feat(mentor): bulk assignment + coalesced emails + team intros on round open

Round-page bulk-assign UI
- Checkboxes on every project row, header select-all, primary-tinted action
  toolbar that appears when 1+ rows are selected with an "Assign mentor…"
  CTA and Clear. Dialog lists the mentor pool with search (name/email/
  country/expertise), load indicator, and a radio picker.
- Always-visible tip strip when nothing is selected explains the bulk flow
  and offers a one-click "Select all N without a mentor" shortcut.
- New tRPC procedure `mentor.bulkAssign({ mentorId, projectIds })` assigns
  one mentor to many projects in a transaction; idempotent on the per-pair
  `(projectId, mentorId)` unique; per-project in-app notifications still
  fire for each team.
- Mutation invalidates listMentoringProjects, getProjectsNeedingMentor,
  getMentoringImportCandidates, getMentorPool, getRoundStats, project.list
  so the page reflects the new state without a refresh.

Coalesced mentor emails
- New `sendMentorBulkAssignmentEmail` (single email listing every newly-
  assigned project + workspace links) used by `mentor.bulkAssign` and
  `mentor.autoAssignBulkForRound`. The previously-silent auto-fill flow
  now emails mentors at the end of the batch, one combined email per
  mentor regardless of how many projects they received.

Team introduction emails when the round opens
- New `sendTeamMentorIntroductionEmail` lists every assigned mentor with
  name + email and a link to the workspace, so teams can reach out
  directly.
- `activateRound` (round-engine) fires the introduction for every project
  in a MENTORING round that has active mentors when the round opens.
- `mentor.assign`, `mentor.bulkAssign`, and `autoAssignBulkForRound` also
  fire the introduction immediately when the project's MENTORING round is
  already ROUND_ACTIVE — so mentors added mid-round still reach the team.
- Idempotency via the new `MentorAssignment.teamIntroducedAt` column
  (migration 20260526114936) — independent from `notificationSentAt` so
  pre-existing mentor-side stamps don't suppress the team-side email.

prisma/migrations/20260526114936_mentor_assignment_team_introduced_at/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "MentorAssignment" ADD COLUMN     "teamIntroducedAt" TIMESTAMP(3);

prisma/schema.prisma

@@ -1281,9 +1281,16 @@ model MentorAssignment {
   assignedAt DateTime               @default(now())
   assignedBy String? // Admin who assigned
 
-  // Per-assignment email idempotency: stamped once the assignment notification email is sent.
+  // Per-assignment email idempotency: stamped once the MENTOR-side notification
+  // email has been sent (the "you've been assigned a project" email to the mentor).
   notificationSentAt DateTime?
 
+  // Stamped once the TEAM has been introduced to this mentor (the "meet your
+  // mentor" email with mentor contact info). Fired by `activateRound` for
+  // MENTORING rounds and by mentor.assign when the project's MENTORING round
+  // is already ROUND_ACTIVE. Independent from notificationSentAt above.
+  teamIntroducedAt DateTime?
+
   // AI assignment metadata
   aiConfidenceScore   Float?
   expertiseMatchScore Float?

src/components/admin/round/mentoring-projects-table.tsx

@@ -2,6 +2,7 @@
 
 import { useMemo, useState } from 'react'
 import Link from 'next/link'
+import { toast } from 'sonner'
 import { trpc } from '@/lib/trpc/client'
 import {
   Table,
@@ -15,7 +16,24 @@ import { Badge } from '@/components/ui/badge'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
 import { Skeleton } from '@/components/ui/skeleton'
-import { Search, UserPlus, ArrowRight, Sparkles } from 'lucide-react'
+import { Checkbox } from '@/components/ui/checkbox'
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from '@/components/ui/dialog'
+import {
+  Search,
+  UserPlus,
+  ArrowRight,
+  Sparkles,
+  Loader2,
+  Download,
+  X,
+} from 'lucide-react'
 import { CountryDisplay } from '@/components/shared/country-display'
 
 type Filter = 'all' | 'unassigned' | 'assigned' | 'wants_only'
@@ -23,12 +41,106 @@ type Filter = 'all' | 'unassigned' | 'assigned' | 'wants_only'
 export function MentoringProjectsTable({ roundId }: { roundId: string }) {
   const [search, setSearch] = useState('')
   const [filter, setFilter] = useState<Filter>('all')
+  const [selected, setSelected] = useState<Set<string>>(new Set())
+  const [bulkOpen, setBulkOpen] = useState(false)
+  const [chosenMentorId, setChosenMentorId] = useState<string>('')
+  const [mentorSearch, setMentorSearch] = useState('')
+
+  const utils = trpc.useUtils()
 
   const { data, isLoading } = trpc.round.listMentoringProjects.useQuery(
     { roundId },
     { refetchInterval: 30_000 },
   )
 
