cache.ts

import { getEventsForOffer } from '@/server/events/log';
import type { ActivityEvent } from '@/server/events/types';

// Cache is valid only while the offer's tail is an investigation_completed
// event — any material state change (offer_updated, activity_status_changed,
// milestone_completed, etc.) lands after the investigation and invalidates it,
// which is what prompts the "Re-investigate" affordance.
export function findCachedInvestigation(
  offerId: string,
  _atSeq: number,
): Extract<ActivityEvent, { kind: 'investigation_completed' }> | null {
  const events = getEventsForOffer(offerId);
  for (let i = events.length - 1; i >= 0; i--) {
    const event = events[i];
    if (event.kind === 'investigation_completed') return event;
    return null;
  }
  return null;
}