MAINT-15 round 2: in-repo differential check, full-hold with-reading check

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

goodwe_controller/DECISIONS/MAINT-15-hold-ends-without-soc.md

@@ -37,7 +37,11 @@ line is true without a reading: it names minutes of hold, not a level.
 
 - It does not check that the pack is still full at the end of the hold.
 - It does not say why the reading was lost.
-- With a reading, nothing changes (proved by a differential trace against
-  release/1.0 in `test_maint15.py`).
+- With a reading, nothing changes. `test_maint15.py` section 7 compares the new
+  HOLD tick by tick with a frozen copy of the release/1.0 HOLD branch (phase,
+  setpoint, owner, events, `last_completed`) at four `hold_min` values. A wider
+  trace of the whole cycle (800 seeded runs against db9e231) was run outside the
+  repo; its script and log are kept under `scratch/MAINT-15/` of the dev
+  workspace, not in this repository.
 - A state file written by an older version with `phase: hold` loads and ends on
   time; the file is not changed in format.