message.go

package relay

// -----------------------------------------------------------------------------
// Message Types
// -----------------------------------------------------------------------------

// MessageType identifies the type of message in the protocol.
// Both agents and clients use these message types.
type MessageType string

// Message types for the protocol.
const (
	// Control messages
	MessageTypeRegister  MessageType = "register"  // Agent/client registration
	MessageTypeHeartbeat MessageType = "heartbeat" // Keep-alive ping/pong

	// Session lifecycle
	MessageTypeSessionOpen  MessageType = "session:open"  // Request to open a new session
	MessageTypeSessionClose MessageType = "session:close" // Request to close a session
	MessageTypeSessionReady MessageType = "session:ready" // Confirmation that session is ready

	// Session data
	MessageTypeSessionData MessageType = "session:data" // Raw data for a session

	// PTY-specific messages
	MessageTypePTYResize MessageType = "pty:resize" // Terminal resize event

	// Error handling
	MessageTypeError MessageType = "error" // Error response
)

// Message is the universal envelope for all messages between server, agents, and clients.
// It provides a uniform structure that supports multiple sessions per connection.
type Message struct {
	// Type identifies what kind of message this is.
	Type MessageType `json:"type"`

	// SessionID identifies which session this message belongs to.
	// Empty for control messages like register/heartbeat.
	SessionID SessionID `json:"session_id,omitempty"`

	// Payload contains the message-specific data.
	// For session data, this is the raw bytes being transmitted.
	// For control messages, this may be JSON-encoded metadata.
	Payload []byte `json:"payload,omitempty"`

	// Metadata contains optional key-value pairs for extensibility.
	// Used for things like error codes, PTY dimensions, tunnel targets, etc.
	Metadata map[string]string `json:"metadata,omitempty"`
}

// AgentMessage is an alias for Message for backwards compatibility.
// Deprecated: Use Message directly.
type AgentMessage = Message