This package contains the data structures for the Agent-to-Agent (A2A) communication protocol.

The models package provides type-safe structures for:

• JSON-RPC 2.0 messages
• Agent metadata and capabilities
• Task management
• Error handling

• JSONRPCMessage: Base interface for all JSON-RPC messages
• JSONRPCMessageIdentifier: Interface for identifying JSON-RPC messages
• JSONRPCRequest: Request object structure
• JSONRPCResponse: Response object structure
• JSONRPCError: Error object structure

• AgentCard: Agent metadata card
• AgentProvider: Provider information
• AgentCapabilities: Agent capabilities
• AgentSkill: Agent skill definition
• AgentAuthentication: Authentication details

• Task: Task representation
• TaskStatus: Task status information
• TaskState: Task state enumeration
• Message: Message content
• Part: Message part (text, file, data)
• Artifact: Task output artifact

• TaskSendParams: Parameters for sending a task
• TaskQueryParams: Parameters for querying a task
• TaskIDParams: Parameters for task ID-based operations
• PushNotificationConfig: Push notification configuration

package main

import (
    "a2a/models"
)

func main() {
    // Create a task message
    message := models.Message{
        Role: "user",
        Parts: []models.Part{
            {
                Type: stringPtr("text"),
                Text: stringPtr("Hello, A2A agent!"),
            },
        },
    }

    // Create task parameters
    params := models.TaskSendParams{
        ID:      "task-1",
        Message: message,
    }

    // Use the parameters...
}

The package defines standard error codes for the A2A protocol:

• ErrorCodeParseError: Invalid JSON
• ErrorCodeInvalidRequest: Invalid request format
• ErrorCodeMethodNotFound: Method not found
• ErrorCodeInvalidParams: Invalid parameters
• ErrorCodeInternalError: Internal server error
• ErrorCodeTaskNotFound: Task not found
• ErrorCodeTaskAlreadyExists: Task already exists
• ErrorCodeTaskInProgress: Task in progress
• ErrorCodeTaskCompleted: Task already completed
• ErrorCodeTaskCanceled: Task already canceled
• ErrorCodeTaskFailed: Task already failed
• ErrorCodeInvalidTaskState: Invalid task state transition
• ErrorCodeInvalidTaskID: Invalid task ID
• ErrorCodeInvalidMessage: Invalid message format
• ErrorCodeInvalidPart: Invalid message part
• ErrorCodeInvalidArtifact: Invalid artifact format
• ErrorCodeInvalidFileContent: Invalid file content
• ErrorCodeInvalidURI: Invalid URI format
• ErrorCodeInvalidAuthentication: Invalid authentication
• ErrorCodeAuthenticationRequired: Authentication required
• ErrorCodeAuthenticationFailed: Authentication failed
• ErrorCodeRateLimitExceeded: Rate limit exceeded
• ErrorCodeQuotaExceeded: Quota exceeded
• ErrorCodeServiceUnavailable: Service unavailable
• ErrorCodeTimeout: Request timeout
• ErrorCodeConnectionError: Connection error
• ErrorCodeProtocolError: Protocol error
• ErrorCodeUnknownError: Unknown error

Run the tests with:

go test ./...

The test suite verifies:

• JSON serialization/deserialization
• Type validation
• Error handling
• Task state transitions