docs(6209): test prose in the present tense — "used to", "previously", "before this" restated as the failure shape

Twenty-eight test files described the code they guard by what it did
before a fix. Each is now the property and the failure it prevents, in the
present tense: the backfill snapshot, the per-dial calibration query, the
rule scope, the lesson trigger filter, the subshell global, the trash owner
scope, the version readout fallback, and others. A docstring line that
narrated the backup suite's own history is removed.

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

tests/test_services_plugin_context.py

@@ -86,9 +86,8 @@ async def test_build_autoinject_hint_titles_only_with_margin_gate():
     assert "get_note(id)" in out["context"]
     assert "↳" not in out["context"]
     # Telemetry fired for BOTH retrievals this path runs: the scored menu and
-    # the reuse-slot query competing against it. The slot's query used to be
-    # the one unlogged retrieval on this path — the hit it displaced was in
-    # retrieval_logs, and the query that displaced it must be too.
+    # the reuse-slot query competing against it. The hit the slot displaces is
+    # in retrieval_logs, so the query that displaced it must be too.
     sources = [c.kwargs["source"] for c in rec.call_args_list]
     assert sources == ["auto_inject", "reuse_slot", "lesson_slot"]
 
@@ -235,9 +234,9 @@ async def test_a_project_id_that_does_not_resolve_is_reported_not_dropped():
     another instance, or names a deleted project, the session has to be told —
     it cannot infer it from an absence.
 
-    This used to render nothing whatsoever: the branch hung off `if project_id`
-    as an `elif`, so an id that was sent and failed took the outer arm, found
-    no project, and fell out of the block having said nothing at all.
+    The trap is a branch hung off `if project_id` as an `elif`: an id that was
+    sent and failed takes the outer arm, finds no project, and falls out of the
+    block having said nothing at all.
     """
     from scribe.services.plugin_context import build_session_context
     with patch("scribe.services.plugin_context.projects_svc.get_project",