- Add _EVENT_TYPE_TO_METHOD class-level mapping (ClassVar[dict[str, str]]) to
convert A2A event types to JSON-RPC 2.0 method names:
TaskStatusUpdateEvent → task/statusUpdate
TaskArtifactUpdateEvent → task/artifactUpdate
- Refactor SseEventFormatter.format() to produce JSON-RPC 2.0 notification
envelope: {"jsonrpc": "2.0", "method": "...", "params": {...}}
- Move event data fields into params object; include taskId (from plan_id)
in params when plan_id is present, per spec §Streaming Architecture
- Remove non-spec fields (event_id, event_type, timestamp, plan_id) from
the data payload; these remain in SSE envelope headers (event: and id:)
- Update BDD feature to verify JSON-RPC 2.0 structure for both event types,
events with/without plan_id, custom data in params, and exclusion of
non-spec fields
- Fix pre-existing type errors in step definitions: replace try/except
ImportError pattern with direct imports and use behave.runner.Context
for proper static typing (0 pyright errors)
ISSUES CLOSED: #1502
Add Server-Sent Events (SSE) streaming infrastructure to the A2A
event system, enabling real-time delivery of task status updates
and artifact notifications.
Key changes:
- Defined SSE event type constants: TASK_STATUS_UPDATE
(TaskStatusUpdateEvent) and TASK_ARTIFACT_UPDATE
(TaskArtifactUpdateEvent) per the A2A protocol specification.
- Added SseEventFormatter class that converts A2aEvent instances
to text/event-stream format with event, id, and data fields.
Includes keepalive formatting for long-lived connections.
- Added EventBusBridge class that subscribes to the internal
EventBus (ReactiveEventBus) and translates DomainEvent instances
into A2aEvent instances published to the A2aEventQueue. Maps
plan lifecycle events (PLAN_CREATED, PLAN_PHASE_CHANGED, etc.)
to TaskStatusUpdateEvent and checkpoint events to
TaskArtifactUpdateEvent.
- Bridge handles closed queue gracefully via contextlib.suppress.
- Added 8 Behave scenarios covering SSE formatting, event type
constants, EventBusBridge translation for both status and
artifact events, closed queue handling, and JSON payload
validation.
ISSUES CLOSED: #875
freemo