Make the session cookie name configurable for a staging deployment

Groundwork for testmodul.qrmaster.net, a second stack running the `test` branch on a real
qrmaster.net subdomain.

Production scopes its session cookie to .qrmaster.net, so the browser sends it to every
subdomain including staging. With both environments naming the cookie `userId`, the
browser holds two cookies of the same name and cookies.get() picks one arbitrarily -
staging logins would look randomly signed-out. AUTH_COOKIE_NAME lets staging pick
`userId_test` instead. Production keeps the `userId` default; changing it there would
invalidate every existing session.

Wired getAuthCookieName() into the six places that named the cookie literally. The account
deletion route now expires both the host-only and the domain-scoped variant like the logout
route already does, instead of a single cookies().delete() that would leave the other one
behind.

NEXT_PUBLIC_WWW_URL and NEXT_PUBLIC_APP_URL become build ARGs so the same image can be
built pointing at the staging host - the defaults keep a plain production build byte
identical to before. Like COOKIE_DOMAIN these must exist at build time, because process.env
is inlined into the Edge middleware bundle.

robots.ts now serves Disallow-all unless NEXT_PUBLIC_INDEXABLE is true. Staging otherwise
returns the production robots.txt and invites crawlers to index a duplicate of www.

docker-compose.test.yml is the staging overlay. Two things it must get right, both verified
against `docker compose config`:

- db and redis need `networks: !override`. Compose MERGES the networks mapping from the base
  file, and since qrmaster-network is external and shared, a plain list left them attached
  to it - `db` would then resolve to two containers and staging could read and write the
  production database.
- The web entrypoint is replaced so `prisma migrate deploy` never runs. prisma/migrations
  stopped in April 2026 and the schema has moved on through manual SQL since, so applying
  them to a fresh database would build a stale schema. Staging gets its schema from
  `pg_dump --schema-only` against production instead.

Verified: tsc clean, production build succeeds, and the merged compose config confirms
staging keeps db/redis off the shared network while production resolves unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app/(main)/api/auth/google/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from 'next/server';
 import { db } from '@/lib/db';
 import {
   appendExpiredCookies,
+  getAuthCookieName,
   getAuthCookieOptions,
   getCookieDomain,
   getFlowCookieOptions,
@@ -224,7 +225,7 @@ export async function GET(request: NextRequest) {
     const redirectUrl = new URL(urlForPath(onboardingTarget));
 
     const response = NextResponse.redirect(redirectUrl.toString());
-    response.cookies.set('userId', signUserId(user.id), getAuthCookieOptions());
+    response.cookies.set(getAuthCookieName(), signUserId(user.id), getAuthCookieOptions());
     response.cookies.delete({ name: GOOGLE_OAUTH_STATE_COOKIE_NAME, path: '/', domain: getCookieDomain() });
     response.cookies.delete({ name: POST_AUTH_REDIRECT_COOKIE_NAME, path: '/', domain: getCookieDomain() });
     // Must stay after the last cookies.set()/delete() call - see appendExpiredCookies.

src/app/(main)/api/auth/logout/route.ts

@@ -1,6 +1,6 @@
 import { NextResponse } from 'next/server';
 import { ATTRIBUTION_COOKIE_NAME } from '@/lib/revops';
-import { appendExpiredCookies } from '@/lib/cookieConfig';
+import { appendExpiredCookies, getAuthCookieName } from '@/lib/cookieConfig';
 
 export async function POST() {
   const response = NextResponse.json({ success: true });
@@ -9,7 +9,7 @@ export async function POST() {
   // it can only ever emit one variant per cookie. Logout has to expire both the
   // host-only and the domain-scoped variant (see appendExpiredCookies).
   appendExpiredCookies(response.headers, [
-    { name: 'userId', httpOnly: true },
+    { name: getAuthCookieName(), httpOnly: true },
     { name: 'newsletter-admin', httpOnly: true },
     { name: ATTRIBUTION_COOKIE_NAME, httpOnly: false },
   ]);

src/app/(main)/api/auth/verify-email/route.ts

@@ -1,6 +1,6 @@
 import { NextRequest, NextResponse } from 'next/server';
 import { db } from '@/lib/db';
-import { getAuthCookieOptions } from '@/lib/cookieConfig';
+import { getAuthCookieName, getAuthCookieOptions } from '@/lib/cookieConfig';
 import { signUserId } from '@/lib/session';
 import { sendWelcomeEmail } from '@/lib/email';
 import { appUrl, wwwUrl } from '@/lib/hosts';
@@ -37,6 +37,6 @@ export async function GET(request: NextRequest) {
   }
 
   const response = NextResponse.redirect(appUrl('/onboarding?email_verified=1'));
-  response.cookies.set('userId', signUserId(user.id), getAuthCookieOptions());
+  response.cookies.set(getAuthCookieName(), signUserId(user.id), getAuthCookieOptions());
   return response;
 }

src/app/(main)/api/user/delete/route.ts

@@ -1,5 +1,5 @@
 import { NextRequest, NextResponse } from 'next/server';
-import { cookies } from 'next/headers';
+import { appendExpiredCookies, getAuthCookieName } from '@/lib/cookieConfig';
 import { getSessionUserId } from '@/lib/session';
 import { db } from '@/lib/db';
 import { stripe } from '@/lib/stripe';
@@ -73,10 +73,13 @@ export async function DELETE(request: NextRequest) {
       where: { id: userId },
     });
 
