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_forge_webhook.py

@@ -1,4 +1,4 @@
-"""Forge push webhook (#2691) — signature gate, payload parsing, and the
+"""Forge push webhook — signature gate, payload parsing, and the
 end-to-end drift flag on real Postgres.
 
 The webhook is the seam that makes verification scale: a push names exactly
@@ -43,7 +43,7 @@ def test_signature_gate():
 
 
 def test_delivered_signature_reads_both_forges_headers():
-    """#2693: GitHub signs the same HMAC but ships it as
+    """GitHub signs the same HMAC but ships it as
     X-Hub-Signature-256: sha256=<hex> — the whole webhook payload mapping is
     this header, so pin it."""
     hexsig = _sign(b"{}")