diff --git a/server/utils/adminAlerts.js b/server/utils/adminAlerts.js
index adb1ffa..58b7bd5 100644
--- a/server/utils/adminAlerts.js
+++ b/server/utils/adminAlerts.js
@@ -116,4 +116,49 @@ export async function detectSuspendedMembers() {
   }
 }
 
+function preRegItem(preReg, sublabel) {
+  return {
+    id: String(preReg._id),
+    label: preReg.name || preReg.email,
+    sublabel,
+    href: '/admin/pre-registrants'
+  }
+}
+
+export async function detectPreRegistrantSelectedNotInvited() {
+  await connectDB()
+  const cutoff = daysAgo(ALERT_THRESHOLDS.PREREG_SELECTED_DAYS)
+  const preRegs = await PreRegistration
+    .find({
+      status: 'selected',
+      updatedAt: { $lte: cutoff }
+    })
+    .select('name email updatedAt')
+    .lean()
+  return {
+    type: 'preregistrant_selected_not_invited',
+    severity: 'attention',
+    title: 'Pre-registrants selected but not invited',
+    items: preRegs.map((p) =>
+      preRegItem(p, `${p.email} — ${daysSince(p.updatedAt)} days selected`)
+    )
+  }
+}
+
+export async function detectPreRegistrantExpired() {
+  await connectDB()
+  const preRegs = await PreRegistration
+    .find({ status: 'expired' })
+    .select('name email updatedAt')
+    .lean()
+  return {
+    type: 'preregistrant_expired',
+    severity: 'attention',
+    title: 'Expired pre-registrant invitations',
+    items: preRegs.map((p) =>
+      preRegItem(p, `${p.email} — expired ${daysSince(p.updatedAt)} days ago`)
+    )
+  }
+}
+
 // Aggregator lands in task 8.
diff --git a/tests/server/utils/adminAlerts.test.js b/tests/server/utils/adminAlerts.test.js
index 7f1fa27..120d586 100644
--- a/tests/server/utils/adminAlerts.test.js
+++ b/tests/server/utils/adminAlerts.test.js
@@ -52,9 +52,12 @@ import {
   detectSlackInviteFailed,
   detectNoSlackHandleAfterWeek,
   detectStuckPendingPayment,
-  detectSuspendedMembers
+  detectSuspendedMembers,
+  detectPreRegistrantSelectedNotInvited,
+  detectPreRegistrantExpired
 } from '../../../server/utils/adminAlerts.js'
 import Member from '../../../server/models/member.js'
+import PreRegistration from '../../../server/models/preRegistration.js'
 
 describe('adminAlerts module shell', () => {
   describe('ALERT_THRESHOLDS', () => {
@@ -193,4 +196,59 @@ describe('adminAlerts module shell', () => {
       })
     })
   })
+
+  describe('pre-registrant alerts', () => {
+    beforeEach(() => {
+      vi.clearAllMocks()
+    })
+
+    function mockPreRegFind(result) {
+      PreRegistration.find.mockReturnValue({
+        select: vi.fn().mockReturnValue({
+          lean: vi.fn().mockResolvedValue(result)
+        })
+      })
+    }
+
+    describe('detectPreRegistrantSelectedNotInvited', () => {
+      it('returns selected pre-registrants older than 3 days', async () => {
+        const fourDaysAgo = new Date(Date.now() - 4 * 86400000)
+        mockPreRegFind([
+          { _id: 'p1', name: 'Fin', email: 'fin@example.com', updatedAt: fourDaysAgo }
+        ])
+
+        const alert = await detectPreRegistrantSelectedNotInvited()
+
+        expect(alert.type).toBe('preregistrant_selected_not_invited')
+        expect(alert.severity).toBe('attention')
+        expect(alert.items).toHaveLength(1)
+        expect(alert.items[0]).toEqual({
+          id: 'p1',
+          label: 'Fin',
+          sublabel: 'fin@example.com — 4 days selected',
+          href: '/admin/pre-registrants'
+        })
+
+        const [query] = PreRegistration.find.mock.calls[0]
+        expect(query.status).toBe('selected')
+        expect(query.updatedAt).toEqual({ $lte: expect.any(Date) })
+      })
+    })
+
+    describe('detectPreRegistrantExpired', () => {
+      it('returns expired pre-registrants', async () => {
+        const expiredAt = new Date(Date.now() - 2 * 86400000)
+        mockPreRegFind([
+          { _id: 'p2', name: 'Gus', email: 'gus@example.com', updatedAt: expiredAt }
+        ])
+
+        const alert = await detectPreRegistrantExpired()
+
+        expect(alert.type).toBe('preregistrant_expired')
+        expect(alert.severity).toBe('attention')
+        expect(alert.items[0].label).toBe('Gus')
+        expect(PreRegistration.find).toHaveBeenCalledWith({ status: 'expired' })
+      })
+    })
+  })
 })