docs(6209): preference door, systems and notes tools, lesson surfacing, rule versions, backup round trip, JSON reader, charter search, provenance, location filter

Ten more test files: issue, milestone, rule, decision and snippet numbers
come out of docstrings, comments and messages; the preference door states
what a preference is instead of quoting the framing; the JSON reader says
why jq is not assumed instead of what every hook used to do; the backup
round trip's column warning no longer claims the import side is unguarded.

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

tests/test_integration_backup_rule_usage_roundtrip.py

@@ -1,9 +1,9 @@
-"""Real-Postgres round trip for rule_usage_events (milestone 333 step 1).
+"""Real-Postgres round trip for rule_usage_events.
 
 **This file is the reason the table exists.** `rule_usage_events` could have
 been a `rule_id` column on `note_usage_events` — the row carries no
 note-specific field and the readout is the same shape, which is the strongest
-case for sharing that note #3163 admits. What decided against it is identity at
+case for sharing. What decides against it is identity at
 restore, and that is a claim only a real round trip can support.
 
 The failure it guards is the quiet kind. `note_usage_events`'s importer maps
@@ -17,7 +17,7 @@ So the assertions below are about WHICH MAP resolved the id, and they are
 written to fail if the answer ever becomes "the note one" or "neither".
 
 Same shape as `test_integration_backup_rule_version_roundtrip.py`, which guards
-`rule_versions` against #3182's `arose_from_id` trap on the same seam.
+`rule_versions` against the same id-remapping trap on the same seam.
 """
 import pytest
 import pytest_asyncio
@@ -143,7 +143,7 @@ async def source():
                 user_id=None, rule_id=rule.id,
                 event=SURFACED, source="write_path_rule",
             ),
-            # A departure and its reason (#4212). Seeded here because
+            # A departure and its reason. Seeded here because
             # `detail` is the ONE field on this table that cannot be
             # recomputed: a fresh install re-earns its counts by being used,
             # but a stated reason exists once and is gone if a restore drops
@@ -290,7 +290,7 @@ async def test_the_actor_is_remapped_and_a_missing_one_survives(restored):
     attributed = [e for e in restored["events"] if e.user_id is not None]
     orphaned = [e for e in restored["events"] if e.user_id is None]
     # Four attributed: the surfacing, the pull, and the two outcome rows
-    # added with `detail` (#4212). One orphaned, deliberately.
+    # that carry `detail`. One orphaned, deliberately.
     assert len(attributed) == 4
     assert len(orphaned) == 1, (
         "the event with no actor did not come back. Telemetry outlives the "
@@ -325,10 +325,9 @@ async def test_a_departures_reason_survives_the_round_trip(restored):
     419 was opened to create, undone silently at the one moment nobody is
     watching.
 
-    #4197 is the standing warning behind this test: the backup column guard
-    watches the export side only, so a column added to the model and to the
-    exporter and NOT to the importer round-trips as null with nothing to say
-    so.
+    A column added to the model and to the exporter and NOT to the importer
+    round-trips as null with nothing to say so; this round trip is where that
+    shows up in the data.
     """
     departures = [e for e in restored["events"] if e.event == DEPARTED]
     assert len(departures) == 1