From 17756fc5239fae42fd58a15ce8747e67203e7f87 Mon Sep 17 00:00:00 2001
From: Lucas Berger <me@lucasberger.ca>
Date: Tue, 9 Jun 2026 22:39:11 -0400
Subject: [PATCH] fix(05-review): NEW-WR-01 emit delete changes when server
 returns zero events (whole-cache clear)

Pre-capture all currently-cached rows into pendingDeleteRows before the whole-cache
db.delete() when seenUids.length === 0. The existing >0 branch behavior is unchanged.
Adds a regression test verifying onChanges receives one delete change per cached row
on a full-calendar clear.
---
 apps/api/src/broker/sync.ts        |  8 ++++++
 apps/api/tests/broker/sync.test.ts | 46 ++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/apps/api/src/broker/sync.ts b/apps/api/src/broker/sync.ts
index d4b61cf..a9ed7f1 100644
--- a/apps/api/src/broker/sync.ts
+++ b/apps/api/src/broker/sync.ts
@@ -256,6 +256,14 @@ export async function syncCalendar(
           notInArray(calendarEvents.uid, seenUids),
         ),
       )
+  } else if (onChanges) {
+    // NEW-WR-01: server returned zero events → entire calendar cache will be cleared.
+    // Capture ALL currently-cached rows before the delete so delete-change events
+    // are emitted for each one. Without this, bulk/clear deletions were silently dropped.
+    pendingDeleteRows = await db
+      .select({ uid: calendarEvents.uid, title: calendarEvents.title })
+      .from(calendarEvents)
+      .where(eq(calendarEvents.calendarId, cal.id))
   }
 
   if (seenUids.length > 0) {
diff --git a/apps/api/tests/broker/sync.test.ts b/apps/api/tests/broker/sync.test.ts
index 447d646..732f374 100644
--- a/apps/api/tests/broker/sync.test.ts
+++ b/apps/api/tests/broker/sync.test.ts
@@ -365,4 +365,50 @@ describe('syncCalendar', () => {
     expect(mockDelete).toHaveBeenCalledTimes(1)
     expect(mockDeleteWhere).toHaveBeenCalledTimes(1)
   })
+
+  // NEW-WR-01: When the server returns zero events (whole-cache clear), the
+  // onChanges callback must still receive a 'delete' change for each cached row
+  // that is being pruned. Before this fix, the pendingDeleteRows pre-capture only
+  // ran inside the seenUids.length > 0 branch, so bulk/clear deletions silently
+  // dropped all delete change events.
+  it('NEW-WR-01: emits delete change events for each cached row when server returns zero events', async () => {
+    const { syncCalendar } = await import('../../src/broker/sync.js')
+
+    // First mockWhere call: calendar row lookup (ends in .limit(1)) → { limit: mockLimit }
+    // Second mockWhere call: pending-delete pre-capture (direct await, no .limit()) →
+    //   must return an iterable array of cached rows. Use mockReturnValueOnce for the
+    //   second call so it returns a resolved Promise<array> instead of { limit }.
+    //
+    // Call order when seenUids.length === 0 and onChanges is provided:
+    //   1. db.select().from(calendars).where(...).limit(1) — calendar row lookup
+    //   2. db.select({uid,title}).from(calendarEvents).where(...) — pending-delete capture (awaited directly)
+    mockWhere
+      .mockReturnValueOnce({ limit: mockLimit })  // call 1: calendar row lookup
+      .mockResolvedValueOnce([                     // call 2: pending-delete capture
+        { uid: 'uid-to-delete-1', title: 'Event A' },
+        { uid: 'uid-to-delete-2', title: 'Event B' },
+      ])
+
+    const mockClient = {
+      fetchCalendarObjects: vi.fn().mockResolvedValue([]),
+    }
+    const mockDavCal = {
+      url: 'https://caldav.fastmail.com/dav/calendars/user/test@fm.com/Default/',
+      displayName: 'Test Calendar',
+      ctag: 'ctag-empty',
+      syncToken: null,
+    }
+
+    const collectedChanges: import('../../src/lib/eventChangeDispatcher.js').EventChange[] = []
+    const onChanges = (changes: import('../../src/lib/eventChangeDispatcher.js').EventChange[]) => {
+      collectedChanges.push(...changes)
+    }
+
+    await syncCalendar(mockClient as never, mockDavCal as never, 1, onChanges)
+
+    // The callback must have received one delete change per cached row.
+    expect(collectedChanges).toHaveLength(2)
+    expect(collectedChanges[0]).toMatchObject({ uid: 'uid-to-delete-1', operation: 'delete' })
+    expect(collectedChanges[1]).toMatchObject({ uid: 'uid-to-delete-2', operation: 'delete' })
+  })
 })