/**
 * UsageTracker - Tracks token usage across LLM calls
 *
 * @example
 * ```typescript
 * const tracker = new UsageTracker({
 *   budget: {
 *     maxTotalTokens: 100000,
 *     warningThreshold: 0.8,
 *   },
 * });
 *
 * tracker.onEvent((event) => {
 *   if (event.type === 'usage:budget_warning') {
 *     console.log('Budget warning!', event.status);
 *   }
 * });
 *
 * // Record usage after each LLM call
 * tracker.record({
 *   model: 'claude-sonnet-4-6',
 *   provider: 'anthropic',
 *   tokens: { inputTokens: 1000, outputTokens: 500, totalTokens: 1500 },
 * });
 *
 * // Get stats
 * console.log(tracker.getStats());
 * console.log(tracker.formatTokens(tracker.getTotalTokens()));
 * ```
 */
import type { UsageRecord, UsageStats, BudgetStatus, UsageEventHandler, UsageTrackerOptions, RecordUsageInput } from './types.js';
/**
 * UsageTracker tracks token usage across LLM calls
 */
export declare class UsageTracker {
    private readonly enabled;
    private readonly budget?;
    private readonly sessionId?;
    private readonly eventHandlers;
    /** All usage records */
    private readonly records;
    /** Cached stats (invalidated on new records) */
    private cachedStats?;
    constructor(options?: UsageTrackerOptions);
    /**
     * Record token usage from an LLM call
     */
    record(input: RecordUsageInput): UsageRecord | undefined;
    /**
     * Get aggregated usage statistics
     */
    getStats(): UsageStats;
    /**
     * Get stats for a specific session
     */
    getSessionStats(sessionId: string): UsageStats;
    /**
     * Get total tokens used
     */
    getTotalTokens(): number;
    /**
     * Get total input tokens
     */
    getTotalInputTokens(): number;
    /**
     * Get total output tokens
     */
    getTotalOutputTokens(): number;
    /**
     * Get budget status
     */
    getBudgetStatus(): BudgetStatus;
    /**
     * Check if budget is exceeded
     */
    isBudgetExceeded(): boolean;
    /**
     * Check budget and emit events
     */
    private checkBudget;
    /**
     * Reset all tracking data
     */
    reset(): void;
    /**
     * Get all records
     */
    getRecords(): readonly UsageRecord[];
    /**
     * Get records for a specific session
     */
    getSessionRecords(sessionId: string): UsageRecord[];
    /**
     * Format tokens with commas for display
     */
    formatTokens(tokens: number): string;
    /**
     * Get a human-readable summary
     */
    getSummary(): string;
    /**
     * Register an event handler
     */
    onEvent(handler: UsageEventHandler): () => void;
    /**
     * Emit an event
     */
    private emit;
    /**
     * Check if tracking is enabled
     */
    get isEnabled(): boolean;
    /**
     * Get the number of records
     */
    get size(): number;
}
/**
 * Create a UsageTracker instance
 */
export declare function createUsageTracker(options?: UsageTrackerOptions): UsageTracker;