SAFETY-128 round 2: find late readings from the batteries, not the meter alone

Review B1: the meter fit took repeating house loads (ovens, a heat pump)
for late readings on healthy 1-2 s sites, about 9 % of the recorded
house. B2: at a 5 s meter it never ran. M1: no hysteresis. M2: an
unbounded check.

lateness.Delay now fits how long each battery's reading takes to show
its own request, which the house does not move, from the 1 s reads
(read_inputs -> Answer.watch). The meter fit stays for speed at 1-3 s
meters, but counts only when an ask was slow to start and no battery
fit said on time. Late from 9.5 s after 2 fits, on time under 6.5 s,
dropped after 120 s without a fit. Fits are bounded (a few ms).

Readings on time: no verdict in any reviewer scenario (22 shapes at
1/2/5 s meters, 7 harm runs) nor in 2 days of the recorded house at
1, 2 and 5 s ticks; digests equal to 77fe31b. Late: found 36-68 s after
the start at 1-2 s, about 3 min at 5 s. The row gives the batteries'
delay, or no figure while only the meter has shown it.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/app/main.py

@@ -3137,11 +3137,11 @@ class Controller:
         if a.late_seen != self._late_logged:
             self._late_logged = a.late_seen
             if a.late_seen:
-                self.log_event(f"readings late ({a.delay_s:.0f} s) - holding",
+                self.log_event("readings late - holding",
                                hint=messages.hint("readings_late"))
                 _LOG.warning("Home Assistant readings arrive late, so control "
-                             "holds the battery: READINGS_LATE.")
-                _LOG.debug("READINGS_LATE: the meter shows a power request "
+                             "holds the batteries: READINGS_LATE.")
+                _LOG.debug("READINGS_LATE: the readings show a power request "
                            "%.0f s after it is sent.", a.delay_s)
             else:
                 self.log_event("readings on time", hint=messages.hint(
@@ -3760,6 +3760,10 @@ class Controller:
                 else:
                     _LOG.debug("Meter readings are back.")
 
+        self.answer.watch(now_mono, [(inv.name, inv.standing_w(), inv.batt)
+                                     for inv in self.inverters],  # SAFETY-128
+                          sum(inv.standing_w() for inv in self.inverters),
+                          self.grid)
         if self.inputs_ok:
             if self.inputs_bad_since is not None:
                 self.log_event("inputs recovered",
@@ -7384,7 +7388,7 @@ class Controller:
         if self.answer.late_seen:                             # SAFETY-128
             out.append({"ok": False, "warn": True, "id": "late",
                         "text": messages.row_readings_late(
-                            self.answer.delay_s, self._late_zero)})
+                            self.answer.shown_s, self._late_zero)})
 
         # SAFETY-03. Red while an over-rating clamp is engaged (amber for the
         # integrator bound, SAFETY-40), and the engagement COUNT is shown even