SAFETY-97: "gives nothing" is graded against each battery's idle reading

B's power reading shows -95 to -118 W at idle (standby draw), so the
|reading| < 100 W refusal band never held a refusing B: never at N=2,
and since SAFETY-94's shared rule not at N=1 either (review F1).

Each unit now learns its idle reading (app/idle.py): only while control
runs, the unit is not refused/stale/tripped and its command has stayed
within 50 W for 120 s; first value a 120 s mean, then a 30 min follow;
samples beyond 250 W dropped, value clamped to 250 W; saved per unit and
restored. The shared refusal evidence, compute()'s N=1 engage and end,
the unit refusal ends, the stale-path refusal and SAFETY-42's "parked"
test are centred on it. Until learned it is 0 W, the rule as it was.

Refusing B caught at N=1 28/28/65 s and N=2 24/24/60 s (1/2/5 s
meters), before never; refusing A unchanged. Healthy B with its offset,
SAFETY-94's scenarios, 96 runs: 0 stale, 0 refused. Live replay: 0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019DBUfvndgHwaV339Fvd2gr

goodwe_controller/app/control.py

@@ -485,6 +485,7 @@ def compute(
     probe: bool = False,
     bound: tuple | None = None,
     gave_nothing: bool | None = None,
+    idle_w: float = 0.0,
 ) -> Decision:
     """One control cycle. A cycle is one meter update (~5 s on a HomeWizard P1).
 
@@ -502,6 +503,9 @@ def compute(
                under REFUSED_BELOW_W, one way, for SETTLE_CYCLES spanning
                REFUSED_SPAN_S. A refusal engages only with it. None leaves it
                out (compute() alone, as before).
+    `idle_w`   SAFETY-97: what `actual_w` reads while the batteries give
+               nothing (app/idle.py). The refusal's band and its end are
+               centred on it. 0 is the law as it was.
     """
     reason = "tracking"
     # OPT-11: a bound that leaves out 0 W would FORCE a direction, which no
@@ -828,12 +832,12 @@ def compute(
         # +800 W): at a 1 s meter its 12 cycles end as the reading passes 0.
         if (refused == 0 and frozen and sat_count >= SETTLE_CYCLES
                 and abs(prev_w) > tuning.saturation_w
-                and abs(actual_w) < REFUSED_BELOW_W
+                and abs(actual_w - idle_w) < REFUSED_BELOW_W
                 and gave_nothing is not False):
             refused = 1 if prev_w > 0 else -1
         if refused and refused * i_w < 0:
             refused = 0                          # the loop wants the other way
-        elif refused and refused * actual_w >= PROBE_ANSWER_W:
+        elif refused and refused * (actual_w - idle_w) >= PROBE_ANSWER_W:
             refused = 0                          # it delivers: a probe answered,
             #                                     or a slow reading arriving
         elif refused: