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_task_claims.py

@@ -1,9 +1,9 @@
-"""A task's claim — which session is working it, and how it dies (milestone 381 step 2).
+"""A task's claim — which session is working it, and how it dies.
 
 WHAT THIS PINS
 
   1. **The write that is the work stamps it.** Reaching `in_progress` — by
-     update OR by a create that names it (#3683) — claims the task for whoever
+     update OR by a create that names it — claims the task for whoever
      made the change. Nothing asks the model to claim anything.
   2. **Ending or un-starting the work releases it**, and releasing is
      idempotent.
@@ -287,8 +287,8 @@ async def test_ending_a_session_releases_only_that_sessions_claims(users):
 
 @pytest.mark.integration
 async def test_a_collaborator_with_write_access_can_log_and_so_claims(users):
-    """create_log used to filter on the task's OWNER (a rule #78 violation), so
-    a collaborator on a shared task could not log on it — nor, since logging
+    """create_log filters on who may write the TASK, not on its owner, so a
+    collaborator on a shared task can log on it — nor, since logging
     stamps the claim, ever be seen working it."""
     from scribe.services import sharing, task_logs