merge: PR8 — multi-mentor per team + change-requests + inline previews

Schema: MentorAssignment becomes M:N (composite unique on (projectId, mentorId)).
MentorFile re-scopes to projectId (team-wide); mentorAssignmentId becomes a
nullable audit FK with SetNull. New MentorChangeRequest model + status enum.

Behavior:
- mentor.assign stacks mentors per team; per-team assignment email fires
  once per row (idempotent via notificationSentAt).
- mentor.requestChange / listChangeRequests / resolveChangeRequest provide
  the change-request inbox; mentors are NOT notified, only admins.
- Workspace files re-scoped to project so all co-mentors and team members
  share one file list and chat.
- New inline FilePreview support in the mentor workspace.
- mentor.getProjectMentors surfaces co-mentors on the mentor workspace.

Migration: hand-written, idempotent guards, two-phase backfill on
MentorFile.projectId. Verified against May 7 prod dump with rollback.sql.

PRE-DEPLOY: pull a fresh prod DB dump and re-run the dry-run before
applying the migration to prod (the May 7 snapshot may not include
mentors added since by another admin).

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

prisma/migrations/20260522155652_multi_mentor_per_team/migration.sql

@@ -0,0 +1,78 @@
+-- Hand-written migration for PR8 (multi-mentor per team).
+--
+-- All DDL guarded with IF EXISTS / IF NOT EXISTS so the docker-entrypoint
+-- retry loop is safe to re-run. No regex (the 2026-05-07 prod incident was
+-- caused by Prisma 6 generating regex-based DDL that Postgres rejected).
+-- No BEGIN/COMMIT blocks — Prisma wraps the migration in a transaction.
+
+-- Phase 1: MentorAssignment — drop unique, add composite, add notification field
+ALTER TABLE "MentorAssignment" DROP CONSTRAINT IF EXISTS "MentorAssignment_projectId_key";
+DROP INDEX IF EXISTS "MentorAssignment_projectId_key";
+CREATE UNIQUE INDEX IF NOT EXISTS "MentorAssignment_projectId_mentorId_key"
+  ON "MentorAssignment"("projectId", "mentorId");
+CREATE INDEX IF NOT EXISTS "MentorAssignment_projectId_idx"
+  ON "MentorAssignment"("projectId");
+ALTER TABLE "MentorAssignment" ADD COLUMN IF NOT EXISTS "notificationSentAt" TIMESTAMP(3);
+
+-- Phase 2: MentorFile — re-scope to project (two-phase backfill)
+ALTER TABLE "MentorFile" ADD COLUMN IF NOT EXISTS "projectId" TEXT;
+UPDATE "MentorFile" mf
+   SET "projectId" = ma."projectId"
+  FROM "MentorAssignment" ma
+ WHERE mf."mentorAssignmentId" = ma."id"
+   AND mf."projectId" IS NULL;
+ALTER TABLE "MentorFile" ALTER COLUMN "projectId" SET NOT NULL;
+ALTER TABLE "MentorFile" DROP CONSTRAINT IF EXISTS "MentorFile_projectId_fkey";
+ALTER TABLE "MentorFile" ADD CONSTRAINT "MentorFile_projectId_fkey"
+  FOREIGN KEY ("projectId") REFERENCES "Project"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+CREATE INDEX IF NOT EXISTS "MentorFile_projectId_idx" ON "MentorFile"("projectId");
+
+-- Phase 2b: Make MentorFile.mentorAssignmentId nullable + switch its FK to SetNull
+ALTER TABLE "MentorFile" ALTER COLUMN "mentorAssignmentId" DROP NOT NULL;
+ALTER TABLE "MentorFile" DROP CONSTRAINT IF EXISTS "MentorFile_mentorAssignmentId_fkey";
+ALTER TABLE "MentorFile" ADD CONSTRAINT "MentorFile_mentorAssignmentId_fkey"
+  FOREIGN KEY ("mentorAssignmentId") REFERENCES "MentorAssignment"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- Phase 3: MentorChangeRequest table
+-- Postgres < 14 doesn't support CREATE TYPE ... IF NOT EXISTS, so wrap in a
+-- DO block that swallows duplicate_object errors (idempotent for re-runs).
+DO $$ BEGIN
+  CREATE TYPE "MentorChangeRequestStatus" AS ENUM ('PENDING', 'RESOLVED', 'DISMISSED');
+EXCEPTION
+  WHEN duplicate_object THEN NULL;
+END $$;
+
+CREATE TABLE IF NOT EXISTS "MentorChangeRequest" (
+  "id"                  TEXT NOT NULL,
+  "projectId"           TEXT NOT NULL,
+  "targetAssignmentId"  TEXT,
+  "requestedByUserId"   TEXT,
+  "reason"              TEXT NOT NULL,
+  "status"              "MentorChangeRequestStatus" NOT NULL DEFAULT 'PENDING',
+  "resolvedByUserId"    TEXT,
+  "resolvedAt"          TIMESTAMP(3),
+  "resolutionNote"      TEXT,
+  "createdAt"           TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "updatedAt"           TIMESTAMP(3) NOT NULL,
+  CONSTRAINT "MentorChangeRequest_pkey" PRIMARY KEY ("id")
+);
+
+ALTER TABLE "MentorChangeRequest" DROP CONSTRAINT IF EXISTS "MentorChangeRequest_projectId_fkey";
+ALTER TABLE "MentorChangeRequest" ADD CONSTRAINT "MentorChangeRequest_projectId_fkey"
+  FOREIGN KEY ("projectId") REFERENCES "Project"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+ALTER TABLE "MentorChangeRequest" DROP CONSTRAINT IF EXISTS "MentorChangeRequest_targetAssignmentId_fkey";
+ALTER TABLE "MentorChangeRequest" ADD CONSTRAINT "MentorChangeRequest_targetAssignmentId_fkey"
+  FOREIGN KEY ("targetAssignmentId") REFERENCES "MentorAssignment"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+ALTER TABLE "MentorChangeRequest" DROP CONSTRAINT IF EXISTS "MentorChangeRequest_requestedByUserId_fkey";
+ALTER TABLE "MentorChangeRequest" ADD CONSTRAINT "MentorChangeRequest_requestedByUserId_fkey"
+  FOREIGN KEY ("requestedByUserId") REFERENCES "User"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+ALTER TABLE "MentorChangeRequest" DROP CONSTRAINT IF EXISTS "MentorChangeRequest_resolvedByUserId_fkey";
+ALTER TABLE "MentorChangeRequest" ADD CONSTRAINT "MentorChangeRequest_resolvedByUserId_fkey"
+  FOREIGN KEY ("resolvedByUserId") REFERENCES "User"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+CREATE INDEX IF NOT EXISTS "MentorChangeRequest_projectId_idx" ON "MentorChangeRequest"("projectId");
+CREATE INDEX IF NOT EXISTS "MentorChangeRequest_status_idx" ON "MentorChangeRequest"("status");
+CREATE INDEX IF NOT EXISTS "MentorChangeRequest_targetAssignmentId_idx" ON "MentorChangeRequest"("targetAssignmentId");

prisma/migrations/20260522155652_multi_mentor_per_team/rollback.sql

@@ -0,0 +1,23 @@
+-- PR8 rollback SQL (manual, only safe BEFORE any project has >1 mentor)
+-- Reverses 20260522155652_multi_mentor_per_team
+
+-- MentorChangeRequest: drop new table + enum
+DROP TABLE IF EXISTS "MentorChangeRequest";
+DROP TYPE IF EXISTS "MentorChangeRequestStatus";
+
+-- MentorFile: drop projectId scope + restore mentorAssignmentId as required Cascade
+ALTER TABLE "MentorFile" DROP CONSTRAINT IF EXISTS "MentorFile_projectId_fkey";
+DROP INDEX IF EXISTS "MentorFile_projectId_idx";
+ALTER TABLE "MentorFile" DROP COLUMN IF EXISTS "projectId";
+-- Restoring NOT NULL is safe only if no rows have NULL mentorAssignmentId (true unless multi-mentor assignments were dropped post-migration)
+ALTER TABLE "MentorFile" ALTER COLUMN "mentorAssignmentId" SET NOT NULL;
+ALTER TABLE "MentorFile" DROP CONSTRAINT IF EXISTS "MentorFile_mentorAssignmentId_fkey";
+ALTER TABLE "MentorFile" ADD CONSTRAINT "MentorFile_mentorAssignmentId_fkey"
+  FOREIGN KEY ("mentorAssignmentId") REFERENCES "MentorAssignment"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- MentorAssignment: restore projectId @unique + drop new fields
+DROP INDEX IF EXISTS "MentorAssignment_projectId_mentorId_key";
+DROP INDEX IF EXISTS "MentorAssignment_projectId_idx";
+ALTER TABLE "MentorAssignment" DROP COLUMN IF EXISTS "notificationSentAt";
+-- Re-adding UNIQUE will FAIL if any project has >1 mentor (intended safety signal)
+ALTER TABLE "MentorAssignment" ADD CONSTRAINT "MentorAssignment_projectId_key" UNIQUE ("projectId");

prisma/schema.prisma

@@ -118,7 +118,6 @@ enum NotificationChannel {
   NONE
 }
 
-
 enum PartnerVisibility {
   ADMIN_ONLY
   JURY_VISIBLE
@@ -133,7 +132,6 @@ enum PartnerType {
   OTHER
 }
 
-
 // =============================================================================
 // COMPETITION / ROUND ENGINE ENUMS
 // =============================================================================
@@ -171,7 +169,6 @@ enum ProjectRoundStateValue {
   WITHDRAWN
 }
 
-
 enum CapMode {
   HARD
   SOFT
@@ -428,6 +425,10 @@ model User {
   // Grand-finale logistics
   finalistAttendances AttendingMember[]
 
+  // Mentor change requests
+  mentorChangeRequestsRequested MentorChangeRequest[] @relation("MentorChangeRequester")
+  mentorChangeRequestsResolved  MentorChangeRequest[] @relation("MentorChangeResolver")
+
   @@index([role])
   @@index([status])
 }
@@ -629,7 +630,9 @@ model Project {
   assignments           Assignment[]
   submittedBy           User?                  @relation("ProjectSubmittedBy", fields: [submittedByUserId], references: [id], onDelete: SetNull)
   teamMembers           TeamMember[]
-  mentorAssignment      MentorAssignment?
+  mentorAssignments     MentorAssignment[]
+  mentorFiles           MentorFile[]
+  mentorChangeRequests  MentorChangeRequest[]
   filteringResults      FilteringResult[]
   awardEligibilities    AwardEligibility[]
   awardVotes            AwardVote[]
@@ -1270,7 +1273,7 @@ model TeamMember {
 
 model MentorAssignment {
   id        String @id @default(cuid())
-  projectId String @unique // One mentor per project
+  projectId String // Team can have multiple mentors; uniqueness enforced via composite below
   mentorId  String // User with MENTOR role or expertise
 
   // Assignment tracking
@@ -1278,6 +1281,9 @@ model MentorAssignment {
   assignedAt DateTime               @default(now())
   assignedBy String? // Admin who assigned
 
+  // Per-assignment email idempotency: stamped once the assignment notification email is sent.
+  notificationSentAt DateTime?
+
   // AI assignment metadata
   aiConfidenceScore   Float?
   expertiseMatchScore Float?
@@ -1304,11 +1310,47 @@ model MentorAssignment {
   milestoneCompletions MentorMilestoneCompletion[]
   messages             MentorMessage[]
   files                MentorFile[]
+  changeRequests       MentorChangeRequest[]       @relation("MentorChangeRequestTarget")
 
+  @@unique([projectId, mentorId])
+  @@index([projectId])
   @@index([mentorId])
   @@index([method])
 }
 
+// =============================================================================
+// MENTOR CHANGE REQUESTS
+// =============================================================================
+
+enum MentorChangeRequestStatus {
+  PENDING
+  RESOLVED
+  DISMISSED
+}
+
+model MentorChangeRequest {
+  id                 String                    @id @default(cuid())
+  projectId          String
+  targetAssignmentId String? // Optional: a specific co-mentor the request is about
+  requestedByUserId  String?
+  reason             String                    @db.Text
+  status             MentorChangeRequestStatus @default(PENDING)
+  resolvedByUserId   String?
+  resolvedAt         DateTime?
+  resolutionNote     String?                   @db.Text
+  createdAt          DateTime                  @default(now())
+  updatedAt          DateTime                  @updatedAt
+
+  project          Project           @relation(fields: [projectId], references: [id], onDelete: Cascade)
+  targetAssignment MentorAssignment? @relation("MentorChangeRequestTarget", fields: [targetAssignmentId], references: [id], onDelete: SetNull)
+  requestedBy      User?             @relation("MentorChangeRequester", fields: [requestedByUserId], references: [id], onDelete: SetNull)
+  resolvedBy       User?             @relation("MentorChangeResolver", fields: [resolvedByUserId], references: [id])
+
+  @@index([projectId])
+  @@index([status])
+  @@index([targetAssignmentId])
+}
+
 // =============================================================================
 // FILTERING ROUND SYSTEM
 // =============================================================================
@@ -2449,7 +2491,8 @@ model AssignmentIntent {
 
 model MentorFile {
   id                 String  @id @default(cuid())
-  mentorAssignmentId String
+  projectId          String // Primary access scope: files belong to the team
+  mentorAssignmentId String? // Nullable audit FK: which assignment uploaded; survives mentor drop
   uploadedByUserId   String
 
   fileName    String
@@ -2468,13 +2511,15 @@ model MentorFile {
   createdAt DateTime @default(now())
 
   // Relations
-  mentorAssignment MentorAssignment          @relation(fields: [mentorAssignmentId], references: [id], onDelete: Cascade)
+  project          Project                    @relation(fields: [projectId], references: [id], onDelete: Cascade, onUpdate: Cascade)
+  mentorAssignment MentorAssignment?          @relation(fields: [mentorAssignmentId], references: [id], onDelete: SetNull)
   uploadedBy       User                       @relation("MentorFileUploader", fields: [uploadedByUserId], references: [id])
   promotedBy       User?                      @relation("MentorFilePromoter", fields: [promotedByUserId], references: [id])
   promotedFile     ProjectFile?               @relation("PromotedFromMentorFile", fields: [promotedToFileId], references: [id], onDelete: SetNull)
   comments         MentorFileComment[]
   promotionEvents  SubmissionPromotionEvent[]
 
+  @@index([projectId])
   @@index([mentorAssignmentId])
   @@index([uploadedByUserId])
 }

src/app/(admin)/admin/projects/[id]/mentor/page.tsx

@@ -18,6 +18,8 @@ import { Skeleton } from '@/components/ui/skeleton'
 import { Avatar, AvatarFallback } from '@/components/ui/avatar'
 import { Progress } from '@/components/ui/progress'
 import { Input } from '@/components/ui/input'
+import { Textarea } from '@/components/ui/textarea'
+import { Label } from '@/components/ui/label'
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs'
 import {
   Table,
@@ -27,15 +29,35 @@ import {
   TableHeader,
   TableRow,
 } from '@/components/ui/table'
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from '@/components/ui/dialog'
+import {
+  AlertDialog,
+  AlertDialogAction,
+  AlertDialogCancel,
+  AlertDialogContent,
+  AlertDialogDescription,
+  AlertDialogFooter,
+  AlertDialogHeader,
+  AlertDialogTitle,
+} from '@/components/ui/alert-dialog'
 import {
   AlertTriangle,
   ArrowLeft,
   Bot,
   Check,
+  Inbox,
   Loader2,
   Search,
   Sparkles,
   Users,
+  UserPlus,
 } from 'lucide-react'
 import { getInitials, formatEnumLabel } from '@/lib/utils'
 
@@ -48,14 +70,31 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
   const utils = trpc.useUtils()
   const [search, setSearch] = useState('')
   const [pendingMentorId, setPendingMentorId] = useState<string | null>(null)
+  const [unassignTarget, setUnassignTarget] = useState<{
+    assignmentId: string
+    mentorName: string
+  } | null>(null)
 
   const { data: project, isLoading: projectLoading } = trpc.project.get.useQuery({ id: projectId })
 
-  const { data: candidatesData, isLoading: candidatesLoading } =
-    trpc.mentor.getCandidates.useQuery(
-      { projectId },
-      { enabled: !!project && !project.mentorAssignment },
+  // Already-assigned mentors (full list). Project.get spreads the underlying
+  // `mentorAssignments` relation so we can read it directly.
+  const assignedMentorAssignments = useMemo(() => {
+    if (!project) return []
+    // The Prisma relation is included via `...project` spread; type comes
+    // through the tRPC client.
+    type Assignment = NonNullable<typeof project>['mentorAssignments'][number]
+    return ((project as unknown as { mentorAssignments?: Assignment[] }).mentorAssignments ?? []).filter(
+      (a) => !a.droppedAt,
     )
+  }, [project])
+  const assignedMentorIds = useMemo(
+    () => new Set(assignedMentorAssignments.map((a) => a.mentorId)),
+    [assignedMentorAssignments],
+  )
+
+  const { data: candidatesData, isLoading: candidatesLoading } =
+    trpc.mentor.getCandidates.useQuery({ projectId }, { enabled: !!project })
 
   const {
     data: suggestionsData,
@@ -63,12 +102,12 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
     refetch: refetchSuggestions,
   } = trpc.mentor.getSuggestions.useQuery(
     { projectId, limit: 5 },
-    { enabled: !!project && !project.mentorAssignment },
+    { enabled: !!project },
   )
 
   const assignMutation = trpc.mentor.assign.useMutation({
     onSuccess: () => {
-      toast.success('Mentor assigned')
+      toast.success('Mentor added')
       utils.project.get.invalidate({ id: projectId })
       utils.mentor.getCandidates.invalidate({ projectId })
       utils.mentor.getSuggestions.invalidate({ projectId })
@@ -86,21 +125,31 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
       utils.project.get.invalidate({ id: projectId })
       utils.mentor.getCandidates.invalidate({ projectId })
       utils.mentor.getSuggestions.invalidate({ projectId })
+      setUnassignTarget(null)
+    },
+    onError: (err) => {
+      toast.error(err.message)
+      setUnassignTarget(null)
     },
-    onError: (err) => toast.error(err.message),
   })
 
   const filteredCandidates = useMemo(() => {
     if (!candidatesData) return []
+    const base = candidatesData.candidates.filter((c) => !assignedMentorIds.has(c.id))
     const q = search.trim().toLowerCase()
-    if (!q) return candidatesData.candidates
-    return candidatesData.candidates.filter((c) => {
+    if (!q) return base
+    return base.filter((c) => {
       const hay = [c.name ?? '', c.email, ...(c.expertiseTags ?? []), c.country ?? '']
         .join(' ')
         .toLowerCase()
       return hay.includes(q)
     })
-  }, [candidatesData, search])
+  }, [candidatesData, search, assignedMentorIds])
+
+  const filteredSuggestions = useMemo(() => {
+    if (!suggestionsData) return []
+    return suggestionsData.suggestions.filter((s) => !assignedMentorIds.has(s.mentorId))
+  }, [suggestionsData, assignedMentorIds])
 
   if (projectLoading) return <MentorAssignmentSkeleton />
   if (!project) {
@@ -113,7 +162,6 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
     )
   }
 
