable
+    source_reuse_logger: Any
+    download_monitor: Any
+    start_next_batch_of_downloads: Callable[[str], None]
+    reset_wishlist_auto_processing: Callable[[], None]
+
+
+def run_full_missing_tracks_process(batch_id, playlist_id, tracks_json, deps: MasterDeps):
+    """
+    A master worker that handles the entire missing tracks process:
+    1. Runs the analysis.
+    2. If missing tracks are found, it automatically queues them for download.
+    """
+    try:
+        # PHASE 1: ANALYSIS
+        with tasks_lock:
+            if batch_id in download_batches:
+                download_batches[batch_id]['phase'] = 'analysis'
+                download_batches[batch_id]['analysis_total'] = len(tracks_json)
+                download_batches[batch_id]['analysis_processed'] = 0
+
+        from database.music_database import MusicDatabase
+        db = MusicDatabase()
+        active_server = deps.config_manager.get_active_media_server()
+        analysis_results = []
+
+        # Get force download flag and album context from batch
+        force_download_all = False
+        batch_album_context = None
+        batch_artist_context = None
+        batch_is_album = False
+        with tasks_lock:
+            if batch_id in download_batches:
+                force_download_all = download_batches[batch_id].get('force_download_all', False)
+                batch_is_album = download_batches[batch_id].get('is_album_download', False)
+                batch_album_context = download_batches[batch_id].get('album_context')
+                batch_artist_context = download_batches[batch_id].get('artist_context')
+
+        if force_download_all:
+            logger.warning(f"[Force Download] Force download mode enabled for batch {batch_id} - treating all tracks as missing")
+
+        # Allow duplicate tracks across albums — when enabled, only skip tracks already
+        # owned in THIS album, not tracks owned in other albums
+        allow_duplicates = deps.config_manager.get('wishlist.allow_duplicate_tracks', True)
+        if allow_duplicates and batch_is_album:
+            logger.info("[Duplicates] Allow duplicate tracks enabled — only checking ownership within target album")
+
+        # PREFLIGHT: Pre-populate MusicBrainz release cache for album downloads.
+        # This ensures ALL tracks in the album use the same release MBID during
+        # per-track post-processing, preventing Navidrome album splits.
+        if batch_is_album and batch_album_context and batch_artist_context:
+            try:
+                album_name_pf = batch_album_context.get('name', '')
+                artist_name_pf = batch_artist_context.get('name', '')
+                if album_name_pf and artist_name_pf:
+                    mb_svc = deps.mb_worker.mb_service if deps.mb_worker else None
+                    if mb_svc:
+                        from core.album_consistency import _find_best_release
+                        release = _find_best_release(album_name_pf, artist_name_pf, len(tracks_json), mb_svc)
+                        if release and release.get('id'):
+                            release_mbid = release['id']
+                            _artist_key = artist_name_pf.lower().strip()
+                            _rc_key_norm = (deps.normalize_album_cache_key(album_name_pf), _artist_key)
+                            _rc_key_exact = (album_name_pf.lower().strip(), _artist_key)
+                            with deps.mb_release_cache_lock:
+                                deps.mb_release_cache[_rc_key_norm] = release_mbid
+                                deps.mb_release_cache[_rc_key_exact] = release_mbid
+                            # Also cache the full release detail for tag extraction
+                            with deps.mb_release_detail_cache_lock:
+                                deps.mb_release_detail_cache[release_mbid] = release
+                            logger.info(f"[Preflight] Pre-cached MB release for '{album_name_pf}': "
+                                  f"'{release.get('title', '')}' ({release_mbid[:8]}...)")
+                        else:
+                            logger.warning(f"[Preflight] No MB release found for '{album_name_pf}' — per-track lookup will be used")
+            except Exception as pf_err:
+                logger.error(f"[Preflight] MB release preflight failed: {pf_err}")
+
+        # ALBUM FAST PATH: If this is an album download, try to find the album in the DB first
+        # and match tracks within it — faster and more accurate than N global searches
+        album_tracks_map = {}  # Maps normalized title -> DatabaseTrack for album-scoped matching
+        if batch_is_album and batch_album_context and batch_artist_context and not force_download_all:
+            album_name = batch_album_context.get('name', '')
+            artist_name = batch_artist_context.get('name', '')
+            total_tracks = batch_album_context.get('total_tracks', 0)
+            if album_name and artist_name:
+                try:
+                    db_album, album_confidence = db.check_album_exists_with_editions(
+                        title=album_name, artist=artist_name,
+                        confidence_threshold=0.7,
+                        expected_track_count=total_tracks if total_tracks > 0 else None,
+                        server_source=active_server
+                    )
+                    if db_album and album_confidence >= 0.7:
+                        db_album_tracks = db.get_tracks_by_album(db_album.id)
+                        for t in db_album_tracks:
+                            album_tracks_map[t.title.lower().strip()] = t
+                        logger.info(f"[Album Analysis] Found album '{db_album.title}' in DB with {len(db_album_tracks)} tracks (confidence: {album_confidence:.2f})")
+                    else:
+                        logger.warning(f"[Album Analysis] Album '{album_name}' not found in DB — falling back to per-track search")
+                except Exception as album_err:
+                    logger.error(f"[Album Analysis] Album lookup error: {album_err} — falling back to per-track search")
+
+        for i, track_data in enumerate(tracks_json):
+            # Use original table index if provided (for partial track selection),
+            # otherwise fall back to enumeration index
+            track_index = track_data.get('_original_index', i)
+            track_name = track_data.get('name', '')
+            artists = track_data.get('artists', [])
+            found, confidence = False, 0.0
+
+            # Skip database check if force download is enabled
+            if force_download_all:
+                logger.warning(f"[Force Download] Skipping database check for '{track_name}' - treating as missing")
+                found, confidence = False, 0.0
+            elif album_tracks_map:
+                # Album-scoped matching: check against known album tracks first
+                track_name_lower = track_name.lower().strip()
+                # Direct title match
+                if track_name_lower in album_tracks_map:
+                    found, confidence = True, 1.0
+                else:
+                    # Fuzzy match against album tracks using string similarity
+                    best_sim = 0.0
+                    for db_title_lower, _db_track in album_tracks_map.items():
+                        sim = db._string_similarity(track_name_lower, db_title_lower)
+                        if sim > best_sim:
+                            best_sim = sim
+                    if best_sim >= 0.7:
+                        found, confidence = True, best_sim
+                    else:
+                        # Fall back to global per-track search for this track
+                        # When allow_duplicates is on for album downloads, skip global
+                        # search — the track isn't in THIS album so treat as missing
+                        if allow_duplicates and batch_is_album:
+                            found, confidence = False, 0.0
+                        else:
+                            _fallback_album = batch_album_context.get('name') if batch_album_context else None
+                            for artist in artists:
+                                if isinstance(artist, str):
+                                    artist_name = artist
+                                elif isinstance(artist, dict) and 'name' in artist:
+                                    artist_name = artist['name']
+                                else:
+                                    artist_name = str(artist)
+                                db_track, track_confidence = db.check_track_exists(
+                                    track_name, artist_name, confidence_threshold=0.7, server_source=active_server, album=_fallback_album
+                                )
+                                if db_track and track_confidence >= 0.7:
+                                    found, confidence = True, track_confidence
+                                    break
+            elif allow_duplicates and batch_is_album:
+                # Allow duplicates + album download + album not in DB yet → treat all as missing
+                found, confidence = False, 0.0
+            else:
+                # Non-album download (playlist/single track) — always check global
+                for artist in artists:
+                    # Handle both string format and Spotify API format {'name': 'Artist Name'}
+                    if isinstance(artist, str):
+                        artist_name = artist
+                    elif isinstance(artist, dict) and 'name' in artist:
+                        artist_name = artist['name']
+                    else:
+                        artist_name = str(artist)
+                    db_track, track_confidence = db.check_track_exists(
+                        track_name, artist_name, confidence_threshold=0.7, server_source=active_server
+                    )
+                    if db_track and track_confidence >= 0.7:
+                        found, confidence = True, track_confidence
+                        break
+
+            analysis_results.append({
+                'track_index': track_index, 'track': track_data, 'found': found, 'confidence': confidence
+            })
+
+            # WISHLIST REMOVAL: If track is found in database, check if it should be removed from wishlist
+            if found and confidence >= 0.7:
+                try:
+                    deps.check_and_remove_track_from_wishlist_by_metadata(track_data)
+                except Exception as wishlist_error:
+                    logger.error(f"[Analysis] Error checking wishlist removal for found track: {wishlist_error}")
+
+            with tasks_lock:
+                if batch_id in download_batches:
+                    download_batches[batch_id]['analysis_processed'] = i + 1
+                    # Store incremental results for live updates
+                    download_batches[batch_id]['analysis_results'] = analysis_results.copy()
+
+        missing_tracks = [res for res in analysis_results if not res['found']]
+
+        # Filter explicit tracks if content filter is enabled
+        if not deps.config_manager.get('content_filter.allow_explicit', True):
+            before_count = len(missing_tracks)
+            missing_tracks = [res for res in missing_tracks if not deps.is_explicit_blocked(res.get('track', {}))]
+            skipped = before_count - len(missing_tracks)
+            if skipped > 0:
+                logger.warning(f"[Content Filter] Filtered out {skipped} explicit track(s) from download queue")
+
+        with tasks_lock:
+            if batch_id in download_batches:
+                download_batches[batch_id]['analysis_results'] = analysis_results
+
+        # PHASE 2: TRANSITION TO DOWNLOAD (if necessary)
+        if not missing_tracks:
+            logger.warning(f"Analysis for batch {batch_id} complete. No missing tracks.")
