/**
 * Per-fingerprint event flood guard
 *
 * Lives in `protocol-types` because EVERY producer needs it — node taps, the Nest
 * sink, the gateway, the bridge, and (since the admission decision must happen
 * BEFORE a payload is built) the browser runtime. It is pure logic with no Node
 * APIs, so a browser bundle can carry it. — a token bucket per fingerprint, shared by
 * every bus WRITER (lensEmit, the cluster gateway's observability emit, the
 * bridge env sink mirrors it). One hot fingerprint (an app retrying a fetch in
 * a loop, a valtio store churning per frame) must not be able to write hundreds
 * of lines/sec into events.jsonl: the 2026-07-28 incident sustained ~680 ev/s,
 * grew the bus file to 254 MB in two hours, and OOM-crash-looped every consumer
 * that ingests it. The guard keeps the SIGNAL (the first burst, then a trickle
 * with a `floodSuppressed` count) while dropping the redundant repetition.
 */
export interface FloodAdmit {
    ok: boolean;
    /** Events dropped for this fingerprint since the last admitted one (0 normally). */
    suppressed: number;
}
export interface FloodGuard {
    admit(fingerprint: string): FloodAdmit;
}
export interface FloodGuardOptions {
    /** Instantaneous burst allowance per fingerprint (bucket capacity). Default 30. */
    burst?: number;
    /** Sustained events/sec per fingerprint (bucket refill). Default 5. */
    perSec?: number;
    /** Max distinct fingerprints tracked before stale buckets are evicted. Default 2048. */
    maxKeys?: number;
}
export declare function createEventFloodGuard(opts?: FloodGuardOptions): FloodGuard;