Module client 

HTTP client for sending A2A requests.

Modules

auth

Authentication interceptor and credential storage.

builder

Fluent builder for A2aClient.

client

Core A2aClient struct and constructors.

config

Client configuration types.

discovery

Agent card discovery with HTTP caching.

error

Client error types.

interceptor

Request/response interceptor infrastructure.

methods

Per-method client helpers.

retry

Configurable retry policy for transient client errors.

streaming

SSE client-side streaming support.

tls

TLS connector via rustls.

token_provider

Token acquisition: TokenProvider, OAuth 2.0 client-credentials, and OIDC discovery.

transport

Transport abstraction for A2A client requests.

Structs

A2aClient

A client for communicating with A2A-compliant agents.

AuthInterceptor

A CallInterceptor that injects Authorization headers from a CredentialsStore.

BearerAuthInterceptor

A CallInterceptor that injects Authorization: Bearer <token> from a TokenProvider before every request.

ClientBuilder

Builder for A2aClient.

ClientConfig

Configuration for an crate::A2aClient instance.

ClientRequest

A logical A2A request as seen by interceptors.

ClientResponse

A logical A2A response as seen by interceptors.

EventStream

An async stream of StreamResponse events from an SSE endpoint.

GrpcTransport

gRPC transport for A2A clients.

InMemoryCredentialsStore

An in-memory CredentialsStore backed by an RwLock<HashMap>.

InterceptorChain

An ordered list of CallInterceptors applied to every request.

JsonRpcTransport

JSON-RPC 2.0 transport: HTTP POST to a single endpoint.

OAuth2ClientCredentials

A TokenProvider implementing the OAuth 2.0 client credentials grant (RFC 6749 §4.4) with caching and proactive refresh.

RestTransport

REST transport: HTTP verbs mapped to REST paths.

RetryPolicy

Configuration for automatic retry with exponential backoff.

SessionId

Opaque identifier for a client authentication session.

StaticTokenProvider

A TokenProvider that always returns the same fixed token.

WebSocketTransport

WebSocket transport: JSON-RPC 2.0 over a persistent WebSocket connection.

WebSocketTransportConfig

Configuration for WebSocketTransport::connect_with_config.

Enums

ClientError

Errors that can occur during A2A client operations.

Traits

CallInterceptor

Hooks called before every A2A request and after every response.

CredentialsStore

Persistent storage for auth credentials, keyed by session + scheme.

TokenProvider

A source of bearer access tokens.

Transport

The low-level HTTP transport interface.

Functions

resolve_agent_card

Fetches the AgentCard from the standard well-known path.

Type Aliases

ClientResult

Convenience type alias: Result<T, ClientError>.