/**
 * In-memory Gemini cached-content handle store.
 *
 * Ported from PSYCHE src/llm/caching.py. Uses LRU eviction up to
 * MAX_ENTRIES. `build_cache_key` uses deterministic JSON + sha256.
 *
 * @task T1393 (T1386-W7)
 * @epic T1386
 */
import type { ModelConfig, PromptCachePolicy } from './types-config.js';
export type { PromptCachePolicy } from './types-config.js';
/** In-memory handle for a Gemini cached-content resource. */
export interface GeminiCacheHandle {
    key: string;
    cachedContentName: string;
    expiresAt: Date;
}
/**
 * Build a deterministic cache key for a Gemini cached-content request.
 *
 * Includes transport, model, cache policy, cacheable messages, tools,
 * system instruction, and tool_config — all of which affect the cached
 * content and must be part of the key.
 */
export declare function buildCacheKey(params: {
    config: ModelConfig;
    cachePolicy: PromptCachePolicy;
    cacheableMessages: Array<Record<string, unknown>>;
    tools: Array<Record<string, unknown>> | null | undefined;
    systemInstruction?: string | null;
    toolConfig?: Record<string, unknown> | null;
}): string;
/**
 * Best-effort local LRU cache for Gemini cached-content handles.
 *
 * Uses insertion-order Map with LRU eviction at MAX_ENTRIES limit.
 * Thread-safety: not needed in single-threaded Node.js (no threading).
 */
export declare class InMemoryGeminiCacheStore {
    static readonly MAX_ENTRIES = 1024;
    private readonly _handles;
    /**
     * Get a cached handle by key.
     * Returns null if not found or if expired.
     */
    get(key: string): GeminiCacheHandle | null;
    /**
     * Store a handle. Evicts expired entries, then oldest if over limit.
     * Returns the stored handle.
     */
    set(handle: GeminiCacheHandle): GeminiCacheHandle;
}
/** Module-level singleton cache store (test-patchable). */
export declare const geminiCacheStore: InMemoryGeminiCacheStore;
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