Fix RSS guid collisions and episode titles flagged by Codex review

Codex review on PR #828 found two real bugs and one real stability
issue in the guid/title logic just added:

- Episodes/seasons of the same show share the show's media_id, so the
  old tmdb:<media_id> guid fallback collapsed every episode of an
  un-enriched show onto one guid.
- Episode Item.title stores the episode's own name (e.g. "Pilot"), not
  the show's title, so episode feed titles were unmatchable.
- Guid identity shifted when provider_external_ids gained an imdb_id
  after the item was first published, making existing subscribers see
  a "new" duplicate entry.

Replace the external-id-preference guid with one built from the item's
own immutable natural key (source:media_type:media_id[:sN[:eN]]) —
unique per episode and stable across metadata enrichment — and prefix
episode/season titles with the parent show's title via a small batched
lookup, mirroring the existing _attach_owner_media_statuses pattern.

Also codify PR monitoring as a repo default in AGENTS.md: proactively
watch any PR opened here to green and verify automated review comments
against the code before acting on them.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B92VR5siWNQE2BjGGwbch8

Author: claude

AGENTS.md

@@ -368,6 +368,12 @@ Notes:
 - Review summaries should call out behavior changes, files touched, validation run, and remaining risk.
 - Commit messages should use a short imperative title, then 1–3 bullet clarifications in the body. Optional issue lines: `Fixes #123` / `Refs #456`.
 
+### PR Monitoring (Default Behavior)
+- For any PR opened in this repo — whether the user opened it or Claude did — proactively subscribe to its GitHub activity (e.g. `subscribe_pr_activity`) without waiting to be asked.
+- Drive CI to fully green regardless of cause. Diagnose real failures and fix them; only treat a run as flaky if it died before any test body ran (checkout, dependency install, lost runner), and say so when re-running rather than silently retrying.
+- For automated review comments (e.g. Codex/`chatgpt-codex-connector`), verify each claim against the actual code before acting — read the flagged lines and the code paths they describe. Fix genuine, correctness-affecting findings. For anything speculative, stylistic-only, or that misreads the code, leave a brief reply explaining why rather than churning changes to satisfy noise.
+- Keep the PR's subscription alive until it merges or closes; webhooks don't reliably deliver CI success or new-push events, so re-check state after periods of silence rather than assuming green.
+
 ## Security / Safety Notes
 - `.env` contains secrets and API keys; do not commit it.
 - A process-wide log record factory redacts credentials before any handler writes them (`src/app/log_safety.py`, installed by `src/config/__init__.py`). Do not move the installation later in the start sequence, and do not widen its `except` clause: both faults are silent. See `docs/architecture/log-redaction.md`.

src/lists/feeds.py

@@ -7,7 +7,7 @@
 from django.utils.feedgenerator import Rss201rev2Feed
 from django.views.decorators.http import require_GET
 
-from app.models import MediaManager, MediaTypes, Sources
+from app.models import Item, MediaManager, MediaTypes, Sources
 from app.providers import tmdb
 from app.templatetags.app_tags import media_url
 from lists.models import CustomList, CustomListItem
@@ -89,6 +89,30 @@ def _attach_owner_media_statuses(self, list_items, owner):
             list_item.feed_status = status_by_item_id.get(list_item.item_id, "")
             list_item.feed_description = self._build_item_description(list_item.item)
 
+    def _attach_show_titles(self, list_items):
+        """Attach the parent show's title to episode/season list items."""
+        show_keys = {
+            (list_item.item.source, list_item.item.media_id)
+            for list_item in list_items
+            if list_item.item.media_type
+            in (MediaTypes.EPISODE.value, MediaTypes.SEASON.value)
+        }
+        if not show_keys:
+            return
+
+        sources = {source for source, _media_id in show_keys}
+        media_ids = {media_id for _source, media_id in show_keys}
+        shows = Item.objects.filter(
+            media_type=MediaTypes.TV.value,
+            source__in=sources,
+            media_id__in=media_ids,
+        )
+        title_by_key = {(show.source, show.media_id): show.title for show in shows}
+
+        for list_item in list_items:
+            key = (list_item.item.source, list_item.item.media_id)
+            list_item.feed_show_title = title_by_key.get(key)
+
     def _build_item_description(self, item):
         """Return a local feed description without provider lookups."""
         manual_metadata = getattr(item, "manual_metadata", None) or {}
@@ -134,12 +158,13 @@ def items(self, obj):
             .order_by("-date_added")
         )
         self._attach_owner_media_statuses(list_items, obj.owner)
+        self._attach_show_titles(list_items)
         return list_items
 
     def item_title(self, item):
         """Return the item title with S01E02/year markers for automation tools."""
         media_item = item.item
-        title = media_item.title
+        title = getattr(item, "feed_show_title", None) or media_item.title
 
         if media_item.season_number is not None:
             title += f" S{media_item.season_number:02d}"
@@ -160,34 +185,21 @@ def item_link(self, item):
         """Return the item URL."""
         return self.request.build_absolute_uri(media_url(item.item))
 
