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_integration_backup_rule_version_roundtrip.py

@@ -1,4 +1,4 @@
-"""Real-Postgres round trip for rule_versions (milestone 323 step 1).
+"""Real-Postgres round trip for rule_versions.
 
 Two things here cannot be shown with mocks, and both are the kind that fail
 QUIETLY — a restore reports success and hands back history that is wrong.
@@ -7,7 +7,7 @@ QUIETLY — a restore reports success and hands back history that is wrong.
    A restore that writes it straight through succeeds and attaches every
    snapshot to whatever rule happens to hold that number here — an edit
    history filed against the wrong binding instruction, which is worse than
-   no history at all. This is #3182's `arose_from_id` trap on a new table.
+   no history at all. It is the same trap as a note's `arose_from_id`.
 
 2. **A null actor does not drop the row.** `user_id` is SET NULL precisely so
    history outlives the account that wrote it, so the restore deliberately
@@ -217,7 +217,7 @@ async def test_both_snapshots_come_back(restored):
 
 
 async def test_the_history_attaches_to_the_RESTORED_rule(restored):
-    """#3182's trap. The source rule still exists and holds a different id, so
+    """The remap trap. The source rule still exists and holds a different id, so
     a straight-through copy would file this history against it — or against
     whatever unrelated rule owns that number."""
     new_rule_id = restored["rule"].id