/**
 * Account id normalization
 *
 * Used to distinguish channel account configs in multi-account routing.
 */
export declare const DEFAULT_ACCOUNT_ID = "default";
/**
 * Normalize an account id string.
 *
 * Rules:
 * - Only `a-z`, `0-9`, `_`, `-`
 * - Must not start with `-` or `_`
 * - Max length 64
 * - Empty input -> `default`
 */
export declare function normalizeAccountId(value: string | undefined | null): string;
/**
 * Like `normalizeAccountId`, but empty input yields `undefined` (not `default`).
 */
export declare function normalizeOptionalAccountId(value: string | undefined | null): string | undefined;
/**
 * Whether the value already matches the strict account id pattern.
 */
export declare function isValidAccountId(value: string | undefined | null): boolean;
/**
 * Alias for `normalizeAccountId` (same canonicalization as session segments).
 */
export declare function sanitizeAccountId(value: string | undefined | null): string;