AGUI603

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

Message: SUBAGENT_ERROR for subagentRunId '{subagentRunId}' with no open SUBAGENT_STARTED

Spec grounding

SubagentFinished and SubagentError name a subagent that is currently active

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

Example

A violating stream from the corpus (spec/fixtures/invalid/AGUI603-error-without-start):

{"type":"RUN_STARTED","threadId":"thread_001","runId":"run_001","timestamp":1755300019800}
{"type":"SUBAGENT_ERROR","subagentRunId":"sub_ghost","message":"boom","timestamp":1755300019900}
{"type":"RUN_FINISHED","threadId":"thread_001","runId":"run_001","outcome":{"type":"success"},"timestamp":1755300020000}

Expected findings:

• error AGUI603 at event 1 — SUBAGENT_ERROR for subagentRunId 'sub_ghost' with no open SUBAGENT_STARTED