Documentation Index
Fetch the complete documentation index at: https://docs.aion.to/llms.txt
Use this file to discover all available pages before exploring further.
This page lists all A2A events that Aion Server emits to clients during ADK agent execution,
organized by event category.
Streaming
STREAM_DELTA is a transitory artifact — it is not persisted to the Task’s durable state.
The client uses it for live display only.
| ADK Event | Client Receives |
|---|
| Partial event with content | TaskArtifactUpdateEvent(STREAM_DELTA, append=..., last_chunk=false) |
| Non-partial event with content | TaskArtifactUpdateEvent(STREAM_DELTA, last_chunk=true) + TaskStatusUpdateEvent(working, message=...) |
| Non-partial event without content | TaskArtifactUpdateEvent(STREAM_DELTA, last_chunk=true) |
STREAM_DELTA close events are only emitted if at least one partial event was sent beforehand.
Artifacts
| ADK Event | Client Receives |
|---|
artifact_delta entry in event actions | TaskArtifactUpdateEvent per artifact |
Outbox
a2a_outbox value | Client Receives |
|---|
Message | TaskStatusUpdateEvent(working, message=...) |
Task patch with metadata | TaskStatusUpdateEvent(working) (for metadata) |
Task patch with history messages | N × TaskStatusUpdateEvent(working, message=...) |
Task patch with artifacts | M × TaskArtifactUpdateEvent |
Terminal
Every execution ends with exactly one terminal event.
| Outcome | Client Receives |
|---|
| Agent finishes, no outbox, delta text present | TaskStatusUpdateEvent(working, delta text) + TaskStatusUpdateEvent(completed) |
| Agent finishes, no outbox, no delta text | TaskStatusUpdateEvent(completed) |
Agent finishes with a2a_outbox | (outbox events) + TaskStatusUpdateEvent(completed) |
| Unhandled exception | TaskStatusUpdateEvent(failed) |
