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_inception.py

@@ -1,11 +1,10 @@
-"""Project inception (milestone 297) — step 1: the record's shape.
+"""Project inception — the record's shape.
 
 The WHY a project inherits what it does lives on projects.inception. Pure
-validation is pinned here; the effects are step 3's integration tests.
+validation is pinned here; the effects are the integration tests.
 
-Rules left inception in two steps: the always-on opt-out with the tier
-(milestone 394), and the rulebook subscription with subscriptions (milestone
-414). A rule in a rulebook is global, so there is nothing to choose.
+Rules are not an inception choice: a rule in a rulebook is global, so there is
+nothing to choose.
 """
 from scribe.models.project import Project
 from scribe.services.inception import (
@@ -39,7 +38,7 @@ def test_validate_inception_pins_the_choice_vocabulary():
     # believe a rulebook had been declined.
     assert "unknown inception choice" in validate_inception(
         {"exclude_always_on_rulebooks": [1]})
-    # Same for the subscription choice since milestone 414.
+    # Same for a rulebook subscription choice.
     assert "unknown inception choice" in validate_inception({"subscribe_rulebooks": [2]})
     assert "positive id or null" in validate_inception({"design_system_id": 0})
     assert "positive id or null" in validate_inception({"design_system_id": True})
@@ -71,8 +70,8 @@ def test_normalize_choices_is_canonical_and_complete():
 
 
 def test_standard_systems_vocabulary_reads_the_catalog_not_a_constant():
-    """The vocabulary moved from a module constant to the global catalog table
-    (milestone 307): a constant cannot be a foreign key, so nothing outside a
+    """The vocabulary is the global catalog table, not a module constant: a
+    constant cannot be a foreign key, so nothing outside a
     project could reference an area. The seed and the bootstrap ask must both
     read the table, or the list they show and the list they mint diverge."""
     import inspect