/**
 * Header merging utilities
 * Provides utilities for merging API headers with different strategies
 */
import type { HeaderMergeOptions, HeaderMergeResult, ApiHeaders } from '@plyaz/types/api';
export declare function mergeHeaders(...headerSets: Array<Record<string, string> | undefined>): ApiHeaders;
/**
 * Merge headers with advanced options including immutable headers.
 * Provides more control over the merge process with strategies and conflict resolution.
 *
 * @param existing - Existing headers
 * @param newHeaders - New headers to merge
 * @param options - Merge options
 * @returns Merge result with conflict tracking
 */
export declare function mergeHeadersWithImmutable(existing: ApiHeaders | undefined, newHeaders: ApiHeaders | undefined, options?: HeaderMergeOptions): HeaderMergeResult;
/**
 * Combine multiple header values using comma separation.
 * Useful for headers that support multiple values.
 *
 * @param values - Header values to combine
 * @returns Combined header value
 */
export declare function combineHeaderValues(...values: Array<string | undefined>): string;
/**
 * Parse combined header values back into array.
 *
 * @param value - Combined header value
 * @returns Array of individual values
 */
export declare function parseHeaderValues(value: string): string[];
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