+  const { data: importCandidates } =
+    trpc.round.getMentoringImportCandidates.useQuery({ roundId })
+
+  const { data: mentorPool } = trpc.mentor.getMentorPool.useQuery(
+    {},
+    { enabled: bulkOpen },
+  )
+
+  const bulkAssignMutation = trpc.mentor.bulkAssign.useMutation({
+    onSuccess: (result) => {
+      if (result.assignedCount === 0 && result.skippedCount > 0) {
+        toast.info(
+          `No new assignments — the selected mentor is already on all ${result.skippedCount} project${result.skippedCount === 1 ? '' : 's'}.`,
+        )
+      } else {
+        toast.success(
+          `Assigned mentor to ${result.assignedCount} project${
+            result.assignedCount === 1 ? '' : 's'
+          }${result.skippedCount > 0 ? ` (${result.skippedCount} already had this mentor)` : ''}${
+            result.emailSent ? ' · email sent' : ''
+          }`,
+        )
+      }
+      utils.round.listMentoringProjects.invalidate({ roundId })
+      utils.round.getProjectsNeedingMentor.invalidate({ roundId })
+      utils.round.getMentoringImportCandidates.invalidate({ roundId })
+      utils.mentor.getMentorPool.invalidate()
+      utils.mentor.getRoundStats.invalidate({ roundId })
+      utils.project.list.invalidate()
+      setSelected(new Set())
+      setChosenMentorId('')
+      setMentorSearch('')
+      setBulkOpen(false)
+    },
+    onError: (err) => toast.error(err.message),
+  })
+
+  const advanceMutation = trpc.round.advanceProjects.useMutation({
+    onSuccess: (result) => {
+      toast.success(
+        `Imported ${result.advancedCount} project${
+          result.advancedCount === 1 ? '' : 's'
+        } from ${result.targetRoundName ? '' : ''}${
+          importCandidates?.priorRound?.name ?? 'the prior round'
+        }`,
+      )
+      utils.round.listMentoringProjects.invalidate({ roundId })
+      utils.round.getMentoringImportCandidates.invalidate({ roundId })
+      utils.round.getProjectsNeedingMentor.invalidate({ roundId })
+    },
+    onError: (err) => toast.error(err.message),
+  })
+
+  const importBanner = importCandidates?.priorRound &&
+    importCandidates.pendingCount > 0 && (
+      <div className="flex flex-col gap-2 rounded-md border border-amber-300 bg-amber-50 px-4 py-3 text-sm sm:flex-row sm:items-center sm:justify-between">
+        <div className="text-amber-900">
+          <span className="font-medium">
+            {importCandidates.pendingCount} PASSED project
+            {importCandidates.pendingCount === 1 ? '' : 's'}
+          </span>{' '}
+          from{' '}
+          <span className="font-medium">
+            {importCandidates.priorRound.name}
+          </span>{' '}
+          {importCandidates.pendingCount === 1 ? "isn't" : "aren't"} in this
+          mentoring round yet.
+        </div>
+        <Button
+          size="sm"
+          onClick={() =>
+            advanceMutation.mutate({
+              roundId: importCandidates.priorRound!.id,
+              targetRoundId: roundId,
+            })
+          }
+          disabled={advanceMutation.isPending}
+        >
+          {advanceMutation.isPending ? (
+            <Loader2 className="mr-1.5 h-4 w-4 animate-spin" />
+          ) : (
+            <Download className="mr-1.5 h-4 w-4" />
+          )}
+          Import {importCandidates.pendingCount}
+        </Button>
+      </div>
+    )
+
   const filtered = useMemo(() => {
     if (!data) return []
     const q = search.trim().toLowerCase()
@@ -72,8 +184,20 @@ export function MentoringProjectsTable({ roundId }: { roundId: string }) {
 
   if (!data || data.projects.length === 0) {
     return (
-      <div className="rounded-md border bg-muted/30 px-4 py-12 text-center text-sm text-muted-foreground">
-        No projects in this mentoring round yet.
+      <div className="space-y-3">
+        {importBanner}
+        <div className="rounded-md border bg-muted/30 px-4 py-12 text-center text-sm text-muted-foreground">
+          No projects in this mentoring round yet.
+          {!importBanner && (
+            <>
+              {' '}Use{' '}
+              <span className="font-medium text-foreground">
+                Add Project to Round
+              </span>{' '}
+              to populate it.
+            </>
+          )}
+        </div>
       </div>
     )
   }
@@ -103,6 +227,7 @@ export function MentoringProjectsTable({ roundId }: { roundId: string }) {
 
   return (
     <div className="space-y-3">
+      {importBanner}
       <div className="flex flex-col gap-2 sm:flex-row sm:items-center sm:justify-between">
         <div className="flex flex-wrap gap-1.5">
           <Pill value="all" label="All" count={totals.total} />
@@ -121,10 +246,80 @@ export function MentoringProjectsTable({ roundId }: { roundId: string }) {
         </div>
       </div>
 
+      {selected.size > 0 ? (
+        <div className="flex flex-col gap-2 rounded-md border border-primary/30 bg-primary/5 px-4 py-2.5 text-sm sm:flex-row sm:items-center sm:justify-between">
+          <div>
+            <span className="font-medium">{selected.size}</span>{' '}
+            <span className="text-muted-foreground">
+              project{selected.size === 1 ? '' : 's'} selected
+            </span>
+          </div>
+          <div className="flex flex-wrap gap-2">
+            <Button size="sm" onClick={() => setBulkOpen(true)}>
+              <UserPlus className="mr-1.5 h-4 w-4" />
+              Assign mentor…
+            </Button>
+            <Button
+              size="sm"
+              variant="outline"
+              onClick={() => setSelected(new Set())}
+            >
+              <X className="mr-1 h-4 w-4" />
+              Clear
+            </Button>
+          </div>
+        </div>
+      ) : (
+        <div className="flex items-center justify-between rounded-md border border-dashed bg-muted/20 px-4 py-2 text-xs text-muted-foreground">
+          <span>
+            Tip: tick checkboxes to bulk-assign one mentor to multiple
+            projects in a single click (mentor gets one combined email).
+          </span>
+          {totals.unassigned > 0 && (
+            <button
+              type="button"
+              className="text-xs font-medium text-foreground hover:underline"
+              onClick={() => {
+                setFilter('unassigned')
+                setSelected(
+                  new Set(
+                    data.projects
+                      .filter((p) => p.mentors.length === 0)
+                      .map((p) => p.id),
+                  ),
+                )
+              }}
+            >
+              Select all {totals.unassigned} without a mentor
+            </button>
+          )}
+        </div>
+      )}
+
       <div className="overflow-hidden rounded-md border">
         <Table>
           <TableHeader>
             <TableRow>
+              <TableHead className="w-10">
+                <Checkbox
+                  checked={
+                    filtered.length > 0 &&
+                    filtered.every((p) => selected.has(p.id))
+                  }
+                  onCheckedChange={(checked) => {
+                    setSelected((prev) => {
+                      const next = new Set(prev)
+                      if (checked) {
+                        filtered.forEach((p) => next.add(p.id))
+                      } else {
+                        filtered.forEach((p) => next.delete(p.id))
+                      }
+                      return next
+                    })
+                  }}
+                  aria-label="Select all visible"
+                />
+              </TableHead>
               <TableHead>Project</TableHead>
               <TableHead>Wants?</TableHead>
               <TableHead>Mentors</TableHead>
@@ -135,7 +330,7 @@ export function MentoringProjectsTable({ roundId }: { roundId: string }) {
             {filtered.length === 0 ? (
               <TableRow>
                 <TableCell
-                  colSpan={4}
+                  colSpan={5}
                   className="py-8 text-center text-sm text-muted-foreground"
                 >
                   No projects match the current filter.
@@ -143,7 +338,24 @@ export function MentoringProjectsTable({ roundId }: { roundId: string }) {
               </TableRow>
             ) : (
               filtered.map((p) => (
-                <TableRow key={p.id}>
+                <TableRow
+                  key={p.id}
+                  data-state={selected.has(p.id) ? 'selected' : undefined}
+                >
+                  <TableCell>
+                    <Checkbox
+                      checked={selected.has(p.id)}
+                      onCheckedChange={(checked) =>
+                        setSelected((prev) => {
+                          const next = new Set(prev)
+                          if (checked) next.add(p.id)
+                          else next.delete(p.id)
+                          return next
+                        })
+                      }
+                      aria-label={`Select ${p.title}`}
+                    />
+                  </TableCell>
                   <TableCell>
                     <div className="font-medium">{p.title}</div>
                     <div className="text-xs text-muted-foreground">
@@ -224,6 +436,162 @@ export function MentoringProjectsTable({ roundId }: { roundId: string }) {
           </TableBody>
         </Table>
       </div>
+
+      <Dialog
+        open={bulkOpen}
+        onOpenChange={(next) => {
+          if (!next) {
+            setBulkOpen(false)
+            setChosenMentorId('')
+            setMentorSearch('')
+          }
+        }}
+      >
+        <DialogContent>
+          <DialogHeader>
+            <DialogTitle>
+              Assign mentor to {selected.size} project
+              {selected.size === 1 ? '' : 's'}
+            </DialogTitle>
+            <DialogDescription>
+              Choose one mentor — they'll receive a single email listing every
+              new assignment. Projects where they're already an active mentor
+              will be skipped.
+            </DialogDescription>
+          </DialogHeader>
+
+          <div className="space-y-3">
+            <div className="relative">
+              <Search className="absolute left-2.5 top-1/2 h-3.5 w-3.5 -translate-y-1/2 text-muted-foreground" />
+              <Input
+                value={mentorSearch}
+                onChange={(e) => setMentorSearch(e.target.value)}
+                placeholder="Search mentor by name, email, country, or expertise…"
+                className="pl-8"
+              />
+            </div>
+            <div className="max-h-72 overflow-y-auto rounded-md border">
+              {(() => {
+                const mentors = mentorPool?.mentors ?? []
+                const q = mentorSearch.trim().toLowerCase()
+                const filteredMentors = q
+                  ? mentors.filter((m) =>
+                      [
+                        m.name ?? '',
+                        m.email,
+                        m.country ?? '',
+                        ...(m.expertiseTags ?? []),
+                      ]
+                        .join(' ')
+                        .toLowerCase()
+                        .includes(q),
+                    )
+                  : mentors
+                if (mentors.length === 0) {
+                  return (
+                    <p className="p-4 text-center text-sm text-muted-foreground">
+                      No mentors in the pool yet.{' '}
+                      <Link
+                        href="/admin/members?tab=mentors"
+                        className="underline-offset-2 hover:underline"
+                      >
+                        Add mentors
+                      </Link>
+                      .
+                    </p>
+                  )
+                }
+                if (filteredMentors.length === 0) {
+                  return (
+                    <p className="p-4 text-center text-sm text-muted-foreground">
+                      No mentors match &ldquo;{mentorSearch}&rdquo;.
+                    </p>
+                  )
+                }
+                return filteredMentors.map((m) => {
+                  const isChosen = chosenMentorId === m.id
+                  return (
+                    <label
+                      key={m.id}
+                      className={`flex cursor-pointer items-start gap-3 border-b px-3 py-2 text-sm last:border-b-0 ${
+                        isChosen ? 'bg-accent' : 'hover:bg-muted/50'
+                      }`}
+                    >
+                      <input
+                        type="radio"
+                        name="bulk-mentor"
+                        className="mt-1"
+                        checked={isChosen}
+                        onChange={() => setChosenMentorId(m.id)}
+                      />
+                      <div className="min-w-0 flex-1">
+                        <div className="font-medium">
+                          {m.name ?? 'Unnamed'}
+                        </div>
+                        <div className="truncate text-xs text-muted-foreground">
+                          {m.email}
+                          {m.country && <> · {m.country}</>}
+                        </div>
+                        {m.expertiseTags && m.expertiseTags.length > 0 && (
+                          <div className="mt-1 flex flex-wrap gap-1">
+                            {m.expertiseTags.slice(0, 4).map((t) => (
+                              <Badge
+                                key={t}
+                                variant="secondary"
+                                className="text-[10px]"
+                              >
+                                {t}
+                              </Badge>
+                            ))}
+                            {m.expertiseTags.length > 4 && (
+                              <Badge variant="outline" className="text-[10px]">
+                                +{m.expertiseTags.length - 4}
+                              </Badge>
+                            )}
+                          </div>
+                        )}
+                      </div>
+                      <div className="shrink-0 text-right text-xs tabular-nums text-muted-foreground">
+                        {m.currentAssignments}
+                        {m.maxAssignments != null && `/${m.maxAssignments}`}{' '}
+                        load
+                      </div>
+                    </label>
+                  )
+                })
+              })()}
+            </div>
+          </div>
+
+          <DialogFooter>
+            <Button
+              variant="outline"
+              onClick={() => {
+                setBulkOpen(false)
+                setChosenMentorId('')
+                setMentorSearch('')
+              }}
+            >
+              Cancel
+            </Button>
+            <Button
+              onClick={() =>
+                bulkAssignMutation.mutate({
+                  mentorId: chosenMentorId,
+                  projectIds: Array.from(selected),
+                })
+              }
+              disabled={!chosenMentorId || bulkAssignMutation.isPending}
+            >
+              {bulkAssignMutation.isPending && (
+                <Loader2 className="mr-1.5 h-4 w-4 animate-spin" />
+              )}
+              Assign to {selected.size} project
+              {selected.size === 1 ? '' : 's'}
+            </Button>
+          </DialogFooter>
+        </DialogContent>
+      </Dialog>
     </div>
   )
 }

