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_lesson_insight_round_trip.py

@@ -15,13 +15,13 @@ worth having wherever a record is stored composed and edited in parts: not
 "does the strip remove the marker" — it did — but "does an edit that changes
 nothing change nothing".
 
-WHAT WENT WRONG. The derivation used to filter out body LINES matching the
-trigger marker's pattern, which is `re.M` and therefore matches one line.
-`when_to_apply` is free text and is routinely several paragraphs; the
-composer writes all of it after the marker, so paragraphs 2..n were ordinary
-lines that the filter had no reason to touch. They came back as "the
-insight", the full trigger was prepended again, and the stored lesson gained
-(n-1) paragraphs per update — silently, compounding, and in the half of the
+WHAT GOES WRONG. A derivation that filters out body LINES matching the
+trigger marker's pattern, which is `re.M` and therefore matches one line,
+leaves the rest of the trigger behind. `when_to_apply` is free text and is
+routinely several paragraphs; the composer writes all of it after the marker,
+so paragraphs 2..n are ordinary lines that the filter has no reason to touch.
+They come back as "the insight", the full trigger is prepended again, and the
+stored lesson gains (n-1) paragraphs per update — silently, compounding, and in the half of the
 document that does the retrieving.
 
 On a three-paragraph trigger the body grows by the length of paragraphs 2 and
@@ -180,7 +180,7 @@ def test_the_insight_is_derived_from_the_row_not_from_the_body_alone():
     """Why the function takes a note.
 
     The body on its own does not say where the trigger ends — that is the
-    information the old shape did not have and guessed at. The mirror in
+    information a line-wise filter does not have and guesses at. The mirror in
     `data` is where it comes from, so a caller holding only the body string
     cannot be served, and this pins that the argument is the record."""
     note = _stored(MANY_PARAGRAPHS, INSIGHT, [])