/**
 * Minimal WebSocket abstraction the data plane splices over. Kept as an injected interface so
 * the mux/data-plane code has NO hard dependency on the `ws` package (pure + unit-testable);
 * the composition root adapts a real `ws` socket to this shape.
 */
export interface WebSocketLike {
  send(data: Uint8Array): void
  close(code?: number): void
  onMessage(handler: (data: Uint8Array) => void): void
  onClose(handler: () => void): void
}