/**
 * OpenAICacheStrategy — metrics-only strategy for OpenAI providers.
 *
 * OpenAI auto-caches request prefixes ≥1024 tokens at 50% off.
 * No client-side opt-in markers needed (and no way to influence
 * cache behavior from the client). The strategy:
 *
 *   - **prepareRequest**: pass-through. We can't tell OpenAI what
 *     to cache; they decide automatically. Markers are silently
 *     dropped (the 80% case for OpenAI consumers is "I declared
 *     cache: 'always' for my injections" — that's still meaningful
 *     because (a) it's portable across providers, (b) for OpenAI
 *     the auto-cache may still hit on stable prefixes regardless).
 *   - **extractMetrics**: reads `prompt_tokens_details.cached_tokens`
 *     from OpenAI's usage response so cacheRecorder can surface
 *     hit rates / dollar savings.
 *
 * Auto-registers on module import for: 'openai', 'browser-openai'.
 *
 * Documentation note for consumers (Phase 12 docs): the `cache:`
 * directive on injection definitions is portable but has NO LOCAL
 * EFFECT on OpenAI runs — the provider auto-caches based on prefix
 * length. The directive still ships correctly with the agent and
 * lights up automatically when you swap to Anthropic / Bedrock.
 */
import type { CacheCapabilities, CacheMarker, CacheMetrics, CacheStrategy, CacheStrategyContext } from '../types.js';
import type { LLMRequest } from '../../adapters/types.js';
export declare class OpenAICacheStrategy implements CacheStrategy {
    readonly providerName = "openai";
    readonly capabilities: CacheCapabilities;
    prepareRequest(req: LLMRequest, _candidates: readonly CacheMarker[], _ctx: CacheStrategyContext): Promise<{
        readonly request: LLMRequest;
        readonly markersApplied: readonly CacheMarker[];
    }>;
    extractMetrics(usage: unknown): CacheMetrics | undefined;
}