import type { EventBus } from '../kernel/events.js';
export interface ProviderCacheEntry {
    provider: string;
    input: number;
    cacheRead: number;
    cacheWrite: number;
    /** cacheRead / (cacheRead + input); 0 when nothing cached. */
    hitRatio: number;
}
/**
 * Per-provider prompt-cache accounting for a session. `TokenCounter.cacheStats()`
 * blends every provider into one figure; this splits it so a session that
 * switched providers (fallback, `/model`) can show each provider's real
 * cache-hit ratio.
 *
 * New counters provide an exact per-call `deltaUsage`; older event producers
 * remain compatible through cumulative-snapshot differencing. The explicit
 * delta keeps attribution correct even when asynchronous price lookups settle
 * out of order after a provider switch.
 *
 * **LIFECYCLE WARNING:** The constructor subscribes to `events.on('token.accounted', …)`,
 * creating a permanent listener on the shared EventBus. The **caller MUST invoke
 * `dispose()` on session teardown** (e.g. via the `detachTodosCheckpoint` chain
 * in `packages/cli/src/wiring/session.ts`). Failure to do so leaks the listener
 * across session restarts/resumes — every constructor invocation after the first
 * adds a permanent listener that accumulates unboundedly.
 */
export declare class ProviderCacheLedger {
    private readonly byProvider;
    private last;
    private readonly off;
    constructor(events: EventBus);
    private record;
    /** Distinct providers seen this session. */
    providers(): string[];
    /** Per-provider cache stats, most-cached first. */
    perProvider(): ProviderCacheEntry[];
    /**
     * Unsubscribe from the event bus and release the per-session listener.
     *
     * **The caller MUST invoke `dispose()` on session teardown** — see the
     * constructor's lifecycle warning. Failure to call this method leaves a
     * permanent `token.accounted` listener on the shared EventBus that
     * accumulates unboundedly across session restarts/resumes.
     */
    dispose(): void;
}
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