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_search_scope_shape.py

@@ -3,13 +3,13 @@
 Ordered straight off a `*_embeddings` table, the planner walks the HNSW index:
 it takes ~`hnsw.ef_search` (40) nearest chunks from every owner and project
 and filters them afterwards, so an in-scope record behind 40 nearer ones the
-caller cannot see is silently dropped. The fix is one shape, `_rank_scoped`,
-and these pin that every search goes through it — the rule search was fixed
-alone first, and the other three kept the fault because nothing said they
-were the same query.
+caller cannot see is silently dropped. The remedy is one shape, `_rank_scoped`,
+and these pin that every search goes through it — fixed in one search alone,
+the others keep the fault, because nothing says they are the same query.
 
 The integration lane's crowd tests show the behaviour on a real index; these
-are the guard that fails on the old shape whatever plan Postgres picks.
+are the guard that fails on a rank-then-scope query whatever plan Postgres
+picks.
 """
 from __future__ import annotations
 
@@ -54,7 +54,7 @@ def test_every_semantic_search_ranks_through_the_scoped_shape():
         calls = _calls(fn)
         assert "_rank_scoped" in calls, f"{name} does not rank through _rank_scoped"
         assert "_scoped_chunks" in calls, f"{name} does not build its scope as chunks"
-        # Its own ORDER BY is the old shape: a distance ordered on the
+        # Its own ORDER BY is the rank-then-scope shape: a distance ordered on the
         # embedding table, which the index serves before the scope applies.
         assert "order_by" not in calls, f"{name} orders by distance itself"