fix(mentor): defer in-app-notification emails when mentoring round is draft

Mentor-assignment flows (mentor.assign, autoAssign, bulkAssign,
bulkAutoAssign, autoAssignBulkForRound) call createNotification and
notifyProjectTeam for MENTEE_ASSIGNED / MENTOR_ASSIGNED. Both
notification types have NotificationEmailSetting.sendEmail = true, so
the notification system fires its own styled email in addition to the
explicit mentor-team / coalesced emails on the same code path. The
earlier defer-emails-until-round-open fix only gated the explicit
sendMentorBulkAssignmentEmail / sendMentorTeamAssignmentEmail calls;
this parallel email path kept firing immediately at every assignment.

Result on prod 2026-05-26: Camille Lopez (assigned to 9 projects via
two bulk_assigns) received 7 emails at 15:04 + 1 at 15:32 from the
notification-system path during draft, plus 1 coalesced email at the
18:20 round activation = 9 sends instead of 1. Every PEARL team
member (and equivalents on other teams) received 3 emails for the
same reason.

Fix
- Add `skipEmail?: boolean` to CreateNotificationParams,
  createNotification, createBulkNotifications, and (via spread)
  notifyProjectTeam. When true the in-app notification row still
  fires but the parallel email send is suppressed; the coalesced
  mentor email and team intro at activateRound time remain the
  single source of email truth.
- Wire it up in every mentor-assignment site: compute the existing
  shouldDeferEmailsForProject gate once before the createNotification
  / notifyProjectTeam calls and pass `skipEmail: deferThisEmail`.
  bulkAssign precomputes draftProjectIds for the whole batch.
  autoAssignBulkForRound uses the round's status directly.
- New regression suite (mentor-email-deferral.test.ts, 3 cases):
  vi.mocks @/lib/email, asserts zero outbound sends when round is
  ROUND_DRAFT, confirms in-app notification rows still get written,
  and re-verifies the ACTIVE-round path still emails.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/server/routers/mentor.ts

@@ -465,6 +465,15 @@ export const mentorRouter = router({
         include: { user: { select: { name: true, email: true } } },
       })
 
+      // Defer emails (mentor-side and team-side) while the project's MENTORING
+      // round is still ROUND_DRAFT — `activateRound` coalesces and fires them
+      // when the admin opens the round. In-app notifications still fire so the
+      // staged assignment is visible immediately.
+      const deferThisEmail = await shouldDeferEmailsForProject(
+        ctx.prisma,
+        input.projectId,
+      )
+
       // Notify mentor of new mentee
       await createNotification({
         userId: input.mentorId,
@@ -479,6 +488,7 @@ export const mentorRouter = router({
           teamLeadName: teamLead?.user?.name || 'Team Lead',
           teamLeadEmail: teamLead?.user?.email,
         },
+        skipEmail: deferThisEmail,
       })
 
       // Notify project team of mentor assignment
@@ -493,15 +503,9 @@ export const mentorRouter = router({
           projectName: assignment.project.title,
           mentorName: assignment.mentor.name,
         },
+        skipEmail: deferThisEmail,
       })
 
-      // Defer the mentor-side email if the project's MENTORING round is still
-      // ROUND_DRAFT — `activateRound` will coalesce and send when the admin
-      // opens the round. Otherwise fire the per-assignment email immediately.
-      const deferThisEmail = await shouldDeferEmailsForProject(
-        ctx.prisma,
-        input.projectId,
-      )
       if (
         !deferThisEmail &&
         assignment.notificationSentAt == null &&
@@ -661,6 +665,13 @@ export const mentorRouter = router({
         include: { user: { select: { name: true, email: true } } },
       })
 
+      // Defer email notifications if the project's MENTORING round is still
+      // in draft — activateRound will fire coalesced emails at round-open.
+      const deferThisEmail = await shouldDeferEmailsForProject(
+        ctx.prisma,
+        input.projectId,
+      )
+
       // Notify mentor of new mentee
       await createNotification({
         userId: mentorId,
@@ -675,6 +686,7 @@ export const mentorRouter = router({
           teamLeadName: teamLead?.user?.name || 'Team Lead',
           teamLeadEmail: teamLead?.user?.email,
         },
+        skipEmail: deferThisEmail,
       })
 
