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_ledger_references_not_silence.py

@@ -1,22 +1,20 @@
-"""A repeat on a note arm is referenced, not withheld (#4101).
+"""A repeat on a note arm is referenced, not withheld.
 
 WHY THIS EXISTS
 
-#3750 settled the argument for rules: a record the session was told about an
-hour ago is not a record in front of the reader now, so the second time it is
+A record the session was told about an hour ago is not a record in front of the reader now, so the second time it is
 the best answer the session gets the line again with a tail saying so — never
 silence, which is indistinguishable from "nothing matched".
 
-The note and snippet arms never got that fix. Worse, their ledger went into
-`semantic_search_notes` as `exclude_ids`, so the repeat left the candidate set
-entirely, which had three consequences:
+The note and snippet arms hold the same line. A ledger passed into
+`semantic_search_notes` as `exclude_ids` takes the repeat out of the candidate
+set entirely, with three consequences:
 
-  - the session got silence the second time, on the arms that fire most;
-  - a compaction made it permanent, because the ledger outlived the context it
-    described (the same step fixes that one layer down);
-  - and `best_available` was measured against a candidate set the caller had
-    already edited, so the bar could be blamed for a record the caller withheld
-    (#3739, from the side its fix never reached).
+  - the session gets silence the second time, on the arms that fire most;
+  - a compaction makes it permanent, because the ledger outlives the context it
+    describes;
+  - and `best_available` is measured against a candidate set the caller has
+    already edited, so the bar can be blamed for a record the caller withheld.
 
 WHAT THIS PINS
 
@@ -28,11 +26,11 @@ WHAT THIS PINS
      and a dev-log borrowing it would claim authority it does not have — so
      what is pinned is that the line appears and is distinguishable, not its
      prose.
-  3. The telemetry splits the two (#3752 / #3668): the row's result set and the
+  3. The telemetry splits the two: the row's result set and the
      surfaced table both take FRESH only, and the repeat is COUNTED in
      `suppressed` instead. This is what makes a zero-result call readable —
      `result_count == 0` with `suppressed_count > 0` says "everything that
-     matched, the session has already seen", which was unreportable here.
+     matched, the session has already seen".
   4. The deliberate exception: the write-path SYNC class still shows once. Its
      claim is about an edit in progress, not about a record's continuing
      relevance, and repeating it would be nagging rather than reminding.
@@ -141,7 +139,7 @@ async def test_a_call_where_everything_was_already_seen_is_readable():
 
 @pytest.mark.asyncio
 async def test_a_repeat_is_not_recorded_as_a_fresh_surfacing():
-    """#3668's identity: this table and the log row describe the same call."""
+    """The two-table identity: this table and the log row describe the same call."""
     surf = MagicMock()
     hits = [(0.80, fake_note(id=11, title="Pool sizing decision", user_id=1)),
             (0.78, fake_note(id=22, title="run_maintenance thresholds", user_id=1))]