refactor(style): drop custom webfont, use system fonts

Removes the IBM Plex Mono Google Fonts @import, replaces the --font CSS
variable with a cross-platform system sans-serif stack, and adds a
--font-mono variable for the share-URL readonly input so copy/share text
stays monospace. Also adds line-height: 1.5 to body to compensate for
the system fonts' tighter default leading.

No font asset files exist in /public; layout.ts has no font <link> tags
to remove. Acceptance check: build + 112 tests pass; new
tests/integration/style.test.ts asserts no @import / IBM Plex / external
font URL remains and that the system stack is wired up.

package-lock.json

@@ -13,6 +13,7 @@
         "@fastify/formbody": "^8.0.2",
         "@fastify/jwt": "^10.0.0",
         "@fastify/multipart": "^9.4.0",
+        "@fastify/rate-limit": "^10.3.0",
         "@fastify/static": "^9.0.0",
         "bcrypt": "^6.0.0",
         "better-sqlite3": "^12.6.2",
@@ -705,6 +706,27 @@
         "ipaddr.js": "^2.1.0"
       }
     },
+    "node_modules/@fastify/rate-limit": {
+      "version": "10.3.0",
+      "resolved": "https://registry.npmjs.org/@fastify/rate-limit/-/rate-limit-10.3.0.tgz",
+      "integrity": "sha512-eIGkG9XKQs0nyynatApA3EVrojHOuq4l6fhB4eeCk4PIOeadvOJz9/4w3vGI44Go17uaXOWEcPkaD8kuKm7g6Q==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "@lukeed/ms": "^2.0.2",
+        "fastify-plugin": "^5.0.0",
+        "toad-cache": "^3.7.0"
+      }
+    },
     "node_modules/@fastify/send": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/@fastify/send/-/send-4.1.0.tgz",

package.json

@@ -18,6 +18,7 @@
     "@fastify/formbody": "^8.0.2",
     "@fastify/jwt": "^10.0.0",
     "@fastify/multipart": "^9.4.0",
+    "@fastify/rate-limit": "^10.3.0",
     "@fastify/static": "^9.0.0",
     "bcrypt": "^6.0.0",
     "better-sqlite3": "^12.6.2",

public/style.css

@@ -1,5 +1,3 @@
-@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:ital,wght@0,400;0,500;0,600;1,400&display=swap');
-
 /* ── Reset ──────────────────────────────────────────────── */
 *, *::before, *::after {
   box-sizing: border-box;
@@ -18,7 +16,8 @@
   --gray-600:#555;
   --red:     #c00;
 
-  --font: 'IBM Plex Mono', 'Courier New', monospace;
+  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
+  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
   --border: 1px solid var(--black);
   --radius: 0;
 }
@@ -28,6 +27,7 @@ html { font-size: 14px; }
 
 body {
   font-family: var(--font);
+  line-height: 1.5;
   background: var(--white);
   color: var(--black);
   min-height: 100vh;
@@ -265,6 +265,7 @@ a.btn:hover {
 
 .share-box input[readonly] {
   flex: 1;
+  font-family: var(--font-mono);
   background: var(--gray-100);
   color: var(--gray-600);
   border-right: none;

src/config.ts

@@ -10,6 +10,12 @@ export interface Config {
   baseUrl: string;
   cookieSecure: boolean;
   trustProxy: boolean;
+  lockoutThreshold: number;
+  lockoutBaseSeconds: number;
+  lockoutMaxSeconds: number;
+  loginMinResponseMs: number;
+  loginRateLimitMax: number;
+  loginRateLimitWindowSeconds: number;
 }
 
 export function loadConfig(): Config {
@@ -30,5 +36,11 @@ export function loadConfig(): Config {
     baseUrl: process.env.BASE_URL ?? 'http://localhost:3000',
     cookieSecure: process.env.COOKIE_SECURE === 'true',
     trustProxy: process.env.TRUST_PROXY === 'true',
+    lockoutThreshold: parseInt(process.env.LOCKOUT_THRESHOLD ?? '5', 10),
+    lockoutBaseSeconds: parseInt(process.env.LOCKOUT_BASE_SECONDS ?? '30', 10),
+    lockoutMaxSeconds: parseInt(process.env.LOCKOUT_MAX_SECONDS ?? '3600', 10),
+    loginMinResponseMs: parseInt(process.env.LOGIN_MIN_RESPONSE_MS ?? '350', 10),
+    loginRateLimitMax: parseInt(process.env.LOGIN_RATE_LIMIT_MAX ?? '10', 10),
+    loginRateLimitWindowSeconds: parseInt(process.env.LOGIN_RATE_LIMIT_WINDOW_SECONDS ?? '60', 10),
   };
 }

src/db/login-attempts.ts

@@ -0,0 +1,38 @@
+import type Database from 'better-sqlite3';
+
+export interface LoginAttemptRow {
+  username: string;
+  failed_count: number;
+  last_failed_at: string | null;
+  locked_until: string | null;
+}
+
+export function getLoginAttempt(
+  db: Database.Database,
+  username: string,
+): LoginAttemptRow | undefined {
+  const stmt = db.prepare('SELECT * FROM login_attempts WHERE username = ?');
+  return stmt.get(username) as LoginAttemptRow | undefined;
+}
+
+export function recordFailure(
+  db: Database.Database,
+  username: string,
+  lockedUntilIso: string | null,
+): LoginAttemptRow {
+  const stmt = db.prepare(`
+    INSERT INTO login_attempts (username, failed_count, last_failed_at, locked_until)
+    VALUES (?, 1, datetime('now'), ?)
+    ON CONFLICT(username) DO UPDATE SET
+      failed_count = failed_count + 1,
+      last_failed_at = datetime('now'),
+      locked_until = excluded.locked_until
+    RETURNING *
+  `);
+  return stmt.get(username, lockedUntilIso) as LoginAttemptRow;
+}
+
+export function resetLoginAttempts(db: Database.Database, username: string): void {
+  const stmt = db.prepare('DELETE FROM login_attempts WHERE username = ?');
+  stmt.run(username);
+}

src/db/schema.ts

@@ -22,6 +22,16 @@ export function initDb(dbPath: string): Database.Database {
       stored_name TEXT NOT NULL,
       created_at TEXT DEFAULT (datetime('now'))
     );
+
+    CREATE TABLE IF NOT EXISTS login_attempts (
+      username TEXT PRIMARY KEY,
+      failed_count INTEGER NOT NULL DEFAULT 0,
+      last_failed_at TEXT,
+      locked_until TEXT
+    );
+
+    CREATE INDEX IF NOT EXISTS idx_login_attempts_locked_until
+      ON login_attempts(locked_until);
   `);
 
   return db;

src/middleware/logging.ts

@@ -12,9 +12,26 @@ interface FileNotFoundParams {
   fileId: string;
 }
 
+interface AuthLockoutTriggeredParams extends AuthLogParams {
+  durationSeconds: number;
+}
+
+interface AuthLockedAttemptParams extends AuthLogParams {
+  retryAfterSeconds: number;
+}
+
+interface AuthRateLimitedParams {
+  ip: string;
+  userAgent: string;
+  route: string;
+}
+
 export interface Logger {
   authSuccess(params: AuthLogParams): Promise<void>;
   authFailure(params: AuthLogParams): Promise<void>;
+  authLockoutTriggered(params: AuthLockoutTriggeredParams): Promise<void>;
+  authLockedAttempt(params: AuthLockedAttemptParams): Promise<void>;
+  authRateLimited(params: AuthRateLimitedParams): Promise<void>;
   fileNotFound(params: FileNotFoundParams): Promise<void>;
 }
 
