chore(comments): drop epic, sprint and review-round ids from the code

The code cited its plan instead of saying why: `E28 review J4`, `(R6 S3b)`, `S1 justified…`,
`deep-review round 5`. That plan lives in the private ops repo, so for every reader of this one the
citation was noise, and a sentence whose subject was the plan step ("round 2 showed…") hid its
lesson behind an id. Each one is gone and the "why" kept: a bare citation is deleted, a sentence
carrying a lesson is reworded around it ("a later attempt showed…").

Measured (`scripts/audit_metrics.py`, product code): 652 lines in 270 files carried an epic code by
the definition the next commit holds (507 / 241 by the old, two-digit-only one) -> 0. Across all
code, tests, scripts and configs: ~1100 epic-code lines plus ~320 sprint/round ids.

Behaviour unchanged, checked mechanically: every changed .py file has the same AST once docstrings
are blanked; css/sh/toml/yml/json files are identical once comments are stripped; the only
non-comment changes in TS/JS are test titles, one description string in a contract table, and five
ESLint messages, whose text is all the gates snapshot diff holds. Not touched: Markdown (docs and
the changelog keep their history), Alembic migrations, TV episode notation (`S2 · E5`), DESIGN.md
ids (`C1`, `B4`, `S3h`), tracker ids (`SEC-16`, `DX-17`).

One stale claim fixed on the way: test_hls_reaper's docstring said the player checkpoints "every
10 s whether or not it is playing", which plex/stream.py calls wrong; it now says what the code does.

backend/app/sync/autotag.py

@@ -116,7 +116,7 @@ _TOPIC_SLUGS = {
     "Fashion": "Fashion & Beauty",
     "Physical_attractiveness": "Fashion & Beauty",
     # YouTube links the British page (…/wiki/Humour); the key was "Humor", so no channel ever got Comedy
-    # from its topic (E30).
+    # from its topic.
     "Humour": "Comedy",
     "Entertainment": "Entertainment",
     "Film": "Film",
@@ -300,11 +300,11 @@ def _cleanup_orphan_system_tags(db: Session) -> int:
     """Delete system tags that no longer link to any channel (e.g. after a mapping change) — but not
     one a saved feed view filters on. Views hold tag IDS, and a deleted tag comes back under a new id
     when a channel earns it again, so the view's filter would point at nothing; the feed drops an
-    unknown id, and the view showed the whole feed under its old name (E32 S2).
+    unknown id, and the view showed the whole feed under its old name.
 
     The views are read defensively, and the kept ids are filtered here rather than in SQL: a view
     stored before its route checked the shape (or written around it) must not raise for everyone's
-    job, nor push a `NOT IN` past the driver's bind-parameter limit (E32 review)."""
+    job, nor push a `NOT IN` past the driver's bind-parameter limit."""
     in_views = {
         t
         for (filters,) in db.execute(select(SavedView.filters).where(SavedView.source == "feed"))

backend/app/sync/maintenance.py

@@ -190,7 +190,7 @@ def _revalidate_rolling(db: Session, yt: YouTubeClient, now: datetime) -> dict:
                 .where(Video.unavailable_since.is_(None))
                 # Not one this run already checked: with fewer available videos than the batch, the
                 # loop used to wrap around and re-fetch the same ones until `checked` reached the
-                # batch, spending quota on answers it already had (E32 S2).
+                # batch, spending quota on answers it already had.
                 .where(or_(Video.last_checked_at.is_(None), Video.last_checked_at < now))
                 # NULLS FIRST = never-checked first, then least-recently-checked; equivalent to the old
                 # `(last_checked_at IS NULL) DESC, last_checked_at ASC` but in the exact shape of the

backend/app/sync/playlists.py

@@ -168,7 +168,7 @@ def _load_baseline(pl: Playlist) -> tuple[list[str] | None, set[str]]:
 
 def parse_baseline(pl: Playlist) -> list[str] | None:
     """The last-synced ordered id set, or None when no baseline has been recorded yet (a fresh
-    export, or a link created before S7). None makes the first merge union losslessly."""
+    export, or an older link). None makes the first merge union losslessly."""
     return _load_baseline(pl)[0]
 
