fix: pin sys.platform=linux in test_is_pid_alive_dead — Windows runners take the OpenProcess path so the os.kill mock never fires; test reds whenever PID 1234 is alive on the runner (first hit today, 6/6 sibling tests were already pinned by ca096295). 38 presence tests green.

CHANGELOG.md

@@ -30,6 +30,15 @@ PyPI version — not the changelog header.
   (9.3k → 7.9k chars, under its ~8k injection cap) with the comms doctrine
   intact.
 
+- **Windows flake pinned: `test_is_pid_alive_dead` escaped the ca096295
+  sweep.** That commit's rule — tests mocking `os.kill` must pin
+  `sys.platform="linux"` because Windows takes the ctypes OpenProcess path and
+  never reaches the mock — was applied to every pid-liveness test except this
+  one. It only failed when PID 1234 happened to be alive on the runner
+  (environment lottery, first hit today). Pinned like its siblings. The
+  remaining Windows session_boot reds and the relay mtime-cache flake predate
+  this PR and stay parked.
+
 ## [2026-07-14]
 
 ### Fixed

src/aipass/hooks/tests/test_presence.py

@@ -431,7 +431,7 @@ class TestLiveness:
             mock_kill.assert_called_once_with(1234, 0)
 
     def test_is_pid_alive_dead(self):
-        with patch("os.kill", side_effect=ProcessLookupError):
+        with patch("sys.platform", "linux"), patch("os.kill", side_effect=ProcessLookupError):
             assert presence._is_pid_alive(1234) is False
 
     def test_is_pid_alive_permission_error(self):