/**
 * Performance Metrics Collector
 *
 * Comprehensive metrics collection system for typing performance monitoring.
 * Tracks latency, duration, and rate metrics with statistical analysis.
 *
 * Features:
 * - Per-metric sample collection with context
 * - Statistical summaries (min, max, avg, percentiles)
 * - Budget checking with configurable thresholds
 * - Sample limit management to prevent memory bloat
 * - Timer helpers for duration tracking
 *
 * Metrics tracked:
 * - cursorUpdateLatency: Time to update cursor position (target <2ms)
 * - p0LayoutDuration: P0 layout pass duration (target <5ms)
 * - p1LayoutDuration: P1 layout pass duration (target <50ms)
 * - workerRoundTrip: Worker message round-trip time (target <10ms)
 * - layoutStaleness: Time layout is stale during typing (target <100ms)
 * - geometryFallbackRate: Frequency of DOM measurement fallbacks
 * - cacheMissRate: Cache miss frequency
 * - droppedEvents: Number of dropped input events
 *
 * @module performance-metrics
 */
/**
 * Individual metric sample with timestamp and optional context.
 */
export interface MetricSample {
    /** Timestamp when sample was recorded (ms since epoch) */
    timestamp: number;
    /** Measured value */
    value: number;
    /** Optional contextual information about this sample */
    context?: Record<string, unknown>;
}
/**
 * Statistical summary of a metric's samples.
 */
export interface MetricSummary {
    /** Number of samples */
    count: number;
    /** Minimum value */
    min: number;
    /** Maximum value */
    max: number;
    /** Average (mean) value */
    avg: number;
    /** 50th percentile (median) */
    p50: number;
    /** 95th percentile */
    p95: number;
    /** 99th percentile */
    p99: number;
}
/**
 * All typing performance metrics tracked by the system.
 */
export interface TypingPerfMetrics {
    /** Cursor position update latency samples */
    cursorUpdateLatency: MetricSample[];
    /** P0 (critical) layout pass duration samples */
    p0LayoutDuration: MetricSample[];
    /** P1 (high priority) layout pass duration samples */
    p1LayoutDuration: MetricSample[];
    /** Web Worker round-trip time samples */
    workerRoundTrip: MetricSample[];
    /** Layout staleness duration samples */
    layoutStaleness: MetricSample[];
    /** Geometry fallback rate samples */
    geometryFallbackRate: MetricSample[];
    /** Cache miss rate samples */
    cacheMissRate: MetricSample[];
    /** Dropped input events samples */
    droppedEvents: MetricSample[];
}
/**
 * Budget violation report.
 */
export interface BudgetViolation {
    /** Metric that exceeded budget */
    metric: string;
    /** Measured value that violated budget */
    value: number;
    /** Budget threshold that was exceeded */
    budget: number;
}
/**
 * Performance metrics collector for typing optimization monitoring.
 *
 * Collects samples for various metrics and provides statistical analysis
 * with budget checking.
 *
 * @example
 * ```typescript
 * const metrics = new PerformanceMetricsCollector({
 *   cursorUpdateLatency: 2,
 *   p0LayoutDuration: 5,
 * });
 *
 * // Record a sample
 * metrics.record('cursorUpdateLatency', 1.5);
 *
 * // Use a timer
 * const endTimer = metrics.startTimer('p0LayoutDuration');
 * // ... perform layout ...
 * endTimer();
 *
 * // Get summary
 * const summary = metrics.getSummary('cursorUpdateLatency');
 * console.log(`P95: ${summary.p95}ms`);
 *
 * // Check budgets
 * const violations = metrics.checkBudgets();
 * if (violations.length > 0) {
 *   console.warn('Budget violations:', violations);
 * }
 * ```
 */
export declare class PerformanceMetricsCollector {
    private metrics;
    private maxSamples;
    private budgets;
    /**
     * Creates a new performance metrics collector.
     *
     * @param budgets - Performance budgets for each metric (in ms or rate)
     * @param maxSamples - Maximum samples to retain per metric (default: 1000)
     */
    constructor(budgets?: Partial<Record<keyof TypingPerfMetrics, number>>, maxSamples?: number);
    /**
     * Records a metric sample.
     *
     * Automatically manages sample buffer size by removing oldest samples
     * when the limit is reached.
     *
     * @param metric - Metric key to record
     * @param value - Measured value
     * @param context - Optional contextual information
     *
     * @example
     * ```typescript
     * collector.record('cursorUpdateLatency', 1.8, {
     *   position: 42,
     *   direction: 'forward',
     * });
     * ```
     */
    record(metric: keyof TypingPerfMetrics, value: number, context?: Record<string, unknown>): void;
    /**
     * Starts a timer for duration metrics.
     *
     * Returns a function that, when called, records the elapsed time.
     *
     * @param metric - Duration metric to time
     * @returns Function to call when operation completes
     *
     * @example
     * ```typescript
     * const endTimer = collector.startTimer('p0LayoutDuration');
     * await performLayout();
     * endTimer(); // Records elapsed time
     * ```
     */
    startTimer(metric: keyof TypingPerfMetrics): () => void;
    /**
     * Gets statistical summary for a specific metric.
     *
     * @param metric - Metric key to summarize
     * @returns Statistical summary including percentiles
     *
     * @example
     * ```typescript
     * const summary = collector.getSummary('cursorUpdateLatency');
     * console.log(`P95 latency: ${summary.p95.toFixed(2)}ms`);
     * ```
     */
    getSummary(metric: keyof TypingPerfMetrics): MetricSummary;
    /**
     * Gets summaries for all metrics.
     *
     * @returns Record of all metric summaries
     *
     * @example
     * ```typescript
     * const allSummaries = collector.getAllSummaries();
     * for (const [metric, summary] of Object.entries(allSummaries)) {
     *   console.log(`${metric}: ${summary.avg.toFixed(2)}ms avg`);
     * }
     * ```
     */
    getAllSummaries(): Record<keyof TypingPerfMetrics, MetricSummary>;
    /**
     * Checks if any metrics exceed their configured budgets.
     *
     * Uses P95 values for comparison against budgets.
     *
     * @returns Array of budget violations (empty if all within budget)
     *
     * @example
     * ```typescript
     * const violations = collector.checkBudgets();
     * if (violations.length > 0) {
     *   console.warn('Performance budgets exceeded:', violations);
     *   // Consider triggering fallback
     * }
     * ```
     */
    checkBudgets(): BudgetViolation[];
    /**
     * Exports all raw metric data.
     *
     * Useful for debugging and offline analysis.
     *
     * @returns Complete metrics data structure
     *
     * @example
     * ```typescript
     * const data = collector.export();
     * console.log(JSON.stringify(data, null, 2));
     * ```
     */
    export(): TypingPerfMetrics;
    /**
     * Clears all recorded metrics.
     *
     * Resets all sample arrays to empty state.
     *
     * @example
     * ```typescript
     * collector.clear(); // Start fresh measurement period
     * ```
     */
    clear(): void;
}
/**
 * Global singleton performance metrics collector instance.
 *
 * Configured with default performance budgets for typing optimization.
 *
 * @example
 * ```typescript
 * import { perfMetrics } from './performance-metrics.js';
 *
 * perfMetrics.record('cursorUpdateLatency', 1.5);
 * const summary = perfMetrics.getSummary('cursorUpdateLatency');
 * ```
 */
export declare const perfMetrics: PerformanceMetricsCollector;
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