Fix Soulseek downloads losing collab artist tags

Soulseek matched-download contexts populate `original_search_result`
with `artist` (singular string) and no `artists` list — the full
multi-artist array lives on `track_info` (the matched Spotify track
object). `extract_source_metadata` only read `original_search.artists`,
so the Soulseek path always fell through to the single-artist branch
and TPE1 ended up with the primary artist only. Deezer-direct
downloads were unaffected because their context populates
`original_search.artists` as a proper list.

Lifted artist resolution into a pure helper
`core/metadata/artist_resolution.py:resolve_track_artists` that walks
`original_search.artists` → `track_info.artists` → `artist_dict.name`
fallback chain. Normalizes mixed list-item shapes (Spotify-style
dicts, bare strings, anything else stringified) and drops empty
entries.

13 new tests pin the resolution order, fallback chain, mixed-shape
normalization, whitespace stripping, and empty/none handling. The
existing `_artists_list` no-fall-through test in
`test_multi_artist_tag_settings.py` was updated to reflect the new
contract (always populated; multi-value write still gated on
`len > 1`) plus a new regression test for the Soulseek shape.

Composes with the existing Deezer per-track upgrade (still fires when
single-artist + track_id available) and feat_in_title /
artist_separator settings (still drive the joined ARTIST string
downstream).

core/metadata/artist_resolution.py

@@ -0,0 +1,74 @@
+"""Pure artist-list resolution for tag-write paths.
+
+Single source of truth for "what is the canonical multi-value artists
+list for this track?" Different download paths populate `context` with
+different keys — Deezer-direct downloads stamp `original_search.artists`
+as a proper list, but Soulseek matched downloads only carry `artist`
+(singular string) in `original_search_result` while the full list lives
+on `track_info` (the full Spotify track object).
+
+Resolution order:
+    1. `context.original_search_result.artists` (preferred — already-
+       curated by the source path that constructed the context)
+    2. `context.track_info.artists` (Spotify/Deezer/Tidal full track
+       object — always carries the artists array when matched)
+    3. `[artist_dict.name]` as a single-element fallback when neither
+       carries a list (primary-artist-only)
+
+Each list item may be a dict with a `name` key (Spotify shape), a bare
+string, or any other object — the helper normalizes all three to
+strings and drops empty entries.
+"""
+
+from __future__ import annotations
+
+from typing import Any, Dict, List, Optional
+
+
+def _normalize_artists_iterable(items: Any) -> List[str]:
+    if not isinstance(items, list):
+        return []
+    result: List[str] = []
+    for item in items:
+        if isinstance(item, dict):
+            name = item.get("name")
+            if isinstance(name, str) and name.strip():
+                result.append(name.strip())
+        elif isinstance(item, str):
+            stripped = item.strip()
+            if stripped:
+                result.append(stripped)
+        elif item is not None:
+            text = str(item).strip()
+            if text:
+                result.append(text)
+    return result
+
+
+def resolve_track_artists(
+    original_search: Optional[Dict[str, Any]],
+    track_info: Optional[Dict[str, Any]],
+    artist_dict: Optional[Dict[str, Any]],
+) -> List[str]:
+    """Return the canonical multi-value artists list for tag-write.
+
+    Falls through preferred → track_info → primary-artist fallback. Each
+    candidate is normalized to a list of stripped non-empty strings.
+    Empty list returned only when every candidate is empty/invalid.
+    """
+    if isinstance(original_search, dict):
+        primary = _normalize_artists_iterable(original_search.get("artists"))
+        if primary:
+            return primary
+
+    if isinstance(track_info, dict):
+        secondary = _normalize_artists_iterable(track_info.get("artists"))
+        if secondary:
+            return secondary
+
+    if isinstance(artist_dict, dict):
+        name = artist_dict.get("name")
+        if isinstance(name, str) and name.strip():
+            return [name.strip()]
+
+    return []

core/metadata/source.py

@@ -23,6 +23,7 @@ from core.imports.context import (
     get_source_tag_names,
     normalize_import_context,
 )
+from core.metadata.artist_resolution import resolve_track_artists
 from core.metadata.registry import get_itunes_client
 from database.music_database import get_database
 from core.metadata.common import (
@@ -907,17 +908,13 @@ def extract_source_metadata(context: dict, artist: dict, album_info: dict) -> di
     else:
         logger.warning("Metadata: Using original title as fallback: '%s'", metadata["title"])
 
