feat(workspace): mentor + applicant message previews (§F.2)

mentor.getRecentMessages: last N unread messages from teams across all
of a mentor's assignments. Drives a Recent Messages card on /mentor.

applicant.getMentorConversationPreview: last 3 messages + unread count
for a given project. Drives a 'Conversation with [Mentor]' card on
/applicant — auto-hides when no mentor is assigned.

Both procedures use the existing MentorMessage(projectId, createdAt)
composite index — no new index needed.

Plan: docs/superpowers/plans/2026-04-28-pr6-multi-role-and-workspace-previews.md

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

@@ -17,6 +17,7 @@ import { Skeleton } from '@/components/ui/skeleton'
 import { Textarea } from '@/components/ui/textarea'
 import { CompetitionTimelineSidebar } from '@/components/applicant/competition-timeline'
 import { MentoringRequestCard } from '@/components/applicant/mentoring-request-card'
+import { MentorConversationCard } from '@/components/applicant/mentor-conversation-card'
 import { AnimatedCard } from '@/components/shared/animated-container'
 import { ProjectLogoUpload } from '@/components/shared/project-logo-upload'
 import { Progress } from '@/components/ui/progress'
@@ -401,6 +402,10 @@ export default function ApplicantDashboardPage() {
             </AnimatedCard>
           ))}
 
+          {/* Conversation with assigned mentor (auto-hides when no mentor assigned) */}
+          <MentorConversationCard projectId={project.id} />
+
+
           {/* Jury Feedback Card */}
           {totalEvaluations > 0 && (
             <AnimatedCard index={4}>

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

@@ -41,6 +41,7 @@ import {
 import { formatDateOnly } from '@/lib/utils'
 import { AnimatedCard } from '@/components/shared/animated-container'
 import { CountryDisplay } from '@/components/shared/country-display'
+import { RecentMessagesCard } from '@/components/mentor/recent-messages-card'
 
 // Status badge colors
 const statusColors: Record<string, 'default' | 'secondary' | 'destructive' | 'outline'> = {
@@ -117,6 +118,9 @@ export default function MentorDashboard() {
         </p>
       </div>
 
+      {/* Recent unread messages from teams */}
+      <RecentMessagesCard />
+
       {/* Stats */}
       <div className="grid gap-4 md:grid-cols-3">
         <AnimatedCard index={0}>

src/components/applicant/mentor-conversation-card.tsx

@@ -0,0 +1,60 @@
+'use client'
+
+import Link from 'next/link'
+import { trpc } from '@/lib/trpc/client'
+import { Card, CardContent, 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 { MessageCircle } from 'lucide-react'
+
+interface Props {
+  projectId: string
+}
+
+export function MentorConversationCard({ projectId }: Props) {
+  const { data, isLoading } = trpc.applicant.getMentorConversationPreview.useQuery(
+    { projectId, limit: 3 },
+    { refetchInterval: 30_000 },
+  )
+
+  if (isLoading) return <Skeleton className="h-44 w-full rounded-md" />
+  if (!data || !data.mentor) return null // No mentor assigned — render nothing
+
+  return (
+    <Card>
+      <CardHeader>
+        <CardTitle className="flex items-center justify-between gap-2 text-base">
+          <span className="flex items-center gap-2">
+            <MessageCircle className="h-4 w-4" /> Conversation with{' '}
+            {data.mentor.name ?? data.mentor.email}
+          </span>
+          {data.unreadCount > 0 && <Badge variant="default">{data.unreadCount} new</Badge>}
+        </CardTitle>
+      </CardHeader>
+      <CardContent>
+        {data.messages.length === 0 ? (
+          <p className="text-muted-foreground text-sm">
+            Say hi to your mentor — they&apos;re here to help you sharpen your project.
+          </p>
+        ) : (
+          <ul className="space-y-2">
+            {data.messages.map((m) => (
+              <li key={m.id} className="bg-muted/20 rounded-md border p-2.5">
+                <div className="text-muted-foreground text-xs">
+                  {m.sender.name ?? m.sender.email}
+                </div>
+                <div className="mt-0.5 line-clamp-2 text-sm">{m.message}</div>
+              </li>
+            ))}
+          </ul>
+        )}
+        <div className="mt-3 flex justify-end">
+          <Button asChild size="sm">
+            <Link href="/applicant/mentor">Open chat</Link>
+          </Button>
+        </div>
+      </CardContent>
+    </Card>
+  )
+}