       // Notify project team of mentor assignment
@@ -689,6 +701,7 @@ export const mentorRouter = router({
           projectName: assignment.project.title,
           mentorName: assignment.mentor.name,
         },
+        skipEmail: deferThisEmail,
       })
 
       return assignment
@@ -777,8 +790,22 @@ export const mentorRouter = router({
       let totalAssigned = 0
       let totalSkipped = 0
 
+      // Pre-compute which projects must defer outbound email because their
+      // MENTORING round is still in draft. The in-app notification still
+      // fires; only the parallel notification-system email is suppressed,
+      // exactly like the coalesced mentor email path below. `activateRound`
+      // sends one combined email per mentor + one team intro per project
+      // when the admin opens the round.
+      const draftProjectIds = new Set<string>()
+      for (const project of projects) {
+        if (await shouldDeferEmailsForProject(ctx.prisma, project.id)) {
+          draftProjectIds.add(project.id)
+        }
+      }
+
       for (const project of projects) {
         const alreadyOn = new Set(project.mentorAssignments.map((a) => a.mentorId))
+        const deferForThis = draftProjectIds.has(project.id)
         for (const mentor of validMentors) {
           const bucket = perMentor.get(mentor.id)!
           if (alreadyOn.has(mentor.id)) {
@@ -808,6 +835,7 @@ export const mentorRouter = router({
             linkLabel: 'View Project',
             priority: 'high',
             metadata: { projectName: project.title },
+            skipEmail: deferForThis,
           })
 
           await notifyProjectTeam(project.id, {
@@ -818,6 +846,7 @@ export const mentorRouter = router({
             linkLabel: 'View Project',
             priority: 'high',
             metadata: { projectName: project.title, mentorName: mentor.name },
+            skipEmail: deferForThis,
           })
         }
 
@@ -852,16 +881,7 @@ export const mentorRouter = router({
         }
       }
 
-      // Decide per-project whether to defer email until round-open: projects
-      // whose MENTORING round is still ROUND_DRAFT skip email and stamp now;
-      // `activateRound` will coalesce and send when the admin opens the round.
-      const draftProjectIds = new Set<string>()
-      for (const projectId of touchedProjectIds) {
-        if (await shouldDeferEmailsForProject(ctx.prisma, projectId)) {
-          draftProjectIds.add(projectId)
-        }
-      }
-
+      // `draftProjectIds` was computed before the assignment loop above.
       // One email per mentor, listing only their NEW projects whose mentoring
       // round is NOT in draft. If every new project is deferred, no email.
       for (const bucket of perMentor.values()) {
@@ -1083,6 +1103,12 @@ export const mentorRouter = router({
               include: { user: { select: { name: true, email: true } } },
             })
 
+            // Defer emails when the project's MENTORING round is still in draft.
+            const deferThisEmail = await shouldDeferEmailsForProject(
+              ctx.prisma,
+              project.id,
+            )
+
             // Notify mentor
             await createNotification({
               userId: mentorId,
@@ -1097,6 +1123,7 @@ export const mentorRouter = router({
                 teamLeadName: teamLead?.user?.name || 'Team Lead',
                 teamLeadEmail: teamLead?.user?.email,
               },
+              skipEmail: deferThisEmail,
             })
 
             // Notify project team
@@ -1111,6 +1138,7 @@ export const mentorRouter = router({
                 projectName: assignment.project.title,
                 mentorName: assignment.mentor.name,
               },
+              skipEmail: deferThisEmail,
             })
 
             assigned++
@@ -1164,7 +1192,7 @@ export const mentorRouter = router({
     .mutation(async ({ ctx, input }) => {
       const round = await ctx.prisma.round.findUniqueOrThrow({
         where: { id: input.roundId },
-        select: { id: true, roundType: true, configJson: true },
+        select: { id: true, roundType: true, configJson: true, status: true },
       })
       if (round.roundType !== 'MENTORING') {
         throw new TRPCError({
@@ -1211,6 +1239,11 @@ export const mentorRouter = router({
       let assigned = 0
       let unassignable = 0
 
