fix: tighten auth rate limits to 10/min and add rate limit tests

Reduce login and nostr/session rate limits from 30 to 10 requests per
minute per IP to prevent brute-force attacks. Add tests verifying 429
response after exceeding the limit.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/routes/auth.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi } from 'vitest'
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
 import { Hono } from 'hono'
 import { authRouter } from './auth.js'
 import { generateSecretKey, getPublicKey, finalizeEvent } from 'nostr-tools'
@@ -157,3 +157,63 @@ describe('auth routes', () => {
     expect(res.status).toBe(401)
   })
 })
+
+describe('auth rate limiting', () => {
+  let prodApp: InstanceType<typeof Hono>
+  let cleanup: ReturnType<typeof setInterval>
+
+  beforeEach(async () => {
+    vi.resetModules()
+    process.env.NODE_ENV = 'production'
+    process.env.JWT_SECRET = 'test-secret-for-rate-limit-testing'
+    const rateLimitMod = await import('../middleware/rate-limit.js')
+    cleanup = rateLimitMod.cleanupInterval
+    const authMod = await import('./auth.js')
+    prodApp = new Hono()
+    prodApp.route('/api/auth', authMod.authRouter)
+  })
+
+  afterEach(() => {
+    process.env.NODE_ENV = 'test'
+    delete process.env.JWT_SECRET
+    clearInterval(cleanup)
+  })
+
+  it('login: returns 429 after exceeding 10 requests per minute', async () => {
+    // Send 10 requests (within limit)
+    for (let i = 0; i < 10; i++) {
+      const res = await prodApp.request('/api/auth/login', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ pubkey: '0'.repeat(64) }),
+      })
+      expect(res.status).not.toBe(429)
+    }
+
+    // 11th request should be rate limited
+    const res = await prodApp.request('/api/auth/login', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ pubkey: '0'.repeat(64) }),
+    })
+    expect(res.status).toBe(429)
+    const body = await res.json() as { error: string; retryAfterSec: number }
+    expect(body.error).toContain('Too many requests')
+    expect(body.retryAfterSec).toBeGreaterThan(0)
+  })
+
+  it('nostr/session: returns 429 after exceeding 10 requests per minute', async () => {
+    // Send 10 requests (within limit)
+    for (let i = 0; i < 10; i++) {
+      await prodApp.request('/api/auth/nostr/session', {
+        method: 'POST',
+      })
+    }
+
+    // 11th request should be rate limited
+    const res = await prodApp.request('/api/auth/nostr/session', {
+      method: 'POST',
+    })
+    expect(res.status).toBe(429)
+  })
+})

server/src/routes/auth.ts

@@ -25,8 +25,8 @@ authRouter.get("/check-name/:name", async (c) => {
   return c.json({ available: existing.length === 0 })
 })
 
-// Login with Nostr pubkey (rate limited: 30 per minute per IP)
-authRouter.post('/login', rateLimit(60_000, 30), async (c) => {
+// Login with Nostr pubkey (rate limited: 10 per minute per IP)
+authRouter.post('/login', rateLimit(60_000, 10), async (c) => {
   const parsed = loginSchema.safeParse(await c.req.json().catch(() => ({})))
   if (!parsed.success) {
     return c.json({ error: 'Invalid pubkey.' }, 400)
@@ -365,7 +365,7 @@ import { verifyNip98Token } from '../middleware/nip98.js'
 import { createJwt, extractPubkeyFromAuth } from '../middleware/jwt.js'
 
 // POST /nostr/session — authenticate with NIP-98, receive JWT
-authRouter.post('/nostr/session', rateLimit(60_000, 30), async (c) => {
+authRouter.post('/nostr/session', rateLimit(60_000, 10), async (c) => {
   // Extract NIP-98 token from headers (try multiple header names)
   const authHeader = c.req.header('Authorization')
     || c.req.header('nostr-authorization')