fix(plex): address S1 code-review findings

- Restore synchronize_session=False on the remove-bulk Core delete (the 2.0
  default is 'auto'; keep the pre-conversion contract explicit).
- _episode_nav: list(...scalars()) instead of [r[0] for r in ...all()], matching
  the house style used across the conversion.
- Extract app/plex/lookups.by_rating_key() and migrate the get-by-rating_key
  pattern at 13 sites (imgcache x4, _shared.item_or_404, playback show/season,
  browse x6).
- Coverage: add TestFacetsWithData (the converted wsq aggregation with real
  data — the highest-risk untested builder), TestPlaylistAndCollectionEndpoints
  (playlist CRUD + collections list), and an item-state playback test.

Full suite 256 passed, 2 skipped; ruff clean.

backend/app/plex/imgcache.py

@@ -9,11 +9,11 @@ The cache directory (``cache.CACHE_DIR``) is shared with the subtitle cache (see
 """
 
 from fastapi import Response
-from sqlalchemy import select
 from sqlalchemy.orm import Session
 
 from app.models import PlexCollection, PlexItem, PlexSeason, PlexShow
 from app.plex.cache import CACHE_DIR
+from app.plex.lookups import by_rating_key
 
 _EXT_CT = [("jpg", "image/jpeg"), ("png", "image/png"), ("webp", "image/webp")]
 _CT_EXT = {ct: ext for ext, ct in _EXT_CT}
@@ -25,24 +25,16 @@ SIZES = {"thumb": (400, 600), "art": (1280, 720)}
 def key_for(db: Session, rating_key: str, variant: str) -> str | None:
     """The stored Plex image path for a known rating_key (item/show/season). Only mirrored keys
     are proxyable — this is not an open image proxy."""
-    it = db.execute(
-        select(PlexItem).where(PlexItem.rating_key == rating_key)
-    ).scalars().first()
+    it = by_rating_key(db, PlexItem, rating_key)
     if it is not None:
         return it.art_key if variant == "art" else it.thumb_key
-    sh = db.execute(
-        select(PlexShow).where(PlexShow.rating_key == rating_key)
-    ).scalars().first()
+    sh = by_rating_key(db, PlexShow, rating_key)
     if sh is not None:
         return sh.art_key if variant == "art" else sh.thumb_key
-    se = db.execute(
-        select(PlexSeason).where(PlexSeason.rating_key == rating_key)
-    ).scalars().first()
+    se = by_rating_key(db, PlexSeason, rating_key)
     if se is not None:
         return se.thumb_key
-    col = db.execute(
-        select(PlexCollection).where(PlexCollection.rating_key == rating_key)
-    ).scalars().first()
+    col = by_rating_key(db, PlexCollection, rating_key)
     if col is not None:
         return col.thumb_key
     return None

backend/app/plex/lookups.py

@@ -0,0 +1,11 @@
+"""Small shared Plex row lookups, so the get-by-rating_key pattern lives in one place."""
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+
+def by_rating_key(db: Session, model, rating_key: str):
+    """The mirrored row for a Plex rating_key, or None. `model` is any of the rating_key-keyed Plex
+    tables (PlexItem / PlexShow / PlexSeason / PlexCollection)."""
+    return db.execute(
+        select(model).where(model.rating_key == str(rating_key))
+    ).scalars().first()

backend/app/routes/plex/_shared.py

@@ -3,20 +3,18 @@
 import logging
 
 from fastapi import HTTPException
-from sqlalchemy import select
 from sqlalchemy.orm import Session
 
 from app.models import (
     PlexItem,
 )
+from app.plex.lookups import by_rating_key
 
 log = logging.getLogger("siftlode.plex")
 
 
 def item_or_404(db: Session, rating_key: str) -> PlexItem:
-    it = db.execute(
-        select(PlexItem).where(PlexItem.rating_key == str(rating_key))
-    ).scalars().first()
+    it = by_rating_key(db, PlexItem, rating_key)
     if it is None:
         raise HTTPException(status_code=404, detail="Unknown Plex item")
     return it

backend/app/routes/plex/browse.py

@@ -43,6 +43,7 @@ from app.plex import people as plex_people
 from app.plex import rollup, subtitles
 from app.plex import sync as plex_sync
 from app.plex.client import PlexClient, PlexError, PlexNotConfigured
+from app.plex.lookups import by_rating_key
 from app.routes._common import owned_or_404
 from app.routes.admin import admin_user
 from app.routes.feed import to_tsquery_str
@@ -738,9 +739,7 @@ def collections(
 