-    def _external_guid(self, media_item):
-        """Return a stable external id for the item, or None if unresolved."""
-        external_ids = media_item.provider_external_ids or {}
-
-        imdb_id = external_ids.get("imdb_id")
-        if imdb_id:
-            return f"imdb:{imdb_id}"
-
-        tvdb_id = external_ids.get("tvdb_id")
-        if tvdb_id:
-            return f"tvdb:{tvdb_id}"
-
-        tmdb_id = external_ids.get("tmdb_id")
-        if tmdb_id:
-            return f"tmdb:{tmdb_id}"
-
-        if media_item.source == Sources.TMDB.value:
-            return f"tmdb:{media_item.media_id}"
+    def item_guid(self, item):
+        """Return a guid from the item's own immutable natural key."""
+        media_item = item.item
+        guid = f"{media_item.source}:{media_item.media_type}:{media_item.media_id}"
 
-        return None
+        if media_item.season_number is not None:
+            guid += f":s{media_item.season_number}"
+            if media_item.episode_number is not None:
+                guid += f":e{media_item.episode_number}"
 
-    def item_guid(self, item):
-        """Return a stable external id, falling back to the detail link."""
-        return self._external_guid(item.item) or self.item_link(item)
+        return guid
 
     def item_guid_is_permalink(self, item):
         """Return whether the guid is a dereferenceable URL."""
-        return self._external_guid(item.item) is None
+        return False
 
     def item_categories(self, item):
         """Return the media type as an RSS category for filtering."""

src/lists/tests/test_views.py

@@ -3361,13 +3361,19 @@ def test_movie_title_includes_year(self):
 
         self.assertIn("RSS Feed Movie (2024)", titles)
 
-    def test_episode_title_includes_season_episode_markers(self):
-        """Episode items get "S01E02" markers for automation-tool matching."""
+    def test_episode_title_uses_show_title_not_episode_name(self):
+        """Episode titles are prefixed with the show's title, not the episode's own name."""
+        Item.objects.create(
+            media_id="tmdb-show-1",
+            source=Sources.TMDB.value,
+            media_type=MediaTypes.TV.value,
+            title="RSS Feed Show",
+        )
         episode = Item.objects.create(
-            media_id="tmdb-episode-1",
+            media_id="tmdb-show-1",
             source=Sources.TMDB.value,
             media_type=MediaTypes.EPISODE.value,
-            title="RSS Feed Show",
+            title="Pilot",
             season_number=1,
             episode_number=2,
         )
@@ -3378,9 +3384,38 @@ def test_episode_title_includes_season_episode_markers(self):
         titles = [item.findtext("title") for item in root.findall("./channel/item")]
 
         self.assertIn("RSS Feed Show S01E02", titles)
+        self.assertNotIn("Pilot S01E02", titles)
 
-    def test_guid_uses_imdb_id_when_available(self):
-        """Items with a resolved IMDb id get a stable, non-permalink guid."""
+    def test_guid_unique_per_episode_of_same_show(self):
+        """Episodes of the same show get distinct guids, not a shared show-level guid."""
+        episode1 = Item.objects.create(
+            media_id="tmdb-show-2",
+            source=Sources.TMDB.value,
+            media_type=MediaTypes.EPISODE.value,
+            title="Episode One",
+            season_number=1,
+            episode_number=1,
+        )
+        episode2 = Item.objects.create(
+            media_id="tmdb-show-2",
+            source=Sources.TMDB.value,
+            media_type=MediaTypes.EPISODE.value,
+            title="Episode Two",
+            season_number=1,
+            episode_number=2,
+        )
+        CustomListItem.objects.create(custom_list=self.custom_list, item=episode1)
+        CustomListItem.objects.create(custom_list=self.custom_list, item=episode2)
+
+        response = self.client.get(reverse("list_rss", args=[self.custom_list.id]))
+        root = ET.fromstring(response.content)
+        guids = {item.findtext("guid") for item in root.findall("./channel/item")}
+
+        self.assertIn("tmdb:episode:tmdb-show-2:s1:e1", guids)
+        self.assertIn("tmdb:episode:tmdb-show-2:s1:e2", guids)
+
+    def test_guid_ignores_provider_external_ids(self):
+        """Guid is derived from the item's own natural key, not mutable external ids."""
         movie = Item.objects.create(
             media_id="tmdb-movie-2",
             source=Sources.TMDB.value,
@@ -3398,18 +3433,18 @@ def test_guid_uses_imdb_id_when_available(self):
             if item.findtext("title") == "RSS Feed Movie With IMDb"
         )
 
-        self.assertEqual(guid.text, "imdb:tt1234567")
+        self.assertEqual(guid.text, "tmdb:movie:tmdb-movie-2")
         self.assertEqual(guid.get("isPermaLink"), "false")
 
-    def test_guid_falls_back_to_link_without_external_id(self):
-        """Items with no resolvable external id keep a permalink guid."""
+    def test_guid_is_never_a_permalink(self):
+        """Guid is always a stable id, never the internal detail-page URL."""
         response = self.client.get(reverse("list_rss", args=[self.custom_list.id]))
         root = ET.fromstring(response.content)
         item = root.find("./channel/item")
         guid = item.find("guid")
 
-        self.assertEqual(guid.text, item.findtext("link"))
-        self.assertEqual(guid.get("isPermaLink"), "true")
+        self.assertEqual(guid.text, "igdb:game:rss-1")
+        self.assertEqual(guid.get("isPermaLink"), "false")
 
     def test_item_category_reflects_media_type(self):
         """RSS items expose their media type as a category."""