fix(amazon): wire amazon into all streaming-source guards

`validation.py` had amazon absent from `_streaming_sources`, causing
Amazon TrackResult objects (bitrate=None, size=0) to fall through to
the Soulseek P2P code path and get rejected by
`filter_results_by_quality_preference`. Every album track was marked
not found.

Fix: add 'amazon' to every streaming-source guard tuple/set that was
previously missing it:
- core/downloads/validation.py — primary bug fix (quality-filter bypass)
- core/downloads/status.py — _STREAMING_SOURCE_NAMES frozenset
- core/downloads/task_worker.py — hybrid fallback client map
- core/imports/side_effects.py — || filename→stream-id extraction
- web_server.py — is_streaming_source, transfer list display,
  candidate source label, _try_source_reuse, _store_batch_source
- tests/test_download_plugin_conformance.py — registry count + parametrize

Also updates the 2.5.3 What's New entry to drop the stale
"not yet wired" disclaimer.

core/downloads/status.py

@@ -87,7 +87,7 @@ class StatusDeps:
 # Streaming sources the engine fallback applies to. Soulseek goes through
 # slskd's live_transfers path and must NOT hit the engine fallback.
 _STREAMING_SOURCE_NAMES = frozenset((
-    'youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud',
+    'youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon',
 ))
 
 # Keep these in sync with the engine plugins' state strings.

core/downloads/task_worker.py

@@ -294,7 +294,7 @@ def download_track_worker(task_id: str, batch_id: Optional[str], deps: TaskWorke
                 source_clients = {
                     name: orch.client(name)
                     for name in ('soulseek', 'youtube', 'tidal', 'qobuz',
-                                 'hifi', 'deezer_dl', 'lidarr', 'soundcloud')
+                                 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon')
                 }
 
                 # The orchestrator tried sources in order but stopped at the first with results.

core/downloads/validation.py

@@ -79,7 +79,7 @@ def get_valid_candidates(results, spotify_track, query):
 
     # Streaming sources (YouTube, Tidal, Qobuz, HiFi, Deezer, SoundCloud) return structured API results
     # with proper artist/title metadata — score using the same matching engine as Soulseek
-    _streaming_sources = ("youtube", "tidal", "qobuz", "hifi", "deezer_dl", "soundcloud")
+    _streaming_sources = ("youtube", "tidal", "qobuz", "hifi", "deezer_dl", "soundcloud", "amazon")
     if results[0].username in _streaming_sources:
         source_label = results[0].username.replace('_dl', '').title()
         expected_artists = spotify_track.artists if spotify_track else []

core/imports/side_effects.py

@@ -235,7 +235,7 @@ def record_library_history_download(context: Dict[str, Any]) -> None:
         source_track_id = search_result.get("track_id", "") or search_result.get("id", "") or ti.get("id", "")
         source_track_title = search_result.get("title", "") or search_result.get("name", "")
         source_artist = search_result.get("artist", "")
-        if source_filename and "||" in source_filename and username in ("tidal", "youtube", "qobuz", "hifi", "deezer_dl", "lidarr", "soundcloud"):
+        if source_filename and "||" in source_filename and username in ("tidal", "youtube", "qobuz", "hifi", "deezer_dl", "lidarr", "soundcloud", "amazon"):
             stream_id = source_filename.split("||")[0]
             if stream_id and not source_track_id:
                 source_track_id = stream_id

tests/test_download_plugin_conformance.py

@@ -59,6 +59,7 @@ def _import_plugin_classes():
     from core.deezer_download_client import DeezerDownloadClient
     from core.lidarr_download_client import LidarrDownloadClient
     from core.soundcloud_client import SoundcloudClient
+    from core.amazon_download_client import AmazonDownloadClient
 
     return {
         'soulseek': SoulseekClient,
@@ -69,10 +70,11 @@ def _import_plugin_classes():
         'deezer': DeezerDownloadClient,
         'lidarr': LidarrDownloadClient,
         'soundcloud': SoundcloudClient,
+        'amazon': AmazonDownloadClient,
     }
 
 
-def test_default_registry_registers_all_eight_sources():
+def test_default_registry_registers_all_sources():
     """Smoke check that the foundation registry knows about every
     source the orchestrator historically dispatched to. If someone
     drops a registration here, every other test in this module would
@@ -82,7 +84,7 @@ def test_default_registry_registers_all_eight_sources():
     registry = build_default_registry()
     expected = {
         'soulseek', 'youtube', 'tidal', 'qobuz',
-        'hifi', 'deezer', 'lidarr', 'soundcloud',
+        'hifi', 'deezer', 'lidarr', 'soundcloud', 'amazon',
     }
     assert set(registry.names()) == expected
 
