/**
 * Agent-to-Agent Protocol (A2A) — minimal open spec for one agent to
 * invoke another over JSON-RPC 2.0. Companion to MCP (which is
 * model-to-tool); A2A is agent-to-agent task delegation, approvals,
 * and streaming status updates.
 *
 * Version: 2026-04.
 */
declare const A2A_PROTOCOL_VERSION = "2026-04";
interface A2AAgentCard {
    /** Stable identifier (reverse-DNS or npm scope recommended). */
    id: string;
    name: string;
    description?: string;
    version: string;
    /** Skills the agent advertises. */
    skills: A2ASkillDescriptor[];
    /** Optional JSON Schema for expected context on `task/invoke`. */
    contextSchema?: Record<string, unknown>;
    /** Human-facing URL (docs, source, demo). */
    homepage?: string;
    /** Icon URL for marketplaces. */
    icon?: string;
}
interface A2ASkillDescriptor {
    name: string;
    description?: string;
    /** JSON Schema of the expected task input. */
    inputSchema?: Record<string, unknown>;
    /** Advertised capabilities the caller can rely on. */
    capabilities?: {
        streaming?: boolean;
        cancellation?: boolean;
        requiresApproval?: boolean;
    };
}
interface A2AInvokeParams {
    skill: string;
    input: Record<string, unknown>;
    /** Caller context (user id, tenant, trace id). */
    context?: Record<string, unknown>;
    /** Set true for streaming via `task/status` notifications. */
    stream?: boolean;
}
interface A2AInvokeResult {
    taskId: string;
    /** Terminal state for non-streaming invocations; 'running' for stream. */
    status: 'completed' | 'failed' | 'running' | 'requires-approval';
    output?: Record<string, unknown>;
    error?: {
        code: number;
        message: string;
        data?: unknown;
    };
}
interface A2ATaskStatusNotification {
    taskId: string;
    status: 'running' | 'completed' | 'failed' | 'requires-approval';
    progress?: number;
    partial?: Record<string, unknown>;
    output?: Record<string, unknown>;
    error?: {
        code: number;
        message: string;
    };
}
interface A2ACancelParams {
    taskId: string;
    reason?: string;
}
interface A2AApproveParams {
    taskId: string;
    decision: 'approved' | 'rejected';
    approver?: string;
    metadata?: Record<string, unknown>;
}
type A2AMethod = 'agent/card' | 'task/invoke' | 'task/cancel' | 'task/approve' | 'task/status';
declare function validateAgentCard(raw: unknown): A2AAgentCard;

export { type A2AAgentCard, type A2AApproveParams, type A2ACancelParams, type A2AInvokeParams, type A2AInvokeResult, type A2AMethod, type A2ASkillDescriptor, type A2ATaskStatusNotification, A2A_PROTOCOL_VERSION, validateAgentCard };