fix(broker): reconcile deletes into cache + resync before marking outbox done

Two write-path cache bugs surfaced during Gate 2 live testing:

P1 (delete didn't work / ghost event): syncCalendar only UPSERTED events
present on Fastmail and never removed cache rows for events that disappeared.
A successful CalDAV delete left the row in calendar_events forever, so
GET /api/events kept returning it and the UI showed a ghost that 'wouldn't
delete' (even after refresh). Add a prune step: delete calendar_events rows for
this calendar whose uid is absent from the server response (scoped to cal.id so
it never touches another calendar or the other member's rows — BUG B). Empty
server result prunes the whole calendar's cache.

P2 (edit needed a manual refresh): the outbox worker marked a row 'done' BEFORE
triggerTargetedResync refreshed the cache. The PWA's SyncStateToast invalidates
['events'] the instant sync-status flips to 'done', so it refetched stale cache.
Re-sync first, then mark done — 'done' now guarantees the cache reflects the write.

Tests: +2 prune regressions (present-subset prune, empty-server prune-all).

apps/api/src/broker/sync.ts

@@ -18,7 +18,7 @@
 import type { DAVCalendar } from 'tsdav'
 import type { FastmailClient } from './client.js'
 import ICAL from 'ical.js'
-import { and, eq } from 'drizzle-orm'
+import { and, eq, notInArray } from 'drizzle-orm'
 import { db } from '../db/client.js'
 import { calendars, calendarEvents } from '../db/schema.js'
 
@@ -73,6 +73,9 @@ export async function syncCalendar(
   const objects = await client.fetchCalendarObjects({ calendar: davCal })
 
   // 4. Parse each VCALENDAR/VEVENT and upsert into calendar_events.
+  //    Track every uid we see on the server so step 5 can prune cache rows that
+  //    no longer exist on Fastmail (deletes — local or external).
+  const seenUids: string[] = []
   for (const obj of objects) {
     if (!obj.data) continue
 
@@ -92,6 +95,7 @@ export async function syncCalendar(
     const dtstart = vevent.getFirstPropertyValue('dtstart') as ICAL.Time | null
     const uid = vevent.getFirstPropertyValue('uid') as string | null
     if (!uid) continue
+    seenUids.push(uid)
 
     // D-13 / Pitfall #3: isDate=true → DATE column; isDate=false → TIMESTAMP column
     const allDay: boolean = dtstart?.isDate ?? false
@@ -133,4 +137,19 @@ export async function syncCalendar(
         },
       })
   }
+
+  // 5. Prune deletes: remove cached events for THIS calendar whose uid is no
+  //    longer present on the server. Without this, a deleted event (local delete
+  //    via the outbox, or an external delete in another client) lingers in
+  //    calendar_events forever — GET /api/events keeps returning it and the UI
+  //    shows a ghost event that "won't delete". Scoped to cal.id so it never
+  //    touches another calendar or the other household member's rows (BUG B).
+  //    When the server returns zero events, prune the whole calendar's cache.
+  if (seenUids.length > 0) {
+    await db
+      .delete(calendarEvents)
+      .where(and(eq(calendarEvents.calendarId, cal.id), notInArray(calendarEvents.uid, seenUids)))
+  } else {
+    await db.delete(calendarEvents).where(eq(calendarEvents.calendarId, cal.id))
+  }
 }