+
+            # Record sync history — all tracks found, nothing to download
+            tracks_found = sum(1 for r in analysis_results if r.get('found'))
+            try:
+                db_sh = MusicDatabase()
+                db_sh.update_sync_history_completion(batch_id, tracks_found=tracks_found, tracks_downloaded=0, tracks_failed=0)
+                # Save per-track results (all found, no downloads)
+                track_results = []
+                for res in analysis_results:
+                    td = res.get('track', {})
+                    artists = td.get('artists', [])
+                    first_artist = (artists[0].get('name', artists[0]) if isinstance(artists[0], dict) else str(artists[0])) if artists else ''
+                    alb = td.get('album', '')
+                    # Extract image
+                    _img = ''
+                    _alb_obj = td.get('album', {})
+                    if isinstance(_alb_obj, dict):
+                        _alb_imgs = _alb_obj.get('images', [])
+                        if _alb_imgs and isinstance(_alb_imgs, list) and len(_alb_imgs) > 0:
+                            _img = _alb_imgs[0].get('url', '') if isinstance(_alb_imgs[0], dict) else ''
+                    track_results.append({
+                        'index': res.get('track_index', 0),
+                        'name': td.get('name', ''),
+                        'artist': first_artist,
+                        'album': alb.get('name', '') if isinstance(alb, dict) else str(alb or ''),
+                        'image_url': _img,
+                        'duration_ms': td.get('duration_ms', 0),
+                        'source_track_id': td.get('id', ''),
+                        'status': 'found' if res.get('found') else 'not_found',
+                        'confidence': round(res.get('confidence', 0.0), 3),
+                        'matched_track': None,
+                        'download_status': None,
+                    })
+                if track_results:
+                    db_sh.update_sync_history_track_results(batch_id, json.dumps(track_results))
+            except Exception:
+                pass
+
+            is_auto_batch = False
+            with tasks_lock:
+                if batch_id in download_batches:
+                    is_auto_batch = download_batches[batch_id].get('auto_initiated', False)
+                    download_batches[batch_id]['phase'] = 'complete'
+                    download_batches[batch_id]['completion_time'] = time.time()  # Track for auto-cleanup
+
+                    # Update YouTube playlist phase to 'download_complete' if this is a YouTube playlist
+                    if playlist_id.startswith('youtube_'):
+                        url_hash = playlist_id.replace('youtube_', '')
+                        if url_hash in deps.youtube_playlist_states:
+                            deps.youtube_playlist_states[url_hash]['phase'] = 'download_complete'
+                            logger.warning(f"Updated YouTube playlist {url_hash} to download_complete phase (no missing tracks)")
+
+                    # Update Tidal playlist phase to 'download_complete' if this is a Tidal playlist
+                    if playlist_id.startswith('tidal_'):
+                        tidal_playlist_id = playlist_id.replace('tidal_', '')
+                        if tidal_playlist_id in deps.tidal_discovery_states:
+                            deps.tidal_discovery_states[tidal_playlist_id]['phase'] = 'download_complete'
+                            logger.warning(f"Updated Tidal playlist {tidal_playlist_id} to download_complete phase (no missing tracks)")
+
+                    # Update Deezer playlist phase to 'download_complete' if this is a Deezer playlist
+                    if playlist_id.startswith('deezer_'):
+                        deezer_playlist_id = playlist_id.replace('deezer_', '')
+                        if deezer_playlist_id in deps.deezer_discovery_states:
+                            deps.deezer_discovery_states[deezer_playlist_id]['phase'] = 'download_complete'
+                            logger.warning(f"Updated Deezer playlist {deezer_playlist_id} to download_complete phase (no missing tracks)")
+
+                    # Update Spotify Public playlist phase to 'download_complete' if this is a Spotify Public playlist
+                    if playlist_id.startswith('spotify_public_'):
+                        spotify_public_url_hash = playlist_id.replace('spotify_public_', '')
+                        if spotify_public_url_hash in deps.spotify_public_discovery_states:
+                            deps.spotify_public_discovery_states[spotify_public_url_hash]['phase'] = 'download_complete'
+                            logger.warning(f"Updated Spotify Public playlist {spotify_public_url_hash} to download_complete phase (no missing tracks)")
+
+            # Handle auto-initiated wishlist completion even when no missing tracks
+            if is_auto_batch and playlist_id == 'wishlist':
+                logger.warning("[Auto-Wishlist] No missing tracks found - calling auto-completion handler to toggle cycle and reschedule")
+                deps.missing_download_executor.submit(deps.process_failed_tracks_to_wishlist_exact_with_auto_completion, batch_id)
+
+            return
+
+        logger.warning(f" transitioning batch {batch_id} to download phase with {len(missing_tracks)} tracks.")
+
+        # Read batch context (quick lock) before doing any network I/O
+        with tasks_lock:
+            if batch_id not in download_batches: return
+            batch = download_batches[batch_id]
+            batch_album_context = batch.get('album_context')
+            batch_artist_context = batch.get('artist_context')
+            batch_is_album = batch.get('is_album_download', False)
+            batch_playlist_folder_mode = batch.get('playlist_folder_mode', False)
+            batch_playlist_name = batch.get('playlist_name', 'Unknown Playlist')
+
+        # === ALBUM PRE-FLIGHT: Search for complete album folder before track-by-track ===
+        # Only run pre-flight when Soulseek is the download source (or hybrid with soulseek)
+        preflight_source = None
+        preflight_tracks = None
+        dl_source_mode = deps.config_manager.get('download_source.mode', 'hybrid')
+        _dl_hybrid_order = deps.config_manager.get('download_source.hybrid_order', ['hifi', 'youtube', 'soulseek'])
+        _dl_hybrid_first = _dl_hybrid_order[0] if _dl_hybrid_order else deps.config_manager.get('download_source.hybrid_primary', 'hifi')
+        soulseek_is_source = dl_source_mode == 'soulseek' or (
+            dl_source_mode == 'hybrid' and _dl_hybrid_first == 'soulseek'
+        )
+        if batch_is_album and batch_album_context and batch_artist_context and soulseek_is_source:
+            artist_name = batch_artist_context.get('name', '')
+            album_name = batch_album_context.get('name', '')
+            if artist_name and album_name:
+                try:
+                    _sr = deps.source_reuse_logger
+                    _sr.info(f"[Album Pre-flight] Searching for '{artist_name} {album_name}'")
+                    logger.info(f"[Album Pre-flight] Searching Soulseek for complete album: '{artist_name} - {album_name}'")
+
+                    slsk = deps.soulseek_client.soulseek if hasattr(deps.soulseek_client, 'soulseek') else deps.soulseek_client
+
+                    # Try multiple query variations (banned keywords in artist/album name can return 0 results)
+                    album_queries = [f"{artist_name} {album_name}"]
+                    # Clean artist name (remove feat., parentheticals)
+                    clean_artist = re.sub(r'\s*\(.*?\)', '', artist_name).strip()
+                    clean_artist = re.sub(r'\s*(feat\.?|ft\.?|featuring)\s+.*$', '', clean_artist, flags=re.IGNORECASE).strip()
+                    if clean_artist != artist_name:
+                        album_queries.append(f"{clean_artist} {album_name}")
+                    # Album name only (some users file by album)
+                    album_queries.append(album_name)
+
+                    album_results = []
+                    track_results = []
+                    for aq in album_queries:
+                        _sr.info(f"[Album Pre-flight] Trying query: '{aq}'")
+                        track_results, album_results = deps.run_async(slsk.search(aq, timeout=30))
+                        if album_results:
+                            _sr.info(f"[Album Pre-flight] Found {len(album_results)} album results with query: '{aq}'")
+                            break
+                        _sr.info(f"[Album Pre-flight] No album results for query: '{aq}'")
+
+                    if album_results:
+                        # Filter by quality preference
+                        quality_filtered = []
+                        for ar in album_results:
+                            filtered_tracks = slsk.filter_results_by_quality_preference(ar.tracks)
+                            if filtered_tracks:
+                                quality_filtered.append((ar, len(filtered_tracks)))
+
+                        if quality_filtered:
+                            # Sort by track count (most complete album first), then quality score
+                            quality_filtered.sort(key=lambda x: (x[1], x[0].quality_score), reverse=True)
+                            best_album = quality_filtered[0][0]
+
+                            _sr.info(f"[Album Pre-flight] Best album result: {best_album.username}:{best_album.album_path} "
+                                     f"({best_album.track_count} tracks, quality={best_album.dominant_quality})")
+                            logger.info(f"[Album Pre-flight] Found album folder: {best_album.username} — "
+                                  f"{best_album.track_count} tracks ({best_album.dominant_quality})")
+
+                            # Browse the user's folder to get all tracks (may have more than search returned)
+                            browse_files = deps.run_async(slsk.browse_user_directory(best_album.username, best_album.album_path))
+                            if browse_files:
+                                folder_tracks = slsk.parse_browse_results_to_tracks(
+                                    best_album.username, browse_files, directory=best_album.album_path
+                                )
+                                if folder_tracks:
+                                    preflight_source = {
+                                        'username': best_album.username,
+                                        'folder_path': best_album.album_path
+                                    }
+                                    preflight_tracks = folder_tracks
+                                    _sr.info(f"[Album Pre-flight] Browsed folder: {len(folder_tracks)} audio tracks available")
+                                    logger.info(f"[Album Pre-flight] Cached {len(folder_tracks)} tracks from {best_album.username} for source reuse")
+                                else:
+                                    _sr.info("[Album Pre-flight] Browse returned files but no audio tracks")
+                            else:
+                                # Browse failed — fall back to using the search result tracks directly
+                                _sr.info("[Album Pre-flight] Browse failed, using search result tracks directly")
+                                preflight_source = {
+                                    'username': best_album.username,
+                                    'folder_path': best_album.album_path
+                                }
+                                preflight_tracks = best_album.tracks
+                                logger.info(f"[Album Pre-flight] Using {len(best_album.tracks)} tracks from search results (browse unavailable)")
+                        else:
+                            _sr.info("[Album Pre-flight] No album results passed quality filter")
+                            logger.warning("[Album Pre-flight] No album results matched quality preferences")
+                    else:
+                        _sr.info(f"[Album Pre-flight] Search returned no album results (got {len(track_results)} individual tracks)")
+                        logger.warning("[Album Pre-flight] No complete album folders found, falling back to track-by-track search")
+
+                except Exception as preflight_err:
+                    logger.error(f"[Album Pre-flight] Search failed (non-fatal, falling back to track-by-track): {preflight_err}")
+                    deps.source_reuse_logger.info(f"[Album Pre-flight] Exception: {preflight_err}")
+
+        with tasks_lock:
+            if batch_id not in download_batches: return
+
+            download_batches[batch_id]['phase'] = 'downloading'
+
+            # Store album pre-flight results on batch for source reuse
+            if preflight_source and preflight_tracks:
+                download_batches[batch_id]['last_good_source'] = preflight_source
+                download_batches[batch_id]['source_folder_tracks'] = preflight_tracks
+                download_batches[batch_id]['failed_sources'] = set()
+                logger.info(f"[Album Pre-flight] Pre-loaded source reuse data on batch {batch_id}")
+
+            # Compute total_discs for multi-disc album subfolder support
+            # Use ALL tracks (tracks_json), not just missing ones, to correctly detect multi-disc
+            # even when only one disc has missing tracks
+            if batch_is_album and batch_album_context:
+                total_discs = max((t.get('disc_number', 1) for t in tracks_json), default=1)
+                batch_album_context['total_discs'] = total_discs
+                if total_discs > 1:
+                    logger.info(f"[Multi-Disc] Detected {total_discs} discs for album '{batch_album_context.get('name')}'")
+
+            # Pre-compute per-album data for wishlist tracks (grouped by album ID)
+            # Wishlist tracks aren't batch_is_album but each track has disc_number in spotify_data
+            wishlist_album_disc_counts = {}
+            wishlist_album_artist_map = {}  # album_id -> resolved artist context (consistent per album)
+            if playlist_id == 'wishlist':
