/**
 * Field projection helper — comma-separated dotted paths with `*` wildcard.
 * Used to dramatically reduce response token usage on large entities.
 *
 * Examples:
 *   "id,name,description"
 *   "columns.*.name"
 *   "owner.name,tags.*.tagFQN"
 *   "service.`fully.qualified.name`"
 */
/**
 * Project response data to only the requested fields.
 * Returns the data unchanged if `expr` is empty/undefined.
 */
export declare function applyExtractFields<T>(data: T, expr?: string): T | unknown;
export declare const extractFieldsDescription: string;
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