SAFETY-73: a battery that refuses, per inverter, with two or more

SAFETY-52's hold applied per unit at N>1 (owner, 2026-09-27, option R).
A unit that gives < 100 W for 12 cycles in one direction while asked
> 200 W, or trips its stale-reading gate on a ~0 W reading, gets a
P_SAFETY `refused` unit limit closing that direction, so the allocator
hands its share to the others within their own limits. Probe: a +-200 W
pin every 15 min, one unit at a time, only while the site asks 200 W that
way. All units refusing: the site law holds 0 W. Exits reseed the site
target from the wire. INFO plus one WARNING (REFUSES_ABOVE_CUT_OUT) above
the configured cut-out; SAFETY-42/43 no longer report a refusing unit.
N=1 unchanged.

test_refusal_units.py: cases a/b/c on flat and jitter registers against
the old behaviour, probes, recovery, exits; mutations U1-U13 all red.
TEST-19 no-fault campaign: 0 engagements in 5280 runs.

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

goodwe_controller/app/inverter.py

@@ -317,6 +317,16 @@ class Inverter:
             tripped=bool(data.get(self.key("delivery_tripped"), False)),
             reason=str(data.get(self.key("delivery_reason"), "") or ""))
 
+        # SAFETY-73. The direction this unit's battery refuses (+1 give, -1
+        # take, 0 none), when that refusal or its last probe started, the
+        # current probe's start, and the cycles of evidence so far. Memory
+        # only, like SAFETY-52's: stop and start end it. Used at N>1 only.
+        self.refused = 0
+        self.refused_at = None
+        self.probe_from = None
+        self.ref_count = 0
+        self.ref_sign = 0
+
     # -- store ---------------------------------------------------------------
     def key(self, name: str) -> str:
         """This unit's namespaced Store key for `name`. See store.unit_key()."""
@@ -411,6 +421,13 @@ class Inverter:
         return (messages.row_battery_stuck(self.name) if self.batt_fresh.stale
                 else "")
 
+    def refusal_note(self) -> str:
+        """SAFETY-73's status row while this unit's battery refuses."""
+        if not self.refused:
+            return ""
+        return messages.row_battery_refuses(self.name, self.refused,
+                                            self.probe_from is not None)
+
     def link_note(self, now: datetime) -> str:
         """One line for the status page. Empty when there is nothing to say.