Crate klieo_a2a 

Durable A2A v1.0 protocol layer for klieo agents.

Implements the Agent-to-Agent (A2A) v1.0 specification wire types, JSON-RPC envelope, and a server-side dispatcher atop klieo_core::Pubsub + klieo_core::KvStore.

Why durable A2A?

Today A2A runs over HTTP/JSON-RPC + WebSocket. Klieo’s angle: implement the same wire shape over NATS JetStream + KV + JobQueue. Inter-agent calls inherit the durability, leasing, dedup, and DLQ semantics of klieo_core::JobQueue — A2A but work-doesn’t-get-stuck.

Wire-compatible at the JSON-RPC envelope level: a payload produced by adk-python deserialises into our SendMessageParams cleanly. Only the transport differs.

Architecture asymmetry

server::A2aServer takes Arc<dyn Pubsub> (not Arc<dyn RequestReply>) because klieo-core’s klieo_core::RequestReply trait is client-side only. The server listens on <app_prefix>.a2a.<agent_id>.rpc via klieo_core::Pubsub::subscribe and replies by publishing on a per-request reply subject extracted from message headers. A typed server-side trait would tighten the API; deferred until a second protocol-server consumer exists.

Re-exports

pub use auth::RequestContext;

pub use client::A2aClient;

pub use conformance::run_conformance_suite;

pub use conformance::CaseStatus;

pub use conformance::ConformanceCase;

pub use conformance::ConformanceReport;

pub use envelope::codes;

pub use envelope::A2aHeaders;

pub use envelope::A2aMethod;

pub use envelope::JsonRpcError;

pub use envelope::JsonRpcRequest;

pub use envelope::JsonRpcResponse;

pub use error::A2aBuilderError;

pub use error::A2aError;

pub use handler::A2aHandler;

pub use handler::EchoHandler;

pub use server::A2aDispatcher;

pub use server::A2aDispatcherBuilder;

pub use server::A2aServer;

pub use server::TaskEvent;

pub use server::TaskEventSink;

pub use server::TaskEventStream;

pub use server::LEADER_TTL;

pub use task_store::A2aTaskStore;

pub use types::AgentCapabilities;

pub use types::AgentCard;

pub use types::AgentCardSignature;

pub use types::AgentInterface;

pub use types::AgentProvider;

pub use types::AgentSkill;

pub use types::Artifact;

pub use types::CancelTaskParams;

pub use types::DeletePushNotificationConfigParams;

pub use types::GetExtendedAgentCardParams;

pub use types::GetPushNotificationConfigParams;

pub use types::GetTaskParams;

pub use types::ListPushNotificationConfigsParams;

pub use types::ListPushNotificationConfigsResult;

pub use types::ListTasksParams;

pub use types::ListTasksResult;

pub use types::Message;

pub use types::Part;

pub use types::PushNotificationConfig;

pub use types::PushNotificationConfigParams;

pub use types::Role;

pub use types::SendMessageParams;

pub use types::SendMessageResult;

pub use types::SubscribeToTaskParams;

pub use types::Task;

pub use types::TaskStatus;

Modules

auth

A2A-specific request-context bag.

client

Typed client for calling an A2A agent over klieo_core::Pubsub.

conformance

A2A v1.0 conformance suite.

envelope

JSON-RPC 2.0 envelope + A2A method enum + standard A2A headers.

error

A2A error type with JSON-RPC code mapping.

handler

A2aHandler trait + EchoHandler test fixture.

http

HTTP/SSE transport for A2aDispatcher. Streamable HTTP shape per A2A v1.0 §9.4.2: single POST /a2a; server picks JSON vs SSE response based on JSON-RPC method.

server

A2aServer — listens on a NATS-style request/reply subject and dispatches incoming JSON-RPC payloads to an A2aHandler.

task_store

A2aTaskStore — durable Task persistence over klieo_core::KvStore.

types

A2A v1.0 wire types — Part, Message, Artifact, Task, AgentCard.