-    artists = original_search.get("artists")
+    # Resolve canonical artists list. Soulseek matched-download contexts
-    if isinstance(artists, list) and artists:
+    # only carry `original_search.artist` (singular string) — the full
-        all_artists = []
+    # contributors list lives on `track_info` (the matched Spotify/etc
-        for artist_item in artists:
+    # track object). Deezer-direct contexts populate `original_search.artists`
-            if isinstance(artist_item, dict) and artist_item.get("name"):
+    # directly. Pure helper handles all three shapes.
-                all_artists.append(artist_item["name"])
+    all_artists = resolve_track_artists(original_search, track_info, artist_dict)
-            elif isinstance(artist_item, str):
+    if all_artists:
-                all_artists.append(artist_item)
-            else:
-                all_artists.append(str(artist_item))
-
         # Deezer upgrade path: Deezer's `/search` endpoint only returns
         # the primary artist for each track. The full contributors
         # array (feat., remix collaborators, producers credited as

tests/metadata/test_artist_resolution.py

@@ -0,0 +1,79 @@
+from core.metadata.artist_resolution import resolve_track_artists
+
+
+def test_prefers_original_search_artists_when_populated():
+    original = {"artists": [{"name": "Kendrick Lamar"}, {"name": "Rihanna"}]}
+    track = {"artists": [{"name": "Should Not Be Used"}]}
+    artist = {"name": "Primary"}
+
+    assert resolve_track_artists(original, track, artist) == ["Kendrick Lamar", "Rihanna"]
+
+
+def test_falls_back_to_track_info_artists_when_original_lacks_list():
+    # Soulseek context shape: original_search_result has 'artist' (string)
+    # and no 'artists' (list). Full Spotify track object lives on track_info.
+    original = {"artist": "Kendrick Lamar"}
+    track = {"artists": [{"name": "Kendrick Lamar"}, {"name": "Rihanna"}]}
+    artist = {"name": "Kendrick Lamar"}
+
+    assert resolve_track_artists(original, track, artist) == ["Kendrick Lamar", "Rihanna"]
+
+
+def test_falls_back_to_artist_dict_name_when_no_lists_available():
+    original = {"artist": "Solo Artist"}
+    track = {"name": "Track Title"}
+    artist = {"name": "Solo Artist"}
+
+    assert resolve_track_artists(original, track, artist) == ["Solo Artist"]
+
+
+def test_returns_empty_list_when_everything_missing():
+    assert resolve_track_artists(None, None, None) == []
+    assert resolve_track_artists({}, {}, {}) == []
+
+
+def test_handles_bare_string_artist_items():
+    original = {"artists": ["Kendrick Lamar", "Rihanna"]}
+    assert resolve_track_artists(original, None, None) == ["Kendrick Lamar", "Rihanna"]
+
+
+def test_mixed_dict_and_string_items_normalized():
+    original = {"artists": [{"name": "Kendrick Lamar"}, "Rihanna"]}
+    assert resolve_track_artists(original, None, None) == ["Kendrick Lamar", "Rihanna"]
+
+
+def test_strips_whitespace_and_drops_empty_entries():
+    original = {"artists": [{"name": "  Kendrick  "}, {"name": ""}, "  ", "Rihanna"]}
+    assert resolve_track_artists(original, None, None) == ["Kendrick", "Rihanna"]
+
+
+def test_dict_item_without_name_key_skipped():
+    original = {"artists": [{"id": "abc"}, {"name": "Rihanna"}]}
+    assert resolve_track_artists(original, None, None) == ["Rihanna"]
+
+
+def test_non_list_artists_value_falls_through():
+    original = {"artists": "Kendrick Lamar"}  # string, not list
+    track = {"artists": [{"name": "Kendrick Lamar"}, {"name": "Rihanna"}]}
+    assert resolve_track_artists(original, track, None) == ["Kendrick Lamar", "Rihanna"]
+
+
+def test_empty_original_artists_list_falls_through_to_track_info():
+    original = {"artists": []}
+    track = {"artists": [{"name": "Kendrick Lamar"}, {"name": "Rihanna"}]}
+    assert resolve_track_artists(original, track, None) == ["Kendrick Lamar", "Rihanna"]
+
+
+def test_artist_dict_name_blank_returns_empty():
+    assert resolve_track_artists({}, {}, {"name": "   "}) == []
+    assert resolve_track_artists({}, {}, {"name": ""}) == []
+
+
+def test_non_string_artist_items_coerced_to_string():
+    original = {"artists": [123, {"name": "Real Artist"}]}
+    assert resolve_track_artists(original, None, None) == ["123", "Real Artist"]
+
+
+def test_none_artist_items_dropped():
+    original = {"artists": [None, {"name": "Real Artist"}, None]}
+    assert resolve_track_artists(original, None, None) == ["Real Artist"]

tests/metadata/test_multi_artist_tag_settings.py

@@ -99,8 +99,10 @@ class TestArtistsListPopulated:
         assert meta.get("_artists_list") == ["Solo Artist"]
 
     def test_no_artists_falls_through(self):
-        """When search response has no artists list, falls through to
+        """When search response has no artists list, the artist-resolution
-        the single-artist branch — no `_artists_list` written."""
+        helper falls back to the artist_dict.name as a single-element list.
+        Multi-value tag write still no-ops because len([primary]) == 1.
+        """
         from core.metadata import source as src_module
 
         context = {
@@ -109,7 +111,31 @@ class TestArtistsListPopulated:
         }
         with patch.object(src_module, "get_config_manager", return_value=_make_cfg()):
             meta = src_module.extract_source_metadata(context, {"name": "X"}, {})
-        assert "_artists_list" not in meta or meta.get("_artists_list") in (None, [])
+        assert meta.get("_artists_list") == ["X"]
+
+    def test_soulseek_shape_falls_back_to_track_info_artists(self):
+        """Soulseek matched-download regression: original_search_result
+        carries 'artist' (singular string) but no 'artists' list, while
+        track_info (the matched Spotify track object) carries the full
+        multi-artist array. Helper should pull from track_info.
+        """
+        from core.metadata import source as src_module
+
+        context = {
+            "original_search_result": {
+                "title": "DNA.",
+                "artist": "Kendrick Lamar",
+            },
+            "track_info": {
+                "name": "DNA.",
+                "artists": [{"name": "Kendrick Lamar"}, {"name": "Rihanna"}],
+            },
+            "source": "spotify",
+        }
+        with patch.object(src_module, "get_config_manager", return_value=_make_cfg()):
+            meta = src_module.extract_source_metadata(context, {"name": "Kendrick Lamar"}, {})
+        assert meta.get("_artists_list") == ["Kendrick Lamar", "Rihanna"]
+        assert meta.get("artist") == "Kendrick Lamar, Rihanna"
 
 
 # ---------------------------------------------------------------------------

webui/static/helper.js

@@ -3416,6 +3416,7 @@ const WHATS_NEW = {
     '2.5.2': [
         // --- May 13, 2026 — 2.5.2 release ---
         { date: 'May 13, 2026 — 2.5.2 release' },
+        { title: 'Soulseek Downloads: Multi-Artist Tags Now Get Written Properly', desc: 'discord report: tracks downloaded via soulseek were getting tagged with primary artist only (no collab artists), while the same track downloaded via deezer tagged everyone correctly. trace: the soulseek matched-download context constructed `original_search_result` with `artist` (singular string) but no `artists` (list), even though the full multi-artist list lived on `track_info` (the matched spotify track object). `core/metadata/source.py:extract_source_metadata` only read `original_search.artists`, so soulseek path always fell through to the single-artist branch. fix: lifted artist resolution into a pure helper `core/metadata/artist_resolution.py:resolve_track_artists` that walks `original_search.artists` → `track_info.artists` → `artist_dict.name` fallback chain. handles all three list-item shapes (spotify-style dicts, bare strings, anything else stringified). 13 tests pin the resolution order, fallback chain, mixed-shape normalization, whitespace stripping, empty/none handling. composes with the existing deezer per-track upgrade (still fires when single-artist + track_id available) and feat_in_title / artist_separator settings (still drive the joined ARTIST string downstream).', page: 'downloads' },
         { title: 'Download Missing Modal: Tracklist Got A Polish Pass', desc: 'visual tune-up only — column layout untouched. hairline row dividers, accent gradient + edge bar on hover, monospace track numbers (glow accent on row hover), monospace tabular duration. status text in both library-match + download-status columns picks up a leading colored dot with a soft halo (green found / amber missing / blue checking / orange downloading / red failed) and pulses while in-flight. artist column centered. soft scrollbar.', page: 'downloads' },
         { title: 'Search Source Picker: Fix Default Always Sticking To Spotify', desc: 'enhanced search + global search source picker always defaulted to spotify even when the user\'s primary metadata source was deezer / itunes / discogs / etc. trace: `shared-helpers.js:createSearchController` reads `/status.metadata_source` to pick the initial active icon, then checks `SOURCE_LABELS[src]` to validate. backend was returning `metadata_source` as a dict (`{source, connected, response_time, ...}` — used elsewhere for connection-state display), so `SOURCE_LABELS[<dict>]` was always undefined, the `if` guard never fired, and `state.activeSource` silently stayed at the hardcoded `\'spotify\'` default. fix: read `.source` off the dict (with forward-compat fallback to plain-string in case any older /status response shape predates the dict change). other consumers (core.js sidebar tile, helper.js status checker, search.js display) already used `?.source` correctly — this was the only stale call site.', page: 'search' },
         { title: 'Download Discography: No Longer Caps Prolific Artists At 50 Releases', desc: 'discord report: clicking "download discography" on an artist with a deep catalogue (bach, beatles complete box, dance / electronic artists with hundreds of remixes) only showed ~50 albums in the modal. trace: `MetadataLookupOptions(limit=50, max_pages=0)` was hardcoded at the discography endpoint and the artist-detail discography view. spotify\'s `max_pages=0` already paginates through everything (per-page is clamped to 10 internally) so spotify-primary users were unaffected. but deezer / itunes / discogs / hydrabase all honor the outer `limit` as a hard cap. fix: bump `limit` from 50 to 200 at all three call sites (`web_server.py` discography endpoint + artist-detail view + `core/artist_source_detail.py`). 200 matches iTunes\'s and Discogs\'s own internal caps and covers near-everyone\'s full catalogue. spotify behavior unchanged.', page: 'library' },