src/lib/email.ts

@@ -2832,6 +2832,217 @@ export async function sendMentorTeamAssignmentEmail(
   }
 }
 
+function getTeamMentorIntroductionTemplate(
+  recipientName: string | null,
+  projectTitle: string,
+  mentors: { name: string | null; email: string }[],
+  workspaceUrl: string,
+): EmailTemplate {
+  const count = mentors.length
+  const subject =
+    count === 1
+      ? `Your mentor for "${projectTitle}" on MOPC`
+      : `Your ${count} mentors for "${projectTitle}" on MOPC`
+  const greeting = recipientName ? `Hi ${recipientName},` : 'Hi there,'
+
+  const mentorTextLines = mentors
+    .map(
+      (m) => `  • ${m.name ?? 'Mentor'} — ${m.email}`,
+    )
+    .join('\n')
+
+  const text = [
+    greeting,
+    '',
+    count === 1
+      ? `The mentoring round is now open, and your project "${projectTitle}" has a mentor:`
+      : `The mentoring round is now open, and your project "${projectTitle}" has ${count} mentors:`,
+    '',
+    mentorTextLines,
+    '',
+    'You can chat with them, share files, and track milestones in your mentor workspace:',
+    workspaceUrl,
+    '',
+    'Feel free to reach out to them directly by email as well.',
+    '',
+    'The MOPC team',
+  ].join('\n')
+
+  const mentorHtmlList = mentors
+    .map(
+      (m) => `
+        <tr>
+          <td style="padding:6px 0;font-weight:600;color:#0f172a;">${escapeHtml(m.name ?? 'Mentor')}</td>
+          <td style="padding:6px 0;">
+            <a href="mailto:${escapeHtml(m.email)}" style="color:#053d57;text-decoration:none;">${escapeHtml(m.email)}</a>
+          </td>
+        </tr>`,
+    )
+    .join('')
+
+  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;">${count === 1 ? 'Meet your mentor' : `Meet your ${count} mentors`}</h1>
+    </div>
+    <div style="padding:24px 28px;line-height:1.5;font-size:14px;">
+      <p style="margin-top:0;">${recipientName ? `Hi ${escapeHtml(recipientName)},` : 'Hi there,'}</p>
+      <p>${count === 1
+        ? `The mentoring round is now open and a mentor has been assigned to your project <strong>${escapeHtml(projectTitle)}</strong>:`
+        : `The mentoring round is now open and <strong>${count}</strong> mentors have been assigned to your project <strong>${escapeHtml(projectTitle)}</strong>:`}</p>
+      <table style="width:100%;border-collapse:collapse;margin:12px 0 20px;font-size:14px;">${mentorHtmlList}</table>
+      <p style="margin-top:24px;">
+        <a href="${workspaceUrl}" style="display:inline-block;padding:10px 20px;background:#de0f1e;color:#fff;text-decoration:none;border-radius:6px;font-weight:600;">Open Mentor Workspace</a>
+      </p>
+      <p style="margin-top:24px;color:#64748b;font-size:12px;">
+        You can chat with them, share files, and track milestones in the workspace — or reach out to them directly by email.
+      </p>
+    </div>
+    <div style="padding:16px 28px;background:#f1f5f9;color:#64748b;font-size:12px;text-align:center;">
+      Monaco Ocean Protection Challenge
+    </div>
+  </div>
+</body>
+</html>
+  `.trim()
+
+  return { subject, text, html }
+}
+
+/**
+ * Introduce a project team to their assigned mentor(s), with each mentor's
+ * name + email so the team can reach out directly. Sent when the MENTORING
+ * round opens AND any time a mentor is added to a project whose mentoring
+ * round is already open. Never throws.
+ */
+export async function sendTeamMentorIntroductionEmail(
+  recipientEmail: string,
+  recipientName: string | null,
+  projectTitle: string,
+  projectId: string,
+  mentors: { name: string | null; email: string }[],
+): Promise<void> {
+  try {
+    if (mentors.length === 0) return
+    const baseUrl = (process.env.NEXTAUTH_URL || 'https://monaco-opc.com').replace(/\/$/, '')
+    const workspaceUrl = `${baseUrl}/applicant/mentor`
+    const template = getTeamMentorIntroductionTemplate(
+      recipientName,
+      projectTitle,
+      mentors,
+      workspaceUrl,
+    )
+    await sendEmail({
+      to: recipientEmail,
+      subject: template.subject,
+      text: template.text,
+      html: template.html,
+    })
+  } catch (error) {
+    console.error('[sendTeamMentorIntroductionEmail] failed', { recipientEmail, projectId, error })
+  }
+}
+
+function getMentorBulkAssignmentTemplate(
+  name: string,
+  projects: { title: string; url: string }[],
+  mentorDashboardUrl: string,
