Make run_callback compatible with 4.2.0 changes

Author: KoolADE85

dash/mcp/primitives/tools/callback_utils.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+from contextvars import copy_context
 from typing import TYPE_CHECKING, Any
 
 from dash import get_app
@@ -16,23 +17,25 @@
 def run_callback(
     callback: CallbackAdapter, kwargs: dict[str, Any]
 ) -> CallbackExecutionResponse:
-    """Execute a callback via the framework."""
-    body = callback.as_callback_body(kwargs)
+    """Execute a callback via the framework.
 
+    Must be called from inside an active request handler; the backend's
+    request adapter reads cookies/headers/args from the current request.
+    """
+    body = callback.as_callback_body(kwargs)
     app = get_app()
-    with app.server.test_request_context(
-        "/_dash-update-component",
-        method="POST",
-        data=json.dumps(body, default=str),
-        content_type="application/json",
-    ):
-        response = app.dispatch()
-
-    response_text = response.get_data(as_text=True)
-    if response.status_code != 200:
+
+    try:
+        # pylint: disable=protected-access
+        cb_ctx = app._initialize_context(body)
+        func = app._prepare_callback(cb_ctx, body)
+        args = app._inputs_to_vals(cb_ctx.inputs_list + cb_ctx.states_list)
+        ctx = copy_context()
+        partial_func = app._execute_callback(func, args, cb_ctx.outputs_list, cb_ctx)
+        response_text = ctx.run(partial_func)
+    except Exception as err:
         raise CallbackExecutionError(
-            f"Callback {callback.output_id} failed "
-            f"(HTTP {response.status_code}): {response_text[:500]}"
-        )
+            f"Callback {callback.output_id} failed: {err}"
+        ) from err
 
     return json.loads(response_text)