-  const hasMentor = !!project.mentorAssignment
   const teamSize = project.teamMembers?.length ?? 0
   const aiSource = suggestionsData?.source ?? 'ai'
 
@@ -206,80 +254,112 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
         </CardContent>
       </Card>
 
+      {/* ─── Pending Change Requests ─── */}
+      <PendingChangeRequestsPanel projectId={projectId} />
+
       {/* ─── Currently Assigned ─── */}
       <Card>
         <CardHeader>
           <CardTitle className="text-lg">Currently Assigned</CardTitle>
+          <CardDescription>
+            {assignedMentorAssignments.length === 0
+              ? 'No mentors assigned yet'
+              : `${assignedMentorAssignments.length} mentor${
+                  assignedMentorAssignments.length === 1 ? '' : 's'
+                } on this team`}
+          </CardDescription>
         </CardHeader>
         <CardContent>
-          {hasMentor ? (
-            <div className="flex items-center justify-between">
-              <div className="flex items-center gap-4">
+          {assignedMentorAssignments.length === 0 ? (
+            <div className="rounded-md border border-dashed py-8 text-center">
+              <Users className="text-muted-foreground mx-auto mb-2 h-8 w-8" />
+              <p className="text-muted-foreground text-sm">
+                No mentors assigned yet — add one below.
+              </p>
+            </div>
+          ) : (
+            <ul className="divide-y">
+              {assignedMentorAssignments.map((a) => {
+                const m = a.mentor
+                const tags = m.expertiseTags ?? []
+                return (
+                  <li
+                    key={a.id}
+                    className="flex items-start justify-between gap-4 py-4 first:pt-0 last:pb-0"
+                  >
+                    <div className="flex flex-1 items-start gap-4">
                       <Avatar className="h-12 w-12">
                         <AvatarFallback>
-                    {getInitials(
-                      project.mentorAssignment!.mentor.name ||
-                        project.mentorAssignment!.mentor.email,
-                    )}
+                          {getInitials(m.name || m.email)}
                         </AvatarFallback>
                       </Avatar>
-                <div>
+                      <div className="min-w-0 flex-1">
                         <Link
-                    href={`/admin/mentors/${project.mentorAssignment!.mentor.id}`}
+                          href={`/admin/mentors/${m.id}`}
                           className="font-medium hover:underline"
                         >
-                    {project.mentorAssignment!.mentor.name || 'Unnamed'}
+                          {m.name || 'Unnamed'}
                         </Link>
-                  <p className="text-muted-foreground text-sm">
-                    {project.mentorAssignment!.mentor.email}
-                  </p>
-                  {project.mentorAssignment!.mentor.expertiseTags &&
-                    project.mentorAssignment!.mentor.expertiseTags.length > 0 && (
+                        <p className="text-muted-foreground text-sm">{m.email}</p>
+                        {tags.length > 0 && (
                           <div className="mt-1 flex flex-wrap gap-1">
-                        {project.mentorAssignment!.mentor.expertiseTags
-                          .slice(0, 5)
-                          .map((tag: string) => (
+                            {tags.slice(0, 5).map((tag: string) => (
                               <Badge key={tag} variant="secondary" className="text-xs">
                                 {tag}
                               </Badge>
                             ))}
+                            {tags.length > 5 && (
+                              <Badge variant="outline" className="text-xs">
+                                +{tags.length - 5}
+                              </Badge>
+                            )}
                           </div>
                         )}
+                        <p className="text-muted-foreground mt-2 text-xs">
+                          Assigned{' '}
+                          {new Date(a.assignedAt).toLocaleDateString(undefined, {
+                            year: 'numeric',
+                            month: 'short',
+                            day: 'numeric',
+                          })}
+                        </p>
                       </div>
                     </div>
                     <div className="flex flex-col items-end gap-2">
                       <Badge variant="outline" className="text-xs">
-                  {project.mentorAssignment!.method.replace(/_/g, ' ')}
+                        {a.method.replace(/_/g, ' ')}
                       </Badge>
                       <Button
-                  variant="destructive"
+                        variant="outline"
                         size="sm"
-                  onClick={() => unassignMutation.mutate({ projectId })}
+                        onClick={() =>
+                          setUnassignTarget({
+                            assignmentId: a.id,
+                            mentorName: m.name || m.email,
+                          })
+                        }
                         disabled={unassignMutation.isPending}
                       >
-                  {unassignMutation.isPending ? (
-                    <Loader2 className="h-4 w-4 animate-spin" />
-                  ) : (
-                    'Unassign'
-                  )}
+                        Unassign
                       </Button>
                     </div>
-            </div>
-          ) : (
-            <p className="text-muted-foreground text-sm">
-              No mentor assigned yet — pick one below.
-            </p>
+                  </li>
+                )
+              })}
+            </ul>
           )}
         </CardContent>
       </Card>
 
-      {/* ─── Pick a Mentor ─── */}
-      {!hasMentor && (
+      {/* ─── Add a Mentor ─── */}
       <Card>
         <CardHeader>
-            <CardTitle className="text-lg">Pick a Mentor</CardTitle>
+          <CardTitle className="text-lg flex items-center gap-2">
+            <UserPlus className="h-5 w-5" />
+            Add a Mentor
+          </CardTitle>
           <CardDescription>
-              Browse all eligible mentors or use AI to surface the best fits.
+            Stack additional mentors on this team. Browse all eligible mentors or use AI to surface the best fits.
           </CardDescription>
         </CardHeader>
         <CardContent>
@@ -311,7 +391,9 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
                 </div>
               ) : filteredCandidates.length === 0 ? (
                 <div className="text-muted-foreground py-8 text-center text-sm">
-                    No matching mentors. Try a different search.
+                  {assignedMentorIds.size > 0 && search.trim() === ''
+                    ? 'All eligible mentors are already assigned.'
+                    : 'No matching mentors. Try a different search.'}
                 </div>
               ) : (
                 <div className="overflow-hidden rounded-md border">
@@ -376,7 +458,7 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
                                 <Loader2 className="h-4 w-4 animate-spin" />
                               ) : (
                                 <>
-                                    <Check className="mr-1 h-3.5 w-3.5" /> Assign
+                                  <Check className="mr-1 h-3.5 w-3.5" /> Add
                                 </>
                               )}
                             </Button>
@@ -422,13 +504,15 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
                     <Skeleton key={i} className="h-24 w-full" />
                   ))}
                 </div>
-                ) : !suggestionsData || suggestionsData.suggestions.length === 0 ? (
+              ) : filteredSuggestions.length === 0 ? (
                 <p className="text-muted-foreground py-8 text-center text-sm">
-                    No suggestions available.
+                  {assignedMentorIds.size > 0
+                    ? 'All top suggestions are already assigned.'
+                    : 'No suggestions available.'}
                 </p>
               ) : (
                 <div className="space-y-3">
-                    {suggestionsData.suggestions.map((s, i) => (
+                  {filteredSuggestions.map((s, i) => (
                     <div
                       key={s.mentorId}
                       className="flex items-start justify-between rounded-md border p-4"
@@ -503,7 +587,7 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
                           <Loader2 className="h-4 w-4 animate-spin" />
                         ) : (
                           <>
-                              <Check className="mr-1 h-3.5 w-3.5" /> Assign
+                            <Check className="mr-1 h-3.5 w-3.5" /> Add
                           </>
                         )}
                       </Button>
@@ -515,8 +599,284 @@ function MentorAssignmentContent({ projectId }: { projectId: string }) {
           </Tabs>
         </CardContent>
       </Card>
+
+      {/* ─── Unassign confirm ─── */}
+      <AlertDialog
+        open={!!unassignTarget}
+        onOpenChange={(open) => {
+          if (!open) setUnassignTarget(null)
+        }}
+      >
+        <AlertDialogContent>
+          <AlertDialogHeader>
+            <AlertDialogTitle>Unassign mentor?</AlertDialogTitle>
+            <AlertDialogDescription>
+              {unassignTarget
+                ? `Remove ${unassignTarget.mentorName} from this team? Other co-mentors will remain.`
+                : ''}
+            </AlertDialogDescription>
+          </AlertDialogHeader>
+          <AlertDialogFooter>
+            <AlertDialogCancel disabled={unassignMutation.isPending}>
+              Cancel
+            </AlertDialogCancel>
+            <AlertDialogAction
+              onClick={(e) => {
+                e.preventDefault()
+                if (!unassignTarget) return
+                unassignMutation.mutate({ assignmentId: unassignTarget.assignmentId })
+              }}
+              disabled={unassignMutation.isPending}
+            >
+              {unassignMutation.isPending ? (
+                <Loader2 className="h-4 w-4 animate-spin" />
+              ) : (
+                'Unassign'
+              )}
+            </AlertDialogAction>
+          </AlertDialogFooter>
+        </AlertDialogContent>
+      </AlertDialog>
+    </div>
+  )
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Pending Change Requests panel
+// ─────────────────────────────────────────────────────────────────────────────
+
+function PendingChangeRequestsPanel({ projectId }: { projectId: string }) {
+  const utils = trpc.useUtils()
+  const { data: requests, isLoading } = trpc.mentor.listChangeRequests.useQuery({
+    projectId,
+    status: 'PENDING',
+  })
+
+  const [resolveTarget, setResolveTarget] = useState<{
+    id: string
+    status: 'RESOLVED' | 'DISMISSED'
+    requesterName: string
+  } | null>(null)
+  const [resolutionNote, setResolutionNote] = useState('')
+
+  const resolveMutation = trpc.mentor.resolveChangeRequest.useMutation({
+    onSuccess: (_, variables) => {
+      toast.success(
+        `Request marked ${variables.status === 'RESOLVED' ? 'resolved' : 'dismissed'}`,
+      )
+      utils.mentor.listChangeRequests.invalidate()
+      setResolveTarget(null)
+      setResolutionNote('')
+    },
+    onError: (err) => toast.error(err.message),
+  })
+
+  if (isLoading) {
+    return (
+      <Card>
+        <CardHeader>
+          <CardTitle className="text-lg flex items-center gap-2">
+            <Inbox className="h-5 w-5" />
+            Pending change requests
+          </CardTitle>
+        </CardHeader>
+        <CardContent>
+          <Skeleton className="h-24 w-full" />
+        </CardContent>
+      </Card>
+    )
+  }
+
+  if (!requests || requests.length === 0) {
+    return null
+  }
+
+  return (
+    <>
+      <Card className="border-amber-300 dark:border-amber-700">
+        <CardHeader>
+          <CardTitle className="text-lg flex items-center gap-2">
+            <Inbox className="h-5 w-5 text-amber-600" />
+            Pending change requests
+            <Badge variant="secondary" className="ml-1">
+              {requests.length}
+            </Badge>
+          </CardTitle>
+          <CardDescription>
+            Team members or mentors have asked admin to change a mentor on this team.
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <ul className="space-y-3">
+            {requests.map((r) => (
+              <ChangeRequestRow
+                key={r.id}
+                request={r}
+                onResolve={(status) =>
+                  setResolveTarget({
+                    id: r.id,
+                    status,
+                    requesterName:
+                      r.requestedBy?.name ?? r.requestedBy?.email ?? 'Unknown',
+                  })
+                }
+              />
+            ))}
+          </ul>
+        </CardContent>
+      </Card>
+
+      <Dialog
+        open={!!resolveTarget}
+        onOpenChange={(open) => {
+          if (!open) {
+            setResolveTarget(null)
+            setResolutionNote('')
+          }
+        }}
+      >
+        <DialogContent>
+          <DialogHeader>
+            <DialogTitle>
+              {resolveTarget?.status === 'RESOLVED'
+                ? 'Mark request resolved'
+                : 'Dismiss request'}
+            </DialogTitle>
+            <DialogDescription>
+              {resolveTarget?.status === 'RESOLVED'
+                ? `You've taken action on the request from ${resolveTarget?.requesterName}. Optionally add a note explaining what was done.`
+                : `Close the request from ${resolveTarget?.requesterName} without action. Optionally add a note explaining why.`}
+            </DialogDescription>
+          </DialogHeader>
+          <div className="space-y-2">
+            <Label htmlFor="resolution-note">Resolution note (optional)</Label>
+            <Textarea
+              id="resolution-note"
+              value={resolutionNote}
+              onChange={(e) => setResolutionNote(e.target.value)}
+              placeholder="e.g. Replaced Jane with John based on expertise mismatch."
+              rows={4}
+              maxLength={2000}
+            />
+          </div>
+          <DialogFooter>
+            <Button
+              variant="outline"
+              onClick={() => {
+                setResolveTarget(null)
+                setResolutionNote('')
+              }}
+              disabled={resolveMutation.isPending}
+            >
+              Cancel
+            </Button>
+            <Button
+              onClick={() => {
+                if (!resolveTarget) return
+                resolveMutation.mutate({
+                  id: resolveTarget.id,
+                  status: resolveTarget.status,
+                  resolutionNote: resolutionNote.trim() || undefined,
+                })
+              }}
+              disabled={resolveMutation.isPending}
+            >
+              {resolveMutation.isPending ? (
+                <Loader2 className="h-4 w-4 animate-spin" />
+              ) : resolveTarget?.status === 'RESOLVED' ? (
+                'Mark Resolved'
+              ) : (
+                'Dismiss'
+              )}
+            </Button>
+          </DialogFooter>
+        </DialogContent>
+      </Dialog>
+    </>
+  )
+}
+
+type ChangeRequestRowProps = {
+  request: {
+    id: string
+    reason: string
+    createdAt: Date
+    requestedBy: { id: string; name: string | null; email: string } | null
+    targetAssignment: {
+      id: string
+      mentor: { id: string; name: string | null; email: string }
+    } | null
+  }
+  onResolve: (status: 'RESOLVED' | 'DISMISSED') => void
+}
+
+function ChangeRequestRow({ request, onResolve }: ChangeRequestRowProps) {
+  const [expanded, setExpanded] = useState(false)
+  const reasonIsLong = request.reason.length > 240
+  return (
+    <li className="rounded-md border bg-card p-4">
+      <div className="flex items-start justify-between gap-4">
+        <div className="min-w-0 flex-1 space-y-2">
+          <div className="flex flex-wrap items-center gap-x-3 gap-y-1 text-sm">
+            <span className="font-medium">
+              {request.requestedBy?.name ?? request.requestedBy?.email ?? 'Unknown'}
+            </span>
+            {request.requestedBy?.email && request.requestedBy.name && (
+              <span className="text-muted-foreground text-xs">
+                {request.requestedBy.email}
+              </span>
+            )}
+            <span className="text-muted-foreground text-xs">
+              ·{' '}
+              {new Date(request.createdAt).toLocaleDateString(undefined, {
+                year: 'numeric',
+                month: 'short',
+                day: 'numeric',
+              })}
+            </span>
+          </div>
+          {request.targetAssignment && (
+            <div className="text-muted-foreground text-xs">
+              About:{' '}
+              <span className="font-medium">
+                {request.targetAssignment.mentor.name ||
+                  request.targetAssignment.mentor.email}
+              </span>
+            </div>
+          )}
+          <p
+            className={
+              expanded || !reasonIsLong
+                ? 'text-sm whitespace-pre-wrap'
+                : 'text-sm whitespace-pre-wrap line-clamp-4'
+            }
+          >
+            {request.reason}
+          </p>
+          {reasonIsLong && (
+            <button
+              type="button"
+              className="text-primary text-xs hover:underline"
+              onClick={() => setExpanded((v) => !v)}
+            >
+              {expanded ? 'Show less' : 'Show more'}
+            </button>
           )}
         </div>
+        <div className="flex shrink-0 flex-col gap-2">
+          <Button size="sm" onClick={() => onResolve('RESOLVED')}>
+            Mark Resolved
+          </Button>
+          <Button
+            size="sm"
+            variant="outline"
+            onClick={() => onResolve('DISMISSED')}
+          >
+            Dismiss
+          </Button>
+        </div>
+      </div>
+    </li>
   )
 }
 

src/app/(applicant)/applicant/mentor/page.tsx

@@ -1,6 +1,8 @@
 'use client'
 
