/**
 * BreakpointCacheStrategy — for a provider that caches a prefix only where
 * the request marks it (`promptCaching.mode: 'breakpoints'`; Anthropic's
 * `cache_control`).
 *
 * Chosen by CAPABILITY (`cacheStrategyFor`), never by provider name: built
 * from the provider's own declaration, so `withRetry(anthropic())` or an
 * application's routing wrapper caches exactly like the adapter it wraps.
 *
 * What it DOES:
 *   - clamp the candidate markers to the declared `maxBreakpoints`, keeping
 *     the first N in slot order (the most stable prefixes first);
 *   - put them on `LLMRequest.cacheMarkers`, where the adapter reads them;
 *   - read cache metrics off the PORT usage the adapter normalised —
 *     `not applicable` when the declaration says the adapter reports none.
 * What it does NOT: touch the wire. The adapter owns `cache_control`
 * (`adapters/llm/anthropicCacheWire.ts`), and content is never edited.
 */
import type { CacheMarker, CacheMetrics, CacheStrategy, CacheStrategyContext, CacheUsage, PromptCaching } from '../types.js';
import { type Claim } from '../../lib/claim/claim.js';
import type { LLMRequest } from '../../provider-contract/types.js';
export declare class BreakpointCacheStrategy implements CacheStrategy {
    readonly name = "breakpoints";
    private readonly maxBreakpoints;
    private readonly reportsUsage;
    private readonly who;
    private readonly fields?;
    /**
     * @param declared  the provider's `promptCaching` declaration
     * @param who       names the adapter in the meter's evidence sentences,
     *                  e.g. `"the 'anthropic' provider"`
     */
    constructor(declared: Extract<PromptCaching, {
        mode: 'breakpoints';
    }>, who?: string);
    prepareRequest(req: LLMRequest, candidates: readonly CacheMarker[], ctx: CacheStrategyContext): Promise<{
        readonly request: LLMRequest;
        readonly markersApplied: readonly CacheMarker[];
    }>;
    extractMetrics(usage: CacheUsage | undefined): Claim<CacheMetrics>;
}