vtcode-a2a

Agent2Agent (A2A) Protocol support for VT Code. Provides client and server implementations for the A2A protocol, enabling inter-agent communication.

Agent2Agent (A2A) Protocol support for VT Code.

Modules

Module	Purpose
`agent_card`	Agent discovery and capability advertisement
`client`	A2A protocol client
`cli`	CLI interface for A2A commands
`errors`	A2A-specific error types
`rpc`	JSON-RPC message types and protocol constants
`server`	Authenticated HTTP server (feature-gated: `a2a-server`)
`task_manager`	Task lifecycle management
`types`	Core A2A protocol types (Message, Task, Part, etc.)
`webhook`	Push notification support

Features

Feature	Description
`a2a-server`	Enables the HTTP server module (axum, tower, tower-http)

Usage

use vtcode_a2a::{AgentCard, A2aClient, TaskManager};

let card = AgentCard::vtcode_default("http://localhost:8080");
let client = A2aClient::new("http://localhost:8080");

Server security

The agent card endpoint is public for discovery. The /a2a and /a2a/stream endpoints require an Authorization: Bearer <token> header. A2aServerState::new generates a random token; use auth_token() to pass it to a client, or use new_with_auth_token to provide one explicitly. Cross-origin browser access is disabled by default.

Webhook destinations must use HTTPS, or HTTP to the exact localhost host or an IP loopback address. Webhook requests do not follow redirects.

use vtcode_a2a::{A2aClient, AgentCard, TaskManager};
use vtcode_a2a::server::A2aServerState;

let state = A2aServerState::new(TaskManager::new(), AgentCard::vtcode_default("http://localhost:8080"));
let client = A2aClient::new("http://localhost:8080")?.with_bearer_token(state.auth_token());

The vtcode a2a CLI reads the token from VTCODE_A2A_TOKEN. Keeping the token in the environment avoids exposing it in process arguments.

API reference