diff --git a/src/server/routers/application.ts b/src/server/routers/application.ts
index 99e8e13..35f6318 100644
--- a/src/server/routers/application.ts
+++ b/src/server/routers/application.ts
@@ -402,6 +402,7 @@ export const applicationRouter = router({
             email: data.contactEmail,
             name: data.contactName,
             role: 'APPLICANT',
+            roles: ['APPLICANT'],
             status: 'ACTIVE',
             phoneNumber: data.contactPhone,
           },
@@ -474,6 +475,7 @@ export const applicationRouter = router({
                 email: member.email,
                 name: member.name,
                 role: 'APPLICANT',
+                roles: ['APPLICANT'],
                 status: 'NONE',
               },
             })
@@ -790,6 +792,7 @@ export const applicationRouter = router({
             email: data.contactEmail,
             name: data.contactName,
             role: 'APPLICANT',
+            roles: ['APPLICANT'],
             status: 'ACTIVE',
             phoneNumber: data.contactPhone,
           },
diff --git a/src/server/routers/juryGroup.ts b/src/server/routers/juryGroup.ts
index 308e2bf..6df4cc5 100644
--- a/src/server/routers/juryGroup.ts
+++ b/src/server/routers/juryGroup.ts
@@ -440,6 +440,7 @@ export const juryGroupRouter = router({
                 email: invitee.email,
                 name: invitee.name || null,
                 role: 'JURY_MEMBER',
+                roles: ['JURY_MEMBER'],
                 status: 'INVITED',
                 inviteToken,
                 inviteTokenExpiresAt: new Date(Date.now() + expiryMs),
diff --git a/src/server/routers/project.ts b/src/server/routers/project.ts
index 4d5b859..fc1a997 100644
--- a/src/server/routers/project.ts
+++ b/src/server/routers/project.ts
@@ -714,6 +714,7 @@ export const projectRouter = router({
                   email: member.email.toLowerCase(),
                   name: member.name,
                   role: 'APPLICANT',
+                  roles: ['APPLICANT'],
                   status: 'NONE',
                   phoneNumber: member.phone || null,
                 },
diff --git a/src/server/routers/specialAward.ts b/src/server/routers/specialAward.ts
index 4782a03..54de207 100644
--- a/src/server/routers/specialAward.ts
+++ b/src/server/routers/specialAward.ts
@@ -697,6 +697,7 @@ export const specialAwardRouter = router({
                 email: invitee.email,
                 name: invitee.name || null,
                 role: 'JURY_MEMBER',
+                roles: ['JURY_MEMBER'],
                 status: 'INVITED',
                 inviteToken,
                 inviteTokenExpiresAt: new Date(Date.now() + expiryMs),
diff --git a/src/server/routers/user.ts b/src/server/routers/user.ts
index 02cfac9..79af12b 100644
--- a/src/server/routers/user.ts
+++ b/src/server/routers/user.ts
@@ -510,6 +510,7 @@ export const userRouter = router({
       const user = await ctx.prisma.user.create({
         data: {
           ...input,
+          roles: [input.role],
           status: 'INVITED',
           inviteToken,
           inviteTokenExpiresAt: new Date(Date.now() + expiryHours * 60 * 60 * 1000),
@@ -811,6 +812,7 @@ export const userRouter = router({
           email: u.email.toLowerCase(),
           name: u.name,
           role: u.role,
+          roles: [u.role],
           expertiseTags: u.expertiseTags,
           status: input.sendInvitation ? 'INVITED' : 'NONE',
         })),
diff --git a/tests/unit/user-create-roles-populated.test.ts b/tests/unit/user-create-roles-populated.test.ts
new file mode 100644
index 0000000..a27694c
--- /dev/null
+++ b/tests/unit/user-create-roles-populated.test.ts
@@ -0,0 +1,43 @@
+import { describe, it, expect, beforeAll, afterAll } from 'vitest'
+import { prisma, createCaller } from '../setup'
+import { createTestProgram, createTestUser, cleanupTestData, uid } from '../helpers'
+import { userRouter } from '../../src/server/routers/user'
+
+/**
+ * Regression: user-creation paths must populate roles[] with the primary role,
+ * so the invariant role ∈ roles holds for new users (prevents the empty-roles[]
+ * inconsistency that made primary-role mentors un-addable). Covers the admin
+ * `user.create` path as the representative case.
+ */
+describe('user.create — populates roles[] with the primary role', () => {
+  let programId = ''
+  const userIds: string[] = []
+
+  beforeAll(async () => {
+    const program = await createTestProgram()
+    programId = program.id
+  })
+
+  afterAll(async () => {
+    await cleanupTestData(programId, userIds)
+  })
+
+  it('sets roles=[role] on an admin-created user', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const caller = createCaller(userRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const email = `${uid('created')}@test.local`
+    await caller.create({ email, name: 'New Member', role: 'JURY_MEMBER' })
+
+    const created = await prisma.user.findUnique({ where: { email } })
+    expect(created).not.toBeNull()
+    if (created) userIds.push(created.id)
+    expect(created?.role).toBe('JURY_MEMBER')
+    expect(created?.roles).toEqual(['JURY_MEMBER'])
+  })
+})