docs(6209): the remaining test files — lessons, reply moment and shape, retrieval specs and scopes, rule doors and judgments, services, snippets, search scope; five tests renamed to their property

Docstrings, section headers and assertion messages drop the record number,
milestone or step that introduced the behaviour, and incident accounts are
restated as the present-tense failure shape. A dead pointer to a design doc
that is not in the repo is removed.

Renamed to the property they check:
  test_the_old_shape_would_be_caught -> test_a_rank_then_scope_query_is_caught
  test_a_ledger_repeat_no_longer_produces_that_case_at_all -> test_a_ledger_repeat_is_counted_not_withheld
  test_the_header_no_longer_promises_once_per_session -> test_the_header_explains_the_seen_marker
  test_the_portal_case_no_longer_stamps_one_canon_onto_a_whole_file -> test_one_canon_is_not_stamped_onto_a_whole_file
  test_the_repos_own_prose_no_longer_defines_with -> test_the_repos_own_prose_does_not_define_with
  test_the_original_regression_create_note_with_content -> test_the_real_server_refuses_content_on_create_note

Fixture and example ids stay: "note 5" in a supersession chain, "rule 156"
in an illustrative question, `#2275` as the hex-versus-citation case,
`#3244` as the example of a bare number, fixed dates in date-filter tests.

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

tests/test_retrieval_specs.py

@@ -1,8 +1,8 @@
-"""The specs are the registry (milestone 456 step 5).
+"""The specs are the registry.
 
-Three lists used to be kept by hand beside the arms — the tuning table, the
-ranked rows of the telemetry registry, and the rule-usage denominator — with
-tests to make them agree. They are now read off the pipeline's specs. These
+Three lists sit beside the arms — the tuning table, the ranked rows of the
+telemetry registry, and the rule-usage denominator — and all three are read
+off the pipeline's specs rather than kept by hand. These
 pin the derivation itself: every arm is tunable, every ranked source is
 measured with the declaration its spec carries, and the rule-usage
 denominator counts exactly the rule surfaces a ranker chose.
@@ -34,7 +34,7 @@ def test_every_ranked_source_is_measured_as_its_spec_declares():
         point = POINTS[spec.source]
         assert point.kind == UNBIDDEN
         assert point.what == d.what
-        # A quiet source must say why, and only a quiet source may (#2475).
+        # A quiet source must say why, and only a quiet source may.
         assert point.expects_traffic == (not d.quiet_because)
         assert point.quiet_because == d.quiet_because
 
@@ -59,7 +59,7 @@ def test_the_rule_denominator_is_every_rule_surface_a_ranker_chose():
 
 
 def test_an_arm_added_without_tuning_would_be_caught():
-    """Rule 167: the first test has to be able to bite. SURFACES skips an arm
+    """The first test has to be able to bite. SURFACES skips an arm
     with no tuning rather than raising, so an arm added without one would
     silently be untunable — and the order-equality assertion is what notices,
     as this replays with one such arm appended."""