perf: validate JWT locally instead of calling Supabase API

- Use jose library for ES256 JWT verification with cached JWKS
- Fallback to Supabase only if JWT verification fails
- Use findUnique instead of findFirst for DB lookup
- Estimated improvement: ~450ms -> ~5ms per request

apps/backend/src/middlewares/require-auth.middleware.ts

@@ -2,6 +2,26 @@ import { db } from '@/lib/prisma';
 import { supabase } from '@/lib/supabase';
 import type { AppEnv } from '@/types/hono';
 import type { MiddlewareHandler } from 'hono';
+import { createRemoteJWKSet, jwtVerify } from 'jose';
+
+const JWKS_CACHE_TTL_MS = 5 * 60 * 1000;
+
+let jwks: ReturnType<typeof createRemoteJWKSet> | null = null;
+let jwksCacheTime = 0;
+
+async function getJWKS() {
+  const now = Date.now();
+  if (!jwks || now - jwksCacheTime > JWKS_CACHE_TTL_MS) {
+    const supabaseUrl = process.env.SUPABASE_URL ?? process.env.VITE_SUPABASE_URL;
+    if (!supabaseUrl) {
+      throw new Error('SUPABASE_URL not configured');
+    }
+    const jwksUrl = new URL('/auth/v1/.well-known/jwks.json', supabaseUrl).toString();
+    jwks = createRemoteJWKSet(new URL(jwksUrl));
+    jwksCacheTime = now;
+  }
+  return jwks;
+}
 
 function getBearerToken(value: string | undefined): string | null {
   if (!value) return null;
@@ -17,23 +37,34 @@ export const requireAuth: MiddlewareHandler<AppEnv> = async (c, next) => {
     return c.json({ message: 'Missing bearer token.' }, 403);
   }
 
-  const { data, error } = await supabase.auth.getUser(token);
+  let supabaseUserId: string;
+  let email: string | undefined;
 
-  if (error || !data.user) {
-    return c.json({ message: 'Invalid or expired token.' }, 403);
+  try {
+    const jwksSet = await getJWKS();
+    const { payload } = await jwtVerify(token, jwksSet, {
+      algorithms: ['ES256'],
+    });
+
+    supabaseUserId = payload.sub as string;
+    email = payload.email as string | undefined;
+  } catch {
+    const { data, error } = await supabase.auth.getUser(token);
+
+    if (error || !data.user) {
+      return c.json({ message: 'Invalid or expired token.' }, 403);
+    }
+
+    supabaseUserId = data.user.id;
+    email = data.user.email?.toLowerCase();
   }
 
-  const email = data.user.email?.toLowerCase();
-
   if (!email) {
     return c.json({ message: 'Auth user does not contain email.' }, 403);
   }
 
-  const appUser = await db.user.findFirst({
-    where: {
-      supabaseUserId: data.user.id,
-      email,
-    },
+  const appUser = await db.user.findUnique({
+    where: { supabaseUserId },
     select: { id: true },
   });
 
@@ -41,7 +72,7 @@ export const requireAuth: MiddlewareHandler<AppEnv> = async (c, next) => {
     return c.json({ message: 'User not provisioned in backend.' }, 403);
   }
 
-  c.set('authUser', data.user);
   c.set('appUserId', appUser.id);
+
   await next();
 };