a2a-Market UCP Broadcast

Define the transport and protocol shell for intent broadcast in UCP.

Current status: framework release for registration. Prioritize interoperability contracts over optimization.

Scope

• Build intent payload schema and canonical signing routine.
• Broadcast to eligible nodes and track delivery acknowledgements.
• Feed response stream into quote intake service.

Suggested Project Layout

• app/protocol/ucp/intent_message.py
• app/protocol/ucp/signer.py
• app/application/services/broadcast_service.py
• app/infrastructure/ws/ucp_gateway.py

Minimum Contracts (MVP P0)

1. build_intent(payload) normalizes and version-tags message.
2. sign_intent(intent, private_key) returns detached signature object.
3. broadcast(intent_id, target_nodes) returns dispatch receipt ids.
4. collect_acks(intent_id, timeout_ms) returns per-node ack status.

Event Mapping

• Emit INTENT_CREATED before dispatch.
• Emit INTENT_BROADCASTED after fan-out completes.
• Emit NODE_RESPONDED when quote/ack arrives.

Guardrails

• Keep canonical JSON serialization deterministic for signing.
• Record per-node retry counters and stop after configured threshold.
• Attach protocol version in every envelope.

Implementation Backlog

• Add adaptive node selection based on reputation percentile.
• Add dead-letter handling for nodes with repeated timeouts.

Runtime Implementation

• Status: implemented in local runtime package.
• Primary code paths:
• runtime/src/protocol/ucp-client.js
• runtime/src/application/market-agent.js
• Validation: covered by runtime/tests and npm test in runtime/.