+import { useState } from 'react'
 import { useSession } from 'next-auth/react'
+import { format } from 'date-fns'
 import { trpc } from '@/lib/trpc/client'
 import {
   Card,
@@ -9,13 +11,17 @@ import {
   CardHeader,
   CardTitle,
 } from '@/components/ui/card'
+import { Badge } from '@/components/ui/badge'
+import { Button } from '@/components/ui/button'
 import { Skeleton } from '@/components/ui/skeleton'
 import { MentorChat } from '@/components/shared/mentor-chat'
 import { WorkspaceFilesPanel } from '@/components/mentor/workspace-files-panel'
+import { RequestChangeDialog } from './request-change-dialog'
 import {
   MessageSquare,
   UserCircle,
   FileText,
+  UserCog,
 } from 'lucide-react'
 
 export default function ApplicantMentorPage() {
@@ -41,6 +47,8 @@ export default function ApplicantMentorPage() {
     },
   })
 
+  const [isChangeOpen, setIsChangeOpen] = useState(false)
+
   if (dashLoading) {
     return (
       <div className="space-y-6">
@@ -72,7 +80,20 @@ export default function ApplicantMentorPage() {
     )
   }
 
-  const mentor = dashboardData?.project?.mentorAssignment?.mentor
+  const assignments = dashboardData?.project?.mentorAssignments ?? []
+  const hasMentors = assignments.length > 0
+  const primaryAssignment = assignments[0] ?? null
+  const primaryMentor = primaryAssignment?.mentor
+  const hasPendingChangeRequest = !!dashboardData?.hasPendingMentorChangeRequest
+
+  const dialogMentors = assignments
+    .filter((a) => !!a.mentor)
+    .map((a) => ({
+      assignmentId: a.id,
+      name: a.mentor?.name || a.mentor?.email || 'Mentor',
+    }))
+
+  const teamHeading = assignments.length > 1 ? 'Your mentor team' : 'Your mentor'
 
   return (
     <div className="space-y-6">
@@ -83,23 +104,72 @@ export default function ApplicantMentorPage() {
           Mentor Communication
         </h1>
         <p className="text-muted-foreground">
-          Chat with your assigned mentor
+          {assignments.length > 1
+            ? 'Chat with your assigned mentor team'
+            : 'Chat with your assigned mentor'}
         </p>
       </div>
 
-      {/* Mentor info */}
-      {mentor ? (
-        <Card className="bg-muted/50">
-          <CardContent className="p-4">
-            <div className="flex items-center gap-3">
-              <UserCircle className="h-10 w-10 text-muted-foreground" />
-              <div>
-                <p className="font-medium">{mentor.name || 'Mentor'}</p>
-                <p className="text-sm text-muted-foreground">{mentor.email}</p>
+      {/* Mentor list */}
+      {hasMentors ? (
+        <section className="space-y-3">
+          <h2 className="text-lg font-semibold tracking-tight">{teamHeading}</h2>
+          <div className="grid gap-3 md:grid-cols-2">
+            {assignments.map((assignment) => {
+              const mentor = assignment.mentor
+              if (!mentor) return null
+              const expertise = mentor.expertiseTags ?? []
+              return (
+                <Card key={assignment.id} className="bg-muted/50">
+                  <CardContent className="p-4 space-y-3">
+                    <div className="flex items-start gap-3">
+                      <UserCircle className="h-10 w-10 text-muted-foreground shrink-0" />
+                      <div className="min-w-0 flex-1">
+                        <p className="font-medium truncate">
+                          {mentor.name || 'Mentor'}
+                        </p>
+                        <p className="text-sm text-muted-foreground truncate">
+                          {mentor.email}
+                        </p>
+                        {assignment.assignedAt && (
+                          <p className="text-xs text-muted-foreground mt-1">
+                            Assigned since {format(new Date(assignment.assignedAt), 'MMM d, yyyy')}
+                          </p>
+                        )}
                       </div>
                     </div>
+                    {expertise.length > 0 && (
+                      <div className="flex flex-wrap gap-1.5">
+                        {expertise.map((tag) => (
+                          <Badge key={tag} variant="secondary" className="font-normal">
+                            {tag}
+                          </Badge>
+                        ))}
+                      </div>
+                    )}
                   </CardContent>
                 </Card>
+              )
+            })}
+          </div>
+
+          {/* Request change action */}
+          <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-2 pt-1">
+            <p className="text-sm text-muted-foreground">
+              {hasPendingChangeRequest
+                ? "You have a pending mentor change request — admins will follow up soon."
+                : 'Need a different match? Let the program admins know.'}
+            </p>
+            <Button
+              variant="outline"
+              onClick={() => setIsChangeOpen(true)}
+              disabled={hasPendingChangeRequest}
+            >
+              <UserCog className="mr-2 h-4 w-4" />
+              {hasPendingChangeRequest ? 'Change requested' : 'Request a mentor change'}
+            </Button>
+          </div>
+        </section>
       ) : (
         <Card className="bg-muted/50">
           <CardContent className="flex flex-col items-center justify-center py-8">
@@ -113,12 +183,14 @@ export default function ApplicantMentorPage() {
       )}
 
       {/* Chat */}
-      {mentor && (
+      {primaryMentor && (
         <Card>
           <CardHeader>
             <CardTitle>Messages</CardTitle>
             <CardDescription>
-              Your conversation history with {mentor.name || 'your mentor'}
+              {assignments.length > 1
+                ? 'Your conversation history with your mentor team'
+                : `Your conversation history with ${primaryMentor.name || 'your mentor'}`}
             </CardDescription>
           </CardHeader>
           <CardContent>
@@ -136,12 +208,23 @@ export default function ApplicantMentorPage() {
       )}
 
       {/* Files */}
-      {dashboardData?.project?.mentorAssignment?.id && (
+      {primaryAssignment?.id && projectId && (
         <WorkspaceFilesPanel
-          mentorAssignmentId={dashboardData.project.mentorAssignment.id}
+          projectId={projectId}
+          mentorAssignmentId={primaryAssignment.id}
           asApplicant
         />
       )}
+
+      {/* Request change dialog */}
+      {projectId && (
+        <RequestChangeDialog
+          projectId={projectId}
+          mentors={dialogMentors}
+          open={isChangeOpen}
+          onOpenChange={setIsChangeOpen}
+        />
+      )}
     </div>
   )
 }

src/app/(applicant)/applicant/mentor/request-change-dialog.tsx

@@ -0,0 +1,179 @@
+'use client'
+
+import { useEffect, useState } from 'react'
+import { toast } from 'sonner'
+import { Loader2 } from 'lucide-react'
+
+import { trpc } from '@/lib/trpc/client'
+import { Button } from '@/components/ui/button'
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from '@/components/ui/dialog'
+import { Label } from '@/components/ui/label'
+import { Textarea } from '@/components/ui/textarea'
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from '@/components/ui/select'
+
+const REASON_MIN = 10
+const REASON_MAX = 2000
+const TARGET_ANY = '__any__'
+
+type MentorOption = {
+  assignmentId: string
+  name: string
+}
+
+type RequestChangeDialogProps = {
+  projectId: string
+  mentors: MentorOption[]
+  open: boolean
+  onOpenChange: (open: boolean) => void
+}
+
+export function RequestChangeDialog({
+  projectId,
+  mentors,
+  open,
+  onOpenChange,
+}: RequestChangeDialogProps) {
+  const [reason, setReason] = useState('')
+  const [target, setTarget] = useState<string>(TARGET_ANY)
+  const [touched, setTouched] = useState(false)
+
+  const utils = trpc.useUtils()
+  const requestChange = trpc.mentor.requestChange.useMutation({
+    onSuccess: async () => {
+      toast.success(
+        "Your request has been sent to the program admins. We'll review it and follow up.",
+      )
+      onOpenChange(false)
+      // Refresh dashboard so the disabled state for the button updates.
+      await utils.applicant.getMyDashboard.invalidate()
+    },
+    onError: (error) => {
+      toast.error(error.message || 'Could not send your request. Please try again.')
+    },
+  })
+
+  // Reset form when the dialog is closed.
+  useEffect(() => {
+    if (!open) {
+      setReason('')
+      setTarget(TARGET_ANY)
+      setTouched(false)
+    }
+  }, [open])
+
+  const trimmedReason = reason.trim()
+  const reasonTooShort = trimmedReason.length < REASON_MIN
+  const reasonTooLong = trimmedReason.length > REASON_MAX
+  const reasonInvalid = reasonTooShort || reasonTooLong
+  const showReasonError = touched && reasonInvalid
+
+  const handleSubmit = (e: React.FormEvent) => {
+    e.preventDefault()
+    setTouched(true)
+    if (reasonInvalid) return
+
+    requestChange.mutate({
+      projectId,
+      targetAssignmentId: target === TARGET_ANY ? undefined : target,
+      reason: trimmedReason,
+    })
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="sm:max-w-lg">
+        <DialogHeader>
+          <DialogTitle>Request a mentor change</DialogTitle>
+          <DialogDescription>
+            Share a few details so the program admins can follow up with you.
+            Your current mentor will not see this message.
+          </DialogDescription>
+        </DialogHeader>
+        <form onSubmit={handleSubmit} className="space-y-4">
+          {mentors.length > 0 && (
+            <div className="space-y-2">
+              <Label htmlFor="targetMentor">About a specific mentor</Label>
+              <Select value={target} onValueChange={setTarget}>
+                <SelectTrigger id="targetMentor">
+                  <SelectValue placeholder="Any / general" />
+                </SelectTrigger>
+                <SelectContent>
+                  <SelectItem value={TARGET_ANY}>Any / general</SelectItem>
+                  {mentors.map((m) => (
+                    <SelectItem key={m.assignmentId} value={m.assignmentId}>
+                      {m.name}
+                    </SelectItem>
+                  ))}
+                </SelectContent>
+              </Select>
+              <p className="text-xs text-muted-foreground">
+                Optional. Use this if your request is about one of your co-mentors in particular.
+              </p>
+            </div>
+          )}
+          <div className="space-y-2">
+            <Label htmlFor="reason">
+              Why would you like a change?
+            </Label>
+            <Textarea
+              id="reason"
+              value={reason}
+              onChange={(e) => setReason(e.target.value)}
+              onBlur={() => setTouched(true)}
+              placeholder="Tell us why you'd like a change. The admin team will follow up."
+              rows={6}
+              maxLength={REASON_MAX}
+              aria-invalid={showReasonError || undefined}
+              required
+            />
+            <div className="flex items-center justify-between text-xs">
+              {showReasonError ? (
+                <p className="text-destructive">
+                  {reasonTooShort
+                    ? `Please provide at least ${REASON_MIN} characters.`
+                    : `Please keep your message under ${REASON_MAX} characters.`}
+                </p>
+              ) : (
+                <p className="text-muted-foreground">
+                  {REASON_MIN}–{REASON_MAX} characters.
+                </p>
+              )}
+              <p className="text-muted-foreground tabular-nums">
+                {trimmedReason.length}/{REASON_MAX}
+              </p>
+            </div>
+          </div>
+          <DialogFooter>
+            <Button
+              type="button"
+              variant="outline"
+              onClick={() => onOpenChange(false)}
+              disabled={requestChange.isPending}
+            >
+              Cancel
+            </Button>
+            <Button type="submit" disabled={requestChange.isPending}>
+              {requestChange.isPending && (
+                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+              )}
+              Send request
+            </Button>
+          </DialogFooter>
+        </form>
+      </DialogContent>
+    </Dialog>
+  )
+}

src/app/(applicant)/applicant/team/page.tsx

@@ -357,12 +357,12 @@ export default function ApplicantProjectPage() {
             )}
           </div>
 
-          {/* Mentor info */}
-          {project.mentorAssignment?.mentor && (
+          {/* Mentor info — TODO(PR8 Task 7): list ALL assigned mentors */}
+          {project.mentorAssignments?.[0]?.mentor && (
             <div className="rounded-lg border p-3 bg-muted/50">
               <p className="text-sm font-medium mb-1">Assigned Mentor</p>
               <p className="text-sm text-muted-foreground">
-                {project.mentorAssignment.mentor.name} ({project.mentorAssignment.mentor.email})
+                {project.mentorAssignments[0].mentor.name} ({project.mentorAssignments[0].mentor.email})
               </p>
             </div>
           )}

src/app/(mentor)/mentor/projects/[id]/page.tsx

@@ -94,14 +94,18 @@ function ProjectDetailContent({ projectId }: { projectId: string }) {
     },
   })
 
+  // TODO(PR8 Task 9): show co-mentors. For now we pick the first assignment
+  // to keep tracking + chat working unchanged.
+  const primaryAssignment = project?.mentorAssignments?.[0] ?? null
+
   // Track view when project loads
   const trackView = trpc.mentor.trackView.useMutation()
   useEffect(() => {
-    if (project?.mentorAssignment?.id) {
-      trackView.mutate({ mentorAssignmentId: project.mentorAssignment.id })
+    if (primaryAssignment?.id) {
+      trackView.mutate({ mentorAssignmentId: primaryAssignment.id })
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [project?.mentorAssignment?.id])
+  }, [primaryAssignment?.id])
 
   if (isLoading) {
     return <ProjectDetailSkeleton />
@@ -135,7 +139,7 @@ function ProjectDetailContent({ projectId }: { projectId: string }) {
 
   const teamLead = project.teamMembers?.find((m) => m.role === 'LEAD')
   const otherMembers = project.teamMembers?.filter((m) => m.role !== 'LEAD') || []
-  const mentorAssignment = project.mentorAssignment
+  const mentorAssignment = primaryAssignment
   const mentorAssignmentId = mentorAssignment?.id
   const programId = project.program?.id
   const viewerIsAssignedMentor =
@@ -477,7 +481,7 @@ function ProjectDetailContent({ projectId }: { projectId: string }) {
         <CardContent>
           <MentorChat
             messages={mentorMessages || []}
-            currentUserId={project.mentorAssignment?.mentor?.id || ''}
+            currentUserId={primaryAssignment?.mentor?.id || ''}
             onSendMessage={async (message) => {
               await sendMessage.mutateAsync({ projectId, message })
             }}

src/app/(mentor)/mentor/workspace/[projectId]/page.tsx

@@ -1,21 +1,29 @@
 'use client'
 
 import { useParams, useRouter } from 'next/navigation'
+import { useSession } from 'next-auth/react'
 import { trpc } from '@/lib/trpc/client'
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
 import { Button } from '@/components/ui/button'
 import { Badge } from '@/components/ui/badge'
 import { Skeleton } from '@/components/ui/skeleton'
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs'
+import {
+  Tooltip,
+  TooltipContent,
+  TooltipProvider,
+  TooltipTrigger,
+} from '@/components/ui/tooltip'
 import { WorkspaceChat } from '@/components/mentor/workspace-chat'
 import { FilePromotionPanel } from '@/components/mentor/file-promotion-panel'
 import { WorkspaceFilesPanel } from '@/components/mentor/workspace-files-panel'
-import { ArrowLeft, MessageSquare, FileText, Upload } from 'lucide-react'
+import { ArrowLeft, MessageSquare, FileText, Upload, Users } from 'lucide-react'
 import { toast } from 'sonner'
 
 export default function MentorWorkspaceDetailPage() {
   const params = useParams()
   const router = useRouter()
+  const { data: session } = useSession()
   const projectId = params.projectId as string
 
   // Get mentor assignment for this project
@@ -27,6 +35,22 @@ export default function MentorWorkspaceDetailPage() {
     { enabled: !!projectId }
   )
 
+  // Co-mentor visibility (PR8 multi-mentor): show who else is on the team.
+  // Gracefully tolerates stale tabs where the caller no longer has access
+  // (assignment dropped) — query just returns nothing in that case.
+  const { data: projectMentors } = trpc.mentor.getProjectMentors.useQuery(
+    { projectId },
+    { enabled: !!projectId, retry: false }
+  )
+
+  const currentUserId = session?.user?.id
+  const coMentors = (projectMentors ?? []).filter(
+    a => a.mentor.id !== currentUserId
+  )
+  const coMentorNames = coMentors.map(a => a.mentor.name ?? 'Unnamed mentor')
+  const visibleCoMentors = coMentorNames.slice(0, 3)
+  const hiddenCoMentors = coMentorNames.slice(3)
+
   if (isLoading) {
     return (
       <div className="space-y-6">
@@ -70,6 +94,37 @@ export default function MentorWorkspaceDetailPage() {
           {project.teamName && (
             <p className="text-muted-foreground mt-1">{project.teamName}</p>
           )}
+          {coMentors.length > 0 && (
+            <div className="mt-2 flex items-center gap-1.5 text-sm text-muted-foreground">
+              <Users className="h-3.5 w-3.5 shrink-0" />
+              <span>
+                You + {coMentors.length} co-mentor
+                {coMentors.length === 1 ? '' : 's'}:{' '}
+                <span className="text-foreground">
+                  {visibleCoMentors.join(', ')}
+                </span>
+                {hiddenCoMentors.length > 0 && (
+                  <>
+                    {' '}
+                    <TooltipProvider>
+                      <Tooltip>
+                        <TooltipTrigger asChild>
+                          <span className="cursor-help underline decoration-dotted underline-offset-2">
+                            +{hiddenCoMentors.length} more
+                          </span>
+                        </TooltipTrigger>
+                        <TooltipContent>
+                          <div className="text-xs">
+                            {hiddenCoMentors.join(', ')}
+                          </div>
+                        </TooltipContent>
+                      </Tooltip>
+                    </TooltipProvider>
+                  </>
+                )}
+              </span>
+            </div>
+          )}
         </div>
       </div>
 