-    // Clear auth cookie
-    cookies().delete('userId');
+    // Clear auth cookie. Same reasoning as the logout route: both the host-only and the
+    // domain-scoped variant have to be expired, otherwise the survivor keeps a session
+    // pointing at a user row that no longer exists.
+    const response = NextResponse.json({ success: true });
+    appendExpiredCookies(response.headers, [{ name: getAuthCookieName(), httpOnly: true }]);
 
-    return NextResponse.json({ success: true });
+    return response;
   } catch (error) {
     console.error('Error deleting account:', error);
     return NextResponse.json(

src/app/robots.ts

@@ -2,6 +2,17 @@ import { MetadataRoute } from 'next';
 
 export default function robots(): MetadataRoute.Robots {
   const baseUrl = 'https://www.qrmaster.net';
+
+  // Staging (testmodul.qrmaster.net) runs the same code on a real qrmaster.net subdomain.
+  // Without this it would serve the production robots.txt and invite crawlers in, competing
+  // with www for the same content. The layouts already emit a noindex meta tag when this
+  // flag is off; this closes the robots.txt half.
+  if (process.env.NEXT_PUBLIC_INDEXABLE !== 'true') {
+    return {
+      rules: [{ userAgent: '*', disallow: '/' }],
+    };
+  }
+
   const privatePaths = [
     '/api/',
     '/dashboard/',

src/lib/cookieConfig.ts

@@ -26,6 +26,21 @@ export function getCookieDomain(): string | undefined {
   return domain ? domain : undefined;
 }
 
+/**
+ * Name of the session cookie.
+ *
+ * Configurable so a staging deployment on another qrmaster.net subdomain can pick a
+ * distinct name. Production scopes its cookie to `.qrmaster.net`, so the browser sends it
+ * to testmodul.qrmaster.net as well; two cookies with the same name would make
+ * `cookies.get()` ambiguous and staging logins flaky.
+ *
+ * Like COOKIE_DOMAIN this must be set at build time too, because process.env is inlined
+ * into the Edge middleware bundle.
+ */
+export function getAuthCookieName(): string {
+  return process.env.AUTH_COOKIE_NAME?.trim() || 'userId';
+}
+
 /**
  * Get cookie options for authentication cookies
  */

src/lib/session.ts

@@ -1,7 +1,7 @@
 import 'server-only';
 import crypto from 'crypto';
 import { cookies } from 'next/headers';
-import { getAuthCookieOptions } from './cookieConfig';
+import { getAuthCookieName, getAuthCookieOptions } from './cookieConfig';
 
 /**
  * Signed session cookie.
@@ -11,8 +11,6 @@ import { getAuthCookieOptions } from './cookieConfig';
  * detect a tampered/forged cookie and reject it. Format: `<userId>.<signature>`.
  */
 
-export const AUTH_COOKIE_NAME = 'userId';
-
 function getSecret(): string {
   const secret = process.env.NEXTAUTH_SECRET;
   if (!secret) {
@@ -68,12 +66,12 @@ export function verifySignedUserId(value: string | undefined | null): string | n
  * Use this in route handlers instead of reading the `userId` cookie directly.
  */
 export function getSessionUserId(): string | null {
-  return verifySignedUserId(cookies().get(AUTH_COOKIE_NAME)?.value);
+  return verifySignedUserId(cookies().get(getAuthCookieName())?.value);
 }
 
 /**
  * Set the signed auth cookie for the given user id (server component / route handler context).
  */
 export function setSessionCookie(userId: string): void {
-  cookies().set(AUTH_COOKIE_NAME, signUserId(userId), getAuthCookieOptions());
+  cookies().set(getAuthCookieName(), signUserId(userId), getAuthCookieOptions());
 }

src/middleware.ts

@@ -6,7 +6,7 @@ import {
   serializeAttributionCookie,
 } from '@/lib/revops';
 import { verifySignedUserIdEdge } from '@/lib/session-edge';
-import { getCookieDomain } from '@/lib/cookieConfig';
+import { getAuthCookieName, getCookieDomain } from '@/lib/cookieConfig';
 import {
   getAppOrigin,
   getWwwOrigin,
@@ -247,7 +247,7 @@ async function routeRequest(req: NextRequest): Promise<NextResponse> {
   }
 
   // For protected routes, require a validly signed userId cookie
-  const userId = await verifySignedUserIdEdge(req.cookies.get('userId')?.value);
+  const userId = await verifySignedUserIdEdge(req.cookies.get(getAuthCookieName())?.value);
 
   if (!userId) {
     // Not authenticated - redirect to signup, which lives on the marketing host.