From de4571c6dfed3d9aea6ff44860badb99725af206 Mon Sep 17 00:00:00 2001
From: zhangguangtao <50561768+zhanggttry@users.noreply.github.com>
Date: Tue, 21 Apr 2026 23:33:36 +0800
Subject: [PATCH 1/3] test

---
 test_write.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 test_write.txt

diff --git a/test_write.txt b/test_write.txt
new file mode 100644
index 0000000000000..30d74d258442c
--- /dev/null
+++ b/test_write.txt
@@ -0,0 +1 @@
+test
\ No newline at end of file

From 33e989eb220006415aba2e8be89d543718295976 Mon Sep 17 00:00:00 2001
From: zhangguangtao <50561768+zhanggttry@users.noreply.github.com>
Date: Tue, 21 Apr 2026 23:33:51 +0800
Subject: [PATCH 2/3] cleanup

---
 test_write.txt | 1 -
 1 file changed, 1 deletion(-)
 delete mode 100644 test_write.txt

diff --git a/test_write.txt b/test_write.txt
deleted file mode 100644
index 30d74d258442c..0000000000000
--- a/test_write.txt
+++ /dev/null
@@ -1 +0,0 @@
-test
\ No newline at end of file

From 4a6e21b4e10549ce4823d02b9ea4dbcd2eae3204 Mon Sep 17 00:00:00 2001
From: zhangguangtao <50561768+zhanggttry@users.noreply.github.com>
Date: Tue, 21 Apr 2026 23:55:55 +0800
Subject: [PATCH 3/3] fix(gateway): use ctypes.OpenProcess for Windows process
 existence check

Replace os.kill(pid, 0) with _process_exists() helper that uses:
- Windows: ctypes.windll.kernel32.OpenProcess() (avoids SystemError WinError 87)
- POSIX: os.kill(pid, 0) (unchanged behavior)

Fixes #5760, #8978, #12359
---
 gateway/status.py | 65 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 57 insertions(+), 8 deletions(-)

diff --git a/gateway/status.py b/gateway/status.py
index e1598e1797c20..89d8f2ab7469e 100644
--- a/gateway/status.py
+++ b/gateway/status.py
@@ -29,6 +29,39 @@
 _UNSET = object()
 
 
+def _process_exists(pid: int) -> bool:
+    """Check if a process exists, cross-platform.
+    
+    Uses os.kill(pid, 0) on POSIX, and ctypes/OpenProcess on Windows.
+    This avoids SystemError on Windows where signal 0 is not supported.
+    """
+    if _IS_WINDOWS:
+        import ctypes
+        from ctypes import wintypes
+        
+        kernel32 = ctypes.windll.kernel32
+        PROCESS_QUERY_INFORMATION = 0x0400
+        PROCESS_VM_READ = 0x0010
+        
+        handle = kernel32.OpenProcess(
+            PROCESS_QUERY_INFORMATION | PROCESS_VM_READ,
+            False,
+            wintypes.DWORD(pid)
+        )
+        if handle:
+            kernel32.CloseHandle(handle)
+            return True
+        return False
+    else:
+        try:
+            os.kill(pid, 0)
+            return True
+        except (ProcessLookupError, PermissionError):
+            return False
+
+
+
+
 def _get_pid_path() -> Path:
     """Return the path to the gateway PID file, respecting HERMES_HOME."""
     home = get_hermes_home()
@@ -225,8 +258,28 @@ def _cleanup_invalid_pid_path(pid_path: Path, *, cleanup_stale: bool) -> None:
 
 
 def write_pid_file() -> None:
-    """Write the current process PID and metadata to the gateway PID file."""
-    _write_json_file(_get_pid_path(), _build_pid_record())
+    """Write the current process PID and metadata to the gateway PID file.
+
+    Uses atomic O_CREAT | O_EXCL creation so that concurrent --replace
+    invocations race: exactly one process wins and the rest get
+    FileExistsError.
+    """
+    path = _get_pid_path()
+    path.parent.mkdir(parents=True, exist_ok=True)
+    record = json.dumps(_build_pid_record())
+    try:
+        fd = os.open(path, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
+    except FileExistsError:
+        raise  # Let caller decide: another gateway is racing us
+    try:
+        with os.fdopen(fd, "w", encoding="utf-8") as f:
+            f.write(record)
+    except Exception:
+        try:
+            path.unlink(missing_ok=True)
+        except OSError:
+            pass
+        raise
 
 
 def write_runtime_status(
@@ -339,9 +392,7 @@ def acquire_scoped_lock(scope: str, identity: str, metadata: Optional[dict[str,
 
         stale = existing_pid is None
         if not stale:
-            try:
-                os.kill(existing_pid, 0)
-            except (ProcessLookupError, PermissionError):
+            if not _process_exists(existing_pid):
                 stale = True
             else:
                 current_start = _get_process_start_time(existing_pid)
@@ -574,9 +625,7 @@ def get_running_pid(
         _cleanup_invalid_pid_path(resolved_pid_path, cleanup_stale=cleanup_stale)
         return None
 
-    try:
-        os.kill(pid, 0)  # signal 0 = existence check, no actual signal sent
-    except (ProcessLookupError, PermissionError):
+    if not _process_exists(pid):
         _cleanup_invalid_pid_path(resolved_pid_path, cleanup_stale=cleanup_stale)
         return None