/**
 * RequestClient — low-level fetch wrapper.
 *
 * Adds:
 *   - per-request timeoutMs (default 30s)
 *   - AbortSignal composition (caller-supplied AbortSignal + timeout signal)
 *   - retry on idempotent verbs only (GET / HEAD), exponential backoff
 *   - JSON content-type defaulting for JSON bodies
 *
 * Has zero auth knowledge — callers compose headers/auth before passing in.
 * The response is returned RAW (Response object); src/client/response.ts
 * layer parses and wraps into the SDK envelope.
 */
export type RequestClientOptions = {
    /** Default per-request timeout in milliseconds. */
    timeoutMs?: number;
    /** Max retries for idempotent verbs. 0 disables retry. */
    retries?: number;
    /** Initial backoff in ms; doubles on each retry. */
    retryBackoffMs?: number;
};
export type RequestOptions = {
    method?: string;
    headers?: Record<string, string>;
    body?: BodyInit | Record<string, unknown> | undefined;
    signal?: AbortSignal;
    /** Per-call timeout override. */
    timeoutMs?: number;
    /** Per-call retry override. */
    retries?: number;
    /**
     * Awaited immediately before each fetch attempt with the final RequestInit.
     * Mutations to `headers` are honored. Runs per attempt so a hook that
     * refreshes a credential stays correct across retries.
     */
    onRequest?: (request: RequestInit) => Promise<void> | void;
};
export declare class RequestClient {
    private readonly defaultTimeoutMs;
    private readonly defaultRetries;
    private readonly retryBackoffMs;
    constructor(options?: RequestClientOptions);
    request(url: string, options?: RequestOptions): Promise<Response>;
}