@@ -102,7 +104,7 @@ def test_deezer_dl_alias_is_registered_against_deezer_spec():
 
 @pytest.mark.parametrize('plugin_name', [
     'soulseek', 'youtube', 'tidal', 'qobuz',
-    'hifi', 'deezer', 'lidarr', 'soundcloud',
+    'hifi', 'deezer', 'lidarr', 'soundcloud', 'amazon',
 ])
 def test_plugin_class_has_all_required_methods(plugin_name):
     """Every registered plugin class exposes every protocol method
@@ -122,7 +124,7 @@ def test_plugin_class_has_all_required_methods(plugin_name):
 
 @pytest.mark.parametrize('plugin_name', [
     'soulseek', 'youtube', 'tidal', 'qobuz',
-    'hifi', 'deezer', 'lidarr', 'soundcloud',
+    'hifi', 'deezer', 'lidarr', 'soundcloud', 'amazon',
 ])
 def test_plugin_class_async_methods_are_coroutines(plugin_name):
     """Methods declared async in the protocol must be async on every

web_server.py

@@ -5797,7 +5797,7 @@ def start_download():
             if download_id:
                 # Register download for post-processing (simple transfer to /Transfer)
                 context_key = _make_context_key(username, filename)
-                is_streaming_source = username in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud')
+                is_streaming_source = username in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon')
                 with matched_context_lock:
                     matched_downloads_context[context_key] = {
                         'search_result': {
@@ -6179,7 +6179,7 @@ def get_download_status():
             all_streaming_downloads = run_async(download_orchestrator.get_all_downloads())
 
             for download in all_streaming_downloads:
-                if download.username in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud'):
+                if download.username in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon'):
                     source_label = download.username.title()
                     # Convert DownloadStatus to transfer format that frontend expects
                     streaming_transfer = {
@@ -11106,7 +11106,7 @@ def redownload_search_sources(track_id):
                         quality = ext if ext in ('FLAC', 'MP3', 'OPUS', 'OGG', 'M4A', 'WAV') else candidate.quality or ''
                         svc = source_name if source_name != 'default' else 'hybrid'
                         uname = candidate.username
-                        if uname in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud'):
+                        if uname in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon'):
                             svc = uname
                         source_candidates.append({
                             'username': uname,
@@ -16412,7 +16412,7 @@ def _try_source_reuse(task_id, batch_id, track):
     if not source_tracks or not last_source:
         _sr.info("Skipped — no source_tracks or no last_source")
         return False
-    if last_source.get('username') in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud'):
+    if last_source.get('username') in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon'):
         _sr.info(f"Skipped — {last_source.get('username')} source (no folder-based reuse)")
         return False
 
@@ -16514,7 +16514,7 @@ def _store_batch_source(batch_id, username, filename):
     """Browse the successful download's folder and store results on the batch for reuse."""
     _sr = source_reuse_logger
     _sr.info(f"_store_batch_source called: batch={batch_id}, user={username}, file={filename}")
-    if not batch_id or username in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud'):
+    if not batch_id or username in ('youtube', 'tidal', 'qobuz', 'hifi', 'deezer_dl', 'lidarr', 'soundcloud', 'amazon'):
         _sr.info(f"Skipped — no batch_id or streaming source ({username})")
         return
 

webui/static/helper.js

@@ -3415,7 +3415,7 @@ function closeHelperSearch() {
 const WHATS_NEW = {
     '2.5.3': [
         { unreleased: true },
-        { title: 'Amazon Music Download Source', desc: 'new download source backed by T2Tunes proxy. searches the Amazon Music catalog, downloads 24-bit/48kHz FLAC (or Opus 320kbps / Dolby Atmos EAC3 fallback). codec waterfall mirrors the same pattern as Tidal/Qobuz — best quality first, auto-fallback. not yet wired into the main source selector — coming in a follow-up PR.', page: 'settings' },
+        { title: 'Amazon Music Download Source', desc: 'new download source backed by T2Tunes proxy. searches the Amazon Music catalog, downloads 24-bit/48kHz FLAC (or Opus 320kbps / Dolby Atmos EAC3 fallback). codec waterfall mirrors Tidal/Qobuz — best quality first, auto-fallback. selectable as a standalone or hybrid source from Settings.', page: 'settings' },
     ],
     '2.5.2': [
         // --- May 13, 2026 — 2.5.2 release ---