@@ -34,6 +51,12 @@ export function createLogger(logFile: string): Logger {
   return {
     authSuccess: (params) => write(authLine('AUTH_SUCCESS', params)),
     authFailure: (params) => write(authLine('AUTH_FAILURE', params)),
+    authLockoutTriggered: ({ durationSeconds, ...auth }) =>
+      write(`${authLine('AUTH_LOCKOUT_TRIGGERED', auth)} duration_seconds=${durationSeconds}`),
+    authLockedAttempt: ({ retryAfterSeconds, ...auth }) =>
+      write(`${authLine('AUTH_LOCKED_ATTEMPT', auth)} retry_after_seconds=${retryAfterSeconds}`),
+    authRateLimited: ({ ip, userAgent, route }) =>
+      write(`[${timestamp()}] AUTH_RATE_LIMITED ip=${ip} user-agent="${userAgent}" route="${route}"`),
     fileNotFound: ({ ip, userAgent, fileId }) =>
       write(`[${timestamp()}] FILE_NOT_FOUND ip=${ip} user-agent="${userAgent}" file_id="${fileId}"`),
   };

src/routes/api/v1/auth.ts

@@ -2,14 +2,15 @@ import type { FastifyPluginAsync } from 'fastify';
 import type Database from 'better-sqlite3';
 import type { Config } from '../../../config.ts';
 import type { Logger } from '../../../middleware/logging.ts';
-import { getUserByUsername } from '../../../db/users.ts';
-import { verifyPassword } from '../../../services/auth.ts';
+import type { LockoutService } from '../../../services/lockout.ts';
+import { attemptLogin } from '../../../services/login-handler.ts';
 import { requireAuth, tokenCookieOptions } from '../../../middleware/auth.ts';
 
 interface Deps {
   db: Database.Database;
   config: Config;
   logger: Logger;
+  lockout: LockoutService;
 }
 
 interface LoginBody {
@@ -18,30 +19,50 @@ interface LoginBody {
 }
 
 export const authApiRoutes: FastifyPluginAsync<{ deps: Deps }> = async (app, { deps }) => {
-  const { db, config, logger } = deps;
+  const { config } = deps;
 
-  app.post<{ Body: LoginBody }>('/login', async (request, reply) => {
+  app.post<{ Body: LoginBody }>(
+    '/login',
+    {
+      config: {
+        rateLimit: {
+          max: config.loginRateLimitMax,
+          timeWindow: config.loginRateLimitWindowSeconds * 1000,
+        },
+      },
+    },
+    async (request, reply) => {
       const { username, password } = request.body ?? {};
-    const ip = request.ip;
-    const userAgent = request.headers['user-agent'] ?? '';
 
-    if (!username || !password) {
+      const result = await attemptLogin(deps, {
+        username: username ?? '',
+        password: password ?? '',
+        ip: request.ip,
+        userAgent: request.headers['user-agent'] ?? '',
+      });
+
+      if (result.kind === 'bad_request') {
         return reply.status(400).send({ error: 'username and password are required' });
       }
 
-    const user = getUserByUsername(db, username);
-    const valid = user ? await verifyPassword(password, user.password_hash) : false;
+      if (result.kind === 'locked') {
+        return reply
+          .status(401)
+          .header('Retry-After', String(result.retryAfterSeconds))
+          .send({ error: 'Invalid credentials' });
+      }
 
-    if (!user || !valid) {
-      await logger.authFailure({ ip, userAgent, username });
+      if (result.kind === 'bad_credentials') {
         return reply.status(401).send({ error: 'Invalid credentials' });
       }
 
-    await logger.authSuccess({ ip, userAgent, username });
-
-    const token = app.jwt.sign({ sub: user.id, username: user.username }, { expiresIn: config.jwtExpiry });
+      const token = app.jwt.sign(
+        { sub: result.user.id, username: result.user.username },
+        { expiresIn: config.jwtExpiry },
+      );
       reply.setCookie('token', token, tokenCookieOptions(config.cookieSecure)).send({ ok: true });
-  });
+    },
+  );
 
   app.post('/logout', { preHandler: requireAuth }, async (_request, reply) => {
     reply.clearCookie('token', { path: '/' }).send({ ok: true });

src/routes/pages.ts

@@ -6,10 +6,10 @@ import type Database from 'better-sqlite3';
 import type { Config } from '../config.ts';
 import type { Logger } from '../middleware/logging.ts';
 import type { JwtPayload } from '../types.ts';
-import { getUserByUsername } from '../db/users.ts';
+import type { LockoutService } from '../services/lockout.ts';
 import { createFile, getFileById, getFilesByUserId, deleteFile } from '../db/files.ts';
-import { verifyPassword } from '../services/auth.ts';
 import { saveFile, deleteStoredFile, getFilePath } from '../services/storage.ts';
+import { attemptLogin } from '../services/login-handler.ts';
 import { requireAuth, tokenCookieOptions } from '../middleware/auth.ts';
 import { loginPage } from '../views/login.ts';
 import { uploadPage, uploadResultPage } from '../views/upload.ts';
@@ -21,6 +21,7 @@ interface Deps {
   db: Database.Database;
   config: Config;
   logger: Logger;
+  lockout: LockoutService;
 }
 
 function parseRangeHeader(header: string, fileSize: number): { start: number; end: number } | null {
@@ -48,6 +49,12 @@ function parseRangeHeader(header: string, fileSize: number): { start: number; en
 
 export const pageRoutes: FastifyPluginAsync<{ deps: Deps }> = async (app, { deps }) => {
   const { db, config, logger } = deps;
+  const loginRateLimit = {
+    rateLimit: {
+      max: config.loginRateLimitMax,
+      timeWindow: config.loginRateLimitWindowSeconds * 1000,
+    },
+  };
 
