fix: state-replay race, share session options, idealo cheerio type

src/app/api/auth/callback/route.ts

@@ -14,8 +14,14 @@ export async function GET(req: NextRequest) {
     return NextResponse.json({ error: 'state mismatch' }, { status: 400 })
   }
 
+  // Consume the pending login atomically before doing the token exchange
+  // to prevent state replay on concurrent callbacks.
+  const { codeVerifier } = pending
+  delete session.loginInProgress
+  await session.save()
+
   const redirectUri = `${process.env.NEXT_PUBLIC_BASE_URL}/api/auth/callback`
-  const tokens = await exchangeCode({ code, codeVerifier: pending.codeVerifier, redirectUri })
+  const tokens = await exchangeCode({ code, codeVerifier, redirectUri })
   const claims = await verifyIdToken(tokens.id_token)
 
   if (!isAllowedUser(claims.sub)) {
@@ -26,7 +32,6 @@ export async function GET(req: NextRequest) {
   session.userId = claims.sub
   session.email = claims.email
   session.name = claims.name
-  delete session.loginInProgress
   await session.save()
 
   return NextResponse.redirect(new URL('/', req.url))

src/lib/auth/session.ts

@@ -9,7 +9,7 @@ export interface SessionData {
   loginInProgress?: { state: string; codeVerifier: string }
 }
 
-const opts: SessionOptions = {
+export const sessionOptions: SessionOptions = {
   password: process.env.SESSION_PASSWORD || '',
   cookieName: 'preis_tracker_session',
   cookieOptions: {
@@ -21,11 +21,9 @@ const opts: SessionOptions = {
 }
 
 export async function getSession() {
-  if (!opts.password || (typeof opts.password === 'string' && opts.password.length < 32)) {
+  if (!sessionOptions.password || (typeof sessionOptions.password === 'string' && sessionOptions.password.length < 32)) {
     throw new Error('SESSION_PASSWORD must be set to a 32+ char value')
   }
   const c = await cookies()
-  return getIronSession<SessionData>(c, opts)
+  return getIronSession<SessionData>(c, sessionOptions)
 }
-
-export const sessionOptions = opts

src/lib/scrapers/idealo.ts

@@ -49,7 +49,7 @@ export const idealoScraper: PriceScraper = {
   },
 }
 
-function extractJsonLdPrice($: cheerio.CheerioAPI): string | null {
+function extractJsonLdPrice($: cheerio.Root): string | null {
   const scripts = $('script[type="application/ld+json"]')
   for (let i = 0; i < scripts.length; i++) {
     const raw = $(scripts[i]).contents().text()

src/middleware.ts

@@ -1,6 +1,6 @@
 import { NextRequest, NextResponse } from 'next/server'
 import { getIronSession } from 'iron-session'
-import type { SessionData } from '@/lib/auth/session'
+import { sessionOptions, type SessionData } from '@/lib/auth/session'
 
 const PUBLIC_PREFIXES = ['/api/auth/', '/api/cron/', '/_next/', '/favicon']
 
@@ -9,10 +9,7 @@ export async function middleware(req: NextRequest) {
   if (PUBLIC_PREFIXES.some((p) => pathname.startsWith(p))) return NextResponse.next()
 
   const res = NextResponse.next()
-  const session = await getIronSession<SessionData>(req, res, {
-    password: process.env.SESSION_PASSWORD || '',
-    cookieName: 'preis_tracker_session',
-  })
+  const session = await getIronSession<SessionData>(req, res, sessionOptions)
 
   if (!session.userId) {
     if (pathname.startsWith('/api/')) {