src/components/mentor/recent-messages-card.tsx

@@ -0,0 +1,66 @@
+'use client'
+
+import Link from 'next/link'
+import { trpc } from '@/lib/trpc/client'
+import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
+import { Skeleton } from '@/components/ui/skeleton'
+import { MessageCircle } from 'lucide-react'
+
+function formatRelativePast(date: Date | string | null): string {
+  if (!date) return ''
+  const d = typeof date === 'string' ? new Date(date) : date
+  const ms = Date.now() - d.getTime()
+  const minutes = Math.floor(ms / 60_000)
+  const hours = Math.floor(ms / 3_600_000)
+  const days = Math.floor(ms / 86_400_000)
+  if (days > 0) return `${days}d ago`
+  if (hours > 0) return `${hours}h ago`
+  return `${Math.max(0, minutes)}m ago`
+}
+
+export function RecentMessagesCard() {
+  const { data, isLoading } = trpc.mentor.getRecentMessages.useQuery({ limit: 5 })
+
+  return (
+    <Card>
+      <CardHeader>
+        <CardTitle className="flex items-center gap-2 text-base">
+          <MessageCircle className="h-4 w-4" /> Recent Messages
+        </CardTitle>
+      </CardHeader>
+      <CardContent>
+        {isLoading ? (
+          <div className="space-y-2">
+            {[1, 2, 3].map((i) => (
+              <Skeleton key={i} className="h-12 w-full" />
+            ))}
+          </div>
+        ) : !data || data.unread.length === 0 ? (
+          <p className="text-muted-foreground text-sm">
+            No new messages. Your mentees will appear here when they reach out.
+          </p>
+        ) : (
+          <ul className="space-y-3">
+            {data.unread.map((m) => (
+              <li key={m.id}>
+                <Link
+                  href={`/mentor/workspace/${m.project.id}`}
+                  className="hover:bg-muted/40 block rounded-md border p-3"
+                >
+                  <div className="flex items-baseline justify-between gap-2">
+                    <div className="text-sm font-medium">{m.sender.name ?? m.sender.email}</div>
+                    <div className="text-muted-foreground text-xs">
+                      {formatRelativePast(m.createdAt as unknown as Date)}
+                    </div>
+                  </div>
+                  <div className="text-muted-foreground mt-0.5 text-xs">{m.project.title}</div>
+                  <div className="mt-1 line-clamp-2 text-sm">{m.message}</div>
+                </Link>
+              </li>
+            ))}
+          </ul>
+        )}
+      </CardContent>
+    </Card>
+  )
+}

src/server/routers/applicant.ts

@@ -2659,4 +2659,50 @@ export const applicantRouter = router({
 
       return { success: true, roundId: activePrs.roundId, roundName: activePrs.round.name }
     }),
+
+  /**
+   * Last N messages + unread count for the applicant's project mentor workspace.
+   * Drives the 'Conversation with [Mentor]' card on /applicant.
+   */
+  getMentorConversationPreview: protectedProcedure
+    .input(z.object({ projectId: z.string(), limit: z.number().min(1).max(10).default(3) }))
+    .query(async ({ ctx, input }) => {
+      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: 'Not a team member of this project',
+        })
+      }
+
+      const assignment = await ctx.prisma.mentorAssignment.findUnique({
+        where: { projectId: input.projectId },
+        include: { mentor: { select: { id: true, name: true, email: true } } },
+      })
+
+      const [messages, unreadCount] = await Promise.all([
+        ctx.prisma.mentorMessage.findMany({
+          where: { projectId: input.projectId },
+          include: { sender: { select: { id: true, name: true, email: true } } },
+          orderBy: { createdAt: 'desc' },
+          take: input.limit,
+        }),
+        ctx.prisma.mentorMessage.count({
+          where: {
+            projectId: input.projectId,
+            senderId: { not: ctx.user.id },
+            isRead: false,
+          },
+        }),
+      ])
+
+      return {
+        mentor: assignment?.mentor ?? null,
+        messages: messages.reverse(),
+        unreadCount,
+      }
+    }),
 })

src/server/routers/mentor.ts

@@ -1259,6 +1259,30 @@ export const mentorRouter = router({
       return messages
     }),
 
+  /**
+   * Recent unread messages from team members across all of the mentor's
+   * assignments. Drives the 'Recent Messages' card on /mentor.
+   */
+  getRecentMessages: mentorProcedure
+    .input(z.object({ limit: z.number().min(1).max(20).default(5) }).optional())
+    .query(async ({ ctx, input }) => {
+      const limit = input?.limit ?? 5
+      const unread = await ctx.prisma.mentorMessage.findMany({
+        where: {
+          senderId: { not: ctx.user.id },
+          isRead: false,
+          workspace: { mentorId: ctx.user.id },
+        },
+        include: {
+          sender: { select: { id: true, name: true, email: true } },
+          project: { select: { id: true, title: true } },
+        },
+        orderBy: { createdAt: 'desc' },
+        take: limit,
+      })
+      return { unread }
+    }),
+
   /**
    * List all mentor assignments (admin)
    */