[Bug]: Open Responses API: server-tool results (e.g. `execute_code` stdout) are never emitted or persisted as `function_call_output`

[vaibhav-Singh9888]

What happened?

When an agent runs a server-side tool (e.g. execute_code) through POST /api/agents/v1/responses, the tool's result is never emitted on the stream or persisted. The response output contains the function_call item (with arguments) but no matching function_call_output item, so an API consumer sees the call but not its output. (/chat/completions and normal chat surface the result fine.)

Expected
A function_call_output item carrying the tool's textual result, per the Open Responses spec.

Likely cause (code inspection)
The Responses tool-end callback (createResponsesToolEndCallback, api/server/controllers/agents/callbacks.js) early-returns when there's no output.artifact and never emits the tool's text result (output.content) via emitFunctionCallOutputItem. responses.js wires on_tool_end to that artifact-only handler; the on_tool_end in packages/api/src/agents/responses/service.ts that does call emitFunctionCallOutputItem is never wired into the Responses graph.

Version Information

current main (v0.8.8-rc4)

Steps to Reproduce

1. Configure an agent with execute_code enabled.
2. POST /api/agents/v1/responses {"model":"agent_xxx","input":"run python that prints 2+2","stream":false}.
3. Inspect response.output: there is a function_call item but no corresponding function_call_output.

What browsers are you seeing the problem on?

No response

Relevant log output

NA

Screenshots

No response

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