[bug] Agent.step_user_message → inner_step missing required first_input_messge arg

[nanxingw]

Severity: Medium — anyone calling Agent.step_user_message directly hits TypeError immediately. The production REST path is unaffected because it routes through server.send_messages → _step, not through step_user_message.

Where

mirix/agent/agent.py:2599 on origin/main.

Reproduction

agent = await server.load_agent(agent_id, actor=client)
await agent.step_user_message("hello")
# TypeError: Agent.inner_step() missing 1 required positional argument: 'first_input_messge'

Root cause

step_user_message calls:

return await self.inner_step(messages=[user_message], **kwargs)

but inner_step's signature requires first_input_messge as a positional argument (the typo is in the original):

async def inner_step(
    self,
    first_input_messge: Message,
    messages: Union[Message, List[Message]],
    ...
):

Suggested fix

One-line change at mirix/agent/agent.py:2599:

return await self.inner_step(first_input_messge=user_message, messages=[user_message], **kwargs)

Plus a behavioral test in tests/test_agent.py that mocks _get_ai_reply and calls step_user_message, asserting it returns an AgentStepResponse without raising.

Discovery

Surfaced during end-to-end validation of #126 (top-level session_id feature). That PR works around this bug by driving the agent through the production code path server.send_messages → _step (the same path used by REST → queue worker), so step_user_message is never called. This bug is therefore independent of #126 — just a pre-existing latent issue made visible during testing.

Codex review of #126 also flagged this as a medium-severity finding unrelated to that work.

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