+                import json as _json
+                # First pass: collect disc_number and resolve ONE artist per album
+                for t in tracks_json:
+                    sp_data = t.get('spotify_data', {})
+                    if isinstance(sp_data, str):
+                        try:
+                            sp_data = _json.loads(sp_data)
+                        except:
+                            sp_data = {}
+                    album_val = sp_data.get('album')
+                    album_id = album_val.get('id') if isinstance(album_val, dict) else album_val if isinstance(album_val, str) else None
+                    # Fallback album key: use album name when ID is missing (e.g. mirrored playlist tracks)
+                    if not album_id and isinstance(album_val, dict) and album_val.get('name'):
+                        album_id = f"_name_{album_val['name'].lower().strip()}"
+                    disc_num = sp_data.get('disc_number', t.get('disc_number', 1))
+                    if album_id:
+                        wishlist_album_disc_counts[album_id] = max(
+                            wishlist_album_disc_counts.get(album_id, 1), disc_num
+                        )
+                        # Resolve album-level artist once per album (first track wins)
+                        if album_id not in wishlist_album_artist_map:
+                            _wl_source = t.get('source_info') or {}
+                            if isinstance(_wl_source, str):
+                                try:
+                                    _wl_source = _json.loads(_wl_source)
+                                except:
+                                    _wl_source = {}
+                            _wl_album = album_val if isinstance(album_val, dict) else {}
+                            _wl_album_artists = _wl_album.get('artists', [])
+                            # Priority: watchlist artist > album artists > track artists
+                            if _wl_source.get('watchlist_artist_name'):
+                                wishlist_album_artist_map[album_id] = {
+                                    'name': _wl_source['watchlist_artist_name'],
+                                    'id': _wl_source.get('watchlist_artist_id', '')
+                                }
+                            elif _wl_source.get('artist_name'):
+                                wishlist_album_artist_map[album_id] = {'name': _wl_source['artist_name']}
+                            elif _wl_album_artists:
+                                _fa = _wl_album_artists[0]
+                                wishlist_album_artist_map[album_id] = _fa if isinstance(_fa, dict) else {'name': str(_fa)}
+                            else:
+                                _wl_track_artists = sp_data.get('artists', [])
+                                if _wl_track_artists:
+                                    _fa = _wl_track_artists[0]
+                                    wishlist_album_artist_map[album_id] = _fa if isinstance(_fa, dict) else {'name': str(_fa)}
+                                else:
+                                    # Try top-level 'artists' (wishlist format uses plural)
+                                    _tl_artists = t.get('artists', [])
+                                    if _tl_artists:
+                                        _tla = _tl_artists[0]
+                                        _fallback_name = _tla.get('name', str(_tla)) if isinstance(_tla, dict) else str(_tla)
+                                    else:
+                                        _fallback_name = t.get('artist', '')
+                                    wishlist_album_artist_map[album_id] = {'name': _fallback_name or 'Unknown Artist'}
+                            logger.info(f"[Wishlist Album Grouping] Album '{_wl_album.get('name', album_id)}' → artist: '{wishlist_album_artist_map[album_id].get('name', '?')}'")
+
+
+
+            for res in missing_tracks:
+                task_id = str(uuid.uuid4())
+                track_info = res['track'].copy()
+
+                # Add explicit album context to track_info for artist album downloads
+                if batch_is_album and batch_album_context and batch_artist_context:
+                    track_info['_explicit_album_context'] = batch_album_context
+                    track_info['_explicit_artist_context'] = batch_artist_context
+                    track_info['_is_explicit_album_download'] = True
+                    logger.info(f"[Task Creation] Added explicit album context for: {track_info.get('name')}")
+
+                # SPECIAL WISHLIST HANDLING: Inject album context if available to force grouping
+                elif playlist_id == 'wishlist':
+                    # Extract spotify_data again since it might be buried
+                    spotify_data = track_info.get('spotify_data')
+                    if isinstance(spotify_data, str):
+                        try:
+                            spotify_data = json.loads(spotify_data)
+                        except:
+                            spotify_data = {}
+
+                    if not spotify_data:
+                        spotify_data = {}
+
+                    s_album = spotify_data.get('album') or {}
+                    if isinstance(s_album, str):
+                        s_album = {'name': s_album}  # Normalize string album to dict
+                    s_artists = spotify_data.get('artists', [])
+
+                    # We need at least an album name and artist
+                    if s_album and isinstance(s_album, dict) and s_album.get('name'):
+                        # Use pre-computed album-level artist for folder consistency.
+                        # All tracks from the same album get the same artist context,
+                        # preventing folder splits on collab albums (KPOP Demon Hunters, etc.)
+                        album_id_for_lookup = s_album.get('id')
+                        # Fallback album key: match first-pass logic for missing IDs
+                        if not album_id_for_lookup and s_album.get('name'):
+                            album_id_for_lookup = f"_name_{s_album['name'].lower().strip()}"
+                        if not album_id_for_lookup:
+                            album_id_for_lookup = 'wishlist_album'
+                        artist_ctx = wishlist_album_artist_map.get(album_id_for_lookup, {})
+                        if not artist_ctx or not artist_ctx.get('name'):
+                            # Fallback: per-track resolution from artists array
+                            _fb_artists = track_info.get('artists', [])
+                            if _fb_artists:
+                                _fb_a = _fb_artists[0]
+                                _fb_name = _fb_a.get('name', str(_fb_a)) if isinstance(_fb_a, dict) else str(_fb_a)
+                            else:
+                                _fb_name = track_info.get('artist', '')
+                            artist_ctx = {'name': _fb_name or 'Unknown Artist'}
+
+                        # Construct minimal album context
+                        # Ensure images are preserved (important for artwork)
+                        album_id = s_album.get('id', 'wishlist_album')
+                        album_ctx = {
+                            'id': album_id,
+                            'name': s_album.get('name'),
+                            'release_date': s_album.get('release_date', ''),
+                            'total_tracks': s_album.get('total_tracks', 1),
+                            'total_discs': wishlist_album_disc_counts.get(album_id, 1),
+                            'album_type': s_album.get('album_type', 'album'),
+                            'images': s_album.get('images', []) # Pass images array directly
+                        }
+
+                        track_info['_explicit_album_context'] = album_ctx
+                        track_info['_explicit_artist_context'] = artist_ctx
+                        track_info['_is_explicit_album_download'] = True
+                        logger.info(f"[Wishlist] Added album context for: '{track_info.get('name')}' -> '{album_ctx['name']}'")
+
+
+                # Add playlist folder mode flag for sync page playlists
+                if batch_playlist_folder_mode:
+                    track_info['_playlist_folder_mode'] = True
+                    track_info['_playlist_name'] = batch_playlist_name
+                    logger.info(f"[Task Creation] Added playlist folder mode for: {track_info.get('name')} → {batch_playlist_name}")
+                else:
+                    logger.debug(f"[Debug] Task Creation - playlist folder mode NOT enabled for: {track_info.get('name')}")
+
+                download_tasks[task_id] = {
+                    'status': 'pending', 'track_info': track_info,
+                    'playlist_id': playlist_id, 'batch_id': batch_id,
+                    'track_index': res['track_index'], 'retry_count': 0,
+                    'cached_candidates': [], 'used_sources': set(),
+                    'status_change_time': time.time(),
+                    'metadata_enhanced': False
+                }
+                download_batches[batch_id]['queue'].append(task_id)
+
+        deps.download_monitor.start_monitoring(batch_id)
+        deps.start_next_batch_of_downloads(batch_id)
+
+    except Exception as e:
+        logger.error(f"Master worker for batch {batch_id} failed: {e}")
+        traceback.print_exc()
+
+        is_auto_batch = False
+        with tasks_lock:
+            if batch_id in download_batches:
+                is_auto_batch = download_batches[batch_id].get('auto_initiated', False)
+                download_batches[batch_id]['phase'] = 'error'
+                download_batches[batch_id]['error'] = str(e)
+
+                # Reset YouTube playlist phase to 'discovered' if this is a YouTube playlist on error
+                if playlist_id.startswith('youtube_'):
+                    url_hash = playlist_id.replace('youtube_', '')
+                    if url_hash in deps.youtube_playlist_states:
+                        deps.youtube_playlist_states[url_hash]['phase'] = 'discovered'
+                        logger.error(f"Reset YouTube playlist {url_hash} to discovered phase (error)")
+
+        # Handle auto-initiated wishlist errors - reset flag
+        if is_auto_batch and playlist_id == 'wishlist':
+            logger.error("[Auto-Wishlist] Master worker error - resetting auto-processing flag")
+            deps.reset_wishlist_auto_processing()
diff --git a/tests/downloads/test_downloads_master.py b/tests/downloads/test_downloads_master.py
new file mode 100644
index 00000000..5307dd2f
--- /dev/null
+++ b/tests/downloads/test_downloads_master.py
@@ -0,0 +1,684 @@
+"""Tests for core/downloads/master.py — full missing-tracks master worker."""
+
+from __future__ import annotations
+
+import threading
+
+import pytest
+
+from core.downloads import master as mw
+from core.runtime_state import download_batches, download_tasks, tasks_lock
+
+
+# ---------------------------------------------------------------------------
+# Fixtures + fakes
+# ---------------------------------------------------------------------------
+
+@pytest.fixture(autouse=True)
+def reset_state():
+    download_tasks.clear()
+    download_batches.clear()
+    yield
+    download_tasks.clear()
+    download_batches.clear()
+
+
+class _FakeConfig:
+    def __init__(self, values=None):
+        self._v = values or {}
+
+    def get(self, key, default=None):
+        return self._v.get(key, default)
+
+    def get_active_media_server(self):
+        return self._v.get('_active_server', 'plex')
+
+
+class _FakeDB:
+    def __init__(self, found_tracks=None, album=None, album_tracks=None, album_confidence=0.95):
+        self.found_tracks = found_tracks or {}  # (title_lower, artist_lower) -> confidence
+        self.album = album
+        self.album_tracks = album_tracks or []
+        self.album_confidence = album_confidence
+        self.sync_history_calls = []
+        self.track_results_calls = []
+
+    def check_track_exists(self, title, artist, confidence_threshold=0.7, server_source=None, album=None):
+        key = (title.lower().strip(), artist.lower().strip())
+        if key in self.found_tracks:
+            conf = self.found_tracks[key]
+            return (object(), conf)  # (DatabaseTrack-ish, confidence)
+        return (None, 0.0)
+
+    def check_album_exists_with_editions(self, title, artist, confidence_threshold=0.7,
+                                         expected_track_count=None, server_source=None):
+        return (self.album, self.album_confidence)
+
+    def get_tracks_by_album(self, album_id):
+        return self.album_tracks
+
+    def _string_similarity(self, a, b):
+        if a == b:
+            return 1.0
+        if a in b or b in a:
+            return 0.85
+        return 0.0
+
+    def update_sync_history_completion(self, batch_id, **kwargs):
+        self.sync_history_calls.append((batch_id, kwargs))
+
+    def update_sync_history_track_results(self, batch_id, results_json):
+        self.track_results_calls.append((batch_id, results_json))
+
+
+class _DBTrack:
+    def __init__(self, title):
+        self.title = title
+
+
+class _DBAlbum:
+    def __init__(self, id_, title):
+        self.id = id_
+        self.title = title
+
+
+class _FakeSoulseek:
+    def __init__(self, album_results=None, track_results=None, browse_files=None, parsed_tracks=None):
+        self._album_results = album_results or []
+        self._track_results = track_results or []
+        self._browse_files = browse_files
+        self._parsed_tracks = parsed_tracks or []
+        self.search_calls = []
+
+    async def search(self, query, timeout=30):
+        self.search_calls.append(query)
+        return (self._track_results, self._album_results)
+
+    def filter_results_by_quality_preference(self, tracks):
+        return tracks  # no-op, accept all
+
+    async def browse_user_directory(self, username, path):
+        return self._browse_files
+
+    def parse_browse_results_to_tracks(self, username, browse_files, directory):
+        return self._parsed_tracks
+
+
+class _FakeSoulseekWrapper:
+    """Wraps a soulseek client at .soulseek attribute (matches web_server pattern)."""
