docs(6209): seventeen more test files — lesson shape and round trip, rule scope/moments/kind/surfacing, drift, deadlock race, backup, inception, backfill, claims, supersession, ledgers, family shapes

Docstrings and comments state the property and its reason in the present
tense. The session-context ledger test no longer describes the decision it
"used to pin"; the supersession tests state demote-not-filter without the
quote; one-row measurements become the general shape with their figures.

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

tests/test_integration_backup_note_roundtrip.py

@@ -1,4 +1,4 @@
-"""Real-Postgres round trip for the note fields #3182 restored.
+"""Real-Postgres round trip for the note fields a restore carries.
 
 The unit lane can prove a serialiser EMITS a key. It cannot prove a restore
 puts the value back on the right row, and the note->note edges are exactly
@@ -7,8 +7,6 @@ the SOURCE database, so a restore that writes them straight through succeeds,
 reports success, and silently points every edge at whatever record happens to
 hold that number here.
 
-That is why #3182 was not fixed in passing.
-
 These drive the REAL `restore_full_backup`, not a reimplementation of its
 loop. A test that re-derives the remap it is checking would agree with
 whatever the product does, including nothing.
@@ -162,10 +160,10 @@ async def _no_leftover_restored_user():
 
 
 async def test_a_restored_record_keeps_what_it_IS(restored):
-    """#3182's headline. Without note_type and task_kind a restore reported
-    success and handed back a corpus where every snippet and process was a
-    plain note and every issue and spike was `work` — the whole vocabulary
-    milestone 312 and #3128 were about, gone, with nothing to notice it by."""
+    """Without note_type and task_kind a restore reports success and hands
+    back a corpus where every snippet and process is a plain note and every
+    issue and spike is `work` — the record vocabulary gone, with nothing to
+    notice it by."""
     by_title, _ = restored
 
     assert by_title["debounce — rate-limit"].note_type == "snippet"