OPT-15 review: bound unmeasured charge stops, test the hold's rules and M15

- A second unmeasured-headroom stop in a quarter latches the charge: a
  headroom missing every other cycle flipped it 1799 times in 30 min.
- Unit test of the run-edge hold's end conditions and of a small step.
- Outside its probe a refuser does not make the others rest (M15 red).
- DECISIONS: one review line.

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

goodwe_controller/app/main.py

@@ -944,6 +944,7 @@ class Controller:
         self._run_done = {}
         self._mode_trade_was = False
         self._charge_blocked_q = None
+        self._charge_gap_q = None       # OPT-15: an unmeasured stop's quarter
         self._ref_cheap = None
         # OPT-15: a run edge the loop holds at E: (E, step sign, until, the
         # last battery reading).
@@ -2174,13 +2175,17 @@ class Controller:
             blocked=self._charge_blocked_q == quarter,
             done_charge=done_c, done_sell=done_s)
         # A charge the guard or the headroom stopped stays off this period.
-        # OPT-15: only a MEASURED stop latches; an unmeasured headroom (None)
-        # stops this tick only, so a gap cannot cost the whole quarter.
-        if was and self.mode_tick.action != modetrade.CHARGE and (
-                self.mode_tick.why == "peak"
-                or (self.mode_tick.why == "headroom"
-                    and self.arb_headroom_w is not None)):
-            self._charge_blocked_q = quarter
+        # OPT-15: only a MEASURED stop latches; the first unmeasured headroom
+        # (None) in a quarter stops this tick only, so a gap cannot cost the
+        # whole quarter. A second one latches, so gaps cannot flip the charge.
+        if was and self.mode_tick.action != modetrade.CHARGE:
+            why = self.mode_tick.why
+            gap = why == "headroom" and self.arb_headroom_w is None
+            if why == "peak" or (why == "headroom" and not gap) or (
+                    gap and self._charge_gap_q == quarter):
+                self._charge_blocked_q = quarter
+            elif gap:
+                self._charge_gap_q = quarter
         return self.mode_tick
 
     def _run_mark(self, kind, run, packs, out) -> set: