/** Event name — array of strings, like Elixir's [:app, :component, :event] */
export type EventName = readonly string[];
/** Measurements — numeric values only (durations, counts, sizes) */
export type Measurements = Record<string, number>;
/** Metadata — contextual information (ids, classes, reasons) */
export type Metadata = Record<string, unknown>;
/** Handler function signature — called synchronously */
export type TelemetryHandler = (eventName: EventName, measurements: Measurements, metadata: Metadata) => void;
declare class Telemetry {
    /** event key → set of handler entries */
    private handlers;
    /** handler id → list of event keys it is attached to */
    private handlerKeys;
    /**
     * Attach a handler to one or more event names.
     * Throws if a handler with the same id is already attached.
     */
    attach(id: string, eventNames: EventName[], handler: TelemetryHandler): string;
    /**
     * Detach a previously attached handler by id.
     * Returns true if the handler was found and removed.
     */
    detach(id: string): boolean;
    /**
     * Emit a telemetry event. Handlers are called synchronously.
     * If no handlers are attached for this event, this is a no-op (zero allocation).
     * Handler errors are silently caught — they never crash the actor system.
     */
    execute(eventName: EventName, measurements: Measurements, metadata: Metadata): void;
    /**
     * Wrap a function in start/stop/exception telemetry events.
     *
     * - Emits `[...eventName, "start"]` before execution
     * - Emits `[...eventName, "stop"]` after success with `duration_ms`
     * - Emits `[...eventName, "exception"]` on error with `duration_ms` + error
     *
     * Supports both sync and async functions transparently.
     */
    span<T>(eventName: EventName, metadata: Metadata, fn: () => T): T;
    /**
     * Check if any handlers are attached for the given event name.
     * Used to gate instrumentation on hot paths (zero-cost when unattached).
     */
    hasHandlers(eventName: EventName): boolean;
    /** List all attached handler ids. */
    listHandlers(): string[];
    /** Remove all handlers. Useful for test teardown. */
    reset(): void;
}
/** Global telemetry singleton. */
export declare const telemetry: Telemetry;
export declare const TelemetryEvents: {
    readonly actor: {
        readonly spawn: readonly ["libeam", "actor", "spawn"];
        readonly stop: readonly ["libeam", "actor", "stop"];
        readonly init: readonly ["libeam", "actor", "init"];
        readonly handleCall: readonly ["libeam", "actor", "handle_call"];
        readonly handleCast: readonly ["libeam", "actor", "handle_cast"];
    };
    readonly supervisor: {
        readonly crash: readonly ["libeam", "supervisor", "crash"];
        readonly restart: readonly ["libeam", "supervisor", "restart"];
        readonly maxRestarts: readonly ["libeam", "supervisor", "max_restarts"];
    };
    readonly mailbox: {
        readonly overflow: readonly ["libeam", "mailbox", "overflow"];
    };
    readonly genStage: {
        readonly subscribe: readonly ["libeam", "gen_stage", "subscribe"];
        readonly cancel: readonly ["libeam", "gen_stage", "cancel"];
        readonly dispatch: readonly ["libeam", "gen_stage", "dispatch"];
        readonly bufferOverflow: readonly ["libeam", "gen_stage", "buffer_overflow"];
    };
    readonly cluster: {
        readonly join: readonly ["libeam", "cluster", "join"];
        readonly leave: readonly ["libeam", "cluster", "leave"];
    };
    readonly system: {
        readonly shutdown: readonly ["libeam", "system", "shutdown"];
    };
};
export {};
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