+      // Defer outbound emails when the round is still in draft — same gate
+      // used by mentor.assign/bulkAssign. In-app notifications still fire so
+      // the staged assignment is visible to the mentor + team immediately.
+      const deferEmailsForRound = round.status === 'ROUND_DRAFT'
+
       // Coalesce per-mentor so we send ONE email per mentor at the end of the
       // batch, even when the algorithm assigns the same mentor to several teams.
       const perMentor = new Map<
@@ -1287,6 +1320,7 @@ export const mentorRouter = router({
               teamLeadName: teamLead?.user?.name || 'Team Lead',
               teamLeadEmail: teamLead?.user?.email,
             },
+            skipEmail: deferEmailsForRound,
           })
 
           await notifyProjectTeam(project.id, {
@@ -1300,6 +1334,7 @@ export const mentorRouter = router({
               projectName: assignment.project.title,
               mentorName: assignment.mentor.name,
             },
+            skipEmail: deferEmailsForRound,
           })
 
           // Accumulate for the coalesced email

src/server/services/in-app-notification.ts

@@ -169,6 +169,14 @@ interface CreateNotificationParams {
   metadata?: Record<string, unknown>
   groupKey?: string
   expiresAt?: Date
+  /**
+   * When true, the in-app notification still fires but the parallel email
+   * send (via NotificationEmailSetting) is suppressed. Callers use this when
+   * the email belongs to a coalesced/deferred flow that will fire later
+   * (e.g. mentor assignments staged while a MENTORING round is ROUND_DRAFT —
+   * the round-open hook sends a single combined email instead).
+   */
+  skipEmail?: boolean
 }
 
 /**
@@ -189,6 +197,7 @@ export async function createNotification(
     metadata,
     groupKey,
     expiresAt,
+    skipEmail,
   } = params
 
   // Determine icon and priority if not provided
@@ -241,8 +250,11 @@ export async function createNotification(
     },
   })
 
-  // Check if we should also send an email
-  await maybeSendEmail(userId, type, title, message, linkUrl, metadata)
+  // Check if we should also send an email (suppressed when the caller is
+  // deferring the email to a coalesced flow).
+  if (!skipEmail) {
+    await maybeSendEmail(userId, type, title, message, linkUrl, metadata)
+  }
 }
 
 /**
@@ -258,6 +270,8 @@ export async function createBulkNotifications(params: {
   icon?: string
   priority?: NotificationPriority
   metadata?: Record<string, unknown>
+  /** See {@link CreateNotificationParams.skipEmail}. */
+  skipEmail?: boolean
 }): Promise<void> {
   const {
     userIds,
@@ -269,6 +283,7 @@ export async function createBulkNotifications(params: {
     icon,
     priority,
     metadata,
+    skipEmail,
   } = params
 
   const finalIcon = icon || NotificationIcons[type] || 'Bell'
@@ -289,6 +304,8 @@ export async function createBulkNotifications(params: {
     })),
   })
 
+  if (skipEmail) return
+
   // Check email settings once, then send emails only if enabled
   const emailSetting = await prisma.notificationEmailSetting.findUnique({
     where: { notificationType: type },