@@ -104,7 +159,10 @@ export default function MentorWorkspaceDetailPage() {
 
         <TabsContent value="files" className="mt-6">
           {assignment ? (
-            <WorkspaceFilesPanel mentorAssignmentId={assignment.id} />
+            <WorkspaceFilesPanel
+              projectId={projectId}
+              mentorAssignmentId={assignment.id}
+            />
           ) : (
             <Card>
               <CardContent className="text-center py-8">
@@ -117,7 +175,7 @@ export default function MentorWorkspaceDetailPage() {
 
         <TabsContent value="promotion" className="mt-6">
           {assignment ? (
-            <FilePromotionPanel mentorAssignmentId={assignment.id} />
+            <FilePromotionPanel projectId={projectId} />
           ) : (
             <Card>
               <CardContent className="text-center py-8">

src/components/admin/round/mentoring-round-overview.tsx

@@ -9,6 +9,7 @@ import {
   ArrowRight,
   Clock,
   FileText,
+  Inbox,
   MessageCircle,
   Target,
   UserCheck,
@@ -48,6 +49,10 @@ export function MentoringRoundOverview({ roundId }: Props) {
     { refetchInterval: 30_000 },
   )
   const { data: pool, isLoading: poolLoading } = trpc.mentor.getMentorPool.useQuery({})
+  const { data: pendingChangeRequests } = trpc.mentor.listChangeRequests.useQuery(
+    { status: 'PENDING' },
+    { refetchInterval: 30_000 },
+  )
 
   if (statsLoading || poolLoading) {
     return (
@@ -60,6 +65,15 @@ export function MentoringRoundOverview({ roundId }: Props) {
   }
   if (!stats || !pool) return null
 
+  const pendingCount = pendingChangeRequests?.length ?? 0
+  // If there's at least one pending request, deep-link directly into the
+  // first one's project (admins can resolve / view siblings from there).
+  // Otherwise the card stays static.
+  const firstPendingProjectId = pendingChangeRequests?.[0]?.project.id ?? null
+  const changeRequestsHref = firstPendingProjectId
+    ? `/admin/projects/${firstPendingProjectId}/mentor`
+    : null
+
   const requestedPct = stats.totalProjects
     ? Math.round((stats.requestedCount / stats.totalProjects) * 100)
     : 0
@@ -173,6 +187,42 @@ export function MentoringRoundOverview({ roundId }: Props) {
         </CardContent>
       </Card>
 
+      <Card
+        className={`md:col-span-2 xl:col-span-4 ${
+          pendingCount > 0 ? 'border-amber-300 dark:border-amber-700' : ''
+        }`}
+      >
+        <CardContent className="flex items-center justify-between py-4">
+          <div className="flex items-center gap-3">
+            <Inbox
+              className={`h-5 w-5 ${
+                pendingCount > 0 ? 'text-amber-600' : 'text-muted-foreground'
+              }`}
+            />
+            <div>
+              <div className="text-sm font-medium">Pending change requests</div>
+              <div className="text-muted-foreground text-xs">
+                Team members asking admin to swap a mentor
+              </div>
+            </div>
+          </div>
+          <div className="flex items-center gap-3">
+            <div className="text-2xl font-bold tabular-nums">{pendingCount}</div>
+            {changeRequestsHref ? (
+              <Link
+                href={changeRequestsHref}
+                className="text-muted-foreground hover:text-foreground inline-flex items-center text-xs"
+              >
+                Review
+                <ArrowRight className="ml-0.5 h-3 w-3" />
+              </Link>
+            ) : (
+              <span className="text-muted-foreground text-xs">All clear</span>
+            )}
+          </div>
+        </CardContent>
+      </Card>
+
       <Card className="md:col-span-2 xl:col-span-4">
         <CardHeader className="pb-2">
           <CardTitle className="text-sm">Workspace activity</CardTitle>

src/components/mentor/file-promotion-panel.tsx

@@ -17,7 +17,7 @@ import { FileText, Upload, CheckCircle2, ArrowUp } from 'lucide-react'
 import { toast } from 'sonner'
 
 interface FilePromotionPanelProps {
-  mentorAssignmentId: string
+  projectId: string
 }
 
 function formatFileSize(bytes: number): string {
@@ -28,14 +28,14 @@ function formatFileSize(bytes: number): string {
   return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i]
 }
 
-export function FilePromotionPanel({ mentorAssignmentId }: FilePromotionPanelProps) {
+export function FilePromotionPanel({ projectId }: FilePromotionPanelProps) {
   const [selectedSlot, setSelectedSlot] = useState<string>('')
   const utils = trpc.useUtils()
 
   const { data: workspaceFiles = [], isLoading: filesLoading } =
     trpc.mentor.workspaceGetFiles.useQuery(
-      { mentorAssignmentId },
-      { enabled: !!mentorAssignmentId },
+      { projectId },
+      { enabled: !!projectId },
     )
 
   const promoteMutation = trpc.mentor.workspacePromoteFile.useMutation({

src/components/mentor/workspace-files-panel.tsx

@@ -12,10 +12,18 @@ import {
   AlertDialogDescription, AlertDialogFooter, AlertDialogHeader, AlertDialogTitle,
   AlertDialogTrigger,
 } from '@/components/ui/alert-dialog'
-import { FileText, Upload, Download, Trash2, MessageSquare } from 'lucide-react'
+import { Eye, FileText, Upload, Download, Trash2, MessageSquare, X, Loader2 } from 'lucide-react'
 import { formatDistanceToNow } from 'date-fns'
+import { FilePreview, isOfficeFile } from '@/components/shared/file-viewer'
 
 interface Props {
+  /** Project the workspace belongs to — drives file list (project-scoped). */
+  projectId: string
+  /**
+   * One MentorAssignment id on this project — needed only to mint upload tokens
+   * (the token is signed against the assignment + project pair, but the file
+   * itself is project-scoped so co-mentors see it).
+   */
   mentorAssignmentId: string
   /** Set true on the applicant side to label uploads as "Team upload" — purely cosmetic. */
   asApplicant?: boolean
@@ -29,21 +37,21 @@ function formatSize(bytes: number): string {
   return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + ' ' + sizes[i]
 }
 
-export function WorkspaceFilesPanel({ mentorAssignmentId, asApplicant }: Props) {
+export function WorkspaceFilesPanel({ projectId, mentorAssignmentId, asApplicant }: Props) {
   const utils = trpc.useUtils()
   const inputRef = useRef<HTMLInputElement>(null)
   const [uploading, setUploading] = useState(false)
   const [description, setDescription] = useState('')
 
   const { data: files, isLoading } = trpc.mentor.workspaceGetFiles.useQuery(
-    { mentorAssignmentId },
-    { enabled: !!mentorAssignmentId }
+    { projectId },
+    { enabled: !!projectId }
   )
 
   const presign = trpc.mentor.workspaceGetUploadUrl.useMutation()
   const recordUpload = trpc.mentor.workspaceUploadFile.useMutation({
     onSuccess: () => {
-      utils.mentor.workspaceGetFiles.invalidate({ mentorAssignmentId })
+      utils.mentor.workspaceGetFiles.invalidate({ projectId })
       setDescription('')
       toast.success('File uploaded')
     },
@@ -51,7 +59,7 @@ export function WorkspaceFilesPanel({ mentorAssignmentId, asApplicant }: Props)
   const downloadMutation = trpc.mentor.workspaceGetFileDownloadUrl.useMutation()
   const deleteMutation = trpc.mentor.workspaceDeleteFile.useMutation({
     onSuccess: () => {
-      utils.mentor.workspaceGetFiles.invalidate({ mentorAssignmentId })
+      utils.mentor.workspaceGetFiles.invalidate({ projectId })
       toast.success('File deleted')
     },
     onError: (e) => toast.error(e.message),
@@ -83,10 +91,43 @@ export function WorkspaceFilesPanel({ mentorAssignmentId, asApplicant }: Props)
     }
   }
 
+  const [previewFileId, setPreviewFileId] = useState<string | null>(null)
+  const [previewUrl, setPreviewUrl] = useState<string | null>(null)
+  const [previewLoading, setPreviewLoading] = useState(false)
+
+  const canPreviewMime = (m: string, name: string) =>
+    m.startsWith('video/') || m === 'application/pdf' || m.startsWith('image/') || isOfficeFile(m, name)
+
+  const togglePreview = async (file: { id: string; mimeType: string; fileName: string }) => {
+    if (previewFileId === file.id) {
+      setPreviewFileId(null)
+      setPreviewUrl(null)
+      return
+    }
+    setPreviewFileId(file.id)
+    setPreviewUrl(null)
+    setPreviewLoading(true)
+    try {
+      const { url } = await downloadMutation.mutateAsync({ mentorFileId: file.id, disposition: 'inline' })
+      setPreviewUrl(url)
+    } catch (err) {
+      toast.error(err instanceof Error ? err.message : 'Preview failed')
+      setPreviewFileId(null)
+    } finally {
+      setPreviewLoading(false)
+    }
+  }
+
   const handleDownload = async (mentorFileId: string) => {
     try {
-      const { url } = await downloadMutation.mutateAsync({ mentorFileId })
-      window.open(url, '_blank')
+      const { url } = await downloadMutation.mutateAsync({ mentorFileId, disposition: 'attachment' })
+      const a = document.createElement('a')
+      a.href = url
+      a.download = ''
+      a.rel = 'noopener'
+      document.body.appendChild(a)
+      a.click()
+      a.remove()
     } catch (err) {
       toast.error(err instanceof Error ? err.message : 'Download failed')
     }
@@ -141,8 +182,12 @@ export function WorkspaceFilesPanel({ mentorAssignmentId, asApplicant }: Props)
         )}
 
         <ul className="divide-y">
-          {(files ?? []).map((f) => (
-            <li key={f.id} className="flex items-center gap-3 py-3">
+          {(files ?? []).map((f) => {
+            const isOpen = previewFileId === f.id
+            const previewable = canPreviewMime(f.mimeType, f.fileName)
+            return (
+            <li key={f.id} className="py-3 space-y-2">
+              <div className="flex items-center gap-3">
               <FileText className="h-5 w-5 text-muted-foreground shrink-0" />
               <div className="flex-1 min-w-0">
                 <div className="font-medium truncate">{f.fileName}</div>
@@ -160,7 +205,24 @@ export function WorkspaceFilesPanel({ mentorAssignmentId, asApplicant }: Props)
                   <div className="text-xs text-muted-foreground mt-1">{f.description}</div>
                 )}
               </div>
-              <Button variant="ghost" size="icon" onClick={() => handleDownload(f.id)}>
+              {previewable && (
+                <Button
+                  variant="ghost"
+                  size="icon"
+                  onClick={() => togglePreview(f)}
+                  title={isOpen ? 'Close preview' : 'Preview'}
+                  aria-label={isOpen ? 'Close preview' : 'Preview file'}
+                >
+                  {isOpen ? <X className="h-4 w-4" /> : <Eye className="h-4 w-4" />}
+                </Button>
+              )}
+              <Button
+                variant="ghost"
+                size="icon"
+                onClick={() => handleDownload(f.id)}
+                title="Download"
+                aria-label="Download file"
+              >
                 <Download className="h-4 w-4" />
               </Button>
               <AlertDialog>
@@ -184,8 +246,22 @@ export function WorkspaceFilesPanel({ mentorAssignmentId, asApplicant }: Props)
                   </AlertDialogFooter>
                 </AlertDialogContent>
               </AlertDialog>
+              </div>
+              {isOpen && (
+                <div className="rounded-md border bg-muted/30 overflow-hidden">
+                  {previewLoading || !previewUrl ? (
+                    <div className="flex items-center justify-center py-12 text-sm text-muted-foreground">
+                      <Loader2 className="h-4 w-4 mr-2 animate-spin" />
+                      Loading preview…
+                    </div>
+                  ) : (
+                    <FilePreview file={{ mimeType: f.mimeType, fileName: f.fileName }} url={previewUrl} />
+                  )}
+                </div>
+              )}
             </li>
-          ))}
+            )
+          })}
         </ul>
       </CardContent>
     </Card>

src/lib/email.ts

@@ -2752,6 +2752,177 @@ export async function sendMentorOnboardingEmail(email: string, name: string | nu
   await sendEmail({ to: email, subject: template.subject, text: template.text, html: template.html })
 }
 
+// =============================================================================
+// Per-team mentor assignment (fires every time a mentor is added to a project)
+// =============================================================================
+
+function getMentorTeamAssignmentTemplate(
+  name: string,
+  projectTitle: string,
+  workspaceUrl: string,
+): EmailTemplate {
+  const subject = `You've been assigned to a new MOPC project: "${projectTitle}"`
+  const greeting = name ? `Hi ${name},` : 'Hi there,'
+  const text = [
+    greeting,
+    '',
+    `You have been assigned as a mentor to the project "${projectTitle}".`,
+    '',
+    'You may have co-mentors on this team — you can collaborate together in the project workspace.',
+    '',
+    `Open the workspace: ${workspaceUrl}`,
+    '',
+    'The MOPC team',
+  ].join('\n')
+
+  const html = `
+<!DOCTYPE html>
+<html>
+<body style="margin:0;padding:0;background:#f6f8fa;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif;color:#0f172a;">
+  <div style="max-width:560px;margin:32px auto;background:#fff;border-radius:8px;overflow:hidden;box-shadow:0 1px 3px rgba(0,0,0,0.06);">
+    <div style="background:#053d57;padding:24px 28px;color:#fefefe;">
+      <h1 style="margin:0;font-size:20px;font-weight:600;">New mentor assignment</h1>
+    </div>
+    <div style="padding:24px 28px;line-height:1.5;font-size:14px;">
+      <p style="margin-top:0;">${name ? `Hi ${escapeHtml(name)},` : 'Hi there,'}</p>
+      <p>You have been assigned as a mentor to the project <strong>${escapeHtml(projectTitle)}</strong>.</p>
+      <p style="margin-top:24px;">
+        <a href="${workspaceUrl}" style="display:inline-block;padding:10px 20px;background:#de0f1e;color:#fff;text-decoration:none;border-radius:6px;font-weight:600;">Open Project Workspace</a>
+      </p>
+      <p style="margin-top:24px;color:#64748b;font-size:12px;">
+        You may have co-mentors on this team — you can collaborate together in the project workspace.
+      </p>
+    </div>
+    <div style="padding:16px 28px;background:#f1f5f9;color:#64748b;font-size:12px;text-align:center;">
+      Monaco Ocean Protection Challenge
+    </div>
+  </div>
+</body>
+</html>
+  `.trim()
+
+  return { subject, text, html }
+}
+
+/**
+ * Send a per-team mentor assignment email. Fires every time a mentor is added
+ * to a specific project (distinct from the one-time onboarding email).
+ * Idempotency is enforced at the call site via MentorAssignment.notificationSentAt.
+ * Never throws — failures are caught and logged.
+ */
+export async function sendMentorTeamAssignmentEmail(
+  email: string,
+  name: string | null,
+  projectTitle: string,
+  projectId: string,
+): Promise<void> {
+  try {
+    const baseUrl = process.env.NEXTAUTH_URL || 'https://monaco-opc.com'
+    const workspaceUrl = `${baseUrl.replace(/\/$/, '')}/mentor/workspace/${projectId}`
+    const template = getMentorTeamAssignmentTemplate(name || '', projectTitle, workspaceUrl)
+    await sendEmail({ to: email, subject: template.subject, text: template.text, html: template.html })
+  } catch (error) {
+    console.error('[sendMentorTeamAssignmentEmail] failed', { email, projectId, error })
+  }
+}
+
+// =============================================================================
+// Mentor change requests (PR 8) — admin notification when an applicant or admin
+// opens a MentorChangeRequest. Mentors are NOT notified (per design decision).
+// =============================================================================
+
+function getMentorChangeRequestTemplate(
+  projectTitle: string,
+  requesterName: string | null,
+  reason: string,
+  adminDashboardUrl: string,
+): EmailTemplate {
+  const subject = `Mentor change request for "${projectTitle}"`
+  const requesterLabel = requesterName || 'a team member'
+  const text = [
+    'Hi MOPC admins,',
+    '',
+    `A mentor change request has been opened by ${requesterLabel} for the project "${projectTitle}".`,
+    '',
+    'Reason:',
+    `"${reason}"`,
+    '',
+    `Review the request: ${adminDashboardUrl}`,
+    '',
+    'The MOPC team',
+  ].join('\n')
+
+  const html = `
+<!DOCTYPE html>
+<html>
+<body style="margin:0;padding:0;background:#f6f8fa;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif;color:#0f172a;">
+  <div style="max-width:560px;margin:32px auto;background:#fff;border-radius:8px;overflow:hidden;box-shadow:0 1px 3px rgba(0,0,0,0.06);">
+    <div style="background:#053d57;padding:24px 28px;color:#fefefe;">
+      <h1 style="margin:0;font-size:20px;font-weight:600;">Mentor change request</h1>
+    </div>
+    <div style="padding:24px 28px;line-height:1.5;font-size:14px;">
+      <p style="margin-top:0;">Hi MOPC admins,</p>
+      <p>A mentor change request has been opened by <strong>${escapeHtml(requesterLabel)}</strong> for the project <strong>${escapeHtml(projectTitle)}</strong>.</p>
+      <blockquote style="margin:16px 0;padding:12px 16px;background:#f1f5f9;border-left:3px solid #557f8c;border-radius:4px;color:#0f172a;font-style:italic;white-space:pre-wrap;">${escapeHtml(reason)}</blockquote>
+      <p style="margin-top:24px;">
+        <a href="${adminDashboardUrl}" style="display:inline-block;padding:10px 20px;background:#de0f1e;color:#fff;text-decoration:none;border-radius:6px;font-weight:600;">Review Request</a>
+      </p>
+      <p style="margin-top:24px;color:#64748b;font-size:12px;">
+        Mentors are not notified of change requests; only admins see this.
+      </p>
+    </div>
+    <div style="padding:16px 28px;background:#f1f5f9;color:#64748b;font-size:12px;text-align:center;">
+      Monaco Ocean Protection Challenge
+    </div>
+  </div>
+</body>
+</html>
+  `.trim()
+
+  return { subject, text, html }
+}
+
+/**
+ * Notify all SUPER_ADMIN / PROGRAM_ADMIN users that a mentor change request
+ * has been opened for a project. Sends one email per recipient.
+ * Never throws — failures are caught and logged so the calling mutation
+ * (mentor.requestChange) never fails because of email infrastructure issues.
+ */
+export async function sendMentorChangeRequestEmail(
+  adminEmails: string[],
+  projectTitle: string,
+  requesterName: string | null,
+  reason: string,
+  adminDashboardUrl: string,
+): Promise<void> {
+  try {
+    if (adminEmails.length === 0) {
+      console.warn('[sendMentorChangeRequestEmail] no admin recipients; skipping')
+      return
+    }
+    const template = getMentorChangeRequestTemplate(
+      projectTitle,
+      requesterName,
+      reason,
+      adminDashboardUrl,
+    )
+    await Promise.all(
+      adminEmails.map((email) =>
+        sendEmail({
+          to: email,
+          subject: template.subject,
+          text: template.text,
+          html: template.html,
+        }).catch((err) => {
+          console.error('[sendMentorChangeRequestEmail] send failed', { email, err })
+        }),
+      ),
+    )
+  } catch (error) {
+    console.error('[sendMentorChangeRequestEmail] failed', { error })
+  }
+}
+
 function getFinalistConfirmationTemplate(
   name: string,
   projectTitle: string,

