Python: fix(ag-ui): properly handle json serialize with handoff workflows as agent (#3275)

* fix(ag-ui): properly handle json serialize with handoff workflows as agent

* Other improvements around handling non-serializable objects

python/packages/ag-ui/agent_framework_ag_ui/_events.py

@@ -29,7 +29,7 @@ from agent_framework import (
     prepare_function_call_results,
 )
 
-from ._utils import extract_state_from_tool_args, generate_event_id, safe_json_parse
+from ._utils import extract_state_from_tool_args, generate_event_id, make_json_safe, safe_json_parse
 
 logger = logging.getLogger(__name__)
 
@@ -177,7 +177,11 @@ class AgentFrameworkEventBridge:
             self.current_tool_call_id = tool_call_id
 
         if content.arguments:
-            delta_str = content.arguments if isinstance(content.arguments, str) else json.dumps(content.arguments)
+            delta_str = (
+                content.arguments
+                if isinstance(content.arguments, str)
+                else json.dumps(make_json_safe(content.arguments))
+            )
             logger.info(f"Emitting ToolCallArgsEvent with delta_length={len(delta_str)}, id='{tool_call_id}'")
             args_event = ToolCallArgsEvent(
                 tool_call_id=tool_call_id,
@@ -391,7 +395,7 @@ class AgentFrameworkEventBridge:
             args_dict = {
                 "function_name": function_call.name,
                 "function_call_id": function_call.call_id,
-                "function_arguments": function_call.parse_arguments() or {},
+                "function_arguments": make_json_safe(function_call.parse_arguments() or {}),
                 "steps": [
                     {
                         "description": f"Execute {function_call.name}",
@@ -435,7 +439,7 @@ class AgentFrameworkEventBridge:
         args_dict = {
             "function_name": function_call.name,
             "function_call_id": function_call.call_id,
-            "function_arguments": function_call.parse_arguments() or {},
+            "function_arguments": make_json_safe(function_call.parse_arguments() or {}),
             "steps": [
                 {
                     "description": f"Execute {function_call.name}",

python/packages/ag-ui/agent_framework_ag_ui/_message_adapters.py

@@ -17,6 +17,7 @@ from ._utils import (
     AGUI_TO_FRAMEWORK_ROLE,
     FRAMEWORK_TO_AGUI_ROLE,
     get_role_value,
+    make_json_safe,
     normalize_agui_role,
     safe_json_parse,
 )
@@ -265,7 +266,7 @@ def agui_messages_to_agent_framework(messages: list[dict[str, Any]]) -> list[Cha
                 function_payload_dict = cast(dict[str, Any], function_payload)
                 existing_args = function_payload_dict.get("arguments")
                 if isinstance(existing_args, str):
-                    function_payload_dict["arguments"] = json.dumps(modified_args)
+                    function_payload_dict["arguments"] = json.dumps(make_json_safe(modified_args))
                 else:
                     function_payload_dict["arguments"] = modified_args
                 return
@@ -377,7 +378,9 @@ def agui_messages_to_agent_framework(messages: list[dict[str, Any]]) -> list[Cha
                 # a proper FunctionApprovalResponseContent. This enables the agent framework
                 # to execute the approved tool (fix for GitHub issue #3034).
                 accepted = parsed.get("accepted", False) if parsed is not None else False
-                approval_payload_text = result_content if isinstance(result_content, str) else json.dumps(parsed)
+                approval_payload_text = (
+                    result_content if isinstance(result_content, str) else json.dumps(make_json_safe(parsed))
+                )
 
                 # Log the full approval payload to debug modified arguments
                 import logging
@@ -454,7 +457,9 @@ def agui_messages_to_agent_framework(messages: list[dict[str, Any]]) -> list[Cha
 
                         # Keep the original tool call and AG-UI snapshot in sync with approved args.
                         updated_args = (
-                            json.dumps(merged_args) if isinstance(matching_func_call.arguments, str) else merged_args
+                            json.dumps(make_json_safe(merged_args))
+                            if isinstance(matching_func_call.arguments, str)
+                            else merged_args
                         )
                         matching_func_call.arguments = updated_args
                         _update_tool_call_arguments(messages, str(approval_call_id), merged_args)
@@ -462,7 +467,7 @@ def agui_messages_to_agent_framework(messages: list[dict[str, Any]]) -> list[Cha
                         func_call_for_approval = Content.from_function_call(
                             call_id=matching_func_call.call_id,  # type: ignore[arg-type]
                             name=matching_func_call.name,  # type: ignore[arg-type]
-                            arguments=json.dumps(filtered_args),
+                            arguments=json.dumps(make_json_safe(filtered_args)),
                         )
                         logger.info(f"Using modified arguments from approval: {filtered_args}")
                     else:
@@ -767,7 +772,7 @@ def agui_messages_to_snapshot_format(messages: list[dict[str, Any]]) -> list[dic
                 if arguments is None:
                     function_payload_dict["arguments"] = ""
                 elif not isinstance(arguments, str):
-                    function_payload_dict["arguments"] = json.dumps(arguments)
+                    function_payload_dict["arguments"] = json.dumps(make_json_safe(arguments))
 
