a2a-types

Rust types for the A2A v1.0 protocol, generated from the canonical a2a.proto definition vendored in this repository.

Source of truth

All types are generated at build time by prost and pbjson from proto/a2a.proto. There is no hand-written domain model — the proto file is the single source of truth for every field name, type, and serialization format.

Installation

[dependencies]
a2a-types = "0.2.0"

Usage

Every generated type is available directly at the crate root — no sub-module prefix required.

use a2a_types::{Message, Part, Role, SendMessageRequest, part};

let message = Message {
    message_id: "msg_123".to_string(),
    context_id: String::new(),
    task_id: String::new(),
    role: Role::User.into(),
    parts: vec![Part {
        content: Some(part::Content::Text("Hello, agent!".to_string())),
        metadata: None,
        filename: String::new(),
        media_type: "text/plain".to_string(),
    }],
    metadata: None,
    extensions: Vec::new(),
    reference_task_ids: Vec::new(),
};

let request = SendMessageRequest {
    tenant: String::new(),
    message: Some(message),
    configuration: None,
    metadata: None,
};

What is included

oneof payload variants live in sub-modules mirroring the proto structure:

use a2a_types::{part, send_message_response, stream_response};

// Construct a text part
let content = part::Content::Text("hello".to_string());

// Match a stream event
match response.payload {
    Some(stream_response::Payload::StatusUpdate(update)) => { /* ... */ }
    Some(stream_response::Payload::ArtifactUpdate(update)) => { /* ... */ }
    Some(stream_response::Payload::Message(msg)) => { /* ... */ }
    Some(stream_response::Payload::Task(task)) => { /* ... */ }
    None => {}
}

Version compatibility

License

MIT