feat(api): add Better Auth plugin and protected GET /me endpoint

- authPlugin runs preHandler that turns Fastify request headers into a Headers
  object, calls auth.api.getSession, and decorates request.user / request.session
- requireAuth() preHandler short-circuits with 401 when not signed in
- New module modules/me with GET /me returning the authenticated user/session
- env validates BETTER_AUTH_SECRET (≥32) and BETTER_AUTH_URL — must match web
- Restored .js extensions in shared packages so NodeNext-resolution consumers
  (api) typecheck cleanly; Next webpack now uses extensionAlias to map .js → .ts
- Re-enabled NodeNext for packages/auth and packages/db tsconfigs

Verified end-to-end:
- POST /api/auth/sign-in/email on web returns session cookie
- GET /me on api with the cookie returns 200 + user/session
- GET /me without the cookie returns 401

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/.env.example

@@ -7,3 +7,11 @@ LOG_LEVEL=info
 CORS_ORIGINS=http://localhost:3000
 
 DATABASE_URL=postgresql://luciano:luciano%40@localhost:5432/ketopath?schema=public
+
+# Better Auth — DEVE coincidere con apps/web/.env (sessione condivisa)
+BETTER_AUTH_SECRET=
+BETTER_AUTH_URL=http://localhost:3000
+
+# Google OAuth (configurato a fine progetto)
+# GOOGLE_CLIENT_ID=
+# GOOGLE_CLIENT_SECRET=

apps/api/package.json

@@ -15,8 +15,10 @@
     "@fastify/helmet": "^11.1.1",
     "@fastify/rate-limit": "^9.1.0",
     "@fastify/sensible": "^5.6.0",
+    "@ketopath/auth": "workspace:*",
     "@ketopath/db": "workspace:*",
     "@ketopath/shared": "workspace:*",
+    "better-auth": "^1.0.21",
     "fastify": "^4.28.1",
     "fastify-plugin": "^4.5.1",
     "zod": "^3.23.8"

apps/api/src/app.ts

@@ -7,6 +7,8 @@ import Fastify, { type FastifyInstance } from 'fastify';
 import { env } from './config/env.js';
 import { dbRoutes } from './modules/db/db.routes.js';
 import { healthRoutes } from './modules/health/health.routes.js';
+import { meRoutes } from './modules/me/me.routes.js';
+import { authPlugin } from './plugins/auth.js';
 import { prismaPlugin } from './plugins/prisma.js';
 
 export async function buildApp(): Promise<FastifyInstance> {
@@ -36,9 +38,11 @@ export async function buildApp(): Promise<FastifyInstance> {
   });
   await app.register(sensible);
   await app.register(prismaPlugin);
+  await app.register(authPlugin);
 
   await app.register(healthRoutes);
   await app.register(dbRoutes);
+  await app.register(meRoutes);
 
   return app;
 }

apps/api/src/config/env.ts

@@ -15,6 +15,8 @@ const envSchema = z.object({
         .filter(Boolean),
     ),
   DATABASE_URL: z.string().url(),
+  BETTER_AUTH_SECRET: z.string().min(32),
+  BETTER_AUTH_URL: z.string().url(),
 });
 
 export type Env = z.infer<typeof envSchema>;

apps/api/src/modules/me/me.routes.ts

@@ -0,0 +1,10 @@
+import type { FastifyPluginAsync } from 'fastify';
+
+import { requireAuth } from '../../plugins/auth.js';
+
+export const meRoutes: FastifyPluginAsync = async (fastify) => {
+  fastify.get('/me', { preHandler: requireAuth() }, async (request) => ({
+    user: request.user,
+    session: request.session,
+  }));
+};

apps/api/src/plugins/auth.ts

@@ -0,0 +1,39 @@
+import { auth } from '@ketopath/auth';
+import type { FastifyReply, FastifyRequest } from 'fastify';
+import fp from 'fastify-plugin';
+
+type SessionPayload = Awaited<ReturnType<typeof auth.api.getSession>>;
+type User = NonNullable<SessionPayload>['user'];
+type Session = NonNullable<SessionPayload>['session'];
+
+declare module 'fastify' {
+  interface FastifyRequest {
+    user: User | null;
+    session: Session | null;
+  }
+}
+
+export const authPlugin = fp(async (app) => {
+  app.decorateRequest('user', null);
+  app.decorateRequest('session', null);
+
+  app.addHook('preHandler', async (request) => {
+    const headers = new Headers();
+    for (const [key, value] of Object.entries(request.headers)) {
+      if (typeof value === 'string') headers.set(key, value);
+      else if (Array.isArray(value)) headers.set(key, value.join(', '));
+    }
+
+    const result = await auth.api.getSession({ headers });
+    request.user = result?.user ?? null;
+    request.session = result?.session ?? null;
+  });
+});
+
+export function requireAuth() {
+  return async (request: FastifyRequest, reply: FastifyReply): Promise<void> => {
+    if (!request.user || !request.session) {
+      return reply.code(401).send({ error: 'unauthorized' });
+    }
+  };
+}

apps/web/next.config.mjs

@@ -5,10 +5,19 @@ const withNextIntl = createNextIntlPlugin('./src/i18n.ts');
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   reactStrictMode: true,
-  transpilePackages: ['@ketopath/auth', '@ketopath/shared', '@ketopath/ui'],
+  transpilePackages: ['@ketopath/auth', '@ketopath/db', '@ketopath/shared', '@ketopath/ui'],
   experimental: {
     typedRoutes: true,
   },
+  webpack(config) {
+    // I package interni usano .js nelle import (NodeNext). Webpack non lo
+    // risolve di default per i file TS: gli diciamo di provare anche .ts/.tsx.
+    config.resolve.extensionAlias = {
+      ...config.resolve.extensionAlias,
+      '.js': ['.ts', '.tsx', '.js', '.jsx'],
+    };
+    return config;
+  },
 };
 
 export default withNextIntl(nextConfig);

packages/auth/src/index.ts

@@ -1,2 +1,2 @@
-export { auth, type Auth } from './server';
-export { readAuthEnv, type AuthEnv } from './env';
+export { auth, type Auth } from './server.js';
+export { readAuthEnv, type AuthEnv } from './env.js';

packages/auth/src/server.ts

@@ -2,7 +2,7 @@ import { prisma } from '@ketopath/db';
 import { betterAuth } from 'better-auth';
 import { prismaAdapter } from 'better-auth/adapters/prisma';
 
-import { readAuthEnv } from './env';
+import { readAuthEnv } from './env.js';
 
 const env = readAuthEnv();
 

packages/auth/tsconfig.json

@@ -1,11 +1,10 @@
 {
-  "extends": "@ketopath/tsconfig/base.json",
+  "extends": "@ketopath/tsconfig/node.json",
   "compilerOptions": {
     "outDir": "dist",
     "rootDir": "src",
     "composite": true,
-    "lib": ["DOM", "ES2022"],
-    "types": ["node"]
+    "lib": ["DOM", "ES2022"]
   },
   "include": ["src/**/*"],
   "exclude": ["node_modules", "dist"]

packages/db/src/index.ts

@@ -1,4 +1,4 @@
-export { prisma } from './client';
+export { prisma } from './client.js';
 export {
   ActivityLevel,
   CookingTime,