fix(plex): the recs rail's anchor and a held recommendation are named in the reader's language (E30 S1b)

Found in the S1b UAT: 'Mert megnézted: Batman Forever' kept the English title, and
the info page's TMDB recommendations kept TMDB's English titles even for titles we
hold. A held recommendation is now named as the library names it, in the reader's
language; one we lack keeps TMDB's title.

backend/app/plex/tmdb.py

@@ -21,6 +21,7 @@ from sqlalchemy.orm import Session
 from app import logs, sysconfig
 from app.config import settings
 from app.models import PlexItem, PlexPerson, PlexShow
+from app.plex.cards import display_title
 
 log = logs.get_logger(__name__)
 # Politeness throttle: TMDB tolerates ~50 req/s; ~33/s leaves comfortable headroom for a shared host.
@@ -406,10 +407,11 @@ def resolve_library_guids(
     return movies, shows
 
 
-def resolve_recs(db: Session, recs: list[dict] | None) -> list[dict]:
+def resolve_recs(db: Session, recs: list[dict] | None, *, lang: str) -> list[dict]:
     """Tag each recommendation with whether it's in OUR library (matched by guid `tmdb:<id>`, bucketed
     by media_type — see resolve_library_guids) and, if so, its rating_key — so the client can deep-link
-    the ones we have and merely display the rest."""
+    the ones we have and merely display the rest. One we have is named as the library names it, in
+    `lang` (E30); one we lack keeps the title TMDB gave."""
     if not recs:
         return []
     movies, shows = resolve_library_guids(db, recs)
@@ -417,13 +419,19 @@ def resolve_recs(db: Session, recs: list[dict] | None) -> list[dict]:
     for r in recs:
         g = f"tmdb:{r.get('tmdb_id')}"
         row = shows.get(g) if r.get("media_type") == "tv" else movies.get(g)
+        named = {"title": display_title(row, lang)} if row is not None else {}
         out.append(
-            {**r, "in_library": row is not None, "rating_key": row.rating_key if row else None}
+            {
+                **r,
+                **named,
+                "in_library": row is not None,
+                "rating_key": row.rating_key if row else None,
+            }
         )
     return out
 
 
-def serve_block(db: Session, row) -> dict | None:
+def serve_block(db: Session, row, *, lang: str) -> dict | None:
     """The TMDB extras for a movie/show detail response, served from the row (no live TMDB call).
     None until the row has been TMDB-enriched (the client then shows nothing extra)."""
     if row.tmdb_enriched_at is None:
@@ -438,7 +446,7 @@ def serve_block(db: Session, row) -> dict | None:
         "crew": row.crew or [],
         "studios": row.studios or [],
         "production_countries": row.production_countries or [],
-        "recommendations": resolve_recs(db, row.recommendations),
+        "recommendations": resolve_recs(db, row.recommendations, lang=lang),
         "backdrops": row.backdrops or [],
     }
 

backend/app/routes/plex/detail.py

@@ -211,7 +211,7 @@ def show_detail(
             "episode_count": show_roll["episode_count"],
             "collection_keys": sh.collection_keys or [],
             # TMDB enrichment (E5 S2), served from the row.
-            "tmdb": plex_tmdb.serve_block(db, sh),
+            "tmdb": plex_tmdb.serve_block(db, sh, lang=lang),
         },
         "seasons": [_season_block(se, by_season.get(se.id, [])) for se in seasons],
         "related": related,
@@ -517,5 +517,5 @@ def item_detail(
         "next_id": next_id,
         "collections": _collection_strips(db, it, user.id, lang),
         # TMDB enrichment (E5 S2), served from the row — movies only (episodes aren't enriched).
-        "tmdb": plex_tmdb.serve_block(db, it) if it.kind == "movie" else None,
+        "tmdb": plex_tmdb.serve_block(db, it, lang=lang) if it.kind == "movie" else None,
     }

backend/app/routes/plex/discover.py

@@ -313,7 +313,7 @@ def _because_you_watched(
     )
     if anchor is None:
         return None
-    resolved = resolve_recs(db, anchor.recommendations)
+    resolved = resolve_recs(db, anchor.recommendations, lang=lang)
     # Preserve TMDB's recommendation order, keep only in-library hits, and drop the anchor itself.
     rks = [
         r["rating_key"]
@@ -362,7 +362,10 @@ def _because_you_watched(
             items.append(scards[rk])
     if not items:
         return None
-    return {"anchor": {"id": anchor.rating_key, "title": anchor.title}, "items": items}
+    return {
+        "anchor": {"id": anchor.rating_key, "title": display_title(anchor, lang)},
+        "items": items,
+    }
 