+    def __init__(self, inner):
+        self.soulseek = inner
+
+
+class _FakeMonitor:
+    def __init__(self):
+        self.started = []
+
+    def start_monitoring(self, batch_id):
+        self.started.append(batch_id)
+
+
+class _FakeExecutor:
+    def __init__(self):
+        self.submitted = []
+
+    def submit(self, fn, *args):
+        self.submitted.append((fn, args))
+
+
+class _FakeMBSvc:
+    pass
+
+
+class _FakeMBWorker:
+    def __init__(self, svc=None):
+        self.mb_service = svc
+
+
+def _run_async_sync(coro):
+    """Synchronously run a coroutine for tests."""
+    import asyncio
+    return asyncio.get_event_loop().run_until_complete(coro) if not asyncio.iscoroutine(coro) else asyncio.new_event_loop().run_until_complete(coro)
+
+
+def _make_run_async():
+    import asyncio
+    def _runner(coro):
+        loop = asyncio.new_event_loop()
+        try:
+            return loop.run_until_complete(coro)
+        finally:
+            loop.close()
+    return _runner
+
+
+def _build_deps(
+    *,
+    config=None,
+    soulseek=None,
+    run_async=None,
+    mb_worker=None,
+    mb_release_cache=None,
+    mb_release_cache_lock=None,
+    mb_release_detail_cache=None,
+    mb_release_detail_cache_lock=None,
+    normalize_album_cache_key=None,
+    wishlist_remove=None,
+    is_explicit_blocked=None,
+    yt_states=None,
+    tidal_states=None,
+    deezer_states=None,
+    spotify_states=None,
+    executor=None,
+    process_failed_auto=None,
+    source_reuse_logger=None,
+    monitor=None,
+    start_next_batch=None,
+    reset_wishlist_auto=None,
+):
+    return mw.MasterDeps(
+        config_manager=config or _FakeConfig(),
+        soulseek_client=soulseek or _FakeSoulseekWrapper(_FakeSoulseek()),
+        run_async=run_async or _make_run_async(),
+        mb_worker=mb_worker,
+        mb_release_cache=mb_release_cache if mb_release_cache is not None else {},
+        mb_release_cache_lock=mb_release_cache_lock or threading.Lock(),
+        mb_release_detail_cache=mb_release_detail_cache if mb_release_detail_cache is not None else {},
+        mb_release_detail_cache_lock=mb_release_detail_cache_lock or threading.Lock(),
+        normalize_album_cache_key=normalize_album_cache_key or (lambda s: s.lower().strip()),
+        check_and_remove_track_from_wishlist_by_metadata=wishlist_remove or (lambda td: None),
+        is_explicit_blocked=is_explicit_blocked or (lambda td: False),
+        youtube_playlist_states=yt_states if yt_states is not None else {},
+        tidal_discovery_states=tidal_states if tidal_states is not None else {},
+        deezer_discovery_states=deezer_states if deezer_states is not None else {},
+        spotify_public_discovery_states=spotify_states if spotify_states is not None else {},
+        missing_download_executor=executor or _FakeExecutor(),
+        process_failed_tracks_to_wishlist_exact_with_auto_completion=process_failed_auto or (lambda bid: None),
+        source_reuse_logger=source_reuse_logger or _StubLogger(),
+        download_monitor=monitor or _FakeMonitor(),
+        start_next_batch_of_downloads=start_next_batch or (lambda bid: None),
+        reset_wishlist_auto_processing=reset_wishlist_auto or (lambda: None),
+    )
+
+
+class _StubLogger:
+    def info(self, *a, **kw): pass
+    def warning(self, *a, **kw): pass
+    def error(self, *a, **kw): pass
+    def debug(self, *a, **kw): pass
+
+
+def _seed_batch(batch_id, **overrides):
+    base = {
+        'phase': 'queued',
+        'queue': [],
+        'analysis_total': 0,
+        'analysis_processed': 0,
+        'analysis_results': [],
+    }
+    base.update(overrides)
+    download_batches[batch_id] = base
+
+
+# ---------------------------------------------------------------------------
+# PHASE 1: analysis
+# ---------------------------------------------------------------------------
+
+def test_analysis_phase_sets_state(monkeypatch):
+    """Analysis phase marks batch counters; phase moves to 'downloading' when there are missing tracks."""
+    db = _FakeDB()  # found_tracks empty → every track marked missing
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    _seed_batch('B1')
+    deps = _build_deps()
+    tracks = [{'name': 'T1', 'artists': ['A']}]
+
+    mw.run_full_missing_tracks_process('B1', 'P1', tracks, deps)
+
+    # Track was missing → progressed to 'downloading' phase
+    assert download_batches['B1']['phase'] == 'downloading'
+    assert download_batches['B1']['analysis_processed'] == 1
+    assert len(download_batches['B1']['analysis_results']) == 1
+
+
+def test_force_download_treats_all_as_missing(monkeypatch):
+    """force_download_all skips DB check — every track marked missing."""
+    db = _FakeDB(found_tracks={('t1', 'a'): 1.0, ('t2', 'a'): 1.0})  # would otherwise be found
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    _seed_batch('B2', force_download_all=True)
+    deps = _build_deps()
+    tracks = [
+        {'name': 'T1', 'artists': ['A']},
+        {'name': 'T2', 'artists': ['A']},
+    ]
+
+    mw.run_full_missing_tracks_process('B2', 'playlist1', tracks, deps)
+
+    # All 2 tracks should produce queue tasks (treated as missing)
+    assert len(download_batches['B2']['queue']) == 2
+    assert download_batches['B2']['phase'] == 'downloading'
+
+
+def test_found_tracks_trigger_wishlist_removal(monkeypatch):
+    """When DB lookup succeeds, master worker invokes wishlist removal callback."""
+    db = _FakeDB(found_tracks={('t1', 'a'): 0.9})
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    removed = []
+    deps = _build_deps(wishlist_remove=lambda td: removed.append(td.get('name')))
+
+    _seed_batch('B3')
+    tracks = [{'name': 'T1', 'artists': ['A']}]
+
+    mw.run_full_missing_tracks_process('B3', 'P1', tracks, deps)
+
+    assert removed == ['T1']
+
+
+def test_explicit_filter_removes_blocked_tracks(monkeypatch):
+    """When content_filter.allow_explicit=False, blocked tracks dropped from missing set."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    config = _FakeConfig({'content_filter.allow_explicit': False})
+    deps = _build_deps(
+        config=config,
+        is_explicit_blocked=lambda td: td.get('name') == 'BLOCKED',
+    )
+
+    _seed_batch('B4')
+    tracks = [
+        {'name': 'CLEAN', 'artists': ['A']},
+        {'name': 'BLOCKED', 'artists': ['A']},
+    ]
+
+    mw.run_full_missing_tracks_process('B4', 'P1', tracks, deps)
+
+    # only CLEAN survives the filter
+    assert len(download_batches['B4']['queue']) == 1
+
+
+# ---------------------------------------------------------------------------
+# PHASE 2: no missing -> complete + state updates
+# ---------------------------------------------------------------------------
+
+def test_no_missing_marks_batch_complete(monkeypatch):
+    """If every track found in DB, batch transitions directly to complete."""
+    db = _FakeDB(found_tracks={('t1', 'a'): 0.9, ('t2', 'a'): 0.9})
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    _seed_batch('B5')
+    tracks = [
+        {'name': 'T1', 'artists': ['A']},
+        {'name': 'T2', 'artists': ['A']},
+    ]
+
+    mw.run_full_missing_tracks_process('B5', 'P1', tracks, deps)
+
+    assert download_batches['B5']['phase'] == 'complete'
+    assert 'completion_time' in download_batches['B5']
+    assert db.sync_history_calls  # sync history written
+
+
+def test_no_missing_updates_youtube_playlist_state(monkeypatch):
+    """YouTube playlist phase set to 'download_complete' on no-missing."""
+    db = _FakeDB(found_tracks={('t1', 'a'): 0.9})
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    yt_states = {'abc123': {'phase': 'discovered'}}
+    deps = _build_deps(yt_states=yt_states)
+
+    _seed_batch('B6')
+    mw.run_full_missing_tracks_process('B6', 'youtube_abc123', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    assert yt_states['abc123']['phase'] == 'download_complete'
+
+
+def test_no_missing_with_auto_wishlist_submits_completion(monkeypatch):
+    """auto_initiated wishlist batch with no missing tracks submits auto-completion handler."""
+    db = _FakeDB(found_tracks={('t1', 'a'): 0.9})
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    executor = _FakeExecutor()
+    auto_called = []
+    deps = _build_deps(executor=executor, process_failed_auto=lambda bid: auto_called.append(bid))
+
+    _seed_batch('B7', auto_initiated=True)
+    mw.run_full_missing_tracks_process('B7', 'wishlist', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    assert len(executor.submitted) == 1
+    fn, args = executor.submitted[0]
+    assert args == ('B7',)
+
+
+# ---------------------------------------------------------------------------
+# Album fast path
+# ---------------------------------------------------------------------------
+
+def test_album_fast_path_direct_match(monkeypatch):
+    """Album lookup + direct title match → track marked found, no queue entry."""
+    album = _DBAlbum(id_=42, title='Test Album')
+    album_tracks = [_DBTrack('T1'), _DBTrack('T2')]
+    db = _FakeDB(album=album, album_tracks=album_tracks)
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    _seed_batch('B8',
+                is_album_download=True,
+                album_context={'name': 'Test Album', 'total_tracks': 2},
+                artist_context={'name': 'Artist'})
+
+    tracks = [{'name': 'T1', 'artists': ['Artist']}, {'name': 'T2', 'artists': ['Artist']}]
+    mw.run_full_missing_tracks_process('B8', 'album:1', tracks, deps)
+
+    assert download_batches['B8']['phase'] == 'complete'  # all matched
+
+
+def test_album_fast_path_misses_fall_through_to_global(monkeypatch):
+    """Album lookup with track not in album → fuzzy fallback or per-track global search."""