+): EmailTemplate {
+  const count = projects.length
+  const subject =
+    count === 1
+      ? `You've been assigned to a new MOPC project: "${projects[0].title}"`
+      : `You've been assigned to ${count} new MOPC projects`
+  const greeting = name ? `Hi ${name},` : 'Hi there,'
+
+  const textLines = projects
+    .map((p) => `  • ${p.title} — ${p.url}`)
+    .join('\n')
+  const text = [
+    greeting,
+    '',
+    count === 1
+      ? `You have been assigned as a mentor to a new project:`
+      : `You have been assigned as a mentor to ${count} new projects:`,
+    '',
+    textLines,
+    '',
+    'You may have co-mentors on these teams — you can collaborate together in each project workspace.',
+    '',
+    `Open your mentor dashboard: ${mentorDashboardUrl}`,
+    '',
+    'The MOPC team',
+  ].join('\n')
+
+  const htmlList = projects
+    .map(
+      (p) =>
+        `<li style="margin:6px 0;"><a href="${p.url}" style="color:#053d57;text-decoration:none;font-weight:600;">${escapeHtml(p.title)}</a></li>`,
+    )
+    .join('')
+
+  const html = `
+<!DOCTYPE html>
+<html>
+<body style="margin:0;padding:0;background:#f6f8fa;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif;color:#0f172a;">
+  <div style="max-width:560px;margin:32px auto;background:#fff;border-radius:8px;overflow:hidden;box-shadow:0 1px 3px rgba(0,0,0,0.06);">
+    <div style="background:#053d57;padding:24px 28px;color:#fefefe;">
+      <h1 style="margin:0;font-size:20px;font-weight:600;">${count === 1 ? 'New mentor assignment' : `${count} new mentor assignments`}</h1>
+    </div>
+    <div style="padding:24px 28px;line-height:1.5;font-size:14px;">
+      <p style="margin-top:0;">${name ? `Hi ${escapeHtml(name)},` : 'Hi there,'}</p>
+      <p>${count === 1 ? 'You have been assigned as a mentor to a new project:' : `You have been assigned as a mentor to <strong>${count}</strong> new projects:`}</p>
+      <ul style="padding-left:20px;margin:12px 0 20px;">${htmlList}</ul>
+      <p style="margin-top:24px;">
+        <a href="${mentorDashboardUrl}" style="display:inline-block;padding:10px 20px;background:#de0f1e;color:#fff;text-decoration:none;border-radius:6px;font-weight:600;">Open Mentor Dashboard</a>
+      </p>
+      <p style="margin-top:24px;color:#64748b;font-size:12px;">
+        You may have co-mentors on these teams — you can collaborate together in each project workspace.
+      </p>
+    </div>
+    <div style="padding:16px 28px;background:#f1f5f9;color:#64748b;font-size:12px;text-align:center;">
+      Monaco Ocean Protection Challenge
+    </div>
+  </div>
+</body>
+</html>
+  `.trim()
+
+  return { subject, text, html }
+}
+
+/**
+ * Send a coalesced mentor-assignment email when one mentor receives multiple
+ * project assignments in a single bulk operation. Caller passes the list of
+ * NEW assignments (already filtered to exclude any whose notificationSentAt
+ * was previously set). Never throws.
+ */
+export async function sendMentorBulkAssignmentEmail(
+  email: string,
+  name: string | null,
+  projects: { id: string; title: string }[],
+): Promise<void> {
+  try {
+    if (projects.length === 0) return
+    const baseUrl = (process.env.NEXTAUTH_URL || 'https://monaco-opc.com').replace(/\/$/, '')
+    const enriched = projects.map((p) => ({
+      title: p.title,
+      url: `${baseUrl}/mentor/workspace/${p.id}`,
+    }))
+    const template = getMentorBulkAssignmentTemplate(
+      name || '',
+      enriched,
+      `${baseUrl}/mentor`,
+    )
+    await sendEmail({ to: email, subject: template.subject, text: template.text, html: template.html })
+  } catch (error) {
+    console.error('[sendMentorBulkAssignmentEmail] failed', { email, error })
+  }
+}
+
 // =============================================================================
 // Mentor change requests (PR 8) — admin notification when an applicant or admin
 // opens a MentorChangeRequest. Mentors are NOT notified (per design decision).

src/server/routers/mentor.ts

@@ -8,8 +8,10 @@ import {
   type PrismaClient,
 } from '@prisma/client'
 import {
+  sendMentorBulkAssignmentEmail,
   sendMentorChangeRequestEmail,
   sendMentorTeamAssignmentEmail,
+  sendTeamMentorIntroductionEmail,
 } from '@/lib/email'
 import {
   getAIMentorSuggestions,
@@ -46,6 +48,83 @@ import {
   verifyMentorUploadToken,
 } from '@/lib/mentor-upload-token'
 
+/**
+ * Introduce the project team to ALL active mentors via email IF the project's
+ * MENTORING round is currently ROUND_ACTIVE. Idempotent: only emails mentors
+ * whose assignment row has `teamIntroducedAt: null`. If the round is not yet
+ * active, this is a no-op — the activation step will fire the email instead.
+ * Never throws.
+ */
+async function introduceTeamToMentorsIfRoundOpen(
+  prisma: PrismaClient,
+  projectId: string,
+): Promise<void> {
+  try {
+    const project = await prisma.project.findUnique({
+      where: { id: projectId },
+      select: {
+        id: true,
+        title: true,
+        projectRoundStates: {
+          where: {
+            round: { roundType: 'MENTORING', status: 'ROUND_ACTIVE' },
+          },
+          select: { id: true },
+          take: 1,
+        },
+        mentorAssignments: {
+          where: { droppedAt: null, teamIntroducedAt: null },
+          select: {
+            id: true,
+            mentor: { select: { name: true, email: true } },
+          },
+        },
+        teamMembers: {
+          select: { user: { select: { name: true, email: true } } },
+        },
+        submittedByEmail: true,
+        submittedBy: { select: { name: true } },
+      },
+    })
+    if (!project) return
+    if (project.projectRoundStates.length === 0) return // round not active yet
+    const mentors = project.mentorAssignments
+      .filter((a) => a.mentor?.email)
+      .map((a) => ({ name: a.mentor.name, email: a.mentor.email }))
+    if (mentors.length === 0) return
+
+    const recipients = new Map<string, { name: string | null }>()
+    for (const tm of project.teamMembers) {
+      if (tm.user?.email) {
+        recipients.set(tm.user.email, { name: tm.user.name })
+      }
+    }
+    if (
+      project.submittedByEmail &&
+      !recipients.has(project.submittedByEmail)
+    ) {
+      recipients.set(project.submittedByEmail, {
+        name: project.submittedBy?.name ?? null,
+      })
+    }
+    for (const [email, { name }] of recipients) {
+      await sendTeamMentorIntroductionEmail(
+        email,
+        name,
+        project.title,
+        project.id,
+        mentors,
+      )
+    }
+    await prisma.mentorAssignment.updateMany({
+      where: { id: { in: project.mentorAssignments.map((a) => a.id) } },
+      data: { teamIntroducedAt: new Date() },
+    })
+  } catch (e) {
+    console.error('[introduceTeamToMentorsIfRoundOpen] failed (non-fatal):', e)
+  }
+}
+
 /**
  * Throws TRPCError if the given user is neither the assigned mentor
  * nor a team member of the project linked to the assignment.
@@ -414,6 +493,10 @@ export const mentorRouter = router({
         console.error('[Mentor] triggerInProgressOnActivity failed (non-fatal):', e)
       }
 
+      // If the project's MENTORING round is already open, introduce the team
+      // to their mentor(s) by email now. Otherwise the activation hook fires it.
+      await introduceTeamToMentorsIfRoundOpen(ctx.prisma, input.projectId)
+
       return assignment
     }),
 
@@ -564,6 +647,160 @@ export const mentorRouter = router({
       return assignment
     }),
 
+  /**
+   * Bulk-assign ONE mentor to MANY projects in a single transaction. Skips
+   * projects where this mentor is already an active mentor. Sends a single
+   * coalesced email to the mentor listing all newly-assigned projects.
+   * In-app notifications are still per-project so each team is notified.
+   */
+  bulkAssign: adminProcedure
+    .input(
+      z.object({
+        mentorId: z.string(),
+        projectIds: z.array(z.string()).min(1),
+      }),
+    )
+    .mutation(async ({ ctx, input }) => {
+      const mentor = await ctx.prisma.user.findUnique({
+        where: { id: input.mentorId },
+        select: {
+          id: true,
+          name: true,
+          email: true,
+          roles: true,
+          status: true,
+        },
+      })
+      if (!mentor || !mentor.roles.includes('MENTOR')) {
+        throw new TRPCError({
+          code: 'BAD_REQUEST',
+          message: 'Selected user is not a mentor',
+        })
+      }
+
+      const projects = await ctx.prisma.project.findMany({
+        where: { id: { in: input.projectIds } },
+        select: {
+          id: true,
+          title: true,
+          mentorAssignments: {
+            where: { mentorId: mentor.id, droppedAt: null },
+            select: { id: true },
+          },
+        },
+      })
+
+      const newProjects: { id: string; title: string }[] = []
+      const skippedProjects: { id: string; title: string }[] = []
+      const createdAssignmentIds: string[] = []
+
+      for (const p of projects) {
+        if (p.mentorAssignments.length > 0) {
+          skippedProjects.push({ id: p.id, title: p.title })
+          continue
+        }
+        const created = await ctx.prisma.mentorAssignment.create({
+          data: {
+            projectId: p.id,
+            mentorId: mentor.id,
+            method: 'MANUAL',
+            assignedBy: ctx.user.id,
+          },
+        })
+        createdAssignmentIds.push(created.id)
+        newProjects.push({ id: p.id, title: p.title })
+
+        await createNotification({
+          userId: mentor.id,
+          type: NotificationTypes.MENTEE_ASSIGNED,
+          title: 'New Mentee Assigned',
+          message: `You have been assigned to mentor "${p.title}".`,
+          linkUrl: `/mentor/projects/${p.id}`,
+          linkLabel: 'View Project',
+          priority: 'high',
+          metadata: { projectName: p.title },
+        })
+
+        await notifyProjectTeam(p.id, {
+          type: NotificationTypes.MENTOR_ASSIGNED,
+          title: 'Mentor Assigned',
+          message: `${mentor.name || 'A mentor'} has been assigned to support your project.`,
+          linkUrl: `/team/projects/${p.id}`,
+          linkLabel: 'View Project',
+          priority: 'high',
+          metadata: { projectName: p.title, mentorName: mentor.name },
+        })
+
+        // Trigger MENTORING round IN_PROGRESS state transition (best-effort)
+        try {
+          const mentoringPrs = await ctx.prisma.projectRoundState.findFirst({
+            where: {
+              projectId: p.id,
+              round: {
+                roundType: 'MENTORING',
+                status: { in: ['ROUND_ACTIVE', 'ROUND_CLOSED'] },
+              },
+              state: 'PENDING',
+            },
+            select: { roundId: true },
+          })
+          if (mentoringPrs) {
+            await triggerInProgressOnActivity(
+              p.id,
+              mentoringPrs.roundId,
+              ctx.user.id,
+              ctx.prisma,
+            )
+          }
+        } catch (e) {
+          console.error(
+            '[Mentor.bulkAssign] triggerInProgressOnActivity failed (non-fatal):',
+            e,
+          )
+        }
+      }
+
+      // One coalesced email per mentor, with all NEW project assignments.
+      if (newProjects.length > 0 && mentor.email) {
+        await sendMentorBulkAssignmentEmail(mentor.email, mentor.name, newProjects)
+        // Stamp notificationSentAt on every row we just created so single-
+        // assignment retries don't re-notify.
+        await ctx.prisma.mentorAssignment.updateMany({
+          where: { id: { in: createdAssignmentIds } },
+          data: { notificationSentAt: new Date() },
+        })
+      }
+
+      // For each newly-assigned project whose MENTORING round is already open,
+      // introduce the team to the mentor(s) by email.
+      for (const p of newProjects) {
+        await introduceTeamToMentorsIfRoundOpen(ctx.prisma, p.id)
+      }
+
+      await logAudit({
+        prisma: ctx.prisma,
+        userId: ctx.user.id,
+        action: 'MENTOR_BULK_ASSIGN',
+        entityType: 'User',
+        entityId: mentor.id,
+        detailsJson: {
+          mentorEmail: mentor.email,
+          assignedCount: newProjects.length,
+          skippedCount: skippedProjects.length,
+          newProjectIds: newProjects.map((p) => p.id),
+        },
+        ipAddress: ctx.ip,
+        userAgent: ctx.userAgent,
+      })
+
+      return {
+        assignedCount: newProjects.length,
+        skippedCount: skippedProjects.length,
+        skippedProjects,
+        emailSent: newProjects.length > 0,
+      }
+    }),
+
   /**
    * Remove mentor assignment.
    *
@@ -842,6 +1079,18 @@ export const mentorRouter = router({
       let assigned = 0
       let unassignable = 0
 
