feat: add Gravatar support for user avatars

app/layout.tsx

@@ -7,6 +7,7 @@ import { getCurrentUserId } from '@/lib/auth/get-current-user'
 import { UserProvider } from '@/lib/contexts/user-context'
 import { createClient } from '@/lib/supabase/server'
 import { cn } from '@/lib/utils'
+import { getGravatarUrl } from '@/lib/utils/gravatar.server'
 
 import { SidebarProvider } from '@/components/ui/sidebar'
 import { Toaster } from '@/components/ui/sonner'
@@ -57,6 +58,7 @@ export default async function RootLayout({
   children: React.ReactNode
 }>) {
   let user = null
+  let avatarUrl: string | undefined
   const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL
   const supabaseAnonKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY
 
@@ -66,6 +68,10 @@ export default async function RootLayout({
       data: { user: supabaseUser }
     } = await supabase.auth.getUser()
     user = supabaseUser
+    avatarUrl =
+      user?.user_metadata?.avatar_url ||
+      user?.user_metadata?.picture ||
+      (user?.email ? getGravatarUrl(user.email) : undefined)
   }
 
   const userId = user?.id ?? (await getCurrentUserId())
@@ -89,7 +95,7 @@ export default async function RootLayout({
               {userId && <AppSidebar />}
               <KeyboardShortcutHandler />
               <div className="flex flex-col flex-1 min-w-0">
-                <Header user={user} />
+                <Header user={user} avatarUrl={avatarUrl} />
                 <main className="flex flex-1 min-h-0 min-w-0 overflow-hidden">
                   <ArtifactRoot>{children}</ArtifactRoot>
                 </main>

components/header.tsx

@@ -18,9 +18,10 @@ import UserMenu from './user-menu'
 
 interface HeaderProps {
   user: User | null
+  avatarUrl?: string
 }
 
-export const Header: React.FC<HeaderProps> = ({ user }) => {
+export const Header: React.FC<HeaderProps> = ({ user, avatarUrl }) => {
   const { open } = useSidebar()
   const pathname = usePathname()
   const [feedbackOpen, setFeedbackOpen] = useState(false)
@@ -48,7 +49,11 @@ export const Header: React.FC<HeaderProps> = ({ user }) => {
               Feedback
             </Button>
           )}
-          {user ? <UserMenu user={user} /> : <GuestMenu />}
+          {user ? (
+            <UserMenu user={user} avatarUrl={avatarUrl} />
+          ) : (
+            <GuestMenu />
+          )}
         </div>
       </header>
 

components/user-menu.tsx

@@ -26,14 +26,13 @@ import { ThemeMenuItems } from './theme-menu-items'
 
 interface UserMenuProps {
   user: User
+  avatarUrl?: string
 }
 
-export default function UserMenu({ user }: UserMenuProps) {
+export default function UserMenu({ user, avatarUrl }: UserMenuProps) {
   const router = useRouter()
   const userName =
     user.user_metadata?.full_name || user.user_metadata?.name || 'User'
-  const avatarUrl =
-    user.user_metadata?.avatar_url || user.user_metadata?.picture
 
   const getInitials = (name: string, email: string | undefined) => {
     if (name && name !== 'User') {

hooks/use-current-user-image.ts

@@ -1,6 +1,7 @@
 import { useEffect, useState } from 'react'
 
 import { createClient } from '@/lib/supabase/client'
+import { getGravatarUrl } from '@/lib/utils/gravatar'
 
 export const useCurrentUserImage = () => {
   const [image, setImage] = useState<string | null>(null)
@@ -12,7 +13,15 @@ export const useCurrentUserImage = () => {
         if (error) {
           console.error(error)
         }
-        setImage(data.session?.user.user_metadata.avatar_url ?? null)
+        const avatarUrl =
+          data.session?.user.user_metadata.avatar_url ||
+          data.session?.user.user_metadata.picture
+        if (avatarUrl) {
+          setImage(avatarUrl)
+        } else if (data.session?.user.email) {
+          const gravatarUrl = await getGravatarUrl(data.session.user.email)
+          setImage(gravatarUrl)
+        }
       } catch (error) {
         // Supabase not configured, skip silently
       }

lib/utils/__tests__/gravatar.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it } from 'vitest'
+
+import { getGravatarUrl } from '../gravatar'
+
+describe('getGravatarUrl', () => {
+  it('generates a valid Gravatar URL with SHA-256 hash', async () => {
+    const url = await getGravatarUrl('test@example.com')
+    expect(url).toMatch(
+      /^https:\/\/www\.gravatar\.com\/avatar\/[a-f0-9]{64}\?d=404$/
+    )
+  })
+
+  it('normalizes email by trimming and lowercasing', async () => {
+    const url1 = await getGravatarUrl('Test@Example.com')
+    const url2 = await getGravatarUrl('  test@example.com  ')
+    const url3 = await getGravatarUrl('test@example.com')
+    expect(url1).toBe(url3)
+    expect(url2).toBe(url3)
+  })
+
+  it('produces different hashes for different emails', async () => {
+    const url1 = await getGravatarUrl('alice@example.com')
+    const url2 = await getGravatarUrl('bob@example.com')
+    expect(url1).not.toBe(url2)
+  })
+
+  it('generates correct hash for a known email', async () => {
+    // SHA-256 of "miurap400@gmail.com" can be verified independently
+    const url = await getGravatarUrl('miurap400@gmail.com')
+    expect(url).toContain('https://www.gravatar.com/avatar/')
+    expect(url).toContain('?d=404')
+
+    // Extract hash and verify it's a valid 64-char hex string
+    const hash = url
+      .replace('https://www.gravatar.com/avatar/', '')
+      .replace('?d=404', '')
+    expect(hash).toMatch(/^[a-f0-9]{64}$/)
+  })
+})

lib/utils/gravatar.server.ts

@@ -0,0 +1,13 @@
+import crypto from 'crypto'
+
+/**
+ * Generate a Gravatar URL from an email address (server-side, synchronous).
+ * Uses Node.js crypto for SHA-256 hashing.
+ */
+export function getGravatarUrl(email: string): string {
+  const hash = crypto
+    .createHash('sha256')
+    .update(email.trim().toLowerCase())
+    .digest('hex')
+  return `https://www.gravatar.com/avatar/${hash}?d=404`
+}

lib/utils/gravatar.ts

@@ -0,0 +1,17 @@
+/**
+ * Generate a Gravatar URL from an email address.
+ * Uses SHA-256 hashing via Web Crypto API (async, for client-side use).
+ * Returns the URL with `d=404` so that a 404 is returned for unregistered emails,
+ * allowing the UI to fall back to initials or a placeholder icon.
+ */
+export async function getGravatarUrl(email: string): Promise<string> {
+  const normalized = email.trim().toLowerCase()
+  const hashBuffer = await crypto.subtle.digest(
+    'SHA-256',
+    new TextEncoder().encode(normalized)
+  )
+  const hashHex = Array.from(new Uint8Array(hashBuffer))
+    .map(b => b.toString(16).padStart(2, '0'))
+    .join('')
+  return `https://www.gravatar.com/avatar/${hashHex}?d=404`
+}