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_rule_verification.py

@@ -1,4 +1,4 @@
-"""Real-Postgres tests for a rule's CHECK — the write half (milestone 312).
+"""Real-Postgres tests for a rule's CHECK — the write half.
 
 What mocks cannot prove, and what the staleness sweep depends on:
 
@@ -132,7 +132,7 @@ async def test_editing_anything_else_leaves_the_stamp_alone(constraint):
     assert row.why.startswith("act_runner picks the shell")
 
 
-# ── the sweep itself (step 3) ──────────────────────────────────────────
+# ── the sweep itself ───────────────────────────────────────────────────
 
 @pytest_asyncio.fixture
 async def rulebook_of_three():