/**
 * A header with a static value (use only for non-sensitive values)
 */
export interface StaticHeader {
    name: string;
    value: string;
}
/**
 * A header that reads its value from an environment variable at runtime.
 * Use this for sensitive values like API keys and authorization tokens.
 */
export interface EnvHeader {
    name: string;
    /** The name of the environment variable to read at runtime */
    env: string;
}
export type CustomHeader = StaticHeader | EnvHeader;
export type CustomHeaders = CustomHeader[];
export declare const createEmptyHeader: () => StaticHeader;
/**
 * Check if a header uses an environment variable reference
 */
export declare const isEnvHeader: (header: CustomHeader) => header is EnvHeader;
/**
 * Converts CustomHeaders to a Record, resolving environment variables at runtime.
 * Throws if a required env var is not set.
 */
export declare const headersToRecord: (headers: CustomHeaders) => Record<string, string>;