Custom Executors

Implement a2a::server::AgentExecutor to define application behavior.

Required methods

Executors implement task/message operations including:

• SendMessage
• SendStreamingMessage
• GetTask
• ListTasks
• CancelTask

Push-notification config methods have default PushNotificationNotSupported behavior and should be overridden only when the server actually supports them.

Request context

Every executor method receives RequestContext. Use it for auth metadata, transport metadata, and request-scoped policy decisions. Treat metadata as untrusted until validated.

Design guidance

• Keep executor methods small and deterministic.
• Validate inputs at the boundary.
• Return a2a::core::Result<T> with structured errors.
• Avoid shared mutable state unless synchronized and documented.
• Unit-test executor behavior separately from transport mapping.