feat: settle mobile observations before summarizing steps

tests/unit/agents/flash/test_turn_index_snapshot.py

@@ -60,20 +60,21 @@ REFRESHED = [_el(1, "Back", 100, 100), _el(2, "Wi-Fi toggle", 900, 300)]
 
 
 class _FakeSession:
-    """An action session whose observations replay a scripted list sequence."""
+    """An action session whose screen advances after each device action."""
 
     started = True
 
     def __init__(self, observations: list[list[dict]]):
         self.calls: list[tuple[str, dict]] = []
-        self._observations = list(observations)
+        self._observations = observations
 
     async def call(self, name, args):
         self.calls.append((name, dict(args)))
         return ActionResult.success(name, f"{name} dispatched")
 
     async def observe(self, settle_ms=0):
-        elements = self._observations.pop(0) if self._observations else []
+        index = min(len(self.calls) - 1, len(self._observations) - 1)
+        elements = self._observations[index] if self._observations else []
         return ObserveResult(
             ok=True,
             elements_text="\n".join(f"[{e['index']}] {e['text']}" for e in elements),