+    album = _DBAlbum(id_=42, title='Test Album')
+    album_tracks = [_DBTrack('Existing')]
+    db = _FakeDB(
+        album=album,
+        album_tracks=album_tracks,
+        found_tracks={},  # global search finds nothing for Other
+    )
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    _seed_batch('B9',
+                is_album_download=True,
+                album_context={'name': 'Test Album', 'total_tracks': 2},
+                artist_context={'name': 'Artist'})
+
+    # 'Other' is not in album, allow_duplicates default True → marked missing without global search
+    tracks = [{'name': 'Other', 'artists': ['Artist']}]
+    mw.run_full_missing_tracks_process('B9', 'album:1', tracks, deps)
+
+    assert len(download_batches['B9']['queue']) == 1
+
+
+# ---------------------------------------------------------------------------
+# MB release preflight
+# ---------------------------------------------------------------------------
+
+def test_mb_release_preflight_caches_mbid(monkeypatch):
+    """MB preflight caches release MBID under both normalized and exact keys."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    fake_release = {'id': 'mbid-xyz', 'title': 'Test Album'}
+
+    def fake_find_best_release(album, artist, count, svc):
+        return fake_release
+
+    import core.album_consistency as ac
+    monkeypatch.setattr(ac, '_find_best_release', fake_find_best_release)
+
+    cache = {}
+    detail_cache = {}
+    deps = _build_deps(
+        mb_worker=_FakeMBWorker(svc=_FakeMBSvc()),
+        mb_release_cache=cache,
+        mb_release_detail_cache=detail_cache,
+    )
+    _seed_batch('B10',
+                is_album_download=True,
+                album_context={'name': 'Test Album', 'total_tracks': 1},
+                artist_context={'name': 'Artist'})
+
+    mw.run_full_missing_tracks_process('B10', 'album:1', [{'name': 'T1', 'artists': ['Artist']}], deps)
+
+    # Should have cached under both normalized and exact-lower keys
+    assert ('test album', 'artist') in cache
+    assert cache[('test album', 'artist')] == 'mbid-xyz'
+    assert detail_cache['mbid-xyz'] == fake_release
+
+
+def test_mb_release_preflight_skipped_when_no_mb_worker(monkeypatch):
+    """Without mb_worker, preflight quietly skips."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    cache = {}
+    deps = _build_deps(mb_worker=None, mb_release_cache=cache)
+    _seed_batch('B11',
+                is_album_download=True,
+                album_context={'name': 'Album', 'total_tracks': 1},
+                artist_context={'name': 'Artist'})
+
+    mw.run_full_missing_tracks_process('B11', 'album:1', [{'name': 'T1', 'artists': ['Artist']}], deps)
+
+    assert cache == {}  # nothing cached
+
+
+# ---------------------------------------------------------------------------
+# Task creation
+# ---------------------------------------------------------------------------
+
+def test_missing_tracks_create_queue_tasks(monkeypatch):
+    """Missing tracks produce download_tasks + are appended to batch queue."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    _seed_batch('B12')
+
+    tracks = [{'name': 'T1', 'artists': ['A']}, {'name': 'T2', 'artists': ['A']}]
+    mw.run_full_missing_tracks_process('B12', 'P1', tracks, deps)
+
+    assert len(download_batches['B12']['queue']) == 2
+    for task_id in download_batches['B12']['queue']:
+        assert task_id in download_tasks
+        assert download_tasks[task_id]['status'] == 'pending'
+        assert download_tasks[task_id]['batch_id'] == 'B12'
+
+
+def test_album_download_injects_explicit_context(monkeypatch):
+    """Album downloads embed _explicit_album_context + _explicit_artist_context per task."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    album_ctx = {'name': 'Album', 'total_tracks': 1}
+    artist_ctx = {'name': 'Artist'}
+    _seed_batch('B13',
+                is_album_download=True,
+                album_context=album_ctx,
+                artist_context=artist_ctx)
+
+    mw.run_full_missing_tracks_process('B13', 'album:1', [{'name': 'T1', 'artists': ['Artist']}], deps)
+
+    assert len(download_batches['B13']['queue']) == 1
+    task_id = download_batches['B13']['queue'][0]
+    info = download_tasks[task_id]['track_info']
+    assert info['_explicit_album_context'] == album_ctx
+    assert info['_explicit_artist_context'] == artist_ctx
+    assert info['_is_explicit_album_download'] is True
+
+
+def test_wishlist_album_grouping_resolves_artist(monkeypatch):
+    """Wishlist tracks sharing an album_id all get the same artist context."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    _seed_batch('B14')
+
+    # Two tracks on same album with different track-level artists — wishlist grouping
+    # should resolve ONE artist for the album (first track wins).
+    tracks = [
+        {
+            'name': 'T1', 'artists': [{'name': 'Track Artist 1'}],
+            'spotify_data': {
+                'album': {'id': 'A1', 'name': 'Test Album', 'artists': [{'name': 'Album Artist'}]},
+                'artists': [{'name': 'Track Artist 1'}],
+            },
+        },
+        {
+            'name': 'T2', 'artists': [{'name': 'Track Artist 2'}],
+            'spotify_data': {
+                'album': {'id': 'A1', 'name': 'Test Album', 'artists': [{'name': 'Album Artist'}]},
+                'artists': [{'name': 'Track Artist 2'}],
+            },
+        },
+    ]
+    mw.run_full_missing_tracks_process('B14', 'wishlist', tracks, deps)
+
+    assert len(download_batches['B14']['queue']) == 2
+    artist_names = set()
+    for tid in download_batches['B14']['queue']:
+        info = download_tasks[tid]['track_info']
+        artist_names.add(info['_explicit_artist_context']['name'])
+
+    # Both tracks should resolve to the same album-level artist
+    assert len(artist_names) == 1
+    assert 'Album Artist' in artist_names
+
+
+def test_playlist_folder_mode_propagates(monkeypatch):
+    """Playlist folder mode flag carried through to track_info."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    _seed_batch('B15',
+                playlist_folder_mode=True,
+                playlist_name='My Mix')
+
+    mw.run_full_missing_tracks_process('B15', 'P1', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    task_id = download_batches['B15']['queue'][0]
+    info = download_tasks[task_id]['track_info']
+    assert info['_playlist_folder_mode'] is True
+    assert info['_playlist_name'] == 'My Mix'
+
+
+# ---------------------------------------------------------------------------
+# Hand-off to monitor + start_next_batch
+# ---------------------------------------------------------------------------
+
+def test_handoff_starts_monitor_and_next_batch(monkeypatch):
+    """After task creation, master worker starts monitor + next batch."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    monitor = _FakeMonitor()
+    started_next = []
+    deps = _build_deps(monitor=monitor, start_next_batch=lambda bid: started_next.append(bid))
+
+    _seed_batch('B16')
+    mw.run_full_missing_tracks_process('B16', 'P1', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    assert monitor.started == ['B16']
+    assert started_next == ['B16']
+
+
+# ---------------------------------------------------------------------------
+# Multi-disc album_context
+# ---------------------------------------------------------------------------
+
+def test_multi_disc_total_discs_computed(monkeypatch):
+    """For album downloads, total_discs computed from max(disc_number) across all tracks."""
+    db = _FakeDB()
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    deps = _build_deps()
+    album_ctx = {'name': 'Album', 'total_tracks': 3}
+    _seed_batch('B17',
+                is_album_download=True,
+                album_context=album_ctx,
+                artist_context={'name': 'Artist'})
+
+    tracks = [
+        {'name': 'T1', 'artists': ['Artist'], 'disc_number': 1},
+        {'name': 'T2', 'artists': ['Artist'], 'disc_number': 2},
+        {'name': 'T3', 'artists': ['Artist'], 'disc_number': 2},
+    ]
+    mw.run_full_missing_tracks_process('B17', 'album:1', tracks, deps)
+
+    assert album_ctx['total_discs'] == 2
+
+
+# ---------------------------------------------------------------------------
+# Error handler
+# ---------------------------------------------------------------------------
+
+def test_error_handler_marks_batch_error(monkeypatch):
+    """Exception during analysis → batch.phase=error, batch.error=str(exception)."""
+    def boom():
+        raise RuntimeError("DB exploded")
+    monkeypatch.setattr('database.music_database.MusicDatabase', boom)
+
+    deps = _build_deps()
+    _seed_batch('B18')
+
+    mw.run_full_missing_tracks_process('B18', 'P1', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    assert download_batches['B18']['phase'] == 'error'
+    assert 'DB exploded' in download_batches['B18']['error']
+
+
+def test_error_handler_resets_youtube_phase(monkeypatch):
+    """Error on a youtube_<hash> playlist resets that playlist's phase to 'discovered'."""
+    def boom():
+        raise RuntimeError("kaboom")
+    monkeypatch.setattr('database.music_database.MusicDatabase', boom)
+
+    yt_states = {'abc': {'phase': 'downloading'}}
+    deps = _build_deps(yt_states=yt_states)
+    _seed_batch('B19')
+
+    mw.run_full_missing_tracks_process('B19', 'youtube_abc', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    assert yt_states['abc']['phase'] == 'discovered'
+
+
+def test_error_handler_resets_auto_wishlist(monkeypatch):
+    """Auto-initiated wishlist error invokes reset_wishlist_auto_processing callback."""
+    def boom():
+        raise RuntimeError("oops")
+    monkeypatch.setattr('database.music_database.MusicDatabase', boom)
+
+    reset_called = []
+    deps = _build_deps(reset_wishlist_auto=lambda: reset_called.append(True))
+    _seed_batch('B20', auto_initiated=True)
+
+    mw.run_full_missing_tracks_process('B20', 'wishlist', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    assert reset_called == [True]
+
+
+# ---------------------------------------------------------------------------
+# Batch removed mid-flight
+# ---------------------------------------------------------------------------
+
+def test_batch_removed_before_phase_two_returns_cleanly(monkeypatch):
+    """If batch is deleted between analysis and download phase, function returns without crashing."""
+    db = _FakeDB(found_tracks={('t1', 'a'): 0.9})  # marks T1 found → wishlist_remove fires
+    monkeypatch.setattr('database.music_database.MusicDatabase', lambda: db)
+
+    monitor = _FakeMonitor()
+    next_batch_calls = []
+
+    # Wishlist removal callback deletes the batch mid-analysis to simulate cancel.
+    # T1 will be analyzed as 'found' → callback fires → batch deleted.
+    def kill_batch(td):
+        download_batches.pop('B21', None)
+
+    deps = _build_deps(
+        wishlist_remove=kill_batch,
+        monitor=monitor,
+        start_next_batch=lambda bid: next_batch_calls.append(bid),
+    )
+    _seed_batch('B21')
+
+    # Should not raise even though batch vanishes during analysis loop
+    mw.run_full_missing_tracks_process('B21', 'P1', [{'name': 'T1', 'artists': ['A']}], deps)
+
+    # All tracks were 'found' → no missing → no monitor/next_batch calls
+    # (batch was deleted, so phase=complete update silently no-ops)
+    assert monitor.started == []
+    assert next_batch_calls == []
diff --git a/web_server.py b/web_server.py
index f81dfac8..586a35fc 100644
--- a/web_server.py
+++ b/web_server.py
@@ -21582,591 +21582,48 @@ def _on_download_completed(batch_id, task_id, success=True):
 
 
 
+# Master worker for the missing tracks pipeline lives in core/downloads/master.py.
+from core.downloads import master as _downloads_master
+
+
+def _build_master_deps():
+    """Build the MasterDeps bundle from web_server.py globals on each call."""
+    def _reset_wishlist_auto_processing():
+        global wishlist_auto_processing, wishlist_auto_processing_timestamp
+        with wishlist_timer_lock:
+            wishlist_auto_processing = False
+            wishlist_auto_processing_timestamp = 0
+
+    return _downloads_master.MasterDeps(
+        config_manager=config_manager,
+        soulseek_client=soulseek_client,
+        run_async=run_async,
+        mb_worker=mb_worker,
+        mb_release_cache=mb_release_cache,
+        mb_release_cache_lock=mb_release_cache_lock,
+        mb_release_detail_cache=mb_release_detail_cache,
+        mb_release_detail_cache_lock=mb_release_detail_cache_lock,
+        normalize_album_cache_key=normalize_album_cache_key,
+        check_and_remove_track_from_wishlist_by_metadata=_check_and_remove_track_from_wishlist_by_metadata,
+        is_explicit_blocked=_is_explicit_blocked,
+        youtube_playlist_states=youtube_playlist_states,
+        tidal_discovery_states=tidal_discovery_states,
+        deezer_discovery_states=deezer_discovery_states,
+        spotify_public_discovery_states=spotify_public_discovery_states,
+        missing_download_executor=missing_download_executor,
+        process_failed_tracks_to_wishlist_exact_with_auto_completion=_process_failed_tracks_to_wishlist_exact_with_auto_completion,
+        source_reuse_logger=source_reuse_logger,
+        download_monitor=download_monitor,
+        start_next_batch_of_downloads=_start_next_batch_of_downloads,
+        reset_wishlist_auto_processing=_reset_wishlist_auto_processing,
+    )
+
+
 def _run_full_missing_tracks_process(batch_id, playlist_id, tracks_json):
-    """
-    A master worker that handles the entire missing tracks process:
-    1. Runs the analysis.
-    2. If missing tracks are found, it automatically queues them for download.
-    """
-    try:
-        # PHASE 1: ANALYSIS
-        with tasks_lock:
-            if batch_id in download_batches:
-                download_batches[batch_id]['phase'] = 'analysis'
-                download_batches[batch_id]['analysis_total'] = len(tracks_json)
-                download_batches[batch_id]['analysis_processed'] = 0
+    return _downloads_master.run_full_missing_tracks_process(
+        batch_id, playlist_id, tracks_json, _build_master_deps()
+    )
 
-        from database.music_database import MusicDatabase
-        db = MusicDatabase()
-        active_server = config_manager.get_active_media_server()
-        analysis_results = []
-
-        # Get force download flag and album context from batch
-        force_download_all = False
-        batch_album_context = None
-        batch_artist_context = None
-        batch_is_album = False
-        with tasks_lock:
-            if batch_id in download_batches:
-                force_download_all = download_batches[batch_id].get('force_download_all', False)
-                batch_is_album = download_batches[batch_id].get('is_album_download', False)
-                batch_album_context = download_batches[batch_id].get('album_context')
-                batch_artist_context = download_batches[batch_id].get('artist_context')
-
-        if force_download_all:
-            logger.warning(f"[Force Download] Force download mode enabled for batch {batch_id} - treating all tracks as missing")
-
-        # Allow duplicate tracks across albums — when enabled, only skip tracks already
-        # owned in THIS album, not tracks owned in other albums
-        allow_duplicates = config_manager.get('wishlist.allow_duplicate_tracks', True)
-        if allow_duplicates and batch_is_album:
-            logger.info("[Duplicates] Allow duplicate tracks enabled — only checking ownership within target album")
-
-        # PREFLIGHT: Pre-populate MusicBrainz release cache for album downloads.
-        # This ensures ALL tracks in the album use the same release MBID during
-        # per-track post-processing, preventing Navidrome album splits.
-        if batch_is_album and batch_album_context and batch_artist_context:
-            try:
-                album_name_pf = batch_album_context.get('name', '')
-                artist_name_pf = batch_artist_context.get('name', '')
-                if album_name_pf and artist_name_pf:
-                    mb_svc = mb_worker.mb_service if mb_worker else None
-                    if mb_svc:
-                        from core.album_consistency import _find_best_release
-                        release = _find_best_release(album_name_pf, artist_name_pf, len(tracks_json), mb_svc)
-                        if release and release.get('id'):
-                            release_mbid = release['id']
-                            _artist_key = artist_name_pf.lower().strip()
-                            _rc_key_norm = (normalize_album_cache_key(album_name_pf), _artist_key)
-                            _rc_key_exact = (album_name_pf.lower().strip(), _artist_key)
-                            with mb_release_cache_lock:
-                                mb_release_cache[_rc_key_norm] = release_mbid
-                                mb_release_cache[_rc_key_exact] = release_mbid
-                            # Also cache the full release detail for tag extraction
-                            with mb_release_detail_cache_lock:
-                                mb_release_detail_cache[release_mbid] = release
-                            logger.info(f"[Preflight] Pre-cached MB release for '{album_name_pf}': "
-                                  f"'{release.get('title', '')}' ({release_mbid[:8]}...)")
-                        else:
-                            logger.warning(f"[Preflight] No MB release found for '{album_name_pf}' — per-track lookup will be used")
-            except Exception as pf_err:
-                logger.error(f"[Preflight] MB release preflight failed: {pf_err}")
-
-        # ALBUM FAST PATH: If this is an album download, try to find the album in the DB first
-        # and match tracks within it — faster and more accurate than N global searches
-        album_tracks_map = {}  # Maps normalized title -> DatabaseTrack for album-scoped matching
-        if batch_is_album and batch_album_context and batch_artist_context and not force_download_all:
-            album_name = batch_album_context.get('name', '')
-            artist_name = batch_artist_context.get('name', '')
-            total_tracks = batch_album_context.get('total_tracks', 0)
-            if album_name and artist_name:
-                try:
-                    db_album, album_confidence = db.check_album_exists_with_editions(
-                        title=album_name, artist=artist_name,
-                        confidence_threshold=0.7,
-                        expected_track_count=total_tracks if total_tracks > 0 else None,
-                        server_source=active_server
-                    )
-                    if db_album and album_confidence >= 0.7:
-                        db_album_tracks = db.get_tracks_by_album(db_album.id)
-                        for t in db_album_tracks:
-                            album_tracks_map[t.title.lower().strip()] = t
-                        logger.info(f"[Album Analysis] Found album '{db_album.title}' in DB with {len(db_album_tracks)} tracks (confidence: {album_confidence:.2f})")
-                    else:
-                        logger.warning(f"[Album Analysis] Album '{album_name}' not found in DB — falling back to per-track search")
-                except Exception as album_err:
-                    logger.error(f"[Album Analysis] Album lookup error: {album_err} — falling back to per-track search")
-
-        for i, track_data in enumerate(tracks_json):
-            # Use original table index if provided (for partial track selection),
-            # otherwise fall back to enumeration index
-            track_index = track_data.get('_original_index', i)
-            track_name = track_data.get('name', '')
-            artists = track_data.get('artists', [])
-            found, confidence = False, 0.0
-
-            # Skip database check if force download is enabled
-            if force_download_all:
-                logger.warning(f"[Force Download] Skipping database check for '{track_name}' - treating as missing")
-                found, confidence = False, 0.0
-            elif album_tracks_map:
-                # Album-scoped matching: check against known album tracks first
-                track_name_lower = track_name.lower().strip()
-                # Direct title match
-                if track_name_lower in album_tracks_map:
-                    found, confidence = True, 1.0
-                else:
-                    # Fuzzy match against album tracks using string similarity
-                    best_sim = 0.0
-                    for db_title_lower, _db_track in album_tracks_map.items():
-                        sim = db._string_similarity(track_name_lower, db_title_lower)
-                        if sim > best_sim:
-                            best_sim = sim
-                    if best_sim >= 0.7:
-                        found, confidence = True, best_sim
-                    else:
-                        # Fall back to global per-track search for this track
-                        # When allow_duplicates is on for album downloads, skip global
-                        # search — the track isn't in THIS album so treat as missing
-                        if allow_duplicates and batch_is_album:
-                            found, confidence = False, 0.0
-                        else:
-                            _fallback_album = batch_album_context.get('name') if batch_album_context else None
-                            for artist in artists:
-                                if isinstance(artist, str):
-                                    artist_name = artist
-                                elif isinstance(artist, dict) and 'name' in artist:
-                                    artist_name = artist['name']
-                                else:
-                                    artist_name = str(artist)
-                                db_track, track_confidence = db.check_track_exists(
-                                    track_name, artist_name, confidence_threshold=0.7, server_source=active_server, album=_fallback_album
-                                )
-                                if db_track and track_confidence >= 0.7:
-                                    found, confidence = True, track_confidence
-                                    break
-            elif allow_duplicates and batch_is_album:
-                # Allow duplicates + album download + album not in DB yet → treat all as missing
-                found, confidence = False, 0.0
-            else:
-                # Non-album download (playlist/single track) — always check global
-                for artist in artists:
-                    # Handle both string format and Spotify API format {'name': 'Artist Name'}
-                    if isinstance(artist, str):
-                        artist_name = artist
-                    elif isinstance(artist, dict) and 'name' in artist:
-                        artist_name = artist['name']
-                    else:
-                        artist_name = str(artist)
-                    db_track, track_confidence = db.check_track_exists(
-                        track_name, artist_name, confidence_threshold=0.7, server_source=active_server
-                    )
-                    if db_track and track_confidence >= 0.7:
-                        found, confidence = True, track_confidence
-                        break
-
-            analysis_results.append({
-                'track_index': track_index, 'track': track_data, 'found': found, 'confidence': confidence
-            })
-            
-            # WISHLIST REMOVAL: If track is found in database, check if it should be removed from wishlist
-            if found and confidence >= 0.7:
-                try:
-                    _check_and_remove_track_from_wishlist_by_metadata(track_data)
-                except Exception as wishlist_error:
-                    logger.error(f"[Analysis] Error checking wishlist removal for found track: {wishlist_error}")
-
-            with tasks_lock:
-                if batch_id in download_batches:
-                    download_batches[batch_id]['analysis_processed'] = i + 1
-                    # Store incremental results for live updates
-                    download_batches[batch_id]['analysis_results'] = analysis_results.copy()
-
-        missing_tracks = [res for res in analysis_results if not res['found']]
-
-        # Filter explicit tracks if content filter is enabled
-        if not config_manager.get('content_filter.allow_explicit', True):
-            before_count = len(missing_tracks)
-            missing_tracks = [res for res in missing_tracks if not _is_explicit_blocked(res.get('track', {}))]
-            skipped = before_count - len(missing_tracks)
-            if skipped > 0:
-                logger.warning(f"[Content Filter] Filtered out {skipped} explicit track(s) from download queue")
-
-        with tasks_lock:
-            if batch_id in download_batches:
-                download_batches[batch_id]['analysis_results'] = analysis_results
-
-        # PHASE 2: TRANSITION TO DOWNLOAD (if necessary)
-        if not missing_tracks:
-            logger.warning(f"Analysis for batch {batch_id} complete. No missing tracks.")
-
-            # Record sync history — all tracks found, nothing to download
-            tracks_found = sum(1 for r in analysis_results if r.get('found'))
-            try:
-                db_sh = MusicDatabase()
-                db_sh.update_sync_history_completion(batch_id, tracks_found=tracks_found, tracks_downloaded=0, tracks_failed=0)
-                # Save per-track results (all found, no downloads)
-                track_results = []
-                for res in analysis_results:
-                    td = res.get('track', {})
-                    artists = td.get('artists', [])
-                    first_artist = (artists[0].get('name', artists[0]) if isinstance(artists[0], dict) else str(artists[0])) if artists else ''
-                    alb = td.get('album', '')
-                    # Extract image
-                    _img = ''
-                    _alb_obj = td.get('album', {})
-                    if isinstance(_alb_obj, dict):
-                        _alb_imgs = _alb_obj.get('images', [])
-                        if _alb_imgs and isinstance(_alb_imgs, list) and len(_alb_imgs) > 0:
-                            _img = _alb_imgs[0].get('url', '') if isinstance(_alb_imgs[0], dict) else ''
-                    track_results.append({
-                        'index': res.get('track_index', 0),
-                        'name': td.get('name', ''),
-                        'artist': first_artist,
-                        'album': alb.get('name', '') if isinstance(alb, dict) else str(alb or ''),
-                        'image_url': _img,
-                        'duration_ms': td.get('duration_ms', 0),
-                        'source_track_id': td.get('id', ''),
-                        'status': 'found' if res.get('found') else 'not_found',
-                        'confidence': round(res.get('confidence', 0.0), 3),
-                        'matched_track': None,
-                        'download_status': None,
-                    })
-                if track_results:
-                    db_sh.update_sync_history_track_results(batch_id, json.dumps(track_results))
-            except Exception:
-                pass
-
-            is_auto_batch = False
-            with tasks_lock:
-                if batch_id in download_batches:
-                    is_auto_batch = download_batches[batch_id].get('auto_initiated', False)
-                    download_batches[batch_id]['phase'] = 'complete'
-                    download_batches[batch_id]['completion_time'] = time.time()  # Track for auto-cleanup
-
-                    # Update YouTube playlist phase to 'download_complete' if this is a YouTube playlist
-                    if playlist_id.startswith('youtube_'):
-                        url_hash = playlist_id.replace('youtube_', '')
-                        if url_hash in youtube_playlist_states:
-                            youtube_playlist_states[url_hash]['phase'] = 'download_complete'
-                            logger.warning(f"Updated YouTube playlist {url_hash} to download_complete phase (no missing tracks)")
-
-                    # Update Tidal playlist phase to 'download_complete' if this is a Tidal playlist
-                    if playlist_id.startswith('tidal_'):
-                        tidal_playlist_id = playlist_id.replace('tidal_', '')
-                        if tidal_playlist_id in tidal_discovery_states:
-                            tidal_discovery_states[tidal_playlist_id]['phase'] = 'download_complete'
-                            logger.warning(f"Updated Tidal playlist {tidal_playlist_id} to download_complete phase (no missing tracks)")
-
-                    # Update Deezer playlist phase to 'download_complete' if this is a Deezer playlist
-                    if playlist_id.startswith('deezer_'):
-                        deezer_playlist_id = playlist_id.replace('deezer_', '')
-                        if deezer_playlist_id in deezer_discovery_states:
-                            deezer_discovery_states[deezer_playlist_id]['phase'] = 'download_complete'
-                            logger.warning(f"Updated Deezer playlist {deezer_playlist_id} to download_complete phase (no missing tracks)")
-
-                    # Update Spotify Public playlist phase to 'download_complete' if this is a Spotify Public playlist
-                    if playlist_id.startswith('spotify_public_'):
-                        spotify_public_url_hash = playlist_id.replace('spotify_public_', '')
-                        if spotify_public_url_hash in spotify_public_discovery_states:
-                            spotify_public_discovery_states[spotify_public_url_hash]['phase'] = 'download_complete'
-                            logger.warning(f"Updated Spotify Public playlist {spotify_public_url_hash} to download_complete phase (no missing tracks)")
-
-            # Handle auto-initiated wishlist completion even when no missing tracks
-            if is_auto_batch and playlist_id == 'wishlist':
-                logger.warning("[Auto-Wishlist] No missing tracks found - calling auto-completion handler to toggle cycle and reschedule")
-                missing_download_executor.submit(_process_failed_tracks_to_wishlist_exact_with_auto_completion, batch_id)
-
-            return
-
-        logger.warning(f" transitioning batch {batch_id} to download phase with {len(missing_tracks)} tracks.")
-
-        # Read batch context (quick lock) before doing any network I/O
-        with tasks_lock:
-            if batch_id not in download_batches: return
-            batch = download_batches[batch_id]
-            batch_album_context = batch.get('album_context')
-            batch_artist_context = batch.get('artist_context')
-            batch_is_album = batch.get('is_album_download', False)
-            batch_playlist_folder_mode = batch.get('playlist_folder_mode', False)
-            batch_playlist_name = batch.get('playlist_name', 'Unknown Playlist')
-
-        # === ALBUM PRE-FLIGHT: Search for complete album folder before track-by-track ===
-        # Only run pre-flight when Soulseek is the download source (or hybrid with soulseek)
-        preflight_source = None
-        preflight_tracks = None
-        dl_source_mode = config_manager.get('download_source.mode', 'hybrid')
-        _dl_hybrid_order = config_manager.get('download_source.hybrid_order', ['hifi', 'youtube', 'soulseek'])
-        _dl_hybrid_first = _dl_hybrid_order[0] if _dl_hybrid_order else config_manager.get('download_source.hybrid_primary', 'hifi')
-        soulseek_is_source = dl_source_mode == 'soulseek' or (
-            dl_source_mode == 'hybrid' and _dl_hybrid_first == 'soulseek'
-        )
-        if batch_is_album and batch_album_context and batch_artist_context and soulseek_is_source:
-            artist_name = batch_artist_context.get('name', '')
-            album_name = batch_album_context.get('name', '')
-            if artist_name and album_name:
-                try:
-                    _sr = source_reuse_logger
-                    _sr.info(f"[Album Pre-flight] Searching for '{artist_name} {album_name}'")
-                    logger.info(f"[Album Pre-flight] Searching Soulseek for complete album: '{artist_name} - {album_name}'")
-
-                    slsk = soulseek_client.soulseek if hasattr(soulseek_client, 'soulseek') else soulseek_client
-
-                    # Try multiple query variations (banned keywords in artist/album name can return 0 results)
-                    album_queries = [f"{artist_name} {album_name}"]
-                    # Clean artist name (remove feat., parentheticals)
-                    clean_artist = re.sub(r'\s*\(.*?\)', '', artist_name).strip()
-                    clean_artist = re.sub(r'\s*(feat\.?|ft\.?|featuring)\s+.*$', '', clean_artist, flags=re.IGNORECASE).strip()
-                    if clean_artist != artist_name:
-                        album_queries.append(f"{clean_artist} {album_name}")
-                    # Album name only (some users file by album)
-                    album_queries.append(album_name)
-
-                    album_results = []
-                    track_results = []
-                    for aq in album_queries:
-                        _sr.info(f"[Album Pre-flight] Trying query: '{aq}'")
-                        track_results, album_results = run_async(slsk.search(aq, timeout=30))
-                        if album_results:
-                            _sr.info(f"[Album Pre-flight] Found {len(album_results)} album results with query: '{aq}'")
-                            break
-                        _sr.info(f"[Album Pre-flight] No album results for query: '{aq}'")
-
-                    if album_results:
-                        # Filter by quality preference
-                        quality_filtered = []
-                        for ar in album_results:
-                            filtered_tracks = slsk.filter_results_by_quality_preference(ar.tracks)
-                            if filtered_tracks:
-                                quality_filtered.append((ar, len(filtered_tracks)))
-
-                        if quality_filtered:
-                            # Sort by track count (most complete album first), then quality score
-                            quality_filtered.sort(key=lambda x: (x[1], x[0].quality_score), reverse=True)
-                            best_album = quality_filtered[0][0]
-
-                            _sr.info(f"[Album Pre-flight] Best album result: {best_album.username}:{best_album.album_path} "
-                                     f"({best_album.track_count} tracks, quality={best_album.dominant_quality})")
-                            logger.info(f"[Album Pre-flight] Found album folder: {best_album.username} — "
-                                  f"{best_album.track_count} tracks ({best_album.dominant_quality})")
-
-                            # Browse the user's folder to get all tracks (may have more than search returned)
-                            browse_files = run_async(slsk.browse_user_directory(best_album.username, best_album.album_path))
-                            if browse_files:
-                                folder_tracks = slsk.parse_browse_results_to_tracks(
-                                    best_album.username, browse_files, directory=best_album.album_path
-                                )
-                                if folder_tracks:
-                                    preflight_source = {
-                                        'username': best_album.username,
-                                        'folder_path': best_album.album_path
-                                    }
-                                    preflight_tracks = folder_tracks
-                                    _sr.info(f"[Album Pre-flight] Browsed folder: {len(folder_tracks)} audio tracks available")
-                                    logger.info(f"[Album Pre-flight] Cached {len(folder_tracks)} tracks from {best_album.username} for source reuse")
-                                else:
-                                    _sr.info("[Album Pre-flight] Browse returned files but no audio tracks")
-                            else:
-                                # Browse failed — fall back to using the search result tracks directly
-                                _sr.info("[Album Pre-flight] Browse failed, using search result tracks directly")
-                                preflight_source = {
-                                    'username': best_album.username,
-                                    'folder_path': best_album.album_path
-                                }
-                                preflight_tracks = best_album.tracks
-                                logger.info(f"[Album Pre-flight] Using {len(best_album.tracks)} tracks from search results (browse unavailable)")
-                        else:
-                            _sr.info("[Album Pre-flight] No album results passed quality filter")
-                            logger.warning("[Album Pre-flight] No album results matched quality preferences")
-                    else:
-                        _sr.info(f"[Album Pre-flight] Search returned no album results (got {len(track_results)} individual tracks)")
-                        logger.warning("[Album Pre-flight] No complete album folders found, falling back to track-by-track search")
-
-                except Exception as preflight_err:
-                    logger.error(f"[Album Pre-flight] Search failed (non-fatal, falling back to track-by-track): {preflight_err}")