         # Normalize tool_call_id to toolCallId for tool messages
         normalized_msg["role"] = normalize_agui_role(normalized_msg.get("role"))

python/packages/ag-ui/agent_framework_ag_ui/_orchestration/_helpers.py

@@ -12,7 +12,7 @@ from agent_framework import (
     Content,
 )
 
-from .._utils import get_role_value, safe_json_parse
+from .._utils import get_role_value, make_json_safe, safe_json_parse
 
 if TYPE_CHECKING:
     from .._events import AgentFrameworkEventBridge
@@ -252,7 +252,7 @@ def build_safe_metadata(thread_metadata: dict[str, Any] | None) -> dict[str, Any
         return {}
     safe_metadata: dict[str, Any] = {}
     for key, value in thread_metadata.items():
-        value_str = value if isinstance(value, str) else json.dumps(value)
+        value_str = value if isinstance(value, str) else json.dumps(make_json_safe(value))
         if len(value_str) > 512:
             value_str = value_str[:512]
         safe_metadata[key] = value_str

python/packages/ag-ui/agent_framework_ag_ui/_orchestration/_state_manager.py

@@ -8,6 +8,8 @@ from typing import Any
 from ag_ui.core import CustomEvent, EventType
 from agent_framework import ChatMessage, Content
 
+from .._utils import make_json_safe
+
 
 class StateManager:
     """Coordinates state defaults, snapshots, and structured updates."""
@@ -67,7 +69,7 @@ class StateManager:
         if conversation_has_tool_calls and not self._state_from_input:
             return None
 
-        state_json = json.dumps(self.current_state, indent=2)
+        state_json = json.dumps(make_json_safe(self.current_state), indent=2)
         return ChatMessage(
             role="system",
             contents=[

python/packages/ag-ui/agent_framework_ag_ui/_orchestrators.py

@@ -243,7 +243,7 @@ class HumanInTheLoopOrchestrator(Orchestrator):
         if not msg:
             return False
 
-        return bool(msg.additional_properties.get("is_tool_result", False))
+        return bool((msg.additional_properties or {}).get("is_tool_result", False))
 
     async def run(
         self,
@@ -388,7 +388,7 @@ class DefaultOrchestrator(Orchestrator):
 
         response_format = None
         if isinstance(context.agent, ChatAgent):
-            response_format = context.agent.default_options.get("response_format")
+            response_format = (context.agent.default_options or {}).get("response_format")
         skip_text_content = response_format is not None
 
         client_tools = convert_agui_tools_to_agent_framework(context.input_data.get("tools"))

python/packages/ag-ui/agent_framework_ag_ui/_utils.py

@@ -141,11 +141,14 @@ def make_json_safe(obj: Any) -> Any:  # noqa: ANN401
     if isinstance(obj, (datetime, date)):
         return obj.isoformat()
     if is_dataclass(obj):
-        return asdict(obj)  # type: ignore[arg-type]
+        # asdict may return nested non-dataclass objects, so recursively make them safe
+        return make_json_safe(asdict(obj))  # type: ignore[arg-type]
     if hasattr(obj, "model_dump"):
-        return obj.model_dump()  # type: ignore[no-any-return]
+        return make_json_safe(obj.model_dump())  # type: ignore[no-any-return]
+    if hasattr(obj, "to_dict"):
+        return make_json_safe(obj.to_dict())  # type: ignore[no-any-return]
     if hasattr(obj, "dict"):
-        return obj.dict()  # type: ignore[no-any-return]
+        return make_json_safe(obj.dict())  # type: ignore[no-any-return]
     if hasattr(obj, "__dict__"):
         return {key: make_json_safe(value) for key, value in vars(obj).items()}  # type: ignore[misc]
     if isinstance(obj, (list, tuple)):