fix: use thread local isolation the context (#31410)

api/tests/unit_tests/core/workflow/context/test_execution_context.py

@@ -1,6 +1,8 @@
 """Tests for execution context module."""
 
 import contextvars
+import threading
+from contextlib import contextmanager
 from typing import Any
 from unittest.mock import MagicMock
 
@@ -149,6 +151,54 @@ class TestExecutionContext:
 
         assert ctx.user == user
 
+    def test_thread_safe_context_manager(self):
+        """Test shared ExecutionContext works across threads without token mismatch."""
+        test_var = contextvars.ContextVar("thread_safe_test_var")
+
+        class TrackingAppContext(AppContext):
+            def get_config(self, key: str, default: Any = None) -> Any:
+                return default
+
+            def get_extension(self, name: str) -> Any:
+                return None
+
+            @contextmanager
+            def enter(self):
+                token = test_var.set(threading.get_ident())
+                try:
+                    yield
+                finally:
+                    test_var.reset(token)
+
+        ctx = ExecutionContext(app_context=TrackingAppContext())
+        errors: list[Exception] = []
+        barrier = threading.Barrier(2)
+
+        def worker():
+            try:
+                for _ in range(20):
+                    with ctx:
+                        try:
+                            barrier.wait()
+                            barrier.wait()
+                        except threading.BrokenBarrierError:
+                            return
+            except Exception as exc:
+                errors.append(exc)
+                try:
+                    barrier.abort()
+                except Exception:
+                    pass
+
+        t1 = threading.Thread(target=worker)
+        t2 = threading.Thread(target=worker)
+        t1.start()
+        t2.start()
+        t1.join(timeout=5)
+        t2.join(timeout=5)
+
+        assert not errors
+
 
 class TestIExecutionContextProtocol:
     """Test IExecutionContext protocol."""