docs(6209): forty test files — design cascade and stylesheet, embeddings, family canon, forge, backup round trips, inception, placement, platforms, moments, rule move and verification, search scope, facets

Module and test docstrings state what is pinned without the record number
or step that introduced it. Incident accounts become the failure shape in
the present tense: the pipefail head, the code_shapes import, the export
order, the facet dialects, the cross-kind repeat, the write-once kind.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_embedding_yields_to_a_delete.py

@@ -1,4 +1,4 @@
-"""The embedding refresh must LOSE to a delete, not race it (#3262).
+"""The embedding refresh must LOSE to a delete, not race it.
 
 Both upserts replace a record's vectors as delete-then-insert. That takes two
 row locks — the chunk rows, then the parent row via the insert's foreign key —
@@ -32,7 +32,7 @@ def _mock_session(lock_result: object = 7, execute_side_effect=None):
     session = MagicMock()
     claimed = MagicMock()
     claimed.scalar_one_or_none.return_value = lock_result
-    # A task's document carries its work logs (#4251), so the refresh reads
+    # A task's document carries its work logs, so the refresh reads
     # task_logs before it builds chunks. Answered explicitly — left to
     # autovivify, `list(result.all())` would raise and be swallowed, and these
     # tests would be exercising the failure path without saying so.
@@ -72,7 +72,7 @@ async def test_a_note_refresh_claims_the_row_before_rewriting_its_vectors():
 
     sqls = [compiled_sql(c.args[0], dialect=PG) for c in session.execute.call_args_list]
     # Located by what they ARE rather than by position: the work-log read a
-    # task's document needs (#4251) runs before any of this, and an index is
+    # task's document needs runs before any of this, and an index is
     # not what the claim is about.
     claim = next(i for i, sql in enumerate(sqls) if "FOR KEY SHARE NOWAIT" in sql)
     replace = next(