import { VERSION } from "../../version.js";
/**
 * Runtime environment detection for transport selection
 */
export type Runtime = "node" | "browser" | "deno" | "bun" | "workerd" | "unknown";
/**
 * Detect the current JavaScript runtime
 */
export declare function detectRuntime(): Runtime;
/**
 * Check if the current runtime supports HTTP/2 for s2s protocol
 */
export declare function supportsHttp2(): boolean;
/**
 * Check if the current runtime allows setting a custom User-Agent header.
 *
 * Only browsers enforce the Fetch spec's "forbidden header name" restriction
 * that prevents setting User-Agent. All server-side runtimes (Node, Bun,
 * Deno, Cloudflare Workers, etc.) allow it.
 */
export declare function canSetUserAgentHeader(runtime?: Runtime): boolean;
/**
 * Library version used in the default User-Agent header.
 *
 * The actual version string is injected at build time in the compiled
 * JavaScript output based on package.json. See src/version.ts and
 * scripts/postbuild.ts.
 */
export { VERSION };
export declare const DEFAULT_USER_AGENT = "s2-sdk-typescript/0.24.1";
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