 
@@ -209,7 +209,7 @@ def _set_baseline_under_lock(
     meanwhile — lock the list and derive `dirty` from what is there, or the edit would read as
     synced and never reach YouTube. The name too: the lock re-reads a rename made meanwhile, and a
     baseline taken over THAT name matched it, so the list read clean with YouTube's title still the
-    old one (E28 review round 4)."""
+    old one."""
     _lock_or_gone(db, pl)
     _set_baseline(pl, ids, unavailable, name=name)
     recompute_dirty(db, pl)
@@ -322,7 +322,7 @@ def user_sync_claim(db: Session, user_id: int) -> AbstractContextManager[bool]:
 def _mirror_listing(yt: YouTubeClient, ytid: str, count: object, pl_id: int) -> list[str] | None:
     """A mirror's video ids from YouTube, or None when there is nothing to believe: the list was
     deleted between the pull's listing and this read (the next pull drops the mirror as vanished —
-    not a reason to fail every other list, E32 review round 2), or YouTube listed no items for a
+    not a reason to fail every other list), or YouTube listed no items for a
     list it counts as non-empty (`blank_listing`)."""
     try:
         ids = list(yt.iter_my_playlist_video_ids(ytid))

backend/app/sync/runner.py

@@ -187,7 +187,7 @@ def run_rss_poll(db: Session, channels: list[Channel] | None = None) -> dict[str
         # "fix this subscription"; `Connection refused` says "the egress is down".
         # The fallback's count rides along: a red card during an RSS outage should still say
         # whether the uploads are arriving another way.
-        # As data too (E31): the audit log and the inbox say it in the reader's language, the first
+        # As data too: the audit log and the inbox say it in the reader's language, the first
         # failure as its channel and its reason code (`http_404` vs `transport` is that difference).
         first_channel, first_reason = first_failure or ("", "error")
         raise progress.JobFailed(

backend/app/sync/subscriptions.py

@@ -123,7 +123,7 @@ def should_prune(fetched_count: int, existing_count: int) -> bool:
 def vanished[K, V](existing: dict[K, V], listed: Collection[K]) -> list[V]:
     """The local mirrors whose key the remote listing no longer has — none at all when the listing
     is an empty answer that contradicts them (`should_prune`). The YouTube playlist mirrors use it:
-    without it, one blip dropped every mirror (E32 S2)."""
+    without it, one blip dropped every mirror."""
     if not should_prune(len(listed), len(existing)):
         return []
     return [row for key, row in existing.items() if key not in listed]
@@ -132,7 +132,7 @@ def vanished[K, V](existing: dict[K, V], listed: Collection[K]) -> list[V]:
 def blank_listing(listed: Collection, count: object) -> bool:
     """The same rule one level down: no members from a container whose own listing counts some (a
     playlist's `itemCount`) is a blip, not a list emptied. Replacing or merging on it deleted every
-    mirrored item and reset the merge baseline (E32 review)."""
+    mirrored item and reset the merge baseline."""
     return not listed and isinstance(count, int) and count > 0
 
 

backend/app/sync/videos.py

@@ -107,7 +107,7 @@ def stub_from_playlist_item(item: dict, channel_id: str) -> dict | None:
 def _uploads_page(yt: YouTubeClient, channel_id: str, uploads: str, page_token: str | None) -> dict:
     """One page of the channel's uploads. YouTube answers the uploads list of a channel with no
     uploads at all as not found: an empty back-catalogue, so an empty last page — not a failure
-    that left `recent_synced_at` unstamped and charged the channel again on every run (E32 review).
+    that left `recent_synced_at` unstamped and charged the channel again on every run.
     Any other failure raises."""
     try:
         return yt.get_playlist_items(uploads, page_token)