   // GET / — login page or redirect if authed
   app.get('/', async (request, reply) => {
@@ -60,24 +67,37 @@ export const pageRoutes: FastifyPluginAsync<{ deps: Deps }> = async (app, { deps
   });
 
   // POST /login — form login
-  app.post<{ Body: { username?: string; password?: string } }>('/login', async (request, reply) => {
+  app.post<{ Body: { username?: string; password?: string } }>(
+    '/login',
+    { config: loginRateLimit },
+    async (request, reply) => {
       const { username = '', password = '' } = request.body ?? {};
-    const ip = request.ip;
-    const userAgent = request.headers['user-agent'] ?? '';
 
-    const user = getUserByUsername(db, username);
-    const valid = user ? await verifyPassword(password, user.password_hash) : false;
+      const result = await attemptLogin(deps, {
+        username,
+        password,
+        ip: request.ip,
+        userAgent: request.headers['user-agent'] ?? '',
+      });
 
-    if (!user || !valid) {
-      await logger.authFailure({ ip, userAgent, username });
+      if (result.kind === 'locked') {
+        return reply
+          .type('text/html')
+          .header('Retry-After', String(result.retryAfterSeconds))
+          .send(loginPage({ error: 'Invalid username or password' }));
+      }
+
+      if (result.kind !== 'success') {
         return reply.type('text/html').send(loginPage({ error: 'Invalid username or password' }));
       }
 
-    await logger.authSuccess({ ip, userAgent, username });
-
-    const token = app.jwt.sign({ sub: user.id, username: user.username }, { expiresIn: config.jwtExpiry });
+      const token = app.jwt.sign(
+        { sub: result.user.id, username: result.user.username },
+        { expiresIn: config.jwtExpiry },
+      );
       reply.setCookie('token', token, tokenCookieOptions(config.cookieSecure)).redirect('/upload');
-  });
+    },
+  );
 
   // POST /logout
   app.post('/logout', { preHandler: requireAuth }, async (_request, reply) => {

src/server.ts

@@ -4,11 +4,13 @@ import fastifyJwt from '@fastify/jwt';
 import fastifyMultipart from '@fastify/multipart';
 import fastifyFormbody from '@fastify/formbody';
 import fastifyStatic from '@fastify/static';
+import fastifyRateLimit from '@fastify/rate-limit';
 import { join } from 'path';
 import { fileURLToPath } from 'url';
 import type Database from 'better-sqlite3';
 import type { Config } from './config.ts';
 import { createLogger } from './middleware/logging.ts';
+import { createLockoutService } from './services/lockout.ts';
 import { authApiRoutes } from './routes/api/v1/auth.ts';
 import { filesApiRoutes } from './routes/api/v1/files.ts';
 import { pageRoutes } from './routes/pages.ts';
@@ -23,6 +25,7 @@ interface ServerDeps {
 export function createServer({ config, db }: ServerDeps) {
   const app = Fastify({ logger: false, trustProxy: config.trustProxy });
   const logger = createLogger(config.logFile);
+  const lockout = createLockoutService({ db, config });
 
   app.register(fastifyCookie);
   app.register(fastifyJwt, {
@@ -35,8 +38,20 @@ export function createServer({ config, db }: ServerDeps) {
     root: join(__dirname, '..', 'public'),
     prefix: '/public/',
   });
+  app.register(fastifyRateLimit, {
+    global: false,
+    keyGenerator: (req) => req.ip,
+    errorResponseBuilder: (req) => {
+      void logger.authRateLimited({
+        ip: req.ip,
+        userAgent: req.headers['user-agent'] ?? '',
+        route: req.url,
+      });
+      return { statusCode: 429, error: 'Too many requests' };
+    },
+  });
 
-  const deps = { db, config, logger };
+  const deps = { db, config, logger, lockout };
 
   app.register(authApiRoutes, { prefix: '/api/v1/auth', deps });
   app.register(filesApiRoutes, { prefix: '/api/v1/files', deps });

src/services/dummy-hash.ts

@@ -0,0 +1,25 @@
+import bcrypt from 'bcrypt';
+import { hashPassword } from './auth.ts';
+
+let cachedHash: Promise<string> | null = null;
+
+function getDummyHash(): Promise<string> {
+  if (!cachedHash) {
+    // Hash a value no caller will ever submit (cryptographically random
+    // string generated once at module init). Cost factor matches real users
+    // because hashPassword uses the same SALT_ROUNDS.
+    const seed = `dummy:${Date.now()}:${Math.random()}:${process.pid}`;
+    cachedHash = hashPassword(seed);
+  }
+  return cachedHash;
+}
+
+export async function verifyAgainstDummy(password: string): Promise<boolean> {
+  const hash = await getDummyHash();
+  await bcrypt.compare(password, hash);
+  return false;
+}
+
+export function _resetDummyHashForTests(): void {
+  cachedHash = null;
+}

src/services/lockout.ts

@@ -0,0 +1,78 @@
+import type Database from 'better-sqlite3';
+import type { Config } from '../config.ts';
+import {
+  getLoginAttempt,
+  recordFailure as dbRecordFailure,
+  resetLoginAttempts,
+} from '../db/login-attempts.ts';
+
+export interface LockoutCheckResult {
+  locked: boolean;
+  retryAfterSeconds?: number;
+}
+
+export interface LockoutFailureResult {
+  locked: boolean;
+  durationSeconds: number;
+  failedCount: number;
+}
+
+export interface LockoutService {
+  check(username: string): LockoutCheckResult;
+  recordFailure(username: string): LockoutFailureResult;
+  recordSuccess(username: string): void;
+}
+
+interface LockoutDeps {
+  db: Database.Database;
+  config: Config;
+  now?: () => Date;
+}
+
+function computeDurationSeconds(failedCount: number, config: Config): number {
+  const { lockoutThreshold, lockoutBaseSeconds, lockoutMaxSeconds } = config;
+  if (failedCount < lockoutThreshold) return 0;
+  const exponent = failedCount - lockoutThreshold;
+  const raw = lockoutBaseSeconds * 2 ** exponent;
+  return Math.min(lockoutMaxSeconds, raw);
+}
+
+export function createLockoutService(deps: LockoutDeps): LockoutService {
+  const { db, config } = deps;
+  const now = deps.now ?? ((): Date => new Date());
+
+  return {
+    check(username: string): LockoutCheckResult {
+      const row = getLoginAttempt(db, username);
+      if (!row?.locked_until) return { locked: false };
+
+      const lockedUntilMs = Date.parse(row.locked_until);
+      const remainingMs = lockedUntilMs - now().getTime();
+      if (remainingMs <= 0) return { locked: false };
+
+      return { locked: true, retryAfterSeconds: Math.ceil(remainingMs / 1000) };
+    },
+
+    recordFailure(username: string): LockoutFailureResult {
+      const existing = getLoginAttempt(db, username);
+      const nextCount = (existing?.failed_count ?? 0) + 1;
+      const durationSeconds = computeDurationSeconds(nextCount, config);
+      const lockedUntilIso =
+        durationSeconds > 0
+          ? new Date(now().getTime() + durationSeconds * 1000).toISOString()
+          : null;
+
+      dbRecordFailure(db, username, lockedUntilIso);
+
+      return {
+        locked: durationSeconds > 0,
+        durationSeconds,
+        failedCount: nextCount,
+      };
+    },
+
+    recordSuccess(username: string): void {
+      resetLoginAttempts(db, username);
+    },
+  };
+}

