/**
 * Time basis of the date filter for usage metrics.
 * - activity: messages, tokens and models are filtered by `message_metrics.created_at` (the row
 *   that owns the counters), consistent with analytics_timeseries;
 * - session_updated (legacy default): every metric of the sessions whose `updated_at` falls in the
 *   range, so an old session touched today contributes all its historical tokens.
 * Sessions are always filtered by `sessions.updated_at` and events by `runtime_events.occurred_at`.
 */
export declare const TIME_BASES: readonly ["activity", "session_updated"];
export type TimeBasis = (typeof TIME_BASES)[number];
export declare function parseTimeBasis(value: unknown): TimeBasis;
export declare function timeSemantics(basis: TimeBasis): Record<string, string>;