Module message 

Message types for the A2A protocol.

A Message is the fundamental communication unit between a client and an agent. Each message has a MessageRole (ROLE_USER or ROLE_AGENT) and carries one or more Part values.

Part oneof

Part is a flat struct with a PartContent oneof discriminated by field presence: {"text": "hi"}, {"raw": "base64..."}, {"url": "..."}, or {"data": {...}}.

Structs

Message

A message exchanged between a client and an agent.

MessageId

Opaque unique identifier for a Message.

Part

A content part within a Message or crate::artifact::Artifact.

Enums

MessageRole

The originator of a Message.

PartContent

The content of a Part, discriminated by field presence (proto oneof).