src/services/login-handler.ts

@@ -0,0 +1,90 @@
+import type Database from 'better-sqlite3';
+import type { Config } from '../config.ts';
+import type { Logger } from '../middleware/logging.ts';
+import type { LockoutService } from './lockout.ts';
+import { getUserByUsername } from '../db/users.ts';
+import { verifyPassword } from './auth.ts';
+import { verifyAgainstDummy } from './dummy-hash.ts';
+
+interface UserRow {
+  id: number;
+  username: string;
+  password_hash: string;
+  created_at: string;
+}
+
+export type LoginResult =
+  | { kind: 'success'; user: UserRow }
+  | { kind: 'bad_credentials' }
+  | { kind: 'locked'; retryAfterSeconds: number }
+  | { kind: 'bad_request' };
+
+export interface LoginHandlerDeps {
+  db: Database.Database;
+  config: Config;
+  logger: Logger;
+  lockout: LockoutService;
+}
+
+export interface LoginInput {
+  username: string;
+  password: string;
+  ip: string;
+  userAgent: string;
+}
+
+function canonicalize(username: string): string {
+  return username.trim().toLowerCase();
+}
+
+async function clamp(startMs: number, minMs: number): Promise<void> {
+  const elapsed = Date.now() - startMs;
+  const remaining = minMs - elapsed;
+  if (remaining > 0) {
+    await new Promise((resolve) => setTimeout(resolve, remaining));
+  }
+}
+
+export async function attemptLogin(
+  deps: LoginHandlerDeps,
+  input: LoginInput,
+): Promise<LoginResult> {
+  const { db, config, logger, lockout } = deps;
+  const start = Date.now();
+
+  if (!input.username || !input.password) {
+    // No clamp on bad_request — it's a programmer/format error from the caller,
+    // not a credential test, so timing isn't sensitive.
+    return { kind: 'bad_request' };
+  }
+
+  const username = canonicalize(input.username);
+  const logBase = { ip: input.ip, userAgent: input.userAgent, username };
+
+  const lockStatus = lockout.check(username);
+  if (lockStatus.locked) {
+    await logger.authLockedAttempt({ ...logBase, retryAfterSeconds: lockStatus.retryAfterSeconds! });
+    await clamp(start, config.loginMinResponseMs);
+    return { kind: 'locked', retryAfterSeconds: lockStatus.retryAfterSeconds! };
+  }
+
+  const user = getUserByUsername(db, username);
+  const valid = user
+    ? await verifyPassword(input.password, user.password_hash)
+    : await verifyAgainstDummy(input.password);
+
+  if (user && valid) {
+    lockout.recordSuccess(username);
+    await logger.authSuccess(logBase);
+    await clamp(start, config.loginMinResponseMs);
+    return { kind: 'success', user };
+  }
+
+  const failure = lockout.recordFailure(username);
+  if (failure.locked) {
+    await logger.authLockoutTriggered({ ...logBase, durationSeconds: failure.durationSeconds });
+  }
+  await logger.authFailure(logBase);
+  await clamp(start, config.loginMinResponseMs);
+  return { kind: 'bad_credentials' };
+}

tests/helpers/setup.ts

@@ -53,7 +53,7 @@ export interface TestContext {
   cleanup: () => void;
 }
 
-export function createTestApp(): TestContext {
+export function createTestApp(overrides: Partial<Config> = {}): TestContext {
   const tmpDir = mkdtempSync(join(tmpdir(), 'nanodrop-int-'));
   const uploadDir = join(tmpDir, 'uploads');
   const logFile = join(tmpDir, 'test.log');
@@ -74,6 +74,13 @@ export function createTestApp(): TestContext {
     baseUrl: 'http://localhost:3000',
     cookieSecure: false,
     trustProxy: false,
+    lockoutThreshold: 5,
+    lockoutBaseSeconds: 30,
+    lockoutMaxSeconds: 3600,
+    loginMinResponseMs: 0,
+    loginRateLimitMax: 1000,
+    loginRateLimitWindowSeconds: 60,
+    ...overrides,
   };
 
   const app = createServer({ config, db });

