/**
 * Whether a failure message means the selected model cannot be used at all —
 * it does not exist, was retired, or the account has no access. Only these
 * failures are worth retrying on a different model; usage limits, auth and
 * process errors would fail the same way again.
 */
export declare function isModelUnavailableError(message: string): boolean;
/**
 * {@link isModelUnavailableError} for a thrown provider failure. Raw provider
 * errors often carry only a terse body ("model: claude-x", type
 * `not_found_error`), so an HTTP 404 or an explicit `model_not_found` code
 * counts too.
 */
export declare function isModelUnavailableFailure(err: unknown): boolean;