fix: verify /proc/PID/cmdline in isRinging to prevent PID reuse false positives

tests/test_api.py

@@ -1,4 +1,4 @@
-from unittest.mock import patch
+from unittest.mock import patch, MagicMock
 from fastapi.testclient import TestClient
 import tempfile
 import os
@@ -15,6 +15,33 @@ from api.main import app  # noqa: E402
 client = TestClient(app)
 
 
+def test_is_ringing_false_on_pid_reuse():
+    """isRinging returns False when the PID file points to a non-wecker process."""
+    from api.schema import is_wecker_ringing
+
+    fake_pid = 9999
+    with patch("api.schema.PID_FILE", "/tmp/fake_reuse.pid"), \
+         patch("api.schema.os.path.exists", return_value=True), \
+         patch("api.schema.os.kill") as mock_kill, \
+         patch("builtins.open") as mock_open:
+        mock_kill.return_value = None
+
+        pid_file_mock = MagicMock()
+        pid_file_mock.read.return_value = str(fake_pid)
+        cmdline_mock = MagicMock()
+        cmdline_mock.read.return_value = b"systemd-journald"
+
+        def open_side_effect(path, *args, **kwargs):
+            if str(path).endswith("fake_reuse.pid"):
+                return pid_file_mock
+            if str(path) == f"/proc/{fake_pid}/cmdline":
+                return cmdline_mock
+            raise FileNotFoundError(path)
+
+        mock_open.side_effect = open_side_effect
+        assert is_wecker_ringing() is False
+
+
 def test_is_ringing_returns_false_when_not_running():
     """Test that isRinging returns False when no wecker process is running."""
     headers = {"X-API-Key": "test-secret"}