/**
 * Run a server action, retrying it ONCE if the call rejects at the
 * transport layer.
 *
 * iOS Safari (and Safari generally) frequently drops the first POST sent
 * on a keep-alive socket that the server closed while the connection sat
 * idle — e.g. while the user typed their credentials. The request fails
 * instantly with `NSURLErrorNetworkConnectionLost` ("The network
 * connection was lost", -1005); a retry lands on a fresh connection and
 * succeeds. This is why a first login/signup tap shows "An unexpected
 * error occurred" and the second tap works.
 *
 * Only a *thrown* rejection is retried. A server action that returns a
 * value — including an application-level `{ error }` ("Invalid email or
 * password", a rate-limit message) — is a real result and passes
 * straight through untouched. A lost-on-a-stale-socket POST never
 * reached the server, so retrying it once is safe.
 */
export async function retryOnTransportError<T>(fn: () => Promise<T>): Promise<T> {
  try {
    return await fn();
  } catch {
    return await fn();
  }
}