AGUI401

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

Message: REASONING_MESSAGE_CONTENT for messageId '{messageId}' with no open REASONING_MESSAGE_START

Spec grounding

Multiple content events with the same messageId should be concatenated to form the complete visible reasoning.

Source: https://docs.ag-ui.com/concepts/events#reasoningmessagecontent

The spec is not fully explicit here; the ambiguity is tracked as SQ-4 and the severity is capped accordingly (false positives are worse than false negatives).

Example

A violating stream from the corpus (spec/fixtures/invalid/AGUI401-reasoning-content-without-start):

{"type":"RUN_STARTED","threadId":"thread_001","runId":"run_001","timestamp":1755300018400}
{"type":"REASONING_MESSAGE_CONTENT","messageId":"rmsg_ghost","delta":"orphan","timestamp":1755300018500}
{"type":"RUN_FINISHED","threadId":"thread_001","runId":"run_001","outcome":{"type":"success"},"timestamp":1755300018600}

Expected findings:

• error AGUI401 at event 1 — REASONING_MESSAGE_CONTENT for messageId 'rmsg_ghost' with no open REASONING_MESSAGE_START