feat(03-04): implement outbox drain state machine (GREEN)

- runOutboxDrain: drains pending outbox rows, dispatches CalDAV writes
  via broker/write.ts, classifies HTTP responses per D-07/D-08
- CONFLICT_STATUS=412 routes to conflict flow: mark failed, re-sync (D-08)
- TRANSIENT_STATUSES: exponential backoff with MAX_ATTEMPTS=5 dead-letter (D-07)
- HARD_FAIL_STATUSES 400/401/403: fail immediately, no retry (D-07)
- Edit-as-move D-04: create row sorted before delete for same groupId;
  create-fail aborts the paired delete (T-03-14)
- triggerTargetedResync: fetches fresh DAVCalendars, calls syncCalendar (D-06)
- startOutboxWorker: node-cron */15 * * * * * schedule (15s interval)
- Fix test scaffold: vi.hoisted() for mock variables to resolve vitest
  hoisting TDZ issue; simplified mock chain to match and() single .where()

apps/api/tests/broker/outboxWorker.test.ts

@@ -22,15 +22,30 @@ import { runOutboxDrain } from '../../src/broker/outboxWorker.js'
 
 // ── Drizzle DB mock ────────────────────────────────────────────────────────
 // Follows the pattern from PATTERNS.md §Drizzle DB mock in tests.
+//
+// vi.hoisted() is required for variables referenced inside vi.mock() factories.
+// vi.mock() is hoisted to the top of the file by vitest's transform; without
+// vi.hoisted(), variables declared with const/let are in the TDZ when the factory
+// runs (static imports trigger module loading before declarations are evaluated).
 
-const mockUpdateSet = vi.fn().mockReturnValue({ where: vi.fn().mockResolvedValue(undefined) })
-const mockUpdate = vi.fn().mockReturnValue({ set: mockUpdateSet })
+const {
+  mockUpdateSet,
+  mockUpdate,
+  mockWherePending,
+  mockFromFn,
+  mockSelectFn,
+} = vi.hoisted(() => {
+  const mockUpdateSet = vi.fn().mockReturnValue({ where: vi.fn().mockResolvedValue(undefined) })
+  const mockUpdate = vi.fn().mockReturnValue({ set: mockUpdateSet })
+  // mockWherePending is the terminal node of the select chain:
+  //   db.select().from(table).where(and(cond1, cond2)) — resolves to the row array
+  const mockWherePending = vi.fn().mockImplementation(() => Promise.resolve([] as unknown[]))
+  const mockFromFn = vi.fn().mockReturnValue({ where: mockWherePending })
+  const mockSelectFn = vi.fn().mockReturnValue({ from: mockFromFn })
+  return { mockUpdateSet, mockUpdate, mockWherePending, mockFromFn, mockSelectFn }
+})
 
 let mockPendingRows: unknown[] = []
-const mockWherePending = vi.fn().mockImplementation(() => Promise.resolve(mockPendingRows))
-const mockLimitFn = vi.fn().mockReturnValue({ where: mockWherePending })
-const mockFromFn = vi.fn().mockReturnValue({ where: mockLimitFn })
-const mockSelectFn = vi.fn().mockReturnValue({ from: mockFromFn })
 
 vi.mock('../../src/db/client.js', () => ({
   db: {
@@ -84,12 +99,12 @@ describe('runOutboxDrain — state transitions', () => {
   beforeEach(() => {
     vi.clearAllMocks()
     mockPendingRows = []
-    // Restore mock chain after clearAllMocks
+    // Restore mock chain after clearAllMocks:
+    //   db.select().from(table).where(and(cond1, cond2)) → Promise<rows>
     mockUpdateSet.mockReturnValue({ where: vi.fn().mockResolvedValue(undefined) })
     mockUpdate.mockReturnValue({ set: mockUpdateSet })
     mockWherePending.mockImplementation(() => Promise.resolve(mockPendingRows))
-    mockLimitFn.mockReturnValue({ where: mockWherePending })
-    mockFromFn.mockReturnValue({ where: mockLimitFn })
+    mockFromFn.mockReturnValue({ where: mockWherePending })
     mockSelectFn.mockReturnValue({ from: mockFromFn })
   })
 
@@ -167,8 +182,7 @@ describe('runOutboxDrain — edit-as-move ordering (D-04)', () => {
     mockUpdateSet.mockReturnValue({ where: vi.fn().mockResolvedValue(undefined) })
     mockUpdate.mockReturnValue({ set: mockUpdateSet })
     mockWherePending.mockImplementation(() => Promise.resolve(mockPendingRows))
-    mockLimitFn.mockReturnValue({ where: mockWherePending })
-    mockFromFn.mockReturnValue({ where: mockLimitFn })
+    mockFromFn.mockReturnValue({ where: mockWherePending })
     mockSelectFn.mockReturnValue({ from: mockFromFn })
   })