export interface NotificationTypeDefinition {
    key: string;
    title: string | ((data: Record<string, unknown>) => string);
    body?: string | ((data: Record<string, unknown>) => string);
    url?: string | ((data: Record<string, unknown>) => string);
    icon?: string;
    /**
     * Who receives the notification:
     * - `'online'`: every user with an open SSE stream **in this process** at
     *   send time. Presence-based, not account-based — offline users get
     *   nothing (no DB row, no push). Renamed from the misleading `'all'`,
     *   which never reached offline accounts; `send()` throws a migration
     *   error on the old value. For a true all-accounts broadcast, use the
     *   function form and resolve the IDs yourself.
     * - `'admins'`: resolved via the `resolveAdminRecipients` seam on
     *   `createNotificationService` (which throws when the seam is unwired).
     * - `string[]` / function form: explicit user ids (the function receives
     *   the `send()` data payload).
     */
    recipients: 'online' | 'admins' | string[] | ((data: Record<string, unknown>) => Promise<string[]>);
    /**
     * Delivery channels, default `['sse', 'push']`. There is deliberately no
     * `'email'` channel: it was a declared-but-never-implemented contract end.
     * `send()` had no email branch, so declaring it silently
     * degraded to DB-persistence only. The `email` flag on
     * `NotificationPreference` remains as a reserved column for a future
     * implementation.
     */
    channels?: ('sse' | 'push')[];
}