fix(runtime): scope Windows process termination

nanobot/process_runtime.py

@@ -308,26 +308,18 @@ class ManagedProcessRuntime(Generic[_StartOptionsT]):
         return self._wait_for_exit(pid, 2)
 
     def _terminate_windows(self, pid: int, *, timeout_s: int) -> bool:
-        ctrl_break = getattr(signal, "CTRL_BREAK_EVENT", None)
-        if ctrl_break is not None:
-            ctrl_break_sent = False
-            try:
-                os.kill(pid, ctrl_break)
-            except ProcessLookupError:
-                return True
-            except OSError:
-                pass
-            else:
-                ctrl_break_sent = True
-            if ctrl_break_sent and self._wait_for_exit(pid, timeout_s):
-                return True
+        # ``os.kill(pid, CTRL_BREAK_EVENT)`` delegates to
+        # GenerateConsoleCtrlEvent.  That API targets a console process group,
+        # not an individual process, and can interrupt the caller when a
+        # detached/no-window child has no addressable console group.  Keep
+        # termination scoped to the recorded PID tree instead.
         self._subprocess_run(
             ["taskkill", "/PID", str(pid), "/T"],
             check=False,
             stdout=subprocess.DEVNULL,
             stderr=subprocess.DEVNULL,
         )
-        if self._wait_for_exit(pid, 2):
+        if self._wait_for_exit(pid, timeout_s):
             return True
         self._subprocess_run(
             ["taskkill", "/PID", str(pid), "/T", "/F"],

tests/gateway/test_runtime.py

@@ -564,7 +564,7 @@ def test_stop_succeeds_when_process_exits_at_timeout_boundary(tmp_path, monkeypa
     assert result.status.running is False
 
 
-def test_terminate_windows_falls_back_when_ctrl_break_is_rejected(tmp_path, monkeypatch):
+def test_terminate_windows_targets_only_the_recorded_process_tree(tmp_path, monkeypatch):
     taskkill_calls: list[dict] = []
     wait_timeouts: list[int | float] = []
 
@@ -578,12 +578,10 @@ def test_terminate_windows_falls_back_when_ctrl_break_is_rejected(tmp_path, monk
         sleep=lambda _seconds: None,
     )
 
-    monkeypatch.setattr(signal, "CTRL_BREAK_EVENT", 1, raising=False)
-
-    def fake_kill(_pid, _signal):
-        raise OSError(87, "The parameter is incorrect")
-
-    monkeypatch.setattr("nanobot.process_runtime.os.kill", fake_kill)
+    monkeypatch.setattr(
+        "nanobot.process_runtime.os.kill",
+        lambda *_args: pytest.fail("Windows termination must not broadcast a console event"),
+    )
 
     def fake_wait_for_exit(_pid, _timeout_s):
         wait_timeouts.append(_timeout_s)
@@ -593,7 +591,7 @@ def test_terminate_windows_falls_back_when_ctrl_break_is_rejected(tmp_path, monk
     monkeypatch.setattr(runtime, "_wait_for_exit", fake_wait_for_exit)
 
     assert runtime._terminate_windows(12345, timeout_s=20) is True
-    assert wait_timeouts == [2]
+    assert wait_timeouts == [20]
     assert taskkill_calls == [
         {
             "command": ["taskkill", "/PID", "12345", "/T"],