src/lib/mentor-upload-token.ts

@@ -2,6 +2,13 @@ import { createHmac, timingSafeEqual } from 'crypto'
 
 export type MentorUploadPayload = {
   mentorAssignmentId: string
+  /**
+   * Project the upload belongs to. Bound at token-issue time so the file's
+   * project scope can't be tampered with separately from the assignment id.
+   * Required (no legacy fallback) — tokens live <1h, so any in-flight tokens
+   * issued before this field was added expire on their own.
+   */
+  projectId: string
   uploaderUserId: string
   fileName: string
   mimeType: string
@@ -47,5 +54,8 @@ export function verifyMentorUploadToken(token: string): MentorUploadPayload {
   if (typeof payload.exp !== 'number' || payload.exp < Math.floor(Date.now() / 1000)) {
     throw new Error('Invalid mentor upload token: expired')
   }
+  if (typeof payload.projectId !== 'string' || payload.projectId.length === 0) {
+    throw new Error('Invalid mentor upload token: missing projectId')
+  }
   return payload
 }

src/lib/minio.ts

@@ -78,13 +78,17 @@ export async function getPresignedUrl(
   objectKey: string,
   method: 'GET' | 'PUT' = 'GET',
   expirySeconds: number = 900, // 15 minutes default
-  options?: { downloadFileName?: string }
+  options?: { downloadFileName?: string; inline?: boolean; contentType?: string }
 ): Promise<string> {
   const publicClient = getPublicMinioClient()
   if (method === 'GET') {
-    const respHeaders = options?.downloadFileName
-      ? { 'response-content-disposition': `attachment; filename="${options.downloadFileName}"` }
-      : undefined
+    let respHeaders: Record<string, string> | undefined
+    if (options?.inline) {
+      respHeaders = { 'response-content-disposition': 'inline' }
+      if (options.contentType) respHeaders['response-content-type'] = options.contentType
+    } else if (options?.downloadFileName) {
+      respHeaders = { 'response-content-disposition': `attachment; filename="${options.downloadFileName}"` }
+    }
     return publicClient.presignedGetObject(bucket, objectKey, expirySeconds, respHeaders)
   } else {
     return publicClient.presignedPutObject(bucket, objectKey, expirySeconds)

src/server/routers/applicant.ts

@@ -1176,7 +1176,7 @@ export const applicantRouter = router({
           ],
         },
         include: {
-          mentorAssignment: { select: { mentorId: true } },
+          mentorAssignments: { select: { mentorId: true } },
         },
       })
 
@@ -1187,7 +1187,10 @@ export const applicantRouter = router({
         })
       }
 
-      if (!project.mentorAssignment) {
+      // TODO(PR8 Task 7): notify ALL assigned mentors. For now we notify the
+      // first one for legacy parity.
+      const primaryMentorAssignment = project.mentorAssignments[0] ?? null
+      if (!primaryMentorAssignment) {
         throw new TRPCError({
           code: 'BAD_REQUEST',
           message: 'No mentor assigned to this project',
@@ -1207,9 +1210,9 @@ export const applicantRouter = router({
         },
       })
 
-      // Notify the mentor
+      // Notify the (primary) mentor
       await createNotification({
-        userId: project.mentorAssignment.mentorId,
+        userId: primaryMentorAssignment.mentorId,
         type: 'MENTOR_MESSAGE',
         title: 'New Message',
         message: `${ctx.user.name || 'Team member'} sent a message about "${project.title}"`,
@@ -1313,12 +1316,13 @@ export const applicantRouter = router({
         submittedBy: {
           select: { id: true, name: true, email: true },
         },
-        mentorAssignment: {
+        mentorAssignments: {
           include: {
             mentor: {
-              select: { id: true, name: true, email: true },
+              select: { id: true, name: true, email: true, expertiseTags: true },
             },
           },
+          orderBy: { assignedAt: 'asc' },
         },
         wonAwards: {
           select: { id: true, name: true },
@@ -1489,6 +1493,17 @@ export const applicantRouter = router({
       logoUrl = await provider.getDownloadUrl(project.logoKey)
     }
 
+    // Does this user have an open mentor-change request for this project?
+    // (Used by the applicant mentor page to disable the "Request a change" button.)
+    const myPendingChangeRequest = await ctx.prisma.mentorChangeRequest.findFirst({
+      where: {
+        projectId: project.id,
+        requestedByUserId: ctx.user.id,
+        status: 'PENDING',
+      },
+      select: { id: true },
+    })
+
     return {
       project: {
         ...project,
@@ -1502,6 +1517,7 @@ export const applicantRouter = router({
       hasPassedIntake: !!passedIntake,
       isIntakeOpen: !!activeIntakeRound,
       logoUrl,
+      hasPendingMentorChangeRequest: !!myPendingChangeRequest,
     }
   }),
 
@@ -1523,7 +1539,7 @@ export const applicantRouter = router({
       select: {
         id: true,
         programId: true,
-        mentorAssignment: { select: { id: true } },
+        mentorAssignments: { select: { id: true }, take: 1 },
       },
     })
 
@@ -1531,8 +1547,8 @@ export const applicantRouter = router({
       return { hasMentor: false, hasEvaluationRounds: false }
     }
 
-    // Check if mentor is assigned
-    const hasMentor = !!project.mentorAssignment
+    // Check if mentor is assigned (any active assignment counts)
+    const hasMentor = project.mentorAssignments.length > 0
 
     // Check if feedback is available — first check admin settings, then fall back to per-round config
     let hasEvaluationRounds = false
@@ -2689,8 +2705,12 @@ export const applicantRouter = router({
         })
       }
 
-      const assignment = await ctx.prisma.mentorAssignment.findUnique({
+      // TODO(PR8 Task 7): when multiple mentors are assigned, surface them all
+      // in the applicant message thread. For now we display the most recently
+      // assigned (non-dropped) mentor as the "primary".
+      const assignment = await ctx.prisma.mentorAssignment.findFirst({
         where: { projectId: input.projectId },
+        orderBy: { assignedAt: 'desc' },
         include: { mentor: { select: { id: true, name: true, email: true } } },
       })
 

src/server/routers/finalist.ts

@@ -772,7 +772,8 @@ export const finalistRouter = router({
             select: {
               id: true,
               title: true,
-              mentorAssignment: {
+              mentorAssignments: {
+                where: { droppedAt: null, completionStatus: { not: 'completed' } },
                 select: {
                   id: true,
                   completionStatus: true,
@@ -796,10 +797,12 @@ export const finalistRouter = router({
         data: { status: 'SUPERSEDED' },
       })
 
-      // Cascade: drop active mentor assignment (skip if completed or already dropped)
-      const ma = confirmation.project.mentorAssignment
+      // Cascade: drop ALL active mentor assignments (skip dropped/completed —
+      // those were filtered out by the include `where` above). With multi-mentor
+      // (PR8) we propagate the cascade to every active assignment.
+      const activeAssignments = confirmation.project.mentorAssignments
       let cascadedMentorAssignment = false
-      if (ma && !ma.droppedAt && ma.completionStatus !== 'completed') {
+      for (const ma of activeAssignments) {
         await ctx.prisma.mentorAssignment.update({
           where: { id: ma.id },
           data: {
@@ -833,6 +836,7 @@ export const finalistRouter = router({
           reason: input.reason,
           projectId: confirmation.projectId,
           cascadedMentorAssignment,
+          cascadedAssignmentCount: activeAssignments.length,
         },
       })
       return { ok: true, cascadedMentorAssignment }

src/server/routers/mentor.ts

@@ -1,7 +1,16 @@
 import { z } from 'zod'
 import { TRPCError } from '@trpc/server'
 import { router, mentorProcedure, adminProcedure, protectedProcedure } from '../trpc'
-import { MentorAssignmentMethod, type PrismaClient } from '@prisma/client'
+import {
+  MentorAssignmentMethod,
+  MentorChangeRequestStatus,
+  Prisma,
+  type PrismaClient,
+} from '@prisma/client'
+import {
+  sendMentorChangeRequestEmail,
+  sendMentorTeamAssignmentEmail,
+} from '@/lib/email'
 import {
   getAIMentorSuggestions,
   getRoundRobinMentor,
@@ -66,6 +75,42 @@ async function assertWorkspaceAccess(
   throw new TRPCError({ code: 'FORBIDDEN', message: 'You are not a member of this workspace' })
 }
 
+/**
+ * Project-scoped workspace access check (PR8 multi-mentor).
+ *
+ * Allowed when the user is either:
+ *   1) currently assigned as a mentor on this project (droppedAt = null), OR
+ *   2) a team member of the project.
+ *
+ * Also requires at least one active mentor assignment for the project with
+ * workspaceEnabled = true — meaning the project actually has a live workspace.
+ * Throws TRPCError on failure. Returns nothing on success.
+ */
+async function assertProjectWorkspaceAccess(
+  prisma: PrismaClient,
+  userId: string,
+  projectId: string,
+): Promise<void> {
+  const liveMentorAssignment = await prisma.mentorAssignment.findFirst({
+    where: { projectId, droppedAt: null, workspaceEnabled: true },
+    select: { id: true },
+  })
+  if (!liveMentorAssignment) {
+    throw new TRPCError({ code: 'FORBIDDEN', message: 'Workspace is not enabled' })
+  }
+  const mentorOnProject = await prisma.mentorAssignment.findFirst({
+    where: { projectId, mentorId: userId, droppedAt: null },
+    select: { id: true },
+  })
+  if (mentorOnProject) return
+  const teamMembership = await prisma.teamMember.findFirst({
+    where: { projectId, userId },
+    select: { id: true },
+  })
+  if (teamMembership) return
+  throw new TRPCError({ code: 'FORBIDDEN', message: 'You are not a member of this workspace' })
+}
+
 export const mentorRouter = router({
   /**
    * Get AI-suggested mentor matches for a project
@@ -82,18 +127,15 @@ export const mentorRouter = router({
       const project = await ctx.prisma.project.findUniqueOrThrow({
         where: { id: input.projectId },
         include: {
-          mentorAssignment: true,
+          mentorAssignments: true,
         },
       })
 
-      if (project.mentorAssignment) {
-        return {
-          currentMentor: project.mentorAssignment,
-          suggestions: [],
-          source: 'ai' as const,
-          message: 'Project already has a mentor assigned',
-        }
-      }
+      // With multi-mentor (PR8) the project can have several mentors. The
+      // suggestions endpoint is informational — return whatever AI suggests
+      // and let `mentor.assign` enforce per-pair uniqueness. We still surface
+      // an existing primary mentor in the payload so UIs can label it.
+      const primaryMentor = project.mentorAssignments[0] ?? null
 
       // Detect AI configuration so the UI can label "AI matching unavailable"
       // when we fall back to algorithmic ranking. An AI error mid-call still
@@ -140,7 +182,9 @@ export const mentorRouter = router({
       })
 
       return {
-        currentMentor: null,
+        // TODO(PR8 Task 8): return the full mentor list. Legacy field kept
+        // until the admin UI is updated.
+        currentMentor: primaryMentor,
         suggestions: enrichedSuggestions.filter((s) => s.mentor !== null),
         source,
         message: null,
@@ -219,26 +263,24 @@ export const mentorRouter = router({
       })
     )
     .mutation(async ({ ctx, input }) => {
-      // Verify project exists and doesn't have a mentor
+      // Verify project exists (multi-mentor: stacking is allowed; duplicate
+      // (projectId, mentorId) pairs are rejected by the unique constraint
+      // below).
       const project = await ctx.prisma.project.findUniqueOrThrow({
         where: { id: input.projectId },
-        include: { mentorAssignment: true },
       })
 
-      if (project.mentorAssignment) {
-        throw new TRPCError({
-          code: 'CONFLICT',
-          message: 'Project already has a mentor assigned',
-        })
-      }
-
       // Verify mentor exists
       const mentor = await ctx.prisma.user.findUniqueOrThrow({
         where: { id: input.mentorId },
       })
 
-      // Create assignment
-      const assignment = await ctx.prisma.mentorAssignment.create({
+      // Create assignment. P2002 on the composite (projectId, mentorId) unique
+      // constraint means this exact mentor is already on this team — surface a
+      // friendly error.
+      let assignment
+      try {
+        assignment = await ctx.prisma.mentorAssignment.create({
           data: {
             projectId: input.projectId,
             mentorId: input.mentorId,
@@ -265,6 +307,18 @@ export const mentorRouter = router({
             },
           },
         })
+      } catch (err) {
+        if (
+          err instanceof Prisma.PrismaClientKnownRequestError &&
+          err.code === 'P2002'
+        ) {
+          throw new TRPCError({
+            code: 'CONFLICT',
+            message: 'This mentor is already assigned to that project.',
+          })
+        }
+        throw err
+      }
 
       // Audit outside transaction so failures don't roll back the assignment
       await logAudit({
@@ -279,6 +333,8 @@ export const mentorRouter = router({
           mentorId: input.mentorId,
           mentorName: assignment.mentor.name,
           method: input.method,
+          // PR8: per-team assignment (one row per mentor-project pair).
+          assignmentScope: 'per-team',
         },
         ipAddress: ctx.ip,
         userAgent: ctx.userAgent,
@@ -320,6 +376,27 @@ export const mentorRouter = router({
         },
       })
 
+      // Send per-team email notification once per assignment row. Idempotency
+      // is enforced via MentorAssignment.notificationSentAt — a fresh row has
+      // it null. If the same mentor is later dropped and re-assigned (new row,
+      // fresh id), a new email is sent — intentional.
+      if (assignment.notificationSentAt == null && assignment.mentor.email) {
+        await sendMentorTeamAssignmentEmail(
+          assignment.mentor.email,
+          assignment.mentor.name,
+          assignment.project.title,
+          input.projectId,
+        )
+        try {
+          await ctx.prisma.mentorAssignment.update({
+            where: { id: assignment.id },
+            data: { notificationSentAt: new Date() },
+          })
+        } catch (e) {
+          console.error('[Mentor] failed to stamp notificationSentAt (non-fatal):', e)
+        }
+      }
+
       // Auto-transition: mark project IN_PROGRESS in any active MENTORING round
       try {
         const mentoringPrs = await ctx.prisma.projectRoundState.findFirst({
@@ -351,13 +428,16 @@ export const mentorRouter = router({
       })
     )
     .mutation(async ({ ctx, input }) => {
-      // Verify project exists and doesn't have a mentor
+      // Verify project exists and doesn't already have a mentor. Multi-mentor
+      // stacking is reserved for explicit admin assignment via `mentor.assign`;
+      // auto-assignment skips projects that already have at least one mentor
+      // to avoid double-AI-assignments.
       const project = await ctx.prisma.project.findUniqueOrThrow({
         where: { id: input.projectId },
-        include: { mentorAssignment: true },
+        include: { mentorAssignments: { select: { id: true } } },
       })
 
-      if (project.mentorAssignment) {
+      if (project.mentorAssignments.length > 0) {
         throw new TRPCError({
           code: 'CONFLICT',
           message: 'Project already has a mentor assigned',
@@ -485,13 +565,35 @@ export const mentorRouter = router({
     }),
 
   /**
-   * Remove mentor assignment
+   * Remove mentor assignment.
+   *
+   * Multi-mentor (PR8): callers should pass `assignmentId` to target a
+   * specific co-mentor. Legacy callers passing only `projectId` get the
+   * most-recent assignment removed (kept for backward compatibility).
    */
   unassign: adminProcedure
-    .input(z.object({ projectId: z.string() }))
+    .input(
+      z
+        .object({
+          assignmentId: z.string().optional(),
+          projectId: z.string().optional(),
+        })
+        .refine((v) => !!v.assignmentId || !!v.projectId, {
+          message: 'Either assignmentId or projectId is required',
+        }),
+    )
     .mutation(async ({ ctx, input }) => {
-      const assignment = await ctx.prisma.mentorAssignment.findUnique({
-        where: { projectId: input.projectId },
+      const assignment = input.assignmentId
+        ? await ctx.prisma.mentorAssignment.findUnique({
+            where: { id: input.assignmentId },
+            include: {
+              mentor: { select: { id: true, name: true } },
+              project: { select: { id: true, title: true } },
+            },
+          })
+        : await ctx.prisma.mentorAssignment.findFirst({
+            where: { projectId: input.projectId! },
+            orderBy: { assignedAt: 'desc' },
             include: {
               mentor: { select: { id: true, name: true } },
               project: { select: { id: true, title: true } },
@@ -501,13 +603,13 @@ export const mentorRouter = router({
       if (!assignment) {
         throw new TRPCError({
           code: 'NOT_FOUND',
-          message: 'No mentor assignment found for this project',
+          message: 'No mentor assignment found',
         })
       }
 
