/** Whether `next` is an older version than `held` (unversioned records are never called older). */
export const olderThan = (next: { meta?: { versionId?: string } }, held: { meta?: { versionId?: string } } | undefined): boolean => {
    if (!next.meta?.versionId || !held?.meta?.versionId) return false;
    const a = Number(next.meta.versionId);
    const b = Number(held.meta.versionId);
    return Number.isFinite(a) && Number.isFinite(b) && a < b;
};

/** `list` with `next` in place of its record (or added), unless the list already holds a newer version of it. */
export const withNewer = <T extends { id?: string; meta?: { versionId?: string } }>(list: T[], next: T): T[] => {
    const held = list.find((entry) => entry.id === next.id);
    if (held && olderThan(next, held)) return list;
    return held ? list.map((entry) => (entry.id === next.id ? next : entry)) : [...list, next];
};