tests/unit/mentor-email-deferral.test.ts

@@ -0,0 +1,228 @@
+/**
+ * Regression: mentor-assignment emails must be deferred while the
+ * project's MENTORING round is still ROUND_DRAFT. The earlier fix only
+ * deferred the explicit `sendMentorBulkAssignmentEmail` path; the parallel
+ * in-app-notification → email path (MENTEE_ASSIGNED, MENTOR_ASSIGNED) kept
+ * firing immediately, causing duplicate sends both at assign-time AND
+ * again when activateRound coalesced the same assignments. Verified
+ * against prod incident 2026-05-26 (Camille Lopez received 9 emails).
+ *
+ * These tests assert that:
+ *   - in DRAFT: in-app notifications still create rows, but the styled
+ *     notification email is NOT sent;
+ *   - in ACTIVE: the styled notification email IS sent (legacy behaviour
+ *     preserved when the round is open).
+ */
+
+import { afterAll, beforeEach, describe, expect, it, vi } from 'vitest'
+import { prisma, createCaller } from '../setup'
+import {
+  createTestUser,
+  createTestProgram,
+  createTestProject,
+  cleanupTestData,
+  uid,
+} from '../helpers'
+import { mentorRouter } from '../../src/server/routers/mentor'
+import type { UserRole } from '@prisma/client'
+
+vi.mock('@/lib/email', async () => {
+  const actual = await vi.importActual<typeof import('@/lib/email')>('@/lib/email')
+  return {
+    ...actual,
+    sendStyledNotificationEmail: vi.fn(async () => undefined),
+    sendMentorTeamAssignmentEmail: vi.fn(async () => undefined),
+    sendMentorBulkAssignmentEmail: vi.fn(async () => undefined),
+    sendTeamMentorIntroductionEmail: vi.fn(async () => undefined),
+  }
+})
+
+const email = await import('@/lib/email')
+const sendStyledMock = email.sendStyledNotificationEmail as ReturnType<typeof vi.fn>
+const sendMentorBulkMock = email.sendMentorBulkAssignmentEmail as ReturnType<typeof vi.fn>
+const sendTeamIntroMock = email.sendTeamMentorIntroductionEmail as ReturnType<typeof vi.fn>
+
+async function makeMentor(): Promise<{ id: string; email: string }> {
+  const id = uid('mentor')
+  const u = await prisma.user.create({
+    data: {
+      id,
+      email: `${id}@test.local`,
+      name: `Mentor ${id}`,
+      role: 'MENTOR' as UserRole,
+      roles: ['MENTOR'] as UserRole[],
+      status: 'ACTIVE',
+      // Email path requires the user to opt into emails. Default for new test
+      // users is EMAIL so styled-email sends fire when the gate is open.
+      notificationPreference: 'EMAIL',
+    },
+  })
+  return { id: u.id, email: u.email }
+}
+
+async function makeTeamMember(projectId: string): Promise<string> {
+  const id = uid('teamuser')
+  const u = await prisma.user.create({
+    data: {
+      id,
+      email: `${id}@test.local`,
+      name: `Team ${id}`,
+      role: 'APPLICANT' as UserRole,
+      roles: ['APPLICANT'] as UserRole[],
+      status: 'ACTIVE',
+      notificationPreference: 'EMAIL',
+    },
+  })
+  await prisma.teamMember.create({
+    data: { projectId, userId: u.id, role: 'MEMBER' },
+  })
+  return u.id
+}
+
+async function attachToMentoringRound(
+  programId: string,
+  projectId: string,
+  status: 'ROUND_DRAFT' | 'ROUND_ACTIVE',
+): Promise<string> {
+  const slug = uid()
+  const competition = await prisma.competition.create({
+    data: {
+      name: `Comp ${slug}`,
+      slug: `comp-${slug}`,
+      programId,
+      status: 'ACTIVE',
+    },
+  })
+  const round = await prisma.round.create({
+    data: {
+      name: `Mentoring ${slug}`,
+      slug: `mentoring-${slug}`,
+      roundType: 'MENTORING',
+      sortOrder: 1,
+      status,
+      competitionId: competition.id,
+    },
+  })
+  await prisma.projectRoundState.create({
+    data: { roundId: round.id, projectId },
+  })
+  return round.id
+}
+
+describe('mentor-assignment email deferral (regression for 2026-05-26 duplicate-email incident)', () => {
+  const programIds: string[] = []
