/**
 * Authentication Middleware
 *
 * Provides optional API key authentication for securing endpoints.
 * Authentication is disabled by default; enable by setting TX_API_KEY env var.
 */
import { HttpServerRequest, HttpServerResponse } from "@effect/platform";
import { Effect } from "effect";
/**
 * Check if authentication is enabled.
 */
export declare const isAuthEnabled: () => boolean;
/**
 * Extract API key from request headers.
 * Supports both Authorization header (Bearer token) and X-Api-Key header.
 * @internal Exported for testing.
 */
export declare const extractApiKey: (headers: Record<string, string | undefined>) => string | null;
/**
 * Constant-time string comparison to prevent timing attacks.
 * Uses Node.js crypto.timingSafeEqual for proper constant-time comparison.
 * @internal Exported for testing.
 */
export declare const timingSafeEqual: (provided: string, expected: string) => boolean;
/**
 * Effect HTTP authentication middleware.
 * Only validates if TX_API_KEY environment variable is set.
 * If not set, all requests pass through.
 */
export declare const authMiddleware: <E, R>(httpApp: import("@effect/platform/HttpApp").Default<E, R>) => Effect.Effect<HttpServerResponse.HttpServerResponse, E, HttpServerRequest.HttpServerRequest | R>;
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