 
 def _editable_collection_or_403(db: Session, rating_key: str) -> PlexCollection:
-    col = db.execute(
-        select(PlexCollection).where(PlexCollection.rating_key == str(rating_key))
-    ).scalars().first()
+    col = by_rating_key(db, PlexCollection, rating_key)
     if col is None:
         raise HTTPException(status_code=404, detail="Unknown collection")
     if not _collection_editable(col):
@@ -882,9 +881,7 @@ def collection_set_editable(
 ) -> dict:
     """Mark an existing Plex collection as 'mine to edit' (or unmark). Smart / auto-list collections
     (IMDb/TMDb/…) can never be made editable — they're regenerated outside Plex."""
-    col = db.execute(
-        select(PlexCollection).where(PlexCollection.rating_key == str(rating_key))
-    ).scalars().first()
+    col = by_rating_key(db, PlexCollection, rating_key)
     if col is None:
         raise HTTPException(status_code=404, detail="Unknown collection")
     want = body.editable
@@ -1008,9 +1005,7 @@ def create_playlist(
     count = 0
     thumb_rk = None
     if seed:
-        it = db.execute(
-            select(PlexItem).where(PlexItem.rating_key == seed)
-        ).scalars().first()
+        it = by_rating_key(db, PlexItem, seed)
         if it is not None:
             db.add(PlexPlaylistItem(playlist_id=pl.id, item_id=it.id, position=0))
             count, thumb_rk = 1, it.rating_key
@@ -1105,9 +1100,7 @@ def playlist_add_item(
     db: Session = Depends(get_db),
 ) -> dict:
     pl = _own_playlist_or_404(db, pid, user)
-    it = db.execute(
-        select(PlexItem).where(PlexItem.rating_key == body.item_rating_key)
-    ).scalars().first()
+    it = by_rating_key(db, PlexItem, body.item_rating_key)
     if it is None:
         raise HTTPException(status_code=404, detail="Unknown item")
     exists = db.execute(
@@ -1137,9 +1130,7 @@ def playlist_remove_item(
     db: Session = Depends(get_db),
 ) -> dict:
     pl = _own_playlist_or_404(db, pid, user)
-    it = db.execute(
-        select(PlexItem).where(PlexItem.rating_key == str(item_rating_key))
-    ).scalars().first()
+    it = by_rating_key(db, PlexItem, item_rating_key)
     if it is not None:
         db.execute(
             delete(PlexPlaylistItem).where(
@@ -1237,7 +1228,8 @@ def playlist_remove_bulk(
         removed = db.execute(
             delete(PlexPlaylistItem).where(
                 PlexPlaylistItem.playlist_id == pid, PlexPlaylistItem.item_id.in_(ids)
-            )
+            ),
+            execution_options={"synchronize_session": False},
         ).rowcount
         if removed:
             pl.updated_at = datetime.now(timezone.utc)
@@ -1332,9 +1324,7 @@ def show_detail(
     db: Session = Depends(get_db),
 ) -> dict:
     """A show's seasons + episodes (the drill-down view) with per-user watch state."""
-    sh = db.execute(
-        select(PlexShow).where(PlexShow.rating_key == str(rating_key))
-    ).scalars().first()
+    sh = by_rating_key(db, PlexShow, rating_key)
     if sh is None:
         raise HTTPException(status_code=404, detail="Unknown Plex show")
     seasons = db.execute(
@@ -1633,18 +1623,16 @@ def _collection_strips(db: Session, it: PlexItem, user_id: int) -> list[dict]:
 def _episode_nav(db: Session, it: PlexItem) -> tuple[str | None, str | None]:
     if it.kind != "episode" or it.show_id is None:
         return None, None
-    keys = [
-        r[0]
-        for r in db.execute(
+    keys = list(
+        db.execute(
             select(PlexItem.rating_key)
             .where(PlexItem.show_id == it.show_id, PlexItem.kind == "episode")
             .order_by(
                 PlexItem.season_number.asc().nullsfirst(),
                 PlexItem.episode_number.asc().nullsfirst(),
             )
-        )
-        .all()
-    ]
+        ).scalars()
+    )
     try:
         i = keys.index(it.rating_key)
     except ValueError:

