diff --git a/server/src/routes/__tests__/oauth-social.test.js b/server/src/routes/__tests__/oauth-social.test.js
new file mode 100644
index 0000000..9e60924
--- /dev/null
+++ b/server/src/routes/__tests__/oauth-social.test.js
@@ -0,0 +1,41 @@
+import { describe, it, expect } from 'vitest'
+import { prisma } from '../../lib/prisma.js'
+
+describe('OAuth — User model fields', () => {
+  it('stores displayName, firstName, lastName, gender, avatar fields on User model', async () => {
+    const user = await prisma.user.create({
+      data: {
+        email: 'test-oauth@example.com',
+        displayName: 'Test User',
+        firstName: 'Test',
+        lastName: 'User',
+        gender: 'male',
+        avatar: 'https://example.com/avatar.jpg',
+      },
+    })
+
+    expect(user.displayName).toBe('Test User')
+    expect(user.firstName).toBe('Test')
+    expect(user.lastName).toBe('User')
+    expect(user.gender).toBe('male')
+    expect(user.avatar).toBe('https://example.com/avatar.jpg')
+
+    await prisma.user.delete({ where: { id: user.id } })
+  })
+
+  it('allows nullable fields', async () => {
+    const user = await prisma.user.create({
+      data: {
+        email: 'test-oauth-null@example.com',
+      },
+    })
+
+    expect(user.displayName).toBeNull()
+    expect(user.firstName).toBeNull()
+    expect(user.lastName).toBeNull()
+    expect(user.gender).toBeNull()
+    expect(user.avatar).toBeNull()
+
+    await prisma.user.delete({ where: { id: user.id } })
+  })
+})