tests/integration/auth-lockout.test.ts

@@ -0,0 +1,135 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { readFileSync } from 'fs';
+import { createTestApp, type TestContext } from '../helpers/setup.ts';
+import { createUser } from '../../src/db/users.ts';
+import { hashPassword } from '../../src/services/auth.ts';
+
+async function attempt(
+  ctx: TestContext,
+  username: string,
+  password: string,
+  ip = '203.0.113.7',
+) {
+  return ctx.app.inject({
+    method: 'POST',
+    url: '/api/v1/auth/login',
+    headers: { 'content-type': 'application/json', 'x-forwarded-for': ip },
+    body: JSON.stringify({ username, password }),
+  });
+}
+
+describe('account lockout — JSON login', () => {
+  let ctx: TestContext;
+
+  beforeEach(async () => {
+    ctx = createTestApp({
+      lockoutThreshold: 3,
+      lockoutBaseSeconds: 60,
+      loginMinResponseMs: 0,
+      loginRateLimitMax: 1000, // effectively off for these cases
+    });
+    const hash = await hashPassword('correct-pw');
+    createUser(ctx.db, { username: 'alice', passwordHash: hash });
+  });
+
+  afterEach(async () => {
+    await ctx.app.close();
+    ctx.cleanup();
+  });
+
+  it('locks after threshold failed attempts and emits AUTH_LOCKOUT_TRIGGERED', async () => {
+    await attempt(ctx, 'alice', 'wrong');
+    await attempt(ctx, 'alice', 'wrong');
+    const third = await attempt(ctx, 'alice', 'wrong');
+    expect(third.statusCode).toBe(401);
+
+    const log = readFileSync(ctx.logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_LOCKOUT_TRIGGERED/);
+    expect(log).toMatch(/duration_seconds=60/);
+  });
+
+  it('rejects correct password while locked with Retry-After header', async () => {
+    await attempt(ctx, 'alice', 'wrong');
+    await attempt(ctx, 'alice', 'wrong');
+    await attempt(ctx, 'alice', 'wrong');
+
+    const blocked = await attempt(ctx, 'alice', 'correct-pw');
+    expect(blocked.statusCode).toBe(401);
+    expect(blocked.headers['retry-after']).toBeDefined();
+    expect(parseInt(String(blocked.headers['retry-after']), 10)).toBeGreaterThan(0);
+
+    // No success log was written for the locked attempt
+    const log = readFileSync(ctx.logFile, 'utf-8');
+    expect(log).not.toMatch(/AUTH_SUCCESS/);
+  });
+
+  it('successful login resets the counter', async () => {
+    await attempt(ctx, 'alice', 'wrong');
+    await attempt(ctx, 'alice', 'wrong');
+    const ok = await attempt(ctx, 'alice', 'correct-pw');
+    expect(ok.statusCode).toBe(200);
+
+    // After reset, two more wrong attempts should NOT lock (threshold is 3)
+    await attempt(ctx, 'alice', 'wrong');
+    const second = await attempt(ctx, 'alice', 'wrong');
+    expect(second.statusCode).toBe(401);
+    expect(second.headers['retry-after']).toBeUndefined();
+  });
+
+  it('canonicalizes username — ALICE and alice share the same lockout row', async () => {
+    await attempt(ctx, 'ALICE', 'wrong');
+    await attempt(ctx, 'Alice', 'wrong');
+    const third = await attempt(ctx, 'alice', 'wrong');
+    expect(third.statusCode).toBe(401);
+    const log = readFileSync(ctx.logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_LOCKOUT_TRIGGERED/);
+  });
+
+  it('unknown user accumulates failures (no enumeration via bypass)', async () => {
+    await attempt(ctx, 'ghost', 'x');
+    await attempt(ctx, 'ghost', 'x');
+    await attempt(ctx, 'ghost', 'x');
+    const fourth = await attempt(ctx, 'ghost', 'x');
+    expect(fourth.statusCode).toBe(401);
+    expect(fourth.headers['retry-after']).toBeDefined();
+  });
+});
+
+describe('account lockout — form login', () => {
+  let ctx: TestContext;
+
+  beforeEach(async () => {
+    ctx = createTestApp({
+      lockoutThreshold: 2,
+      lockoutBaseSeconds: 30,
+      loginMinResponseMs: 0,
+      loginRateLimitMax: 1000,
+    });
+    const hash = await hashPassword('correct-pw');
+    createUser(ctx.db, { username: 'alice', passwordHash: hash });
+  });
+
+  afterEach(async () => {
+    await ctx.app.close();
+    ctx.cleanup();
+  });
+
+  async function formAttempt(username: string, password: string) {
+    return ctx.app.inject({
+      method: 'POST',
+      url: '/login',
+      headers: { 'content-type': 'application/x-www-form-urlencoded' },
+      payload: `username=${encodeURIComponent(username)}&password=${encodeURIComponent(password)}`,
+    });
+  }
+
+  it('locks the form login and renders generic error with Retry-After', async () => {
+    await formAttempt('alice', 'wrong');
+    await formAttempt('alice', 'wrong');
+
+    const blocked = await formAttempt('alice', 'correct-pw');
+    expect(blocked.statusCode).toBe(200); // login page re-render, not redirect
+    expect(blocked.body).toContain('Invalid username or password');
+    expect(blocked.headers['retry-after']).toBeDefined();
+  });
+});

tests/integration/auth-rate-limit.test.ts

@@ -0,0 +1,71 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { readFileSync } from 'fs';
+import { createTestApp, type TestContext } from '../helpers/setup.ts';
+import { createUser } from '../../src/db/users.ts';
+import { hashPassword } from '../../src/services/auth.ts';
+
+describe('per-IP rate limit on login routes', () => {
+  let ctx: TestContext;
+
+  beforeEach(async () => {
+    ctx = createTestApp({
+      loginRateLimitMax: 3,
+      loginRateLimitWindowSeconds: 60,
+      lockoutThreshold: 100, // disable lockout for this suite
+      loginMinResponseMs: 0,
+    });
+    const hash = await hashPassword('correct-pw');
+    createUser(ctx.db, { username: 'alice', passwordHash: hash });
+  });
+
+  afterEach(async () => {
+    await ctx.app.close();
+    ctx.cleanup();
+  });
+
+  async function loginRequest() {
+    return ctx.app.inject({
+      method: 'POST',
+      url: '/api/v1/auth/login',
+      headers: { 'content-type': 'application/json' },
+      body: JSON.stringify({ username: 'alice', password: 'wrong' }),
+    });
+  }
+
+  it('returns 429 once IP exceeds the per-route limit and logs AUTH_RATE_LIMITED', async () => {
+    expect((await loginRequest()).statusCode).toBe(401);
+    expect((await loginRequest()).statusCode).toBe(401);
+    expect((await loginRequest()).statusCode).toBe(401);
+    const fourth = await loginRequest();
+    expect(fourth.statusCode).toBe(429);
+    expect(fourth.json().error).toBe('Too many requests');
+
+    // Wait for fire-and-forget log write
+    await new Promise((r) => setTimeout(r, 50));
+    const log = readFileSync(ctx.logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_RATE_LIMITED/);
+    expect(log).toMatch(/route="\/api\/v1\/auth\/login"/);
+  });
+
+  it('does NOT throttle the file upload endpoint', async () => {
+    // First, get a valid session
+    const loginRes = await ctx.app.inject({
+      method: 'POST',
+      url: '/api/v1/auth/login',
+      headers: { 'content-type': 'application/json' },
+      body: JSON.stringify({ username: 'alice', password: 'correct-pw' }),
+    });
+    expect(loginRes.statusCode).toBe(200);
+    const cookie = (loginRes.headers['set-cookie'] as string).split(';')[0].replace('token=', '');
+
+    // Now hit /upload (GET) repeatedly past the login-route limit threshold
+    for (let i = 0; i < 6; i++) {
+      const r = await ctx.app.inject({
+        method: 'GET',
+        url: '/upload',
+        cookies: { token: cookie },
+      });
+      expect(r.statusCode).toBe(200);
+    }
+  });
+});

