/**
 * [WHO]: AgentLogger, createLogger(), structured logging for agent sessions
 * [FROM]: No external dependencies
 * [TO]: Consumed by core/runtime/agent-session.ts, core/extensions-host/runner.ts, core/tools/*
 * [HERE]: core/platform/utils/logger.ts - structured JSON logging with session/turn/span tracing
 */
/** Log levels in priority order */
export type LogLevel = "debug" | "info" | "warn" | "error";
/** Structured log entry */
export interface LogEntry {
    /** Timestamp in ISO 8601 */
    timestamp: string;
    /** Log level */
    level: LogLevel;
    /** Human-readable message */
    message: string;
    /** Session ID for correlation */
    sessionId?: string;
    /** Turn index within session */
    turnId?: number;
    /** Tool call ID for tool execution tracing */
    toolCallId?: string;
    /** Component/module source */
    component?: string;
    /** Duration in milliseconds (for spans) */
    durationMs?: number;
    /** Additional structured data */
    data?: Record<string, unknown>;
}
/** Logger configuration */
export interface LoggerConfig {
    /** Minimum log level (default: "info") */
    level?: LogLevel;
    /** Session ID (set once per session) */
    sessionId?: string;
    /** Component name prefix */
    component?: string;
    /** Custom output handler (default: console.error for warn/error, console.log for info/debug) */
    handler?: (entry: LogEntry) => void;
}
/** Format a LogEntry as a single-line JSON string */
export declare function formatLogEntry(entry: LogEntry): string;
/**
 * AgentLogger — structured logger with session/turn/span tracing.
 *
 * Usage:
 * ```typescript
 * const logger = createLogger({ sessionId: "abc123", component: "compaction" });
 * logger.info("Compaction started", { turnId: 5 });
 * logger.warn("Slow tool execution", { toolCallId: "call_123", durationMs: 5000 });
 * ```
 */
export interface AgentLogger {
    debug(message: string, data?: Record<string, unknown>): void;
    info(message: string, data?: Record<string, unknown>): void;
    warn(message: string, data?: Record<string, unknown>): void;
    error(message: string, data?: Record<string, unknown>): void;
    /** Create a child logger with additional context */
    child(extra: {
        component?: string;
        turnId?: number;
        toolCallId?: string;
    }): AgentLogger;
    /** Measure duration of an async operation */
    measure<T>(label: string, fn: () => Promise<T>, data?: Record<string, unknown>): Promise<T>;
}
/**
 * Create a new AgentLogger instance.
 */
export declare function createLogger(config?: LoggerConfig): AgentLogger;
/**
 * No-op logger that discards all output.
 * Useful for tests or when logging is disabled.
 */
export declare const noopLogger: AgentLogger;