/** Reversible fetch wrapper for proxy dispatch and fixed headers. */
import { AsyncLocalStorage } from 'node:async_hooks';
export interface ProxyContext {
    proxyUrl?: string;
    provider: string;
    model: string;
    /** Fixed extra headers of the matched rule; direct mode may send them too. */
    headers?: Readonly<Record<string, string>>;
}
export declare const als: AsyncLocalStorage<ProxyContext>;
/** Install the wrapper only when a route or fixed header may be applied. */
export declare function shouldWrapFetch(config: {
    enabled: boolean;
    defaultProxy?: string;
    defaultProxyHostId?: string;
    proxyHosts?: ReadonlyArray<{
        id: string;
        proxyUrl: string;
    }>;
    rules?: ReadonlyArray<{
        proxyUrl?: string;
        proxyHostId?: string;
        headers?: Readonly<Record<string, string>>;
        headerValueSources?: Readonly<Record<string, string>>;
        enabled?: boolean;
    }>;
}): boolean;
/** Minimal logger face so the host can route diagnostics through ctx.logger. */
export interface FetchWrapLogger {
    error?(msg: string): void;
}
/** Add configured headers only when the request does not already have them. */
export declare function applyExtraHeaders(base: Headers, extra: Readonly<Record<string, string>> | undefined): Headers;
/** Wrap global fetch and return a disposer safe for overlapping HMR instances. */
export declare function installFetchWrapper(log?: FetchWrapLogger): () => void;
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