AGUI604

Severity: error · Group: Subagents · Checked in: core · Since: 0.x

Message: SUBAGENT_STARTED subagentRunId '{subagentRunId}' never closed with SUBAGENT_FINISHED or SUBAGENT_ERROR

Spec grounding

Every started subagent is closed before RunFinished.

Source: https://docs.ag-ui.com/concepts/subagents#rules-clients-enforce

Example

A violating stream from the corpus (spec/fixtures/invalid/AGUI604-subagent-unterminated):

{"type":"RUN_STARTED","threadId":"thread_001","runId":"run_001","timestamp":1755300020100}
{"type":"SUBAGENT_STARTED","subagentRunId":"sub_001","name":"researcher","timestamp":1755300020200}
{"type":"RUN_FINISHED","threadId":"thread_001","runId":"run_001","outcome":{"type":"success"},"timestamp":1755300020300}

Expected findings:

• error AGUI604 at event 2 — SUBAGENT_STARTED subagentRunId 'sub_001' never closed with SUBAGENT_FINISHED or SUBAGENT_ERROR