/**
 * A cache entry tracking file read history and content state.
 */
export interface CacheEntry {
    /** SHA-256 hash of the file content at last read/update. */
    contentHash: string;
    /** Stored content (only in with_content mode). */
    content?: string | undefined;
    lineCount: number;
    byteSize: number;
    firstReadAt: number;
    lastReadAt: number;
    readCount: number;
    /** Estimated LLM tokens: Math.ceil(byteSize / 4). */
    tokenEstimate: number;
    /** Cumulative tokens saved by cache hits. */
    tokensSaved: number;
    /** OCC version counter, increments on every external modification. */
    version: number;
}
export interface ConflictInfo {
    yourVersion: number;
    currentVersion: number;
    diffSinceRead?: string | undefined;
}
export type CacheStatus = 'miss' | 'unchanged' | 'modified';
/**
 * FileStateCache, File state tracking with Optimistic Concurrency Control.
 *
 * Tracks files that have been read by tools/agents, detects external modifications,
 * and provides conflict information for OCC workflows.
 */
export declare class FileStateCache {
    private readonly mode;
    private readonly maxMemoryBytes;
    private cache;
    private totalMemBytes;
    private totalReads;
    private cacheHits;
    constructor(options?: {
        mode?: 'hash_only' | 'with_content';
        maxMemoryMB?: number;
    });
    /**
     * Look up the current state of a file.
     *
     * - miss: file has never been cached
     * - unchanged: content hash matches what we last saw
     * - modified: content hash differs (external modification)
     *
     * In `with_content` mode, a unified diff is included when status is 'modified'.
     */
    lookup(filePath: string): {
        status: CacheStatus;
        entry?: CacheEntry | undefined;
        diff?: string | undefined;
    };
    /**
     * Record that a file was read or written by a tool/agent.
     * Creates or updates the cache entry.
     */
    update(filePath: string, content: string, metadata?: {
        tool?: string;
        agent?: string;
    }): void;
    /**
     * Check for an OCC conflict: has the file been modified since `expectedVersion`?
     * Returns null if no conflict, or ConflictInfo if the version has advanced.
     */
    checkConflict(filePath: string, expectedVersion: number): ConflictInfo | null;
    /**
     * Remove a file from the cache.
     */
    invalidate(filePath: string): void;
    /**
     * Return cache statistics.
     */
    getStats(): {
        uniqueFiles: number;
        totalReads: number;
        hitRate: number;
        tokensSaved: number;
        memoryMB: number;
    };
    /**
     * Clear all cached entries.
     */
    clear(): void;
    private hash;
    private evictIfNeeded;
}
/**
 * Generate a simple unified diff between two strings.
 * Uses line-by-line LCS diff, not the Myers algorithm.
 */
export declare function unifiedDiff(oldContent: string, newContent: string, label: string, contextLines?: number): string;
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