docs(6209): snippets, rule embeddings, notes, ledger ageing and references, routes, reporting, handshake, lesson kind, request deadlines, contract-around-change, family models

Twelve more test files drop issue, milestone, rule, note, lesson and
snippet numbers and the dated or one-project figures that recorded how
each property was found; the docstrings state the property and why it
holds. The contract-around-the-change guard keeps the dict-key example as
the failure a signature-watcher misses.

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

tests/test_family_models.py

@@ -1,11 +1,10 @@
-"""Family canon's schema — the parts that need no database (milestone 463 step 1).
+"""Family canon's schema — the parts that need no database.
 
 The constraints themselves, against real Postgres, are in
 tests/test_integration_family_canon.py. These pin that the migration and the
-model agree on every whitelist (rule 36: a value one side accepts and the
+model agree on every whitelist (a value one side accepts and the
 other refuses only fails at INSERT time, which CI's unit lane never reaches),
-and that the seed ships nothing an install other than this one would find
-foreign (rule 115).
+and that the seed ships nothing a stranger's install would find foreign.
 """
 from __future__ import annotations
 
@@ -62,14 +61,14 @@ def test_the_column_defaults_match_the_first_state_of_each_lifecycle():
 def test_a_canon_ideas_scope_lives_on_the_idea_and_nowhere_else():
     """One scope source. A rule topic is linked FROM the idea and carries no
     platforms of its own, so the two cannot disagree about who a standard
-    reaches (#4221's two-sources-of-truth shape)."""
+    reaches — two sources of truth."""
     from scribe.models.rulebook import RulebookTopic
 
     assert "topic_id" in family.FamilyIdea.__table__.c
     assert not {c.name for c in RulebookTopic.__table__.c} & {"platform_id", "platform_ids"}
 
 
-# --- a decision read as precedent (#5131) ------------------------------------------
+# --- a decision read as precedent ------------------------------------------------
 
 def _assessment():
     reason = "the APK is built in CI and signed with the one release key"