+      // Coalesce per-mentor so we send ONE email per mentor at the end of the
+      // batch, even when the algorithm assigns the same mentor to several teams.
+      const perMentor = new Map<
+        string,
+        {
+          email: string | null
+          name: string | null
+          assignmentIds: string[]
+          projects: { id: string; title: string }[]
+        }
+      >()
+
       for (const { project } of projectStates) {
         try {
           let mentorId: string | null = null
@@ -883,7 +1132,7 @@ export const mentorRouter = router({
               aiReasoning,
             },
             include: {
-              mentor: { select: { id: true, name: true } },
+              mentor: { select: { id: true, name: true, email: true } },
               project: { select: { title: true } },
             },
           })
@@ -921,6 +1170,17 @@ export const mentorRouter = router({
             },
           })
 
+          // Accumulate for the coalesced email
+          const bucket = perMentor.get(mentorId) ?? {
+            email: assignment.mentor.email ?? null,
+            name: assignment.mentor.name ?? null,
+            assignmentIds: [],
+            projects: [],
+          }
+          bucket.assignmentIds.push(assignment.id)
+          bucket.projects.push({ id: project.id, title: assignment.project.title })
+          perMentor.set(mentorId, bucket)
+
           assigned++
         } catch (err) {
           console.error(
@@ -932,6 +1192,46 @@ export const mentorRouter = router({
         }
       }
 
+      // Send one coalesced email per mentor, then stamp notificationSentAt so
+      // re-running the bulk doesn't double-notify.
+      for (const bucket of perMentor.values()) {
+        if (!bucket.email || bucket.projects.length === 0) continue
+        await sendMentorBulkAssignmentEmail(
+          bucket.email,
+          bucket.name,
+          bucket.projects,
+        )
+        try {
+          await ctx.prisma.mentorAssignment.updateMany({
+            where: { id: { in: bucket.assignmentIds } },
+            data: { notificationSentAt: new Date() },
+          })
+        } catch (e) {
+          console.error(
+            '[Mentor.autoAssignBulkForRound] failed to stamp notificationSentAt (non-fatal):',
+            e,
+          )
+        }
+      }
+
+      // If the mentoring round is already open at the time of bulk auto-fill,
+      // introduce each team to their new mentor(s). If the round is still
+      // DRAFT, the activation hook will email later.
+      const roundStatus = await ctx.prisma.round.findUnique({
+        where: { id: input.roundId },
+        select: { status: true },
+      })
+      if (roundStatus?.status === 'ROUND_ACTIVE') {
+        const introducedProjects = new Set<string>()
+        for (const bucket of perMentor.values()) {
+          for (const p of bucket.projects) {
+            if (introducedProjects.has(p.id)) continue
+            introducedProjects.add(p.id)
+            await introduceTeamToMentorsIfRoundOpen(ctx.prisma, p.id)
+          }
+        }
+      }
+
       const skipped = await ctx.prisma.projectRoundState.count({
         where: {
           roundId: input.roundId,

src/server/routers/round.ts

@@ -266,6 +266,55 @@ export const roundRouter = router({
       return { count, eligibleTotal, mentorPoolSize }
     }),
 