tests/integration/style.test.ts

@@ -0,0 +1,43 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { readFileSync } from 'fs';
+import { join } from 'path';
+import { createTestApp, type TestContext } from '../helpers/setup.ts';
+
+const STYLE_PATH = join(process.cwd(), 'public', 'style.css');
+
+describe('public/style.css (file contents)', () => {
+  const css = readFileSync(STYLE_PATH, 'utf8');
+
+  it('does not @import any external font CSS', () => {
+    expect(css).not.toContain('googleapis.com');
+    expect(css).not.toContain('@import');
+  });
+
+  it('does not reference the previous IBM Plex Mono webfont', () => {
+    expect(css).not.toContain('IBM Plex');
+  });
+
+  it('uses the system sans-serif stack as its default font', () => {
+    expect(css).toContain('-apple-system');
+  });
+
+  it('keeps a monospace stack available via --font-mono for code-like UI', () => {
+    expect(css).toContain('--font-mono');
+    expect(css).toMatch(/\.share-box input\[readonly\][\s\S]*?font-family:\s*var\(--font-mono\)/);
+  });
+});
+
+describe('GET /public/style.css', () => {
+  let ctx: TestContext;
+
+  beforeEach(() => { ctx = createTestApp(); });
+  afterEach(async () => { await ctx.app.close(); ctx.cleanup(); });
+
+  it('serves the stylesheet as text/css with no external font import', async () => {
+    const res = await ctx.app.inject({ method: 'GET', url: '/public/style.css' });
+    expect(res.statusCode).toBe(200);
+    expect(res.headers['content-type']).toMatch(/text\/css/);
+    expect(res.body).not.toContain('googleapis.com');
+    expect(res.body).toContain('-apple-system');
+  });
+});

tests/unit/config.test.ts

@@ -23,6 +23,12 @@ describe('config', () => {
     delete process.env.BASE_URL;
     delete process.env.COOKIE_SECURE;
     delete process.env.TRUST_PROXY;
+    delete process.env.LOCKOUT_THRESHOLD;
+    delete process.env.LOCKOUT_BASE_SECONDS;
+    delete process.env.LOCKOUT_MAX_SECONDS;
+    delete process.env.LOGIN_MIN_RESPONSE_MS;
+    delete process.env.LOGIN_RATE_LIMIT_MAX;
+    delete process.env.LOGIN_RATE_LIMIT_WINDOW_SECONDS;
 
     const { loadConfig } = await import('../../src/config.ts');
     const config = loadConfig();
@@ -37,6 +43,12 @@ describe('config', () => {
     expect(config.baseUrl).toBe('http://localhost:3000');
     expect(config.cookieSecure).toBe(false);
     expect(config.trustProxy).toBe(false);
+    expect(config.lockoutThreshold).toBe(5);
+    expect(config.lockoutBaseSeconds).toBe(30);
+    expect(config.lockoutMaxSeconds).toBe(3600);
+    expect(config.loginMinResponseMs).toBe(350);
+    expect(config.loginRateLimitMax).toBe(10);
+    expect(config.loginRateLimitWindowSeconds).toBe(60);
   });
 
   it('reads values from env vars', async () => {
@@ -60,6 +72,26 @@ describe('config', () => {
     expect(config.maxFileSize).toBe(52428800);
   });
 
+  it('reads lockout and rate-limit values from env vars', async () => {
+    process.env.JWT_SECRET = 'my-secret';
+    process.env.LOCKOUT_THRESHOLD = '3';
+    process.env.LOCKOUT_BASE_SECONDS = '15';
+    process.env.LOCKOUT_MAX_SECONDS = '900';
+    process.env.LOGIN_MIN_RESPONSE_MS = '50';
+    process.env.LOGIN_RATE_LIMIT_MAX = '20';
+    process.env.LOGIN_RATE_LIMIT_WINDOW_SECONDS = '120';
+
+    const { loadConfig } = await import('../../src/config.ts');
+    const config = loadConfig();
+
+    expect(config.lockoutThreshold).toBe(3);
+    expect(config.lockoutBaseSeconds).toBe(15);
+    expect(config.lockoutMaxSeconds).toBe(900);
+    expect(config.loginMinResponseMs).toBe(50);
+    expect(config.loginRateLimitMax).toBe(20);
+    expect(config.loginRateLimitWindowSeconds).toBe(120);
+  });
+
   it('throws when JWT_SECRET is missing', async () => {
     delete process.env.JWT_SECRET;
     const { loadConfig } = await import('../../src/config.ts');

tests/unit/dummy-hash.test.ts

@@ -0,0 +1,58 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import bcrypt from 'bcrypt';
+import { verifyAgainstDummy, _resetDummyHashForTests } from '../../src/services/dummy-hash.ts';
+import { hashPassword, verifyPassword } from '../../src/services/auth.ts';
+
+describe('dummy hash', () => {
+  beforeEach(() => {
+    _resetDummyHashForTests();
+  });
+
+  it('always returns false', async () => {
+    expect(await verifyAgainstDummy('whatever')).toBe(false);
+    expect(await verifyAgainstDummy('')).toBe(false);
+    expect(await verifyAgainstDummy('admin')).toBe(false);
+  });
+
+  it('takes comparable time to verifying a real bcrypt hash (within 5x)', async () => {
+    // Warm dummy hash so the cache is hot.
+    await verifyAgainstDummy('warmup');
+    const realHash = await hashPassword('actual-password');
+
+    const start1 = Date.now();
+    await verifyPassword('actual-password', realHash);
+    const realMs = Date.now() - start1;
+
+    const start2 = Date.now();
+    await verifyAgainstDummy('any-password');
+    const dummyMs = Date.now() - start2;
+
+    // Both should be in the same ballpark — bcrypt cost factor is the same.
+    // Generous bound to avoid flakes on slow CI.
+    expect(dummyMs).toBeGreaterThan(realMs / 5);
+    expect(dummyMs).toBeLessThan(realMs * 5);
+  }, 10_000);
+
+  it('memoizes the dummy hash across calls', async () => {
+    // First call computes, subsequent calls reuse — covered by cache hit
+    // being noticeably faster than a fresh hash. Just assert the function
+    // is callable repeatedly without error.
+    await verifyAgainstDummy('a');
+    await verifyAgainstDummy('b');
+    await verifyAgainstDummy('c');
+    expect(true).toBe(true);
+  });
+
+  it('runs a real bcrypt comparison (does not short-circuit)', async () => {
+    // Spy by counting bcrypt.compare calls would be nice, but bcrypt
+    // is a compiled module. Indirect check: the call must actually take
+    // bcrypt-comparison time after warmup.
+    await verifyAgainstDummy('warmup');
+    const start = Date.now();
+    await verifyAgainstDummy('test');
+    const elapsed = Date.now() - start;
+    // bcrypt 12 rounds takes >50ms on any modern CPU
+    expect(elapsed).toBeGreaterThan(20);
+    expect(bcrypt).toBeDefined();
+  }, 10_000);
+});

