MAINT-21 round 2: keep the move pure - revert the added DECISIONS text, restore cut comments

Router T241: the comments commit had put new rationale into
MAIN-orchestration.md and cut comment lines that the note at 56fc41f did not
hold.

- DECISIONS/MAIN-orchestration.md is the 56fc41f text plus the one sentence
  that the Controller is split into app/main.py and app/ctl_*.py.
- Comments whose content is not in a DECISIONS note at 56fc41f are back in the
  code verbatim: MAINT-05 one config, the SAFETY-02, SAFETY-42/34,
  SAFETY-30 site half, SAFETY-31 and SAFETY-18 latch blocks in __init__, the
  _grade_store_migration docstring and comment, the trade_power_w docstring,
  the rows.py docstrings.
- Kept: cuts of text already in the note, the SMA-10 / SAFETY-137 / SMA-2
  pointers, the SAFETY-32 line fix.

No code change: maint21_same_ast OK, maint20_same_code -OO same.

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

goodwe_controller/app/main.py

@@ -288,8 +288,12 @@ class Controller(InputsMixin, WritesMixin, TradeMixin, CycleMixin, AlarmsMixin,
             self.log_event("maintenance history did not move over cleanly: "
                            + self.maint_migration.explain(),
                            hint=messages.hint("maint_history"))
-        # MAINT-05: one config, N machines: the options describe the
-        # PROCEDURE; the SCHEDULE and HISTORY are per pack, in the store.
+        # MAINT-05: one config, N machines: the `maintenance_*` options
+        # describe the PROCEDURE (same on every pack); the SCHEDULE and HISTORY
+        # are per pack, in the store. A per-entry config block would be a
+        # second shape for CFG-04 and a fifth place for `maintenance_charge_w`
+        # to disagree with config.yaml; two procedures would be a roster-schema
+        # card.
         _maint_cfg = MaintConfig.from_options(opts)
         _one_pack = len(self.inverters) <= 1
         self.maints = [
@@ -307,9 +311,12 @@ class Controller(InputsMixin, WritesMixin, TradeMixin, CycleMixin, AlarmsMixin,
                 tz=site_tz)     # MAINT-10: the start hour's zone, from amain()
             for i, inv in enumerate(self.inverters)]
 
-        # SAFETY-02: one watchdog per actuator, restored from ITS OWN
-        # namespaced keys and graded on every start.
-        # DECISIONS/MAIN-orchestration.md.
+        # SAFETY-02: one watchdog per actuator, each restored from ITS OWN
+        # namespaced store keys (a trip on B latches B, A keeps commanding).
+        # Restored, because a latch held only in memory is cleared by the
+        # restart an operator tries first. Graded on every start: a
+        # disagreement with the flat value re-arms by hand and shouts (the
+        # fail-safe direction is ON). DECISIONS/MAIN-orchestration.md.
         self._grade_store_migration(store)
         for inv in self.inverters:
             if inv.sign_wd.tripped:
@@ -329,9 +336,12 @@ class Controller(InputsMixin, WritesMixin, TradeMixin, CycleMixin, AlarmsMixin,
                                hint=messages.hint("stop_restored",
                                                   unit=inv.name))
 
-        # SAFETY-42 + SAFETY-34: a latch that does NOT act, restored so the
-        # ALARM survives; `_delivery_announced` is per process, so a restart
-        # clears the flag and keeps the latch. DECISIONS/MAIN-orchestration.md.
+        # SAFETY-42 + SAFETY-34: a latch that does NOT act, unlike SAFETY-02's
+        # and SAFETY-31's (which command 0 W). It is restored so the ALARM
+        # survives (2026-09-02: an outage unseen for 6 h 25 m with the detector
+        # correct); `delivery.py` argues reporting rather than acting.
+        # `_delivery_announced` is per process (as `_circ_announced`): a
+        # restart clears the flag and keeps the latch.
         self._delivery_announced = set()
         for inv in self.inverters:
             if inv.delivery_wd.tripped:
@@ -348,9 +358,12 @@ class Controller(InputsMixin, WritesMixin, TradeMixin, CycleMixin, AlarmsMixin,
                                hint=messages.hint("not_delivering",
                                                   unit=inv.name))
 
-        # SAFETY-30: the SITE half of the sign check: armed only at N>=2 (at
-        # one inverter it is constructed and never evaluated), restored with
-        # FLAT keys. DECISIONS/SAFETY-30-per-unit-sign.md.
+        # SAFETY-30: the SITE half of the sign check, one per site, armed only
+        # at N>=2: the SUM of the standing commands against P1. At a roster of
+        # one it is constructed and never evaluated (arming it would duplicate
+        # `inverters[0].sign_wd`: two latches, two banners, a false-positive
+        # record spent twice); `cycle()` enforces it. Restored from the store
+        # with FLAT keys (store.py). DECISIONS/SAFETY-30-per-unit-sign.md.
         self.site_sign_wd = SignWatchdog(
             self.site_sign_cfg,
             tripped=bool(store.data.get("site_sign_tripped", False)),
@@ -372,12 +385,15 @@ class Controller(InputsMixin, WritesMixin, TradeMixin, CycleMixin, AlarmsMixin,
         self._arm_sign_watchdogs()
 
         # SAFETY-18: the frozen-but-fresh meter detector (freeze.py). NOT
-        # restored: it does not act. DECISIONS/MAIN-orchestration.md.
+        # restored from the store: it does not act, so it does not latch; a
+        # restart re-derives it within one `meter_freeze_s`.
         self.freeze_wd = FreezeWatchdog(
             FreezeWatchdogConfig(hold_s=float(opts.get("meter_freeze_s", 300))))
 
-        # SAFETY-31: one per site, RESTORED because it acts, with SITE-level
-        # keys. DECISIONS/MAIN-orchestration.md.
+        # SAFETY-31: one per site, RESTORED (unlike SAFETY-18): a trip files a
+        # P_SAFETY SET that stops every inverter, and a cleared latch would
+        # restart straight into the loop it stopped. SITE-level keys, not
+        # namespaced: circulating power is defined over the roster (store.py).
         self.circ_wd = CirculationWatchdog(
             CirculationConfig(
                 min_w=float(opts.get("circulation_w",