 
 @router.get("/discover")

backend/tests/test_plex_lang.py

@@ -230,6 +230,25 @@ def _seed_rails(db):
             PlexPlaylistItem(playlist_id=pl.id, item_id=ep.id, position=1),
         ]
     )
+    # TMDB extras: m2 recommends m1 (held) and a title we lack; m1, watched, anchors the recs rail.
+    m1.guid = "tmdb:1"
+    m1.tmdb_enriched_at = datetime(2024, 1, 1, tzinfo=timezone.utc)
+    m1.recommendations = [{"tmdb_id": 2, "title": "EN Only", "media_type": "movie"}]
+    m2 = db.query(PlexItem).filter_by(rating_key="m2").one()
+    m2.guid = "tmdb:2"
+    m2.tmdb_enriched_at = datetime(2024, 1, 1, tzinfo=timezone.utc)
+    m2.recommendations = [
+        {"tmdb_id": 1, "title": "English Title", "media_type": "movie"},
+        {"tmdb_id": 77, "title": "Elsewhere", "media_type": "movie"},
+    ]
+    db.add(
+        PlexState(
+            user_id=user.id,
+            item_id=m1.id,
+            status="watched",
+            watched_at=datetime(2024, 3, 1, tzinfo=timezone.utc),
+        )
+    )
     sysconfig.set_value(db, "plex_enabled", True)
     db.commit()
     return user, pl.id
@@ -259,6 +278,14 @@ def test_every_card_rail_serves_the_readers_language(db, monkeypatch, override_d
         ("Magyar Cím", None),
         ("Kezdet", "Magyar Sorozat"),
     ]
+    # A recommendation we hold is named as the library names it; the rail's anchor too.
+    recs = get("/api/plex/item/m2?lang=hu")["tmdb"]["recommendations"]
+    assert [(r["title"], r["in_library"]) for r in recs] == [
+        ("Magyar Cím", True),
+        ("Elsewhere", False),
+    ]
+    byw = get("/api/plex/discover?scope=both&lang=hu")["because_you_watched"]
+    assert byw["anchor"]["title"] == "Magyar Cím"
     home = get("/api/discover?lang=hu")["continue_watching"]
     plex = [c for c in home if c["source"] == "plex"]
     assert [c["title"] for c in plex] == ["Magyar Sorozat"]

backend/tests/test_plex_tmdb.py

@@ -255,13 +255,13 @@ def test_serve_block_none_until_enriched_and_resolves_recs(db):
     db.add_all([sequel, fresh])
     db.commit()
 
-    assert tmdb.serve_block(db, fresh) is None  # not enriched yet
+    assert tmdb.serve_block(db, fresh, lang="en") is None  # not enriched yet
 
     tmdb.apply_tmdb_detail(fresh, tmdb.parse_tmdb(MOVIE_PAYLOAD, "movie"))
     fresh.tmdb_enriched_at = datetime.now(timezone.utc)
     db.commit()
 
-    block = tmdb.serve_block(db, fresh)
+    block = tmdb.serve_block(db, fresh, lang="en")
     assert block is not None
     assert block["budget"] == 6000000
     assert block["keywords"] == ["mafia", "crime family"]
@@ -409,6 +409,7 @@ def test_resolve_recs_matches_by_media_type_not_bare_id(db):
                 {"tmdb_id": 500, "title": "Movie 500", "media_type": "movie"},
                 {"tmdb_id": 900, "title": "Show 900", "media_type": "tv"},
             ],
+            lang="en",
         )
     }
     assert miss[500]["in_library"] is False and miss[500]["rating_key"] is None
@@ -423,6 +424,7 @@ def test_resolve_recs_matches_by_media_type_not_bare_id(db):
                 {"tmdb_id": 900, "media_type": "movie"},
                 {"tmdb_id": 500, "media_type": "tv"},
             ],
+            lang="en",
         )
     }
     assert hit[900]["in_library"] is True and hit[900]["rating_key"] == "m900"