video: resolve the video server independently of the music active pointer

The video side now uses a configured Plex/Jellyfin on its own (resolve_video_
server), not config_manager.get_active_media_server(). So a music-only server
(Navidrome/SoulSync) never applies to video, and 'Navidrome for music + Plex for
video' works. Order: explicit video pick (video_server setting) → music-active if
video-capable → the single configured one → Plex if both → None. Seam tests cover
each case incl. the mixed setup.

api/video/libraries.py

@@ -20,10 +20,9 @@ def register_routes(bp):
     def video_libraries():
         from . import get_video_db
         try:
-            from core.video.sources import list_video_libraries
-            from config.settings import config_manager
+            from core.video.sources import list_video_libraries, resolve_video_server
             libs = list_video_libraries() or {"server": None, "movies": [], "tv": []}
-            server = libs.get("server") or config_manager.get_active_media_server()
+            server = libs.get("server") or resolve_video_server()
             libs["selected"] = (get_video_db().get_library_selection(server)
                                 if server else {"movies": None, "tv": None})
             return jsonify(libs)
@@ -35,9 +34,11 @@ def register_routes(bp):
     def save_video_libraries():
         from . import get_video_db
         try:
-            from config.settings import config_manager
+            from core.video.sources import resolve_video_server
             body = request.get_json(silent=True) or {}
-            server = config_manager.get_active_media_server()
+            server = resolve_video_server()
+            if not server:
+                return jsonify({"error": "no video server"}), 400
             get_video_db().set_library_selection(server, body.get("movies"), body.get("tv"))
             return jsonify({"status": "saved", "server": server})
         except Exception:

core/video/sources.py

@@ -63,17 +63,61 @@ def _parse_jf_providers(item) -> dict:
     }
 
 
+def resolve_video_server(db=None):
+    """The server the VIDEO side uses — a configured Plex/Jellyfin, resolved
+    INDEPENDENTLY of the music 'active server' pointer (so e.g. Navidrome-for-music
+    + Plex-for-video works, and music-only servers never apply here). Returns
+    'plex' | 'jellyfin' | None. Order: explicit video pick → the music-active one if
+    it's video-capable → the single configured one → Plex if both → None."""
+    try:
+        from config.settings import config_manager
+    except Exception:
+        return None
+    plex_ok = bool((config_manager.get_plex_config() or {}).get("base_url"))
+    jelly_ok = bool((config_manager.get_jellyfin_config() or {}).get("base_url"))
+
+    pref = None
+    if db is None:
+        try:
+            from database.video_database import VideoDatabase
+            db = VideoDatabase()
+        except Exception:
+            db = None
+    if db is not None:
+        try:
+            pref = db.get_setting("video_server")
+        except Exception:
+            pref = None
+    if pref == "plex" and plex_ok:
+        return "plex"
+    if pref == "jellyfin" and jelly_ok:
+        return "jellyfin"
+
+    active = config_manager.get_active_media_server()
+    if active == "plex" and plex_ok:
+        return "plex"
+    if active == "jellyfin" and jelly_ok:
+        return "jellyfin"
+    if plex_ok and not jelly_ok:
+        return "plex"
+    if jelly_ok and not plex_ok:
+        return "jellyfin"
+    if plex_ok and jelly_ok:
+        return "plex"
+    return None
+
+
 def _build_source(movies_lib=None, tv_lib=None):
-    """Build a media source for the active server, restricted to the named
-    Movies/TV libraries when given. Reuses the SHARED connection config — but
-    Plex gets a dedicated long-timeout connection for the bulk scan."""
+    """Build a media source for the VIDEO server (see resolve_video_server),
+    restricted to the named Movies/TV libraries when given. Reuses the SHARED
+    connection config — but Plex gets a dedicated long-timeout connection."""
     try:
         from config.settings import config_manager
     except Exception:
         logger.exception("video sources: config unavailable")
         return None
 
-    server = config_manager.get_active_media_server()
+    server = resolve_video_server()
 
     if server == "plex":
         cfg = config_manager.get_plex_config() or {}
@@ -103,11 +147,12 @@ def _build_source(movies_lib=None, tv_lib=None):
 
 
 def _load_selection():
-    """The user's Movies/TV library choice for the active server (or {})."""
+    """The user's Movies/TV library choice for the VIDEO server (or {})."""
     try:
-        from config.settings import config_manager
         from database.video_database import VideoDatabase
-        server = config_manager.get_active_media_server()
+        server = resolve_video_server()
+        if not server:
+            return {}
         return VideoDatabase().get_library_selection(server)
     except Exception:
         logger.exception("video sources: could not load library selection")

tests/test_video_server_resolution.py

@@ -0,0 +1,52 @@
+"""Seam tests: the video side resolves its server (Plex/Jellyfin) INDEPENDENTLY
+of the music 'active server' pointer — so music-only servers never apply and a
+mixed setup (Navidrome music + Plex video) works."""
+
+from __future__ import annotations
+
+import config.settings as cs
+import pytest
+
+from core.video.sources import resolve_video_server
+from database.video_database import VideoDatabase
+
+
+def _set_cm(monkeypatch, plex, jelly, active):
+    class CM:
+        def get_plex_config(self): return {"base_url": "http://p", "token": "t"} if plex else {}
+        def get_jellyfin_config(self): return {"base_url": "http://j"} if jelly else {}
+        def get_active_media_server(self): return active
+    monkeypatch.setattr(cs, "config_manager", CM())
+
+
+@pytest.fixture()
+def vdb(tmp_path):
+    return VideoDatabase(database_path=str(tmp_path / "v.db"))
+
+
+def test_plex_only(monkeypatch, vdb):
+    _set_cm(monkeypatch, True, False, "plex")
+    assert resolve_video_server(vdb) == "plex"
+
+
+def test_jellyfin_only(monkeypatch, vdb):
+    _set_cm(monkeypatch, False, True, "jellyfin")
+    assert resolve_video_server(vdb) == "jellyfin"
+
+
+def test_none_when_only_a_music_server(monkeypatch, vdb):
+    _set_cm(monkeypatch, False, False, "navidrome")
+    assert resolve_video_server(vdb) is None
+
+
+def test_independent_of_music_active(monkeypatch, vdb):
+    # Navidrome is the music server, but Plex is configured → video uses Plex.
+    _set_cm(monkeypatch, True, False, "navidrome")
+    assert resolve_video_server(vdb) == "plex"
+
+
+def test_both_configured_default_then_explicit_pick(monkeypatch, vdb):
+    _set_cm(monkeypatch, True, True, "plex")
+    assert resolve_video_server(vdb) == "plex"           # falls back to the active one
+    vdb.set_setting("video_server", "jellyfin")
+    assert resolve_video_server(vdb) == "jellyfin"       # explicit video pick wins