+  const userIds: string[] = []
+
+  beforeEach(() => {
+    sendStyledMock.mockClear()
+    sendMentorBulkMock.mockClear()
+    sendTeamIntroMock.mockClear()
+  })
+
+  afterAll(async () => {
+    for (const programId of programIds) {
+      await prisma.mentorAssignment.deleteMany({ where: { project: { programId } } })
+      await prisma.teamMember.deleteMany({ where: { project: { programId } } })
+      await cleanupTestData(programId, [])
+    }
+    if (userIds.length > 0) {
+      await prisma.user.deleteMany({ where: { id: { in: userIds } } })
+    }
+  })
+
+  it('mentor.assign in DRAFT round creates in-app notif rows but sends ZERO emails', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `defer-draft-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Draft Project' })
+    await attachToMentoringRound(program.id, project.id, 'ROUND_DRAFT')
+
+    const mentor = await makeMentor()
+    userIds.push(mentor.id)
+    const teamUser = await makeTeamMember(project.id)
+    userIds.push(teamUser)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    await caller.assign({ projectId: project.id, mentorId: mentor.id })
+
+    expect(sendStyledMock).not.toHaveBeenCalled()
+    expect(sendMentorBulkMock).not.toHaveBeenCalled()
+    expect(sendTeamIntroMock).not.toHaveBeenCalled()
+
+    // In-app notification rows still fire so admin + mentor see staged state.
+    const mentorNotifs = await prisma.inAppNotification.findMany({
+      where: { userId: mentor.id, type: 'MENTEE_ASSIGNED' },
+    })
+    expect(mentorNotifs.length).toBe(1)
+    const teamNotifs = await prisma.inAppNotification.findMany({
+      where: { userId: teamUser, type: 'MENTOR_ASSIGNED' },
+    })
+    expect(teamNotifs.length).toBe(1)
+  })
+
+  it('mentor.assign in ACTIVE round still sends the per-assignment emails (legacy behaviour preserved)', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `defer-active-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Active Project' })
+    await attachToMentoringRound(program.id, project.id, 'ROUND_ACTIVE')
+
+    const mentor = await makeMentor()
+    userIds.push(mentor.id)
+    const teamUser = await makeTeamMember(project.id)
+    userIds.push(teamUser)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    await caller.assign({ projectId: project.id, mentorId: mentor.id })
+
+    // Either styled notif email OR the explicit team-intro email is allowed
+    // to fire here — point is: at least one outbound email happens when the
+    // round is open. The DRAFT test above is the one that must stay at zero.
+    const sentCount =
+      sendStyledMock.mock.calls.length + sendTeamIntroMock.mock.calls.length
+    expect(sentCount).toBeGreaterThan(0)
+  })
+
+  it('mentor.bulkAssign in DRAFT round sends ZERO emails across multiple projects', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `defer-bulk-${uid()}` })
+    programIds.push(program.id)
+    const p1 = await createTestProject(program.id, { title: 'BulkDraft 1' })
+    const p2 = await createTestProject(program.id, { title: 'BulkDraft 2' })
+    const p3 = await createTestProject(program.id, { title: 'BulkDraft 3' })
+    await attachToMentoringRound(program.id, p1.id, 'ROUND_DRAFT')
+    await attachToMentoringRound(program.id, p2.id, 'ROUND_DRAFT')
+    await attachToMentoringRound(program.id, p3.id, 'ROUND_DRAFT')
+
+    const mentor = await makeMentor()
+    userIds.push(mentor.id)
+    userIds.push(await makeTeamMember(p1.id))
+    userIds.push(await makeTeamMember(p2.id))
+    userIds.push(await makeTeamMember(p3.id))
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    await caller.bulkAssign({
+      mentorIds: [mentor.id],
+      projectIds: [p1.id, p2.id, p3.id],
+    })
+
+    expect(sendStyledMock).not.toHaveBeenCalled()
+    expect(sendMentorBulkMock).not.toHaveBeenCalled()
+    expect(sendTeamIntroMock).not.toHaveBeenCalled()
+  })
+})