/**
 * v0.4 wire-format types. Mirrors the A2A protocol Part/Message shape per the
 * parent plan ("Part shape: flat, no `kind` discriminator").
 *
 * NOTE: These are the on-wire shapes. SDK constructor helpers in envelope.ts
 * may accept richer input and normalize to these shapes before serialization.
 */

export type Role = "user" | "agent";

/**
 * Flat Part. Exactly one of {text, data, url, raw} MUST be present; the
 * presence selects the variant. mediaType is REQUIRED for data/url/raw
 * variants, OPTIONAL for text (defaults to "text/plain" if omitted).
 */
export interface Part {
  text?: string;
  data?: unknown;
  url?: string;
  raw?: Uint8Array;

  mediaType?: string;
  filename?: string;
  metadata?: Record<string, unknown>;
}

export interface Message {
  messageId: string;
  role: Role;
  parts: Part[];
  taskId?: string;
  contextId?: string;
  metadata?: Record<string, unknown>;
}