export interface ToolCallEvent {
    tool: string;
    durationMs: number;
    outcome: "ok" | "error" | "timeout";
    errorCode?: string;
}
export interface ToolStat {
    calls: number;
    success: number;
    errors: number;
    errorCodes: Record<string, number>;
    lastCalledAt: number;
    lastSuccessAt: number | null;
    lastErrorAt: number | null;
    totalDurationMs: number;
}
export interface ToolStatsDoc {
    version: 1;
    startedAt: number;
    updatedAt: number;
    totalCalls: number;
    tools: Record<string, ToolStat>;
}
/**
 * Per-process writer. One instance per project path. Loads existing
 * stats from disk on construction; subsequent record() calls update
 * the in-memory doc and schedule a debounced atomic flush. dispose()
 * is the synchronous escape hatch — call from process shutdown.
 */
export declare class ToolStatsWriter {
    private filePath;
    private doc;
    private dirty;
    private flushTimer;
    private flushDelayMs;
    constructor(projectPath: string, opts?: {
        flushDelayMs?: number;
    });
    private loadOrInit;
    /**
     * Record a single tool-call event. Updates the in-memory doc and
     * schedules a debounced flush. Never throws.
     */
    record(event: ToolCallEvent): void;
    private scheduleFlush;
    /**
     * Flush in-memory doc to disk atomically. Used by both the debounced
     * timer and dispose(). Atomicity via tmp+rename so concurrent readers
     * (sverklo profile suggest) never see a half-written file.
     */
    flushSync(): void;
    /**
     * Synchronous flush + cancel pending timer. Call from process shutdown
     * paths so the last in-memory updates land on disk before exit.
     */
    dispose(): void;
    /** Path the writer flushes to. Useful for tests + the read API below. */
    getFilePath(): string;
}
/**
 * Read the structured tool-stats doc for a project. Returns null if no
 * stats have been recorded yet — callers fall back to scanning
 * activity.jsonl in that case.
 */
export declare function readToolStats(projectPath: string): ToolStatsDoc | null;