       // Delete assignment
       await ctx.prisma.mentorAssignment.delete({
-        where: { projectId: input.projectId },
+        where: { id: assignment.id },
       })
 
       // Audit outside transaction so failures don't roll back the unassignment
@@ -518,7 +620,7 @@ export const mentorRouter = router({
         entityType: 'MentorAssignment',
         entityId: assignment.id,
         detailsJson: {
-          projectId: input.projectId,
+          projectId: assignment.project.id,
           projectTitle: assignment.project.title,
           mentorId: assignment.mentor.id,
           mentorName: assignment.mentor.name,
@@ -546,7 +648,7 @@ export const mentorRouter = router({
       const projects = await ctx.prisma.project.findMany({
         where: {
           programId: input.programId,
-          mentorAssignment: null,
+          mentorAssignments: { none: {} },
           wantsMentorship: true,
         },
         select: { id: true },
@@ -716,7 +818,7 @@ export const mentorRouter = router({
         where: {
           roundId: input.roundId,
           project: {
-            mentorAssignment: null,
+            mentorAssignments: { none: {} },
             // Only assign mentors to projects whose team has confirmed they will
             // attend the grand finale. This skips PENDING/DECLINED/EXPIRED/SUPERSEDED
             // confirmations and any project without a confirmation row at all.
@@ -834,7 +936,7 @@ export const mentorRouter = router({
         where: {
           roundId: input.roundId,
           project: {
-            mentorAssignment: { isNot: null },
+            mentorAssignments: { some: {} },
             ...(eligibility === 'requested_only' ? { wantsMentorship: true } : {}),
           },
         },
@@ -906,13 +1008,13 @@ export const mentorRouter = router({
         ctx.prisma.projectRoundState.count({
           where: {
             roundId: input.roundId,
-            project: { wantsMentorship: true, mentorAssignment: { isNot: null } },
+            project: { wantsMentorship: true, mentorAssignments: { some: {} } },
           },
         }),
         ctx.prisma.projectRoundState.count({
           where: {
             roundId: input.roundId,
-            project: { mentorAssignment: { isNot: null } },
+            project: { mentorAssignments: { some: {} } },
           },
         }),
         ctx.prisma.mentorMessage.count({
@@ -1107,7 +1209,11 @@ export const mentorRouter = router({
           status: true,
           oceanIssue: true,
           competitionCategory: true,
-          mentorAssignment: {
+          mentorAssignments: {
+            // TODO(PR8 Task 8): surface all mentors in the activity view.
+            // For now keep the legacy single-mentor activity row by picking the
+            // latest-assigned, non-dropped assignment (or the most-recent overall).
+            orderBy: { assignedAt: 'desc' },
             select: {
               id: true,
               method: true,
@@ -1157,7 +1263,10 @@ export const mentorRouter = router({
 
       const rows = projects.map((p) => {
         // Treat a dropped mentor assignment as if no mentor is assigned.
-        const ma = p.mentorAssignment && !p.mentorAssignment.droppedAt ? p.mentorAssignment : null
+        // TODO(PR8 Task 8): surface all mentors. Legacy shape: pick the most
+        // recent non-dropped assignment for the activity row.
+        const firstActive = p.mentorAssignments.find((a) => !a.droppedAt) ?? null
+        const ma = firstActive
         const lastMessageAt = ma?.messages[0]?.createdAt ?? null
         const lastFileAt = ma?.files[0]?.createdAt ?? null
         const lastActivityAt = [lastMessageAt, lastFileAt]
@@ -1235,6 +1344,50 @@ export const mentorRouter = router({
     return assignments
   }),
 
+  /**
+   * List all active mentors assigned to a project (PR8 multi-mentor).
+   *
+   * Returns one row per active MentorAssignment (droppedAt = null) with the
+   * mentor's id + name. Used by the mentor workspace page to display the
+   * co-mentor team so each mentor knows who else they're working with.
+   *
+   * Authorization: caller must be an active mentor on the project (or an
+   * admin via mentorProcedure). Non-assigned mentors get FORBIDDEN.
+   */
+  getProjectMentors: mentorProcedure
+    .input(z.object({ projectId: z.string() }))
+    .query(async ({ ctx, input }) => {
+      const isAdmin = ['SUPER_ADMIN', 'PROGRAM_ADMIN'].includes(ctx.user.role)
+
+      if (!isAdmin) {
+        const ownAssignment = await ctx.prisma.mentorAssignment.findFirst({
+          where: {
+            projectId: input.projectId,
+            mentorId: ctx.user.id,
+            droppedAt: null,
+          },
+          select: { id: true },
+        })
+        if (!ownAssignment) {
+          throw new TRPCError({
+            code: 'FORBIDDEN',
+            message: 'You are not assigned to mentor this project',
+          })
+        }
+      }
+
+      const assignments = await ctx.prisma.mentorAssignment.findMany({
+        where: { projectId: input.projectId, droppedAt: null },
+        select: {
+          id: true,
+          mentor: { select: { id: true, name: true } },
+        },
+        orderBy: { assignedAt: 'asc' },
+      })
+
+      return assignments
+    }),
+
   /**
    * Get detailed project info for a mentor's assigned project
    */
@@ -1279,7 +1432,7 @@ export const mentorRouter = router({
           files: {
             orderBy: { createdAt: 'desc' },
           },
-          mentorAssignment: {
+          mentorAssignments: {
             include: {
               mentor: {
                 select: { id: true, name: true, email: true },
@@ -2080,6 +2233,7 @@ export const mentorRouter = router({
       const exp = Math.floor(Date.now() / 1000) + 3600
       const uploadToken = signMentorUploadToken({
         mentorAssignmentId: assignment.id,
+        projectId: assignment.projectId,
         uploaderUserId: ctx.user.id,
         fileName: input.fileName,
         mimeType: input.mimeType,
@@ -2136,45 +2290,55 @@ export const mentorRouter = router({
     }),
 
   /**
-   * List files in a workspace. Authorized for the assigned mentor or any
-   * project team member.
+   * List files in a project's mentor workspace. Authorized for any mentor
+   * currently assigned to the project, or any team member of the project.
+   *
+   * Project-scoped (PR8): all co-mentors share one file list, and files
+   * survive even when an originating assignment is later dropped.
    */
   workspaceGetFiles: protectedProcedure
-    .input(z.object({ mentorAssignmentId: z.string() }))
+    .input(z.object({ projectId: z.string() }))
     .query(async ({ ctx, input }) => {
-      await assertWorkspaceAccess(ctx.prisma, ctx.user.id, input.mentorAssignmentId)
-      return workspaceGetFilesService(input.mentorAssignmentId, ctx.prisma)
+      await assertProjectWorkspaceAccess(ctx.prisma, ctx.user.id, input.projectId)
+      return workspaceGetFilesService(input.projectId, ctx.prisma)
     }),
 
   /**
    * Issue a short-lived presigned GET URL to download a workspace file.
    */
   workspaceGetFileDownloadUrl: protectedProcedure
-    .input(z.object({ mentorFileId: z.string() }))
+    .input(z.object({
+      mentorFileId: z.string(),
+      disposition: z.enum(['inline', 'attachment']).default('attachment'),
+    }))
     .mutation(async ({ ctx, input }) => {
       const file = await ctx.prisma.mentorFile.findUnique({
         where: { id: input.mentorFileId },
-        select: { bucket: true, objectKey: true, fileName: true, mentorAssignmentId: true },
+        select: { bucket: true, objectKey: true, fileName: true, mimeType: true, projectId: true },
       })
       if (!file) throw new TRPCError({ code: 'NOT_FOUND', message: 'File not found' })
-      await assertWorkspaceAccess(ctx.prisma, ctx.user.id, file.mentorAssignmentId)
+      await assertProjectWorkspaceAccess(ctx.prisma, ctx.user.id, file.projectId)
       const url = await getPresignedUrl(file.bucket, file.objectKey, 'GET', 900,
-        { downloadFileName: file.fileName })
+        input.disposition === 'inline'
+          ? { inline: true, contentType: file.mimeType }
+          : { downloadFileName: file.fileName })
       return { url }
     }),
 
   /**
-   * Delete a workspace file (uploader or assigned mentor only).
+   * Delete a workspace file. Authorized for the uploader, any mentor
+   * currently assigned to the file's project, or any team member of the
+   * file's project. Final auth check lives in the service.
    */
   workspaceDeleteFile: protectedProcedure
     .input(z.object({ mentorFileId: z.string() }))
     .mutation(async ({ ctx, input }) => {
       const file = await ctx.prisma.mentorFile.findUnique({
         where: { id: input.mentorFileId },
-        select: { mentorAssignmentId: true },
+        select: { projectId: true },
       })
       if (!file) throw new TRPCError({ code: 'NOT_FOUND', message: 'File not found' })
-      await assertWorkspaceAccess(ctx.prisma, ctx.user.id, file.mentorAssignmentId)
+      await assertProjectWorkspaceAccess(ctx.prisma, ctx.user.id, file.projectId)
       try {
         await workspaceDeleteFileService(
           { mentorFileId: input.mentorFileId, userId: ctx.user.id },
@@ -2204,12 +2368,12 @@ export const mentorRouter = router({
     .mutation(async ({ ctx, input }) => {
       const file = await ctx.prisma.mentorFile.findUnique({
         where: { id: input.mentorFileId },
-        select: { mentorAssignmentId: true },
+        select: { projectId: true },
       })
       if (!file) {
         throw new TRPCError({ code: 'NOT_FOUND', message: 'File not found' })
       }
-      await assertWorkspaceAccess(ctx.prisma, ctx.user.id, file.mentorAssignmentId)
+      await assertProjectWorkspaceAccess(ctx.prisma, ctx.user.id, file.projectId)
       return workspaceAddFileComment(
         {
           mentorFileId: input.mentorFileId,
@@ -2414,4 +2578,243 @@ export const mentorRouter = router({
         })),
       }
     }),
+
+  // ===========================================================================
+  // Mentor change requests (PR8)
+  //
+  // Applicants (team members) or admins can open a PENDING change request for
+  // a project — optionally targeting a specific co-mentor assignment. Admins
+  // are notified by email; mentors are intentionally NOT notified, even after
+  // resolution (per design decision in the PR8 plan).
+  // ===========================================================================
+
+  /**
+   * Open a new mentor change request. Allowed for:
+   *   • SUPER_ADMIN / PROGRAM_ADMIN (any project), or
+   *   • a team member of the target project.
+   *
+   * Rejects with CONFLICT if the same user already has an open (PENDING) request
+   * for the same project. The raw `reason` is intentionally NOT included in
+   * audit logs — only its length — for privacy. Email delivery to admins is
+   * best-effort and never throws.
+   */
+  requestChange: protectedProcedure
+    .input(
+      z.object({
+        projectId: z.string().min(1),
+        targetAssignmentId: z.string().min(1).optional(),
+        reason: z.string().min(10).max(2000),
+      }),
+    )
+    .mutation(async ({ ctx, input }) => {
+      const isAdmin = ['SUPER_ADMIN', 'PROGRAM_ADMIN'].includes(ctx.user.role)
+
+      // Authorization: admin OR team member of the project
+      if (!isAdmin) {
+        const teamMembership = await ctx.prisma.teamMember.findFirst({
+          where: { projectId: input.projectId, userId: ctx.user.id },
+          select: { id: true },
+        })
+        if (!teamMembership) {
+          throw new TRPCError({
+            code: 'FORBIDDEN',
+            message: 'You are not a member of this project',
+          })
+        }
+      }
+
+      // Load project (also confirms it exists) and validate optional target
+      const project = await ctx.prisma.project.findUnique({
+        where: { id: input.projectId },
+        select: { id: true, title: true },
+      })
+      if (!project) {
+        throw new TRPCError({ code: 'NOT_FOUND', message: 'Project not found' })
+      }
+
+      if (input.targetAssignmentId) {
+        const targetAssignment = await ctx.prisma.mentorAssignment.findUnique({
+          where: { id: input.targetAssignmentId },
+          select: { id: true, projectId: true },
+        })
+        if (!targetAssignment || targetAssignment.projectId !== input.projectId) {
+          throw new TRPCError({
+            code: 'BAD_REQUEST',
+            message: 'Target assignment does not belong to this project',
+          })
+        }
+      }
+
+      // One open request per (user, project)
+      const existingOpen = await ctx.prisma.mentorChangeRequest.findFirst({
+        where: {
+          projectId: input.projectId,
+          requestedByUserId: ctx.user.id,
+          status: MentorChangeRequestStatus.PENDING,
+        },
+        select: { id: true },
+      })
+      if (existingOpen) {
+        throw new TRPCError({
+          code: 'CONFLICT',
+          message: 'You already have an open mentor change request for this project.',
+        })
+      }
+
+      const created = await ctx.prisma.mentorChangeRequest.create({
+        data: {
+          projectId: input.projectId,
+          targetAssignmentId: input.targetAssignmentId ?? null,
+          requestedByUserId: ctx.user.id,
+          reason: input.reason,
+          status: MentorChangeRequestStatus.PENDING,
+        },
+        select: { id: true, status: true, createdAt: true },
+      })
+
+      // Notify admins (best-effort, never throw)
+      try {
+        const admins = await ctx.prisma.user.findMany({
+          where: {
+            OR: [
+              { roles: { has: 'SUPER_ADMIN' } },
+              { roles: { has: 'PROGRAM_ADMIN' } },
+            ],
+            status: 'ACTIVE',
+          },
+          select: { email: true },
+        })
+        const baseUrl = process.env.NEXTAUTH_URL || 'https://monaco-opc.com'
+        const adminDashboardUrl = `${baseUrl.replace(/\/$/, '')}/admin/projects/${input.projectId}/mentor`
+        await sendMentorChangeRequestEmail(
+          admins.map((a) => a.email),
+          project.title,
+          ctx.user.name ?? null,
+          input.reason,
+          adminDashboardUrl,
+        )
+      } catch (err) {
+        // Defense-in-depth: the helper already has its own try/catch
+        console.error('[mentor.requestChange] notify admins failed:', err)
+      }
+
+      await logAudit({
+        prisma: ctx.prisma,
+        userId: ctx.user.id,
+        action: 'MENTOR_CHANGE_REQUEST_CREATE',
+        entityType: 'MentorChangeRequest',
+        entityId: created.id,
+        detailsJson: {
+          projectId: input.projectId,
+          targetAssignmentId: input.targetAssignmentId ?? null,
+          reasonLength: input.reason.length,
+        },
+      })
+
+      return created
+    }),
+
+  /**
+   * Admin inbox — list MentorChangeRequest rows, optionally filtered by status
+   * and/or project. PENDING rows are surfaced first; within each status group
+   * rows are ordered by createdAt desc. No pagination (low-volume admin view).
+   */
+  listChangeRequests: adminProcedure
+    .input(
+      z
+        .object({
+          status: z.nativeEnum(MentorChangeRequestStatus).optional(),
+          projectId: z.string().optional(),
+        })
+        .optional(),
+    )
+    .query(async ({ ctx, input }) => {
+      const where: Prisma.MentorChangeRequestWhereInput = {}
+      if (input?.status) where.status = input.status
+      if (input?.projectId) where.projectId = input.projectId
+
+      const rows = await ctx.prisma.mentorChangeRequest.findMany({
+        where,
+        include: {
+          project: { select: { id: true, title: true } },
+          targetAssignment: {
+            select: {
+              id: true,
+              mentor: { select: { id: true, name: true, email: true } },
+            },
+          },
+          requestedBy: { select: { id: true, name: true, email: true } },
+          resolvedBy: { select: { id: true, name: true, email: true } },
+        },
+        // PENDING first, then RESOLVED/DISMISSED. Within each: newest first.
+        orderBy: [{ status: 'asc' }, { createdAt: 'desc' }],
+      })
+
+      // Enum order is PENDING < RESOLVED < DISMISSED alphabetically — DISMISSED
+      // is "D" so it sorts before PENDING. Re-sort in JS to guarantee PENDING
+      // appears first regardless of enum string ordering.
+      const statusRank: Record<MentorChangeRequestStatus, number> = {
+        [MentorChangeRequestStatus.PENDING]: 0,
+        [MentorChangeRequestStatus.RESOLVED]: 1,
+        [MentorChangeRequestStatus.DISMISSED]: 2,
+      }
+      return rows.sort((a, b) => {
+        const sa = statusRank[a.status] - statusRank[b.status]
+        if (sa !== 0) return sa
+        return b.createdAt.getTime() - a.createdAt.getTime()
+      })
+    }),
+
+  /**
+   * Admin resolves a PENDING request as RESOLVED or DISMISSED. Re-resolution
+   * is rejected. No email or notification is sent to the requester or mentors
+   * (per PR8 design decision — mentors are never informed of change requests).
+   */
+  resolveChangeRequest: adminProcedure
+    .input(
+      z.object({
+        id: z.string().min(1),
+        status: z.enum(['RESOLVED', 'DISMISSED']),
+        resolutionNote: z.string().max(2000).optional(),
+      }),
+    )
+    .mutation(async ({ ctx, input }) => {
+      const existing = await ctx.prisma.mentorChangeRequest.findUnique({
+        where: { id: input.id },
+        select: { id: true, status: true, projectId: true },
+      })
+      if (!existing) {
+        throw new TRPCError({ code: 'NOT_FOUND', message: 'Request not found' })
+      }
+      if (existing.status !== MentorChangeRequestStatus.PENDING) {
+        throw new TRPCError({
+          code: 'BAD_REQUEST',
+          message: 'Request already resolved',
+        })
+      }
+
+      const updated = await ctx.prisma.mentorChangeRequest.update({
+        where: { id: existing.id },
+        data: {
+          status: input.status as MentorChangeRequestStatus,
+          resolvedByUserId: ctx.user.id,
+          resolvedAt: new Date(),
+          resolutionNote: input.resolutionNote ?? null,
+        },
+      })
+
+      await logAudit({
+        prisma: ctx.prisma,
+        userId: ctx.user.id,
+        action: 'MENTOR_CHANGE_REQUEST_RESOLVE',
+        entityType: 'MentorChangeRequest',
+        entityId: existing.id,
+        detailsJson: {
+          status: input.status,
+          projectId: existing.projectId,
+        },
+      })
+
+      return updated
+    }),
 })

src/server/routers/project.ts

@@ -188,7 +188,7 @@ export const projectRouter = router({
           orClauses.push({ assignments: { some: { userId: ctx.user.id } } })
         }
         if (userHasRole(ctx.user, 'MENTOR')) {
-          orClauses.push({ mentorAssignment: { mentorId: ctx.user.id } })
+          orClauses.push({ mentorAssignments: { some: { mentorId: ctx.user.id } } })
         }
         if (userHasRole(ctx.user, 'APPLICANT')) {
           orClauses.push({ teamMembers: { some: { userId: ctx.user.id } } })
@@ -511,7 +511,7 @@ export const projectRouter = router({
             },
             orderBy: { joinedAt: 'asc' },
           },
-          mentorAssignment: {
+          mentorAssignments: {
             include: {
               mentor: {
                 select: { id: true, name: true, email: true, expertiseTags: true, profileImageKey: true, profileImageProvider: true },
@@ -585,14 +585,18 @@ export const projectRouter = router({
         }))
       )
 
