type SubjectIdentifiers = {
    externalId?: unknown;
    identityProvider?: unknown;
};
type SanitizedSubjectIdentifiers = {
    externalId?: string;
    identityProvider?: string;
};
/**
 * Sanitizes optional subject identifiers loaded from storage or request state.
 *
 * Treats nullish values, empty strings, and serialized sentinel strings from
 * previous buggy writes as absent fields.
 */
export declare function sanitizeSubjectIdentifiers(identifiers: SubjectIdentifiers): SanitizedSubjectIdentifiers;
export {};