-                    source_reuse_logger.info(f"[Album Pre-flight] Exception: {preflight_err}")
-
-        with tasks_lock:
-            if batch_id not in download_batches: return
-
-            download_batches[batch_id]['phase'] = 'downloading'
-
-            # Store album pre-flight results on batch for source reuse
-            if preflight_source and preflight_tracks:
-                download_batches[batch_id]['last_good_source'] = preflight_source
-                download_batches[batch_id]['source_folder_tracks'] = preflight_tracks
-                download_batches[batch_id]['failed_sources'] = set()
-                logger.info(f"[Album Pre-flight] Pre-loaded source reuse data on batch {batch_id}")
-
-            # Compute total_discs for multi-disc album subfolder support
-            # Use ALL tracks (tracks_json), not just missing ones, to correctly detect multi-disc
-            # even when only one disc has missing tracks
-            if batch_is_album and batch_album_context:
-                total_discs = max((t.get('disc_number', 1) for t in tracks_json), default=1)
-                batch_album_context['total_discs'] = total_discs
-                if total_discs > 1:
-                    logger.info(f"[Multi-Disc] Detected {total_discs} discs for album '{batch_album_context.get('name')}'")
-
-            # Pre-compute per-album data for wishlist tracks (grouped by album ID)
-            # Wishlist tracks aren't batch_is_album but each track has disc_number in spotify_data
-            wishlist_album_disc_counts = {}
-            wishlist_album_artist_map = {}  # album_id -> resolved artist context (consistent per album)
-            if playlist_id == 'wishlist':
-                import json as _json
-                # First pass: collect disc_number and resolve ONE artist per album
-                for t in tracks_json:
-                    sp_data = t.get('spotify_data', {})
-                    if isinstance(sp_data, str):
-                        try:
-                            sp_data = _json.loads(sp_data)
-                        except:
-                            sp_data = {}
-                    album_val = sp_data.get('album')
-                    album_id = album_val.get('id') if isinstance(album_val, dict) else album_val if isinstance(album_val, str) else None
-                    # Fallback album key: use album name when ID is missing (e.g. mirrored playlist tracks)
-                    if not album_id and isinstance(album_val, dict) and album_val.get('name'):
-                        album_id = f"_name_{album_val['name'].lower().strip()}"
-                    disc_num = sp_data.get('disc_number', t.get('disc_number', 1))
-                    if album_id:
-                        wishlist_album_disc_counts[album_id] = max(
-                            wishlist_album_disc_counts.get(album_id, 1), disc_num
-                        )
-                        # Resolve album-level artist once per album (first track wins)
-                        if album_id not in wishlist_album_artist_map:
-                            _wl_source = t.get('source_info') or {}
-                            if isinstance(_wl_source, str):
-                                try:
-                                    _wl_source = _json.loads(_wl_source)
-                                except:
-                                    _wl_source = {}
-                            _wl_album = album_val if isinstance(album_val, dict) else {}
-                            _wl_album_artists = _wl_album.get('artists', [])
-                            # Priority: watchlist artist > album artists > track artists
-                            if _wl_source.get('watchlist_artist_name'):
-                                wishlist_album_artist_map[album_id] = {
-                                    'name': _wl_source['watchlist_artist_name'],
-                                    'id': _wl_source.get('watchlist_artist_id', '')
-                                }
-                            elif _wl_source.get('artist_name'):
-                                wishlist_album_artist_map[album_id] = {'name': _wl_source['artist_name']}
-                            elif _wl_album_artists:
-                                _fa = _wl_album_artists[0]
-                                wishlist_album_artist_map[album_id] = _fa if isinstance(_fa, dict) else {'name': str(_fa)}
-                            else:
-                                _wl_track_artists = sp_data.get('artists', [])
-                                if _wl_track_artists:
-                                    _fa = _wl_track_artists[0]
-                                    wishlist_album_artist_map[album_id] = _fa if isinstance(_fa, dict) else {'name': str(_fa)}
-                                else:
-                                    # Try top-level 'artists' (wishlist format uses plural)
-                                    _tl_artists = t.get('artists', [])
-                                    if _tl_artists:
-                                        _tla = _tl_artists[0]
-                                        _fallback_name = _tla.get('name', str(_tla)) if isinstance(_tla, dict) else str(_tla)
-                                    else:
-                                        _fallback_name = t.get('artist', '')
-                                    wishlist_album_artist_map[album_id] = {'name': _fallback_name or 'Unknown Artist'}
-                            logger.info(f"[Wishlist Album Grouping] Album '{_wl_album.get('name', album_id)}' → artist: '{wishlist_album_artist_map[album_id].get('name', '?')}'")
-
-
-
-            for res in missing_tracks:
-                task_id = str(uuid.uuid4())
-                track_info = res['track'].copy()
-
-                # Add explicit album context to track_info for artist album downloads
-                if batch_is_album and batch_album_context and batch_artist_context:
-                    track_info['_explicit_album_context'] = batch_album_context
-                    track_info['_explicit_artist_context'] = batch_artist_context
-                    track_info['_is_explicit_album_download'] = True
-                    logger.info(f"[Task Creation] Added explicit album context for: {track_info.get('name')}")
-
-                # SPECIAL WISHLIST HANDLING: Inject album context if available to force grouping
-                elif playlist_id == 'wishlist':
-                    # Extract spotify_data again since it might be buried
-                    spotify_data = track_info.get('spotify_data')
-                    if isinstance(spotify_data, str):
-                        try:
-                            spotify_data = json.loads(spotify_data)
-                        except:
-                            spotify_data = {}
-                    
-                    if not spotify_data:
-                        spotify_data = {}
-
-                    s_album = spotify_data.get('album') or {}
-                    if isinstance(s_album, str):
-                        s_album = {'name': s_album}  # Normalize string album to dict
-                    s_artists = spotify_data.get('artists', [])
-
-                    # We need at least an album name and artist
-                    if s_album and isinstance(s_album, dict) and s_album.get('name'):
-                        # Use pre-computed album-level artist for folder consistency.
-                        # All tracks from the same album get the same artist context,
-                        # preventing folder splits on collab albums (KPOP Demon Hunters, etc.)
-                        album_id_for_lookup = s_album.get('id')
-                        # Fallback album key: match first-pass logic for missing IDs
-                        if not album_id_for_lookup and s_album.get('name'):
-                            album_id_for_lookup = f"_name_{s_album['name'].lower().strip()}"
-                        if not album_id_for_lookup:
-                            album_id_for_lookup = 'wishlist_album'
-                        artist_ctx = wishlist_album_artist_map.get(album_id_for_lookup, {})
-                        if not artist_ctx or not artist_ctx.get('name'):
-                            # Fallback: per-track resolution from artists array
-                            _fb_artists = track_info.get('artists', [])
-                            if _fb_artists:
-                                _fb_a = _fb_artists[0]
-                                _fb_name = _fb_a.get('name', str(_fb_a)) if isinstance(_fb_a, dict) else str(_fb_a)
-                            else:
-                                _fb_name = track_info.get('artist', '')
-                            artist_ctx = {'name': _fb_name or 'Unknown Artist'}
-
-                        # Construct minimal album context
-                        # Ensure images are preserved (important for artwork)
-                        album_id = s_album.get('id', 'wishlist_album')
-                        album_ctx = {
-                            'id': album_id,
-                            'name': s_album.get('name'),
-                            'release_date': s_album.get('release_date', ''),
-                            'total_tracks': s_album.get('total_tracks', 1),
-                            'total_discs': wishlist_album_disc_counts.get(album_id, 1),
-                            'album_type': s_album.get('album_type', 'album'),
-                            'images': s_album.get('images', []) # Pass images array directly
-                        }
-
-                        track_info['_explicit_album_context'] = album_ctx
-                        track_info['_explicit_artist_context'] = artist_ctx
-                        track_info['_is_explicit_album_download'] = True
-                        logger.info(f"[Wishlist] Added album context for: '{track_info.get('name')}' -> '{album_ctx['name']}'")
-
-
-                # Add playlist folder mode flag for sync page playlists
-                if batch_playlist_folder_mode:
-                    track_info['_playlist_folder_mode'] = True
-                    track_info['_playlist_name'] = batch_playlist_name
-                    logger.info(f"[Task Creation] Added playlist folder mode for: {track_info.get('name')} → {batch_playlist_name}")
-                else:
-                    logger.debug(f"[Debug] Task Creation - playlist folder mode NOT enabled for: {track_info.get('name')}")
-
-                download_tasks[task_id] = {
-                    'status': 'pending', 'track_info': track_info,
-                    'playlist_id': playlist_id, 'batch_id': batch_id,
-                    'track_index': res['track_index'], 'retry_count': 0,
-                    'cached_candidates': [], 'used_sources': set(),
-                    'status_change_time': time.time(),
-                    'metadata_enhanced': False
-                }
-                download_batches[batch_id]['queue'].append(task_id)
-
-        download_monitor.start_monitoring(batch_id)
-        _start_next_batch_of_downloads(batch_id)
-
-    except Exception as e:
-        logger.error(f"Master worker for batch {batch_id} failed: {e}")
-        import traceback
-        traceback.print_exc()
-
-        is_auto_batch = False
-        with tasks_lock:
-            if batch_id in download_batches:
-                is_auto_batch = download_batches[batch_id].get('auto_initiated', False)
-                download_batches[batch_id]['phase'] = 'error'
-                download_batches[batch_id]['error'] = str(e)
-
-                # Reset YouTube playlist phase to 'discovered' if this is a YouTube playlist on error
-                if playlist_id.startswith('youtube_'):
-                    url_hash = playlist_id.replace('youtube_', '')
-                    if url_hash in youtube_playlist_states:
-                        youtube_playlist_states[url_hash]['phase'] = 'discovered'
-                        logger.error(f"Reset YouTube playlist {url_hash} to discovered phase (error)")
-
-        # Handle auto-initiated wishlist errors - reset flag
-        if is_auto_batch and playlist_id == 'wishlist':
-            logger.error("[Auto-Wishlist] Master worker error - resetting auto-processing flag")
-            global wishlist_auto_processing, wishlist_auto_processing_timestamp
-            with wishlist_timer_lock:
-                wishlist_auto_processing = False
-                wishlist_auto_processing_timestamp = 0
 
 # Post-processing verification worker logic lives in core/downloads/post_processing.py.
 from core.downloads import post_processing as _downloads_post_processing