+  /**
+   * For a MENTORING round, find the immediately-prior round in the same
+   * competition and report how many of its PASSED projects are not yet
+   * present in this round. Drives the "Import from prior round" CTA so
+   * admins don't have to manually pick projects via the From-Round modal.
+   */
+  getMentoringImportCandidates: adminProcedure
+    .input(z.object({ roundId: z.string() }))
+    .query(async ({ ctx, input }) => {
+      const round = await ctx.prisma.round.findUniqueOrThrow({
+        where: { id: input.roundId },
+        select: { roundType: true, competitionId: true, sortOrder: true },
+      })
+      if (round.roundType !== 'MENTORING') {
+        return { priorRound: null, pendingCount: 0 }
+      }
+      const prior = await ctx.prisma.round.findFirst({
+        where: {
+          competitionId: round.competitionId,
+          sortOrder: { lt: round.sortOrder },
+        },
+        orderBy: { sortOrder: 'desc' },
+        select: { id: true, name: true, status: true },
+      })
+      if (!prior) return { priorRound: null, pendingCount: 0 }
+      if (prior.status !== 'ROUND_ACTIVE' && prior.status !== 'ROUND_CLOSED') {
+        return {
+          priorRound: { id: prior.id, name: prior.name, status: prior.status },
+          pendingCount: 0,
+        }
+      }
+      const existingInTarget = await ctx.prisma.projectRoundState.findMany({
+        where: { roundId: input.roundId },
+        select: { projectId: true },
+      })
+      const existingIds = new Set(existingInTarget.map((s) => s.projectId))
+      const passedInPrior = await ctx.prisma.projectRoundState.findMany({
+        where: { roundId: prior.id, state: 'PASSED' },
+        select: { projectId: true },
+      })
+      const pendingCount = passedInPrior.filter(
+        (s) => !existingIds.has(s.projectId),
+      ).length
+      return {
+        priorRound: { id: prior.id, name: prior.name, status: prior.status },
+        pendingCount,
+      }
+    }),
+
   /**
    * List projects in a MENTORING round with their (multi-)mentor assignments.
    * Drives the per-team assignment table on the round Projects tab so admins

src/server/services/round-engine.ts

@@ -16,6 +16,7 @@ import { logAudit } from '@/server/utils/audit'
 import { safeValidateRoundConfig } from '@/types/competition-configs'
 import { expireIntentsForRound } from './assignment-intent'
 import { processRoundClose } from './round-finalization'
+import { sendTeamMentorIntroductionEmail } from '@/lib/email'
 
 // ─── Types ──────────────────────────────────────────────────────────────────
 
@@ -211,6 +212,86 @@ export async function activateRound(
       } catch (mentoringError) {
         console.error('[RoundEngine] Mentoring pass-through failed (non-fatal):', mentoringError)
       }
+
+      // Introduce teams to their mentors via email when the round opens.
+      // Idempotent via MentorAssignment.teamIntroducedAt — separate from the
+      // mentor-side notificationSentAt so the team email fires even when the
+      // mentor was assigned (and notified) before the round opened.
+      try {
+        const projectsToIntroduce = await prisma.project.findMany({
+          where: {
+            projectRoundStates: { some: { roundId } },
+            mentorAssignments: {
+              some: { droppedAt: null, teamIntroducedAt: null },
+            },
+          },
+          select: {
+            id: true,
+            title: true,
+            mentorAssignments: {
+              where: { droppedAt: null },
+              select: {
+                id: true,
+                teamIntroducedAt: true,
+                mentor: { select: { name: true, email: true } },
+              },
+            },
+            teamMembers: {
+              select: { user: { select: { name: true, email: true } } },
+            },
+            submittedByEmail: true,
+            submittedBy: { select: { name: true } },
+          },
+        })
+        for (const p of projectsToIntroduce) {
+          const mentors = p.mentorAssignments
+            .filter((a) => a.mentor?.email)
+            .map((a) => ({
+              name: a.mentor.name,
+              email: a.mentor.email,
+            }))
+          if (mentors.length === 0) continue
+
+          // Build a unique recipient set: team-member users with emails,
+          // plus the original submitter (in case they're not on the team yet).
+          const recipients = new Map<string, { name: string | null }>()
+          for (const tm of p.teamMembers) {
+            if (tm.user?.email) {
+              recipients.set(tm.user.email, { name: tm.user.name })
+            }
+          }
+          if (
+            p.submittedByEmail &&
+            !recipients.has(p.submittedByEmail)
+          ) {
+            recipients.set(p.submittedByEmail, {
+              name: p.submittedBy?.name ?? null,
+            })
+          }
+
+          for (const [email, { name }] of recipients) {
+            await sendTeamMentorIntroductionEmail(email, name, p.title, p.id, mentors)
+          }
+
+          // Stamp every mentor-assignment row so re-activation doesn't re-send.
+          const idsToStamp = p.mentorAssignments
+            .filter((a) => a.teamIntroducedAt == null)
+            .map((a) => a.id)
+          if (idsToStamp.length > 0) {
+            await prisma.mentorAssignment.updateMany({
+              where: { id: { in: idsToStamp } },
+              data: { teamIntroducedAt: new Date() },
+            })
+          }
+        }
+        if (projectsToIntroduce.length > 0) {
+          console.log(
+            `[RoundEngine] MENTORING round open: introduced mentors for ${projectsToIntroduce.length} project(s)`,
+          )
+        }
+      } catch (introError) {
+        console.error('[RoundEngine] Team-mentor introduction failed (non-fatal):', introError)
+      }
     }
 
     return {