fix(resolve): prefer the series over a same-named movie on title collision

A library can hold a movie and a TV series with the exact same title (real
case: the 2017 "Baywatch" film vs the 242-episode 1989 series). resolve_title
checked movie_map first and returned unconditionally, so the "Baywatch
Marathon" channel resolved to the lone movie and looped one film instead of
the series — visible to the user as a marathon channel "stuck on a movie."

On a movie/series collision, keep whichever copy has more PLAYABLE programs —
the same tie-break build_library_index already uses to stop a dead duplicate
shadowing the real show. A real series beats a lone movie; an all-missing
series still yields to the movie. Plain titles and non-collisions are
unchanged. Fix lands on every path that resolves titles (initial deploy, live
re-resolve, surgical/apply).

Covered by test_resolve_title_collision.py (series-wins, movie-kept-when-dead,
no-collision-unchanged).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: AlpineArchitecture

backend/tests/test_resolve_title_collision.py

@@ -0,0 +1,51 @@
+"""test_resolve_title_collision.py — a movie and a series with the same exact title.
+
+Real bug: the library held both the 2017 "Baywatch" film and the 242-episode 1989
+series. resolve_title checked movie_map first and returned unconditionally, so the
+"Baywatch Marathon" channel looped the lone movie instead of the series. The fix
+prefers whichever copy has more PLAYABLE programs.
+"""
+
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+import channel_engine
+
+
+def _movie(title, state="ok"):
+    return {"program": {"title": title, "state": state}}
+
+
+def _show(title, n_eps, state="ok"):
+    return {
+        "title": title,
+        "showId": f"uuid-{title}",
+        "programs": [{"program": {"title": f"{title} S1E{i}", "state": state}} for i in range(n_eps)],
+    }
+
+
+def test_series_beats_same_named_movie():
+    movie_map = {"baywatch": _movie("Baywatch")}
+    show_map = {"baywatch": _show("Baywatch", 242)}
+    item = channel_engine.resolve_title("Baywatch", movie_map, show_map)
+    assert item["type"] == "TV"
+    assert len(item["programs"]) == 242
+
+
+def test_movie_kept_when_series_is_all_missing():
+    movie_map = {"baywatch": _movie("Baywatch")}
+    show_map = {"baywatch": _show("Baywatch", 5, state="missing")}  # dead series, 0 playable
+    item = channel_engine.resolve_title("Baywatch", movie_map, show_map)
+    assert item["type"] == "Movie"
+
+
+def test_no_collision_unchanged():
+    movie_map = {"big movie": _movie("Big Movie")}
+    show_map = {"cheers": _show("Cheers", 10)}
+    assert channel_engine.resolve_title("Big Movie", movie_map, show_map)["type"] == "Movie"
+    assert channel_engine.resolve_title("Cheers", movie_map, show_map)["type"] == "TV"
+    assert channel_engine.resolve_title("Nope", movie_map, show_map) is None

channel_engine.py

@@ -152,14 +152,27 @@ def _playable(entry):
 
 # ── Title resolution ───────────────────────────────────────────────────────────
 
+def _playable_count(programs):
+    return sum(1 for p in programs if p.get("program", {}).get("state") != "missing")
+
+
 def resolve_title(title, movie_map, show_map):
     key = title.lower().strip()
-    if key in movie_map:
-        p = movie_map[key]
-        return {"type": "Movie", "title": title, "programs": [p]}
-    if key in show_map:
-        s = show_map[key]
-        return {"type": "TV", "title": s["title"], "showId": s["showId"], "programs": s["programs"]}
+    movie = movie_map.get(key)
+    show = show_map.get(key)
+    # Same exact title for a movie AND a series (e.g. the 2017 "Baywatch" film vs the
+    # 1989 series). A plain title can't disambiguate, so prefer whichever has more
+    # PLAYABLE programs — the same tie-break build_library_index uses for dupes. A real
+    # series (many episodes) beats a lone movie; an all-missing series yields to it.
+    if movie and show:
+        if _playable_count(show["programs"]) >= _playable_count([movie]):
+            movie = None
+        else:
+            show = None
+    if movie is not None:
+        return {"type": "Movie", "title": title, "programs": [movie]}
+    if show is not None:
+        return {"type": "TV", "title": show["title"], "showId": show["showId"], "programs": show["programs"]}
     return None