fix: ensure stringified args when emitting tool calls (CopilotKit#2571)

ranst91 · web-flow · commit a0155b03e66c · 2025-10-03T17:05:25.000+02:00
diff --git a/sdk-python/copilotkit/langgraph_agui_agent.py b/sdk-python/copilotkit/langgraph_agui_agent.py
@@ -1,3 +1,4 @@
+import json
 from typing import Dict, Any, List, Optional, Union, AsyncGenerator
 from enum import Enum
 from ag_ui_langgraph import LangGraphAgent
@@ -96,7 +97,8 @@ def _dispatch_event(self, event) -> str:
                     ToolCallArgsEvent(
                         type=EventType.TOOL_CALL_ARGS,
                         tool_call_id=custom_event.value["id"],
-                        delta=custom_event.value["args"],
+                        delta=custom_event.value["args"] if isinstance(custom_event.value["args"], str) else json.dumps(
+                            custom_event.value["args"]),
                         raw_event=event,
                     )
                 )

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,4 @@`
	`1`	`+import json`
`1`	`2`	`from typing import Dict, Any, List, Optional, Union, AsyncGenerator`
`2`	`3`	`from enum import Enum`
`3`	`4`	`from ag_ui_langgraph import LangGraphAgent`
`@@ -96,7 +97,8 @@ def _dispatch_event(self, event) -> str:`
`96`	`97`	`ToolCallArgsEvent(`
`97`	`98`	`type=EventType.TOOL_CALL_ARGS,`
`98`	`99`	`tool_call_id=custom_event.value["id"],`
`99`		`- delta=custom_event.value["args"],`
	`100`	`+ delta=custom_event.value["args"] if isinstance(custom_event.value["args"], str) else json.dumps(`
	`101`	`+ custom_event.value["args"]),`
`100`	`102`	`raw_event=event,`
`101`	`103`	`)`
`102`	`104`	`)`