ControlMode(core,test): Preflight attach_to and harden restart/capture tests

Author: tony

tests/test_control_mode_engine.py

@@ -242,6 +242,16 @@ def flush(self) -> None:  # pragma: no cover - not reached
     class FakeProcess:
         def __init__(self) -> None:
             self.stdin = FakeStdin()
+            self._terminated = False
+
+        def terminate(self) -> None:
+            self._terminated = True
+
+        def kill(self) -> None:  # pragma: no cover - simple stub
+            self._terminated = True
+
+        def wait(self, timeout: float | None = None) -> None:
+            return None
 
     engine = ControlModeEngine()
     engine.process = FakeProcess()  # type: ignore[assignment]