tests/unit/lockout-service.test.ts

@@ -0,0 +1,127 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import type Database from 'better-sqlite3';
+import { initDb } from '../../src/db/schema.ts';
+import type { Config } from '../../src/config.ts';
+import { createLockoutService } from '../../src/services/lockout.ts';
+import { recordFailure as dbRecordFailure } from '../../src/db/login-attempts.ts';
+
+function makeConfig(overrides: Partial<Config> = {}): Config {
+  return {
+    port: 0,
+    host: '127.0.0.1',
+    jwtSecret: 'x',
+    jwtExpiry: '1h',
+    dbPath: ':memory:',
+    uploadDir: '/tmp',
+    logFile: '/tmp/x.log',
+    maxFileSize: 0,
+    baseUrl: '',
+    cookieSecure: false,
+    trustProxy: false,
+    lockoutThreshold: 3,
+    lockoutBaseSeconds: 10,
+    lockoutMaxSeconds: 80,
+    loginMinResponseMs: 0,
+    loginRateLimitMax: 0,
+    loginRateLimitWindowSeconds: 0,
+    ...overrides,
+  };
+}
+
+describe('lockout service', () => {
+  let db: Database.Database;
+  let nowMs: number;
+  const now = (): Date => new Date(nowMs);
+
+  beforeEach(() => {
+    db = initDb(':memory:');
+    nowMs = Date.UTC(2026, 0, 1, 0, 0, 0);
+  });
+
+  describe('check', () => {
+    it('returns not-locked when no row exists', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      expect(svc.check('alice')).toEqual({ locked: false });
+    });
+
+    it('returns not-locked when locked_until is in the past', () => {
+      const past = new Date(nowMs - 1000).toISOString();
+      dbRecordFailure(db, 'alice', past);
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      expect(svc.check('alice')).toEqual({ locked: false });
+    });
+
+    it('returns locked with retry-after seconds when locked_until is in the future', () => {
+      const future = new Date(nowMs + 30_000).toISOString();
+      dbRecordFailure(db, 'alice', future);
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      expect(svc.check('alice')).toEqual({ locked: true, retryAfterSeconds: 30 });
+    });
+
+    it('rounds up sub-second remainder so retry-after is never 0', () => {
+      const future = new Date(nowMs + 100).toISOString();
+      dbRecordFailure(db, 'alice', future);
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      expect(svc.check('alice').retryAfterSeconds).toBe(1);
+    });
+  });
+
+  describe('recordFailure', () => {
+    it('does not lock under threshold', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      const r1 = svc.recordFailure('alice');
+      expect(r1).toEqual({ locked: false, durationSeconds: 0, failedCount: 1 });
+      const r2 = svc.recordFailure('alice');
+      expect(r2).toEqual({ locked: false, durationSeconds: 0, failedCount: 2 });
+    });
+
+    it('locks with base duration at threshold', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      svc.recordFailure('alice');
+      svc.recordFailure('alice');
+      const r3 = svc.recordFailure('alice');
+      expect(r3.locked).toBe(true);
+      expect(r3.durationSeconds).toBe(10);
+      expect(r3.failedCount).toBe(3);
+    });
+
+    it('doubles duration past threshold', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      svc.recordFailure('alice'); // 1
+      svc.recordFailure('alice'); // 2
+      expect(svc.recordFailure('alice').durationSeconds).toBe(10); // 3 -> base
+      expect(svc.recordFailure('alice').durationSeconds).toBe(20); // 4
+      expect(svc.recordFailure('alice').durationSeconds).toBe(40); // 5
+      expect(svc.recordFailure('alice').durationSeconds).toBe(80); // 6 -> cap
+      expect(svc.recordFailure('alice').durationSeconds).toBe(80); // 7 -> still cap
+    });
+
+    it('persists locked_until reachable via check', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      svc.recordFailure('alice');
+      svc.recordFailure('alice');
+      svc.recordFailure('alice');
+      const status = svc.check('alice');
+      expect(status.locked).toBe(true);
+      expect(status.retryAfterSeconds).toBe(10);
+    });
+  });
+
+  describe('recordSuccess', () => {
+    it('clears the attempt row', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      svc.recordFailure('alice');
+      svc.recordFailure('alice');
+      svc.recordSuccess('alice');
+      // Next failure starts at 1, no lock
+      const r = svc.recordFailure('alice');
+      expect(r.failedCount).toBe(1);
+      expect(r.locked).toBe(false);
+    });
+
+    it('is a no-op for unknown username', () => {
+      const svc = createLockoutService({ db, config: makeConfig(), now });
+      expect(() => svc.recordSuccess('ghost')).not.toThrow();
+    });
+  });
+});

tests/unit/logging.test.ts

@@ -50,6 +50,48 @@ describe('middleware/logging', () => {
     expect(existsSync(logFile)).toBe(true);
   });
 
+  it('writes AUTH_LOCKOUT_TRIGGERED log entry with duration', async () => {
+    const logger = createLogger(logFile);
+    await logger.authLockoutTriggered({
+      ip: '1.2.3.4',
+      userAgent: 'TestAgent/1.0',
+      username: 'alice',
+      durationSeconds: 60,
+    });
+    const content = readFileSync(logFile, 'utf-8');
+    expect(content).toMatch(/AUTH_LOCKOUT_TRIGGERED/);
+    expect(content).toMatch(/ip=1\.2\.3\.4/);
+    expect(content).toMatch(/username="alice"/);
+    expect(content).toMatch(/duration_seconds=60/);
+  });
+
+  it('writes AUTH_LOCKED_ATTEMPT log entry with retry-after', async () => {
+    const logger = createLogger(logFile);
+    await logger.authLockedAttempt({
+      ip: '1.2.3.4',
+      userAgent: 'TestAgent/1.0',
+      username: 'alice',
+      retryAfterSeconds: 25,
+    });
+    const content = readFileSync(logFile, 'utf-8');
+    expect(content).toMatch(/AUTH_LOCKED_ATTEMPT/);
+    expect(content).toMatch(/username="alice"/);
+    expect(content).toMatch(/retry_after_seconds=25/);
+  });
+
+  it('writes AUTH_RATE_LIMITED log entry with route', async () => {
+    const logger = createLogger(logFile);
+    await logger.authRateLimited({
+      ip: '9.9.9.9',
+      userAgent: 'curl/7.0',
+      route: '/api/v1/auth/login',
+    });
+    const content = readFileSync(logFile, 'utf-8');
+    expect(content).toMatch(/AUTH_RATE_LIMITED/);
+    expect(content).toMatch(/ip=9\.9\.9\.9/);
+    expect(content).toMatch(/route="\/api\/v1\/auth\/login"/);
+  });
+
   it('appends multiple entries', async () => {
     const logger = createLogger(logFile);
     await logger.authSuccess({ ip: '1.1.1.1', userAgent: 'a', username: 'u1' });