backend/app/routes/plex/playback.py

@@ -30,6 +30,7 @@ from app.models import (
 )
 from app.plex import imgcache, subtitles
 from app.plex import paths as plex_paths
+from app.plex.lookups import by_rating_key
 from app.plex import people as plex_people
 from app.plex import stream as plex_stream
 from app.plex import watch_sync as plex_watch
@@ -412,9 +413,7 @@ def show_state(
     db: Session = Depends(get_db),
 ) -> dict:
     """Mark a whole show watched/unwatched (all its episodes) for the current user + push to Plex."""
-    sh = db.execute(
-        select(PlexShow).where(PlexShow.rating_key == str(rating_key))
-    ).scalars().first()
+    sh = by_rating_key(db, PlexShow, rating_key)
     if sh is None:
         raise HTTPException(status_code=404, detail="Unknown Plex show")
     watched = body.watched
@@ -434,9 +433,7 @@ def season_state(
     db: Session = Depends(get_db),
 ) -> dict:
     """Mark a whole season watched/unwatched (all its episodes) for the current user + push to Plex."""
-    se = db.execute(
-        select(PlexSeason).where(PlexSeason.rating_key == str(rating_key))
-    ).scalars().first()
+    se = by_rating_key(db, PlexSeason, rating_key)
     if se is None:
         raise HTTPException(status_code=404, detail="Unknown Plex season")
     watched = body.watched

backend/tests/test_plex_query_conversion.py

@@ -57,16 +57,21 @@ def _seed(db):
     return {"user": user, "movie_lib": movie_lib, "show_lib": show_lib, "show": show}
 
 
-def _get(db, user, monkeypatch, path):
+def _request(db, user, monkeypatch, method, path, json=None):
     monkeypatch.setattr(state, "_configured_cache", True)  # the request gate 503s an unconfigured app
     app.dependency_overrides[get_db] = lambda: db
     app.dependency_overrides[current_user] = lambda: user
     try:
-        return TestClient(app).get(path)  # no context manager: skip lifespan (scheduler/HLS sweep)
+        client = TestClient(app)  # no context manager: skip lifespan (scheduler/HLS sweep)
+        return client.request(method, path, json=json)
     finally:
         app.dependency_overrides.clear()
 
 
+def _get(db, user, monkeypatch, path):
+    return _request(db, user, monkeypatch, "GET", path)
+
+
 class TestUnifiedLibrary:
     def test_both_scope_unions_movies_and_shows_ordered_by_added(self, db, monkeypatch):
         s = _seed(db)
@@ -197,3 +202,128 @@ class TestSyncUpsertIdempotency:
         assert ep.rating_key == "e1"
         assert ep.show_id == shows[0].id  # episode linked to its show
         assert (ep.season_number, ep.episode_number) == (1, 1)
+
+
+class TestFacetsWithData:
+    """The facets endpoint's wsq builder is the most complex converted query (genre/content-rating
+    JSONB unnest + year/rating/duration bounds + the watch-state join). The existing smoke test only
+    covers the null-genre guard; this locks the aggregated numbers with real data."""
+
+    def test_facet_aggregation(self, db, monkeypatch):
+        movie_lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+        show_lib = PlexLibrary(plex_key="2", title="Shows", kind="show", enabled=True)
+        db.add_all([movie_lib, show_lib])
+        db.flush()
+        db.add_all([
+            PlexItem(rating_key="m1", library_id=movie_lib.id, kind="movie", title="M1",
+                     genres=["Comedy", "Drama"], content_rating="PG", year=2000, rating=7.5,
+                     duration_s=6000),
+            PlexItem(rating_key="m2", library_id=movie_lib.id, kind="movie", title="M2",
+                     genres=["Comedy"], content_rating="R", year=2010, rating=8.0, duration_s=7200),
+            PlexShow(rating_key="s1", library_id=show_lib.id, title="S1",
+                     genres=["Drama"], content_rating="TV-14", year=2005, rating=9.0),
+        ])
+        user = User(email="facetdata@example.com")
+        db.add(user)
+        db.commit()
+
+        body = _get(db, user, monkeypatch, "/api/plex/facets?scope=both").json()
+        assert {g["value"]: g["count"] for g in body["genres"]} == {"Comedy": 2, "Drama": 2}
+        assert {c["value"]: c["count"] for c in body["content_ratings"]} == {
+            "PG": 1, "R": 1, "TV-14": 1
+        }
+        assert (body["year_min"], body["year_max"]) == (2000, 2010)
+        assert body["rating_max"] == 9.0
+        # Duration bounds are movie-only.
+        assert (body["duration_min"], body["duration_max"]) == (6000, 7200)
+
+
+class TestPlaylistAndCollectionEndpoints:
+    """Smoke coverage for the converted CRUD endpoints that had no tests: playlist create/list/detail/
+    add/reorder/remove/delete, and the collections list. A 1.x->2.0 conversion slip in any of these
+    (a lost .scalars(), a wrong .all(), a broken order_by) surfaces here instead of shipping green."""
+
+    def _movie(self, db, lib_id, rk, title):
+        return PlexItem(rating_key=rk, library_id=lib_id, kind="movie", title=title)
+
+    def test_playlist_crud_roundtrip(self, db, monkeypatch):
+        lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+        db.add(lib)
+        db.flush()
+        db.add_all([self._movie(db, lib.id, "m1", "First"), self._movie(db, lib.id, "m2", "Second")])
+        user = User(email="pl@example.com")
+        db.add(user)
+        db.commit()
+
+        # create (seeded with m1) -> item_count 1
+        created = _request(db, user, monkeypatch, "POST", "/api/plex/playlists",
+                           {"title": "Faves", "item_rating_key": "m1"})
+        assert created.status_code == 200, created.text
+        pid = created.json()["id"]
+        assert created.json()["item_count"] == 1
+
+        # list -> the playlist with its count
+        listed = _get(db, user, monkeypatch, "/api/plex/playlists").json()["playlists"]
+        assert [(p["id"], p["item_count"]) for p in listed] == [(pid, 1)]
+
+        # add m2, then reorder to [m2, m1]
+        add = _request(db, user, monkeypatch, "POST", f"/api/plex/playlists/{pid}/items",
+                       {"item_rating_key": "m2"})
+        assert add.status_code == 200, add.text
+        _request(db, user, monkeypatch, "PUT", f"/api/plex/playlists/{pid}/order",
+                 {"item_rating_keys": ["m2", "m1"]})
+        detail = _get(db, user, monkeypatch, f"/api/plex/playlists/{pid}").json()
+        assert [it["id"] for it in detail["items"]] == ["m2", "m1"]  # reorder applied, in order
+
+        # remove m1 -> one item left
+        rm = _request(db, user, monkeypatch, "DELETE", f"/api/plex/playlists/{pid}/items/m1")
+        assert rm.status_code == 200, rm.text
+        after = _get(db, user, monkeypatch, f"/api/plex/playlists/{pid}").json()
+        assert [it["id"] for it in after["items"]] == ["m2"]
+
+        # delete the playlist -> gone from the list
+        _request(db, user, monkeypatch, "DELETE", f"/api/plex/playlists/{pid}")
+        assert _get(db, user, monkeypatch, "/api/plex/playlists").json()["playlists"] == []
+
+    def test_collections_list(self, db, monkeypatch):
+        from app.models import PlexCollection
+        lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+        db.add(lib)
+        db.flush()
+        db.add_all([
+            PlexCollection(rating_key="c1", library_id=lib.id, title="Marvel", child_count=12),
+            PlexCollection(rating_key="c2", library_id=lib.id, title="Pixar", child_count=5),
+        ])
+        user = User(email="col@example.com")
+        db.add(user)
+        db.commit()
+
+        # unified scope (no library param) -> most-populated first
+        body = _get(db, user, monkeypatch, "/api/plex/collections").json()
+        assert [c["title"] for c in body["collections"]] == ["Marvel", "Pixar"]
+        # name filter
+        filtered = _get(db, user, monkeypatch, "/api/plex/collections?q=pix").json()
+        assert [c["title"] for c in filtered["collections"]] == ["Pixar"]
+
+    def test_item_state_watched_then_new(self, db, monkeypatch):
+        # No PlexLink -> the background Plex push is a no-op; only the local PlexState path runs, which
+        # is what the conversion touched (the st lookup + the delete on ->new).
+        lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+        db.add(lib)
+        db.flush()
+        db.add(PlexItem(rating_key="m1", library_id=lib.id, kind="movie", title="M1"))
+        user = User(email="state@example.com")
+        db.add(user)
+        db.commit()
+
+        watched = _request(db, user, monkeypatch, "POST", "/api/plex/item/m1/state",
+                           {"status": "watched"})
+        assert watched.status_code == 200, watched.text
+        assert watched.json()["status"] == "watched"
+        row = db.execute(select(PlexState).where(PlexState.user_id == user.id)).scalars().one()
+        assert row.status == "watched"
+
+        # -> new deletes the state row
+        back = _request(db, user, monkeypatch, "POST", "/api/plex/item/m1/state", {"status": "new"})
+        assert back.status_code == 200, back.text
+        assert db.execute(select(PlexState).where(PlexState.user_id == user.id)).scalars().first() is None