From 26254240249f037fb38344aaf066db4a9a4256af Mon Sep 17 00:00:00 2001
From: xiaodu55 <1704788159@qq.com>
Date: Fri, 2 Oct 2026 22:45:26 +0800
Subject: [PATCH] test(studio): stop the dev server gracefully so its
 persistence flush lands on Windows (#6197)

terminate() is TerminateProcess on Windows: langgraph dev never runs its
shutdown hooks, so .langgraph_ops.pckl is never flushed and state does not
survive the restart the two cross-restart tests exercise. Create the child
with CREATE_NEW_PROCESS_GROUP and stop it via CTRL_BREAK_EVENT (handled by
uvicorn as SIGBREAK) on Windows, keeping terminate() on POSIX and a hard
kill as the timeout fallback.

Fixes #6196

Co-authored-by: xiaodu55 <xiaodu55@users.noreply.github.com>
---
 backend/tests/test_langgraph_studio_routes.py | 36 ++++++++++++-------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/backend/tests/test_langgraph_studio_routes.py b/backend/tests/test_langgraph_studio_routes.py
index 11634149d0..8cf2c793a0 100644
--- a/backend/tests/test_langgraph_studio_routes.py
+++ b/backend/tests/test_langgraph_studio_routes.py
@@ -5,6 +5,7 @@ from __future__ import annotations
 import json
 import os
 import shutil
+import signal
 import socket
 import subprocess
 import sys
@@ -173,6 +174,26 @@ def _run_stateless_scope(client: httpx.Client, run_id: str) -> str:
     return messages[-1]["content"][0]["text"]
 
 
+def _stop_studio_process(process: subprocess.Popen) -> None:
+    """Stop the dev server the way its persistence layer survives.
+
+    ``terminate()`` is TerminateProcess on Windows: the dev server never runs
+    its shutdown hooks, so the dev persistence flush never lands and state
+    does not survive the restart under test. uvicorn handles SIGBREAK,
+    delivered via CTRL_BREAK_EVENT to the child's process group; fall back to
+    a hard kill when the graceful stop does not finish in time.
+    """
+    if os.name == "nt":
+        process.send_signal(signal.CTRL_BREAK_EVENT)
+    else:
+        process.terminate()
+    try:
+        process.wait(timeout=10)
+    except subprocess.TimeoutExpired:
+        process.kill()
+        process.wait(timeout=10)
+
+
 @contextmanager
 def _running_studio_server(
     runtime_dir: Path,
@@ -231,6 +252,7 @@ def _running_studio_server(
             stdout=log_file,
             stderr=subprocess.STDOUT,
             text=True,
+            creationflags=subprocess.CREATE_NEW_PROCESS_GROUP if os.name == "nt" else 0,
         )
 
         base_url = f"http://127.0.0.1:{port}"
@@ -249,12 +271,7 @@ def _running_studio_server(
                 last_error = exc
             time.sleep(0.1)
         else:
-            process.terminate()
-            try:
-                process.wait(timeout=10)
-            except subprocess.TimeoutExpired:
-                process.kill()
-                process.wait(timeout=10)
+            _stop_studio_process(process)
             pytest.fail(f"LangGraph dev server failed to start ({last_error!r}).\n{log_path.read_text(encoding='utf-8')}")
 
         client = httpx.Client(
@@ -267,12 +284,7 @@ def _running_studio_server(
             yield client
         finally:
             client.close()
-            process.terminate()
-            try:
-                process.wait(timeout=10)
-            except subprocess.TimeoutExpired:
-                process.kill()
-                process.wait(timeout=10)
+            _stop_studio_process(process)
 
 
 @pytest.fixture(scope="module")