Python: AG-UI workflow path silently drops function_approval_response from messages #4546

Summary

The AG-UI workflow path emits function_approval_request events to the client (via _emit_content → _emit_approval_request), but if the client responds with function_approvals in messages rather than through the resume payload, those responses are silently dropped.

Root Cause

In _workflow_run.py, _extract_responses_from_messages (line ~126-135) only processes function_result content:

if content.type != "function_result" or not content.call_id:
    continue

This skips function_approval_response content entirely. Meanwhile, the message adapter (_message_adapters.py) converts incoming function_approvals arrays into function_approval_response Content objects, which then go unprocessed.

Impact

• Functional: A valid approval response sent via function_approvals is silently lost. The workflow never receives it.
• Not a security issue: No unauthorized tool execution occurs — the response is dropped, not executed. The workflow engine's AgentExecutor._extract_function_responses also validates against self.pending_requests at a deeper level.

How it works today

The resume payload path (_resume_to_workflow_responses) is the primary mechanism CopilotKit uses to send responses back, and it works correctly. The gap only manifests if a client sends approval responses via the function_approvals message field instead.

Suggested fix

Either:

1. Extend _extract_responses_from_messages to also process function_approval_response content and map them to workflow responses
2. Or document that workflow approval responses must use the resume mechanism, not function_approvals

Option 1 would make the workflow path consistent with how the agent path handles approval responses, reducing client-side confusion about which mechanism to use.