-      const mentorWithAvatar = project.mentorAssignment
+      // TODO(PR8 Task 8): surface all mentors. For now we keep the legacy
+      // single-mentor shape and just pick the first non-dropped assignment
+      // so the admin UI keeps rendering without changes.
+      const primaryAssignment = project.mentorAssignments[0] ?? null
+      const mentorWithAvatar = primaryAssignment
         ? {
-            ...project.mentorAssignment,
+            ...primaryAssignment,
             mentor: {
-              ...project.mentorAssignment.mentor,
+              ...primaryAssignment.mentor,
               avatarUrl: await getUserAvatarUrl(
-                project.mentorAssignment.mentor.profileImageKey,
-                project.mentorAssignment.mentor.profileImageProvider
+                primaryAssignment.mentor.profileImageKey,
+                primaryAssignment.mentor.profileImageProvider
               ),
             },
           }
@@ -1311,7 +1315,7 @@ export const projectRouter = router({
               },
               orderBy: { joinedAt: 'asc' },
             },
-            mentorAssignment: {
+            mentorAssignments: {
               include: {
                 mentor: {
                   select: { id: true, name: true, email: true, expertiseTags: true, profileImageKey: true, profileImageProvider: true },
@@ -1448,18 +1452,21 @@ export const projectRouter = router({
             }
           })
         ),
-        projectRaw.mentorAssignment
-          ? (async () => ({
-              ...projectRaw.mentorAssignment!,
+        // TODO(PR8 Task 8): surface all mentors. Legacy shape — pick the first.
+        (async () => {
+          const primaryMa = projectRaw.mentorAssignments[0] ?? null
+          if (!primaryMa) return null
+          return {
+            ...primaryMa,
             mentor: {
-                ...projectRaw.mentorAssignment!.mentor,
+              ...primaryMa.mentor,
               avatarUrl: await getUserAvatarUrl(
-                  projectRaw.mentorAssignment!.mentor.profileImageKey,
-                  projectRaw.mentorAssignment!.mentor.profileImageProvider
+                primaryMa.mentor.profileImageKey,
+                primaryMa.mentor.profileImageProvider
               ),
             },
-            }))()
-          : Promise.resolve(null),
+          }
+        })(),
       ])
 
       return {

src/server/routers/round.ts

@@ -236,7 +236,7 @@ export const roundRouter = router({
         where: {
           roundId: input.roundId,
           project: {
-            mentorAssignment: null,
+            mentorAssignments: { none: {} },
             ...(eligibility === 'requested_only' ? { wantsMentorship: true } : {}),
           },
         },

src/server/services/mentor-workspace.ts

@@ -152,6 +152,11 @@ export async function markRead(
 
 /**
  * Record a file upload in a workspace.
+ *
+ * `workspaceId` is the originating MentorAssignment id (kept on the row as an
+ * audit-trail FK). We derive the project id from that assignment so the file
+ * is bound to the project — meaning any co-mentor on the project can see/use
+ * it, and the row survives if this particular assignment is later dropped.
  */
 export async function uploadFile(
   params: {
@@ -180,6 +185,7 @@ export async function uploadFile(
 
   return prisma.mentorFile.create({
     data: {
+      projectId: assignment.projectId,
       mentorAssignmentId: params.workspaceId,
       uploadedByUserId: params.uploadedByUserId,
       fileName: params.fileName,
@@ -238,9 +244,6 @@ export async function promoteFile(
   try {
     const file = await prisma.mentorFile.findUnique({
       where: { id: params.mentorFileId },
-      include: {
-        mentorAssignment: { select: { projectId: true } },
-      },
     })
 
     if (!file) {
@@ -265,7 +268,7 @@ export async function promoteFile(
       // Create promotion event
       await tx.submissionPromotionEvent.create({
         data: {
-          projectId: file.mentorAssignment.projectId,
+          projectId: file.projectId,
           roundId: params.roundId,
           slotKey: params.slotKey,
           sourceType: 'MENTOR_FILE',
@@ -281,7 +284,7 @@ export async function promoteFile(
           entityId: params.mentorFileId,
           actorId: params.promotedById,
           detailsJson: {
-            projectId: file.mentorAssignment.projectId,
+            projectId: file.projectId,
             roundId: params.roundId,
             slotKey: params.slotKey,
             fileName: file.fileName,
@@ -297,7 +300,7 @@ export async function promoteFile(
         entityType: 'MentorFile',
         entityId: params.mentorFileId,
         detailsJson: {
-          projectId: file.mentorAssignment.projectId,
+          projectId: file.projectId,
           slotKey: params.slotKey,
         },
       })
@@ -314,14 +317,17 @@ export async function promoteFile(
 }
 
 /**
- * List files for a workspace, newest first, with comment counts and uploader.
+ * List files for a project, newest first, with comment counts and uploader.
+ * Project-scoped: every mentor assigned to the project (and every team member)
+ * sees the same file list, even if some files were uploaded under a now-dropped
+ * assignment.
  */
 export async function getFiles(
-  workspaceId: string,
+  projectId: string,
   prisma: PrismaClient,
 ) {
   return prisma.mentorFile.findMany({
-    where: { mentorAssignmentId: workspaceId },
+    where: { projectId },
     orderBy: { createdAt: 'desc' },
     include: {
       uploadedBy: { select: { id: true, name: true, email: true } },
@@ -331,8 +337,10 @@ export async function getFiles(
 }
 
 /**
- * Delete a file. Caller must be either the uploader OR the assigned mentor.
- * Removes the MinIO object and the DB row + cascade-deletes comments.
+ * Delete a file. Caller must be either the uploader, OR any mentor currently
+ * assigned (not dropped) to the file's project, OR a team member of the
+ * file's project. Removes the MinIO object and the DB row + cascade-deletes
+ * comments.
  */
 export async function deleteFile(
   params: { mentorFileId: string; userId: string },
@@ -341,13 +349,30 @@ export async function deleteFile(
 ): Promise<void> {
   const file = await prisma.mentorFile.findUnique({
     where: { id: params.mentorFileId },
-    include: { mentorAssignment: { select: { mentorId: true } } },
   })
   if (!file) throw new Error('File not found')
   const isUploader = file.uploadedByUserId === params.userId
-  const isMentor = file.mentorAssignment.mentorId === params.userId
-  if (!isUploader && !isMentor) {
-    throw new Error('Only the uploader or the assigned mentor can delete this file')
+  let isAuthorized = isUploader
+  if (!isAuthorized) {
+    const mentorAssignment = await prisma.mentorAssignment.findFirst({
+      where: { projectId: file.projectId, mentorId: params.userId, droppedAt: null },
+      select: { id: true },
+    })
+    if (mentorAssignment) {
+      isAuthorized = true
+    }
+  }
+  if (!isAuthorized) {
+    const teamMembership = await prisma.teamMember.findFirst({
+      where: { projectId: file.projectId, userId: params.userId },
+      select: { id: true },
+    })
+    if (teamMembership) {
+      isAuthorized = true
+    }
+  }
+  if (!isAuthorized) {
+    throw new Error('Only the uploader, an assigned mentor, or a team member can delete this file')
   }
   try {
     await removeStorageObject(file.bucket, file.objectKey)

src/server/services/smart-assignment.ts

@@ -670,7 +670,7 @@ export async function getMentorSuggestionsForProject(
       projectTags: {
         include: { tag: true },
       },
-      mentorAssignment: true,
+      mentorAssignments: true,
     },
   })
 
@@ -714,7 +714,7 @@ export async function getMentorSuggestionsForProject(
 
   for (const mentor of mentors) {
     // Skip if already assigned to this project
-    if (project.mentorAssignment?.mentorId === mentor.id) {
+    if (project.mentorAssignments.some((ma) => ma.mentorId === mentor.id)) {
       continue
     }
 

tests/integration/mentor-file-scope.test.ts

@@ -0,0 +1,138 @@
+/**
+ * PR8 — MentorFile schema invariant check
+ *
+ * The actual data migration (backfill of MentorFile.projectId from the
+ * originating MentorAssignment.projectId) was verified against the May 7
+ * production database dump in Task 2 of PR8. This file is a complementary
+ * schema-invariant check that runs against the current dev DB:
+ *
+ *   1. MentorFile.projectId is now a required column (Prisma validation fails
+ *      when omitted).
+ *   2. Files are scoped to the project, not to a single MentorAssignment —
+ *      deleting the originating assignment leaves the file in place with
+ *      mentorAssignmentId set to NULL (FK SetNull) and projectId unchanged.
+ *      This is what enables team-wide file visibility across co-mentors.
+ */
+
+import { afterAll, describe, expect, it } from 'vitest'
+import { prisma } from '../setup'
+import {
+  createTestUser,
+  createTestProgram,
+  createTestProject,
+  cleanupTestData,
+  uid,
+} from '../helpers'
+
+describe('MentorFile scope invariants (PR8 schema)', () => {
+  const programIds: string[] = []
+  const userIds: string[] = []
+  const mentorFileIds: string[] = []
+
+  afterAll(async () => {
+    if (mentorFileIds.length > 0) {
+      await prisma.mentorFile.deleteMany({ where: { id: { in: mentorFileIds } } })
+    }
+    for (const programId of programIds) {
+      await prisma.mentorAssignment.deleteMany({ where: { project: { programId } } })
+      await prisma.mentorFile.deleteMany({ where: { project: { programId } } })
+      await cleanupTestData(programId, [])
+    }
+    if (userIds.length > 0) {
+      await prisma.user.deleteMany({ where: { id: { in: userIds } } })
+    }
+  })
+
+  it('MentorFile.projectId matches MentorAssignment.projectId when created via the workspace path', async () => {
+    const program = await createTestProgram({ name: `mfscope-match-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Scope Match' })
+    const mentor = await createTestUser('MENTOR')
+    userIds.push(mentor.id)
+
+    const assignment = await prisma.mentorAssignment.create({
+      data: {
+        projectId: project.id,
+        mentorId: mentor.id,
+        method: 'MANUAL',
+        workspaceEnabled: true,
+      },
+    })
+
+    const file = await prisma.mentorFile.create({
+      data: {
+        projectId: project.id,
+        mentorAssignmentId: assignment.id,
+        uploadedByUserId: mentor.id,
+        fileName: 'invariant.pdf',
+        mimeType: 'application/pdf',
+        size: 1024,
+        bucket: 'mopc-files',
+        objectKey: `Scope_Match/mentorship/${Date.now()}-invariant.pdf`,
+      },
+    })
+    mentorFileIds.push(file.id)
+
+    expect(file.projectId).toBe(assignment.projectId)
+  })
+
+  it('creating a MentorFile without a projectId is rejected by Prisma', async () => {
+    const program = await createTestProgram({ name: `mfscope-noproj-${uid()}` })
+    programIds.push(program.id)
+    const mentor = await createTestUser('MENTOR')
+    userIds.push(mentor.id)
+
+    // `projectId` is required in the schema — Prisma should reject this.
+    // Cast away the type for the deliberate omission.
+    await expect(
+      prisma.mentorFile.create({
+        data: {
+          uploadedByUserId: mentor.id,
+          fileName: 'no-project.pdf',
+          mimeType: 'application/pdf',
+          size: 10,
+          bucket: 'mopc-files',
+          objectKey: 'orphan/no-project.pdf',
+        } as unknown as Parameters<typeof prisma.mentorFile.create>[0]['data'],
+      }),
+    ).rejects.toThrow()
+  })
+
+  it('dropping the originating MentorAssignment leaves the MentorFile in place (SetNull)', async () => {
+    const program = await createTestProgram({ name: `mfscope-setnull-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'SetNull Project' })
+    const mentor = await createTestUser('MENTOR')
+    userIds.push(mentor.id)
+
+    const assignment = await prisma.mentorAssignment.create({
+      data: {
+        projectId: project.id,
+        mentorId: mentor.id,
+        method: 'MANUAL',
+        workspaceEnabled: true,
+      },
+    })
+
+    const file = await prisma.mentorFile.create({
+      data: {
+        projectId: project.id,
+        mentorAssignmentId: assignment.id,
+        uploadedByUserId: mentor.id,
+        fileName: 'survives-drop.pdf',
+        mimeType: 'application/pdf',
+        size: 2048,
+        bucket: 'mopc-files',
+        objectKey: `SetNull_Project/mentorship/${Date.now()}-survives.pdf`,
+      },
+    })
+    mentorFileIds.push(file.id)
+
+    await prisma.mentorAssignment.delete({ where: { id: assignment.id } })
+
+    const after = await prisma.mentorFile.findUnique({ where: { id: file.id } })
+    expect(after).not.toBeNull()
+    expect(after?.mentorAssignmentId).toBeNull()
+    expect(after?.projectId).toBe(project.id)
+  })
+})

tests/unit/mentor-assignment-ux.test.ts

@@ -213,12 +213,12 @@ describe('mentor.autoAssignBulkForRound', () => {
 
     expect(result.assigned).toBe(1)
 
-    const requestedAssigned = await prisma.mentorAssignment.findUnique({
+    const requestedAssigned = await prisma.mentorAssignment.findFirst({
       where: { projectId: projWithRequest.id },
     })
     expect(requestedAssigned).not.toBeNull()
 
-    const skippedNotAssigned = await prisma.mentorAssignment.findUnique({
+    const skippedNotAssigned = await prisma.mentorAssignment.findFirst({
       where: { projectId: projWithoutRequest.id },
     })
     expect(skippedNotAssigned).toBeNull()
@@ -291,7 +291,7 @@ describe('mentor.autoAssignBulkForRound', () => {
     expect(result.assigned).toBe(1)
     expect(result.skipped).toBe(1)
 
-    const stillExisting = await prisma.mentorAssignment.findUnique({
+    const stillExisting = await prisma.mentorAssignment.findFirst({
       where: { projectId: projAlreadyAssigned.id },
     })
     expect(stillExisting?.mentorId).toBe(existingMentor.id) // unchanged
@@ -377,17 +377,17 @@ describe('mentor.autoAssignBulkForRound', () => {
 
     expect(result.assigned).toBe(1)
 
-    const confirmedAssigned = await prisma.mentorAssignment.findUnique({
+    const confirmedAssigned = await prisma.mentorAssignment.findFirst({
       where: { projectId: projConfirmed.id },
     })
     expect(confirmedAssigned).not.toBeNull()
 
-    const pendingAssigned = await prisma.mentorAssignment.findUnique({
+    const pendingAssigned = await prisma.mentorAssignment.findFirst({
       where: { projectId: projPending.id },
     })
     expect(pendingAssigned).toBeNull()
 
-    const noConfAssigned = await prisma.mentorAssignment.findUnique({
+    const noConfAssigned = await prisma.mentorAssignment.findFirst({
       where: { projectId: projNoConfirmation.id },
     })
     expect(noConfAssigned).toBeNull()

tests/unit/mentor-round-stats.test.ts

@@ -92,6 +92,7 @@ describe('mentor.getRoundStats', () => {
     })
     await prisma.mentorFile.create({
       data: {
+        projectId: projReqAssigned.id,
         mentorAssignmentId: a1.id,
         uploadedByUserId: mentor.id,
         fileName: 'plan.pdf',

tests/unit/mentor-upload-token.test.ts

@@ -6,6 +6,7 @@ import {
 
 const samplePayload: MentorUploadPayload = {
   mentorAssignmentId: 'ma-123',
+  projectId: 'proj-789',
   uploaderUserId: 'user-456',
   fileName: 'doc.pdf',
   mimeType: 'application/pdf',

tests/unit/mentor-workspace-files.test.ts

@@ -8,6 +8,7 @@ import { signMentorUploadToken } from '../../src/lib/mentor-upload-token'
 
 describe('mentor.workspace files end-to-end', () => {
   let programId: string
+  let projectId: string
   let mentor: { id: string; email: string; role: 'MENTOR' }
   let outsider: { id: string; email: string; role: 'JURY_MEMBER' }
   let assignmentId: string
@@ -18,6 +19,7 @@ describe('mentor.workspace files end-to-end', () => {
     const program = await createTestProgram({ name: `mentor-files-${uid()}` })
     programId = program.id
     const project = await createTestProject(programId, { title: 'Test Project' })
+    projectId = project.id
 
     const m = await createTestUser('MENTOR')
     userIds.push(m.id)
@@ -79,6 +81,7 @@ describe('mentor.workspace files end-to-end', () => {
   it('rejects workspaceUploadFile with a token whose uploader differs from the caller', async () => {
     const forged = signMentorUploadToken({
       mentorAssignmentId: assignmentId,
+      projectId,
       uploaderUserId: 'someone-else',
       fileName: 'x.pdf', mimeType: 'application/pdf', size: 1,
       bucket: 'mopc-files', objectKey: 'a/mentorship/0-x.pdf',
@@ -94,7 +97,7 @@ describe('mentor.workspace files end-to-end', () => {
       mentorAssignmentId: assignmentId, fileName: 'b.pdf', mimeType: 'application/pdf', size: 50,
     })
     await caller.workspaceUploadFile({ uploadToken: a.uploadToken })
-    const files = await caller.workspaceGetFiles({ mentorAssignmentId: assignmentId })
+    const files = await caller.workspaceGetFiles({ projectId })
     expect(files.length).toBeGreaterThanOrEqual(2)
     expect(new Date(files[0].createdAt).getTime()).toBeGreaterThanOrEqual(
       new Date(files[1].createdAt).getTime(),
@@ -104,7 +107,7 @@ describe('mentor.workspace files end-to-end', () => {
   it('refuses workspaceGetFiles to outsiders', async () => {
     const caller = createCaller(mentorRouter, outsider)
     await expect(
-      caller.workspaceGetFiles({ mentorAssignmentId: assignmentId })
+      caller.workspaceGetFiles({ projectId })
     ).rejects.toThrow(/FORBIDDEN|not a member/i)
   })
 

tests/unit/multi-mentor-assignment.test.ts

@@ -0,0 +1,509 @@
+/**
+ * PR8 — Multi-mentor stacking + change-request procedures
+ *
+ * Covers the API surface added by PR8 Tasks 4 + 6:
+ *   - mentor.assign: per-team stacking, P2002 on duplicate (projectId, mentorId),
+ *     idempotent per-row email notification (via MentorAssignment.notificationSentAt),
+ *     re-assignment after drop creates a new row and re-fires the email.
+ *   - mentor.requestChange: auth (team-member or admin), validation, single open
+ *     request per (user, project), target-assignment cross-project guard.
+ *   - mentor.listChangeRequests: admin-only, PENDING-first ordering.
+ *   - mentor.resolveChangeRequest: admin-only, BAD_REQUEST on already-resolved.
+ */
+
+import { afterAll, describe, expect, it } 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'
+
+async function createUserWithRoles(
+  primaryRole: UserRole,
+  rolesArray: UserRole[],
+  overrides: { name?: string; expertiseTags?: string[] } = {},
+) {
+  const id = uid('user')
+  return prisma.user.create({
+    data: {
+      id,
+      email: `${id}@test.local`,
+      name: overrides.name ?? `Test ${primaryRole}`,
+      role: primaryRole,
+      roles: rolesArray,
+      status: 'ACTIVE',
+      expertiseTags: overrides.expertiseTags ?? [],
+    },
+  })
+}
+
+describe('mentor.assign — stacking + per-team email idempotency', () => {
+  const programIds: string[] = []
+  const userIds: string[] = []
+
+  afterAll(async () => {
+    for (const programId of programIds) {
+      await prisma.mentorAssignment.deleteMany({ where: { project: { programId } } })
+      await cleanupTestData(programId, [])
+    }
+    if (userIds.length > 0) {
+      await prisma.user.deleteMany({ where: { id: { in: userIds } } })
+    }
+  })
+
+  it('stacks two different mentors on the same project (both rows active)', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `assign-stack-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Stacking Project' })
+
+    const m1 = await createUserWithRoles('MENTOR', ['MENTOR'], { name: 'M1' })
+    const m2 = await createUserWithRoles('MENTOR', ['MENTOR'], { name: 'M2' })
+    userIds.push(m1.id, m2.id)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    const a1 = await caller.assign({ projectId: project.id, mentorId: m1.id })
+    const a2 = await caller.assign({ projectId: project.id, mentorId: m2.id })
+
+    expect(a1.id).not.toBe(a2.id)
+    expect(a1.mentorId).toBe(m1.id)
+    expect(a2.mentorId).toBe(m2.id)
+
+    const rows = await prisma.mentorAssignment.findMany({
+      where: { projectId: project.id },
+      orderBy: { assignedAt: 'asc' },
+    })
+    expect(rows).toHaveLength(2)
+    expect(rows.every((r) => r.droppedAt === null)).toBe(true)
+  })
+
+  it('rejects duplicate (projectId, mentorId) pair with CONFLICT', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `assign-dup-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Dup Project' })
+    const mentor = await createUserWithRoles('MENTOR', ['MENTOR'])
+    userIds.push(mentor.id)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    await caller.assign({ projectId: project.id, mentorId: mentor.id })
+    await expect(
+      caller.assign({ projectId: project.id, mentorId: mentor.id }),
+    ).rejects.toThrow(/already assigned/i)
+  })
+
+  it('stamps notificationSentAt on first assignment; fires fresh email when same mentor is added to a different project', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `assign-email-${uid()}` })
+    programIds.push(program.id)
+    const project1 = await createTestProject(program.id, { title: 'Project Alpha' })
+    const project2 = await createTestProject(program.id, { title: 'Project Beta' })
+    const mentor = await createUserWithRoles('MENTOR', ['MENTOR'])
+    userIds.push(mentor.id)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const a1 = await caller.assign({ projectId: project1.id, mentorId: mentor.id })
+    const a2 = await caller.assign({ projectId: project2.id, mentorId: mentor.id })
+
+    // assign() returns the row before the post-write stamp; re-read for the
+    // current value.
+    const row1 = await prisma.mentorAssignment.findUnique({ where: { id: a1.id } })
+    const row2 = await prisma.mentorAssignment.findUnique({ where: { id: a2.id } })
+
+    expect(row1?.notificationSentAt).not.toBeNull()
+    expect(row2?.notificationSentAt).not.toBeNull()
+    // Each row carries its own timestamp — they're independent.
+    expect(row1?.id).not.toBe(row2?.id)
+  })
+
+  it('stamps notificationSentAt independently for each co-mentor on the same project', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `assign-comentor-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Co-mentor Project' })
+    const m1 = await createUserWithRoles('MENTOR', ['MENTOR'], { name: 'Co-1' })
+    const m2 = await createUserWithRoles('MENTOR', ['MENTOR'], { name: 'Co-2' })
+    userIds.push(m1.id, m2.id)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    const a1 = await caller.assign({ projectId: project.id, mentorId: m1.id })
+    const a2 = await caller.assign({ projectId: project.id, mentorId: m2.id })
+
+    const row1 = await prisma.mentorAssignment.findUnique({ where: { id: a1.id } })
+    const row2 = await prisma.mentorAssignment.findUnique({ where: { id: a2.id } })
+
+    expect(row1?.notificationSentAt).not.toBeNull()
+    expect(row2?.notificationSentAt).not.toBeNull()
+  })
+
+  it('after a mentor is dropped (assignment row deleted), re-assigning creates a fresh row with a new notificationSentAt', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `assign-redrop-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: 'Re-assign Project' })
+    const mentor = await createUserWithRoles('MENTOR', ['MENTOR'])
+    userIds.push(mentor.id)
+
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const a1 = await caller.assign({ projectId: project.id, mentorId: mentor.id })
+    const stamp1 = (
+      await prisma.mentorAssignment.findUnique({ where: { id: a1.id } })
+    )?.notificationSentAt
+    expect(stamp1).not.toBeNull()
+
+    // Hard-delete the first row (simulates a "fully dropped → repository clean"
+    // state — the unique constraint also blocks any re-assign while the row
+    // exists, so the row must go away).
+    await prisma.mentorAssignment.delete({ where: { id: a1.id } })
+
+    // Re-assign: new row, new notificationSentAt stamp.
+    const a2 = await caller.assign({ projectId: project.id, mentorId: mentor.id })
+    const stamp2 = (
+      await prisma.mentorAssignment.findUnique({ where: { id: a2.id } })
+    )?.notificationSentAt
+
+    expect(a2.id).not.toBe(a1.id)
+    expect(stamp2).not.toBeNull()
+  })
+})
+
+describe('mentor.requestChange / listChangeRequests / resolveChangeRequest', () => {
+  const programIds: string[] = []
+  const userIds: string[] = []
+
+  afterAll(async () => {
+    for (const programId of programIds) {
+      await prisma.mentorChangeRequest.deleteMany({ where: { project: { programId } } })
+      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 } } })
+    }
+  })
+
+  /**
+   * Builds a project with a LEAD team member (applicant), an unrelated
+   * non-team-member (applicant), and an admin. Returns the IDs.
+   */
+  async function setupProjectWithTeam(label: string) {
+    const admin = await createTestUser('SUPER_ADMIN', { name: `Admin ${label}` })
+    userIds.push(admin.id)
+    const program = await createTestProgram({ name: `${label}-${uid()}` })
+    programIds.push(program.id)
+    const project = await createTestProject(program.id, { title: `Project ${label}` })
+    const teamMember = await createUserWithRoles('APPLICANT', ['APPLICANT'], {
+      name: `Team ${label}`,
+    })
+    const outsider = await createUserWithRoles('APPLICANT', ['APPLICANT'], {
+      name: `Outsider ${label}`,
+    })
+    userIds.push(teamMember.id, outsider.id)
+    await prisma.teamMember.create({
+      data: {
+        projectId: project.id,
+        userId: teamMember.id,
+        role: 'LEAD',
+      },
+    })
+    return { admin, program, project, teamMember, outsider }
+  }
+
+  it('team member can open a change request (PENDING)', async () => {
+    const { project, teamMember } = await setupProjectWithTeam('rc-teamok')
+    const caller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    const created = await caller.requestChange({
+      projectId: project.id,
+      reason: 'We would like a mentor with deeper marine biology experience.',
+    })
+    expect(created.status).toBe('PENDING')
+
+    const persisted = await prisma.mentorChangeRequest.findUnique({
+      where: { id: created.id },
+    })
+    expect(persisted?.requestedByUserId).toBe(teamMember.id)
+    expect(persisted?.projectId).toBe(project.id)
+  })
+
+  it('non-team-member non-admin is rejected with FORBIDDEN', async () => {
+    const { project, outsider } = await setupProjectWithTeam('rc-outsider')
+    const caller = createCaller(mentorRouter, {
+      id: outsider.id,
+      email: outsider.email,
+      role: 'APPLICANT',
+    })
+    await expect(
+      caller.requestChange({
+        projectId: project.id,
+        reason: 'I have no business asking for this.',
+      }),
+    ).rejects.toThrow(/FORBIDDEN|not a member/i)
+  })
+
+  it('admin (no team membership) can open a change request', async () => {
+    const { admin, project } = await setupProjectWithTeam('rc-admin')
+    const caller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    const created = await caller.requestChange({
+      projectId: project.id,
+      reason: 'Admin-initiated mentor swap due to internal escalation.',
+    })
+    expect(created.status).toBe('PENDING')
+  })
+
+  it('reason < 10 chars is rejected (Zod validation)', async () => {
+    const { project, teamMember } = await setupProjectWithTeam('rc-short')
+    const caller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    await expect(
+      caller.requestChange({ projectId: project.id, reason: 'too short' }),
+    ).rejects.toThrow()
+  })
+
+  it('opening a second request while the first is still PENDING throws CONFLICT', async () => {
+    const { project, teamMember } = await setupProjectWithTeam('rc-conflict')
+    const caller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    await caller.requestChange({
+      projectId: project.id,
+      reason: 'First request — still pending please review.',
+    })
+    await expect(
+      caller.requestChange({
+        projectId: project.id,
+        reason: 'Second request while first is open.',
+      }),
+    ).rejects.toThrow(/already.*open|CONFLICT/i)
+  })
+
+  it('after the first request is resolved, the same user can open a new one', async () => {
+    const { admin, project, teamMember } = await setupProjectWithTeam('rc-reopen')
+    const teamCaller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    const adminCaller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const first = await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'First request — please address my concerns.',
+    })
+    await adminCaller.resolveChangeRequest({
+      id: first.id,
+      status: 'RESOLVED',
+      resolutionNote: 'Mentor swapped.',
+    })
+
+    const second = await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'Second request — new concern after resolution.',
+    })
+    expect(second.status).toBe('PENDING')
+    expect(second.id).not.toBe(first.id)
+  })
+
+  it('targetAssignmentId belonging to a different project is rejected with BAD_REQUEST', async () => {
+    const { admin, project: projectA, teamMember } = await setupProjectWithTeam('rc-crossproj')
+    // Make a second project + mentor assignment NOT on the requester's project.
+    const otherProgram = await createTestProgram({ name: `rc-other-${uid()}` })
+    programIds.push(otherProgram.id)
+    const otherProject = await createTestProject(otherProgram.id, { title: 'Other proj' })
+    const mentor = await createUserWithRoles('MENTOR', ['MENTOR'])
+    userIds.push(mentor.id)
+    const foreignAssignment = await prisma.mentorAssignment.create({
+      data: {
+        projectId: otherProject.id,
+        mentorId: mentor.id,
+        method: 'MANUAL',
+        assignedBy: admin.id,
+      },
+    })
+
+    const caller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    await expect(
+      caller.requestChange({
+        projectId: projectA.id,
+        targetAssignmentId: foreignAssignment.id,
+        reason: 'Trying to point at a foreign assignment row.',
+      }),
+    ).rejects.toThrow(/does not belong|BAD_REQUEST/i)
+  })
+
+  it('listChangeRequests is FORBIDDEN for applicant', async () => {
+    const { project, teamMember } = await setupProjectWithTeam('rc-list-forbidden')
+    const teamCaller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'A real request, but list should still be admin-only.',
+    })
+    await expect(teamCaller.listChangeRequests({})).rejects.toThrow()
+  })
+
+  it('listChangeRequests returns PENDING rows before non-PENDING rows', async () => {
+    const { admin, project, teamMember } = await setupProjectWithTeam('rc-list-order')
+    const teamCaller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    const adminCaller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    // Create two requests: open one, resolve it; open a second one (still PENDING).
+    const resolvedReq = await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'Will be resolved before the second request opens.',
+    })
+    await adminCaller.resolveChangeRequest({
+      id: resolvedReq.id,
+      status: 'RESOLVED',
+    })
+    const pendingReq = await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'Still pending — should be listed first.',
+    })
+
+    const rows = (await adminCaller.listChangeRequests({ projectId: project.id })) as Array<{
+      id: string
+      status: string
+    }>
+    const ids = rows.map((r) => r.id)
+    // PENDING must come before RESOLVED in the listing.
+    expect(ids.indexOf(pendingReq.id)).toBeLessThan(ids.indexOf(resolvedReq.id))
+    expect(rows[0].status).toBe('PENDING')
+  })
+
+  it('resolveChangeRequest sets resolvedBy/resolvedAt/resolutionNote', async () => {
+    const { admin, project, teamMember } = await setupProjectWithTeam('rc-resolve')
+    const teamCaller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    const adminCaller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const req = await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'Please resolve this request.',
+    })
+    const result = await adminCaller.resolveChangeRequest({
+      id: req.id,
+      status: 'RESOLVED',
+      resolutionNote: 'Replacement mentor assigned.',
+    })
+    expect(result.status).toBe('RESOLVED')
+    expect(result.resolvedByUserId).toBe(admin.id)
+    expect(result.resolvedAt).not.toBeNull()
+    expect(result.resolutionNote).toBe('Replacement mentor assigned.')
+  })
+
+  it('resolveChangeRequest by non-admin is FORBIDDEN', async () => {
+    const { admin, project, teamMember } = await setupProjectWithTeam('rc-resolve-forbid')
+    const teamCaller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    const adminCaller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    const req = await adminCaller.requestChange({
+      projectId: project.id,
+      reason: 'Admin opens, applicant should not resolve.',
+    })
+    await expect(
+      teamCaller.resolveChangeRequest({ id: req.id, status: 'RESOLVED' }),
+    ).rejects.toThrow()
+  })
+
+  it('resolveChangeRequest on an already-resolved request throws BAD_REQUEST', async () => {
+    const { admin, project, teamMember } = await setupProjectWithTeam('rc-resolve-twice')
+    const teamCaller = createCaller(mentorRouter, {
+      id: teamMember.id,
+      email: teamMember.email,
+      role: 'APPLICANT',
+    })
+    const adminCaller = createCaller(mentorRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+    const req = await teamCaller.requestChange({
+      projectId: project.id,
+      reason: 'Will resolve, then try to resolve again.',
+    })
+    await adminCaller.resolveChangeRequest({ id: req.id, status: 'RESOLVED' })
+    await expect(
+      adminCaller.resolveChangeRequest({ id: req.id, status: 'DISMISSED' }),
+    ).rejects.toThrow(/already resolved|BAD_REQUEST/i)
+  })
+})