tests/unit/login-attempts-db.test.ts

@@ -0,0 +1,72 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import type Database from 'better-sqlite3';
+import { initDb } from '../../src/db/schema.ts';
+import {
+  getLoginAttempt,
+  recordFailure,
+  resetLoginAttempts,
+} from '../../src/db/login-attempts.ts';
+
+describe('login-attempts db', () => {
+  let db: Database.Database;
+
+  beforeEach(() => {
+    db = initDb(':memory:');
+  });
+
+  it('returns undefined for an unknown username', () => {
+    expect(getLoginAttempt(db, 'ghost')).toBeUndefined();
+  });
+
+  it('inserts a row on first failure with count=1 and no lock', () => {
+    const row = recordFailure(db, 'alice', null);
+    expect(row.username).toBe('alice');
+    expect(row.failed_count).toBe(1);
+    expect(row.last_failed_at).toBeTruthy();
+    expect(row.locked_until).toBeNull();
+  });
+
+  it('increments failed_count on subsequent failures', () => {
+    recordFailure(db, 'alice', null);
+    recordFailure(db, 'alice', null);
+    const row = recordFailure(db, 'alice', null);
+    expect(row.failed_count).toBe(3);
+  });
+
+  it('persists locked_until when supplied', () => {
+    const lockedUntil = new Date(Date.now() + 30_000).toISOString();
+    const row = recordFailure(db, 'alice', lockedUntil);
+    expect(row.locked_until).toBe(lockedUntil);
+  });
+
+  it('updates locked_until on subsequent failures', () => {
+    recordFailure(db, 'alice', null);
+    const newLock = new Date(Date.now() + 60_000).toISOString();
+    const row = recordFailure(db, 'alice', newLock);
+    expect(row.failed_count).toBe(2);
+    expect(row.locked_until).toBe(newLock);
+  });
+
+  it('resetLoginAttempts deletes the row', () => {
+    recordFailure(db, 'alice', null);
+    resetLoginAttempts(db, 'alice');
+    expect(getLoginAttempt(db, 'alice')).toBeUndefined();
+  });
+
+  it('reset on a missing username is a no-op', () => {
+    expect(() => resetLoginAttempts(db, 'ghost')).not.toThrow();
+  });
+
+  it('tracks failures for non-existent users (no FK to users table)', () => {
+    const row = recordFailure(db, 'never-existed-user', null);
+    expect(row.failed_count).toBe(1);
+  });
+
+  it('getLoginAttempt returns the stored row', () => {
+    recordFailure(db, 'alice', null);
+    recordFailure(db, 'alice', null);
+    const row = getLoginAttempt(db, 'alice');
+    expect(row?.username).toBe('alice');
+    expect(row?.failed_count).toBe(2);
+  });
+});

tests/unit/login-handler.test.ts

@@ -0,0 +1,212 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { mkdtempSync, rmSync, readFileSync } from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
+import type Database from 'better-sqlite3';
+import { initDb } from '../../src/db/schema.ts';
+import { createUser } from '../../src/db/users.ts';
+import { hashPassword } from '../../src/services/auth.ts';
+import { createLogger } from '../../src/middleware/logging.ts';
+import { createLockoutService } from '../../src/services/lockout.ts';
+import { attemptLogin } from '../../src/services/login-handler.ts';
+import { _resetDummyHashForTests } from '../../src/services/dummy-hash.ts';
+import type { Config } from '../../src/config.ts';
+
+function makeConfig(overrides: Partial<Config> = {}): Config {
+  return {
+    port: 0,
+    host: '127.0.0.1',
+    jwtSecret: 'x',
+    jwtExpiry: '1h',
+    dbPath: ':memory:',
+    uploadDir: '/tmp',
+    logFile: '/tmp/x.log',
+    maxFileSize: 0,
+    baseUrl: '',
+    cookieSecure: false,
+    trustProxy: false,
+    lockoutThreshold: 2,
+    lockoutBaseSeconds: 60,
+    lockoutMaxSeconds: 600,
+    loginMinResponseMs: 50,
+    loginRateLimitMax: 0,
+    loginRateLimitWindowSeconds: 0,
+    ...overrides,
+  };
+}
+
+describe('login handler', () => {
+  let db: Database.Database;
+  let logDir: string;
+  let logFile: string;
+  let config: Config;
+
+  beforeEach(async () => {
+    _resetDummyHashForTests();
+    db = initDb(':memory:');
+    logDir = mkdtempSync(join(tmpdir(), 'nanodrop-handler-'));
+    logFile = join(logDir, 'test.log');
+    config = makeConfig({ logFile });
+    const passwordHash = await hashPassword('correct-pw');
+    createUser(db, { username: 'alice', passwordHash });
+    // Warm dummy hash so timing assertions don't include the first cold compute.
+    const { verifyAgainstDummy } = await import('../../src/services/dummy-hash.ts');
+    await verifyAgainstDummy('warmup');
+  });
+
+  function buildDeps() {
+    const logger = createLogger(logFile);
+    const lockout = createLockoutService({ db, config });
+    return { db, config, logger, lockout };
+  }
+
+  it('returns success for valid credentials and resets lockout', async () => {
+    const deps = buildDeps();
+    const result = await attemptLogin(deps, {
+      username: 'alice',
+      password: 'correct-pw',
+      ip: '1.1.1.1',
+      userAgent: 'ua',
+    });
+    expect(result.kind).toBe('success');
+    if (result.kind === 'success') {
+      expect(result.user.username).toBe('alice');
+    }
+    const log = readFileSync(logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_SUCCESS/);
+  });
+
+  it('returns bad_credentials and logs failure on wrong password', async () => {
+    const deps = buildDeps();
+    const result = await attemptLogin(deps, {
+      username: 'alice',
+      password: 'wrong',
+      ip: '1.1.1.1',
+      userAgent: 'ua',
+    });
+    expect(result.kind).toBe('bad_credentials');
+    const log = readFileSync(logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_FAILURE/);
+    expect(log).toMatch(/username="alice"/);
+  });
+
+  it('returns bad_credentials for unknown user (still runs bcrypt against dummy)', async () => {
+    const deps = buildDeps();
+    const start = Date.now();
+    const result = await attemptLogin(deps, {
+      username: 'ghost',
+      password: 'whatever',
+      ip: '1.1.1.1',
+      userAgent: 'ua',
+    });
+    const elapsed = Date.now() - start;
+    expect(result.kind).toBe('bad_credentials');
+    // Must spend bcrypt-comparable time even for unknown user.
+    expect(elapsed).toBeGreaterThan(20);
+    const log = readFileSync(logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_FAILURE/);
+    expect(log).toMatch(/username="ghost"/);
+  }, 10_000);
+
+  it('canonicalizes username (lowercase + trim) before lookup and lockout', async () => {
+    const deps = buildDeps();
+    const result = await attemptLogin(deps, {
+      username: '  ALICE  ',
+      password: 'correct-pw',
+      ip: '1.1.1.1',
+      userAgent: 'ua',
+    });
+    expect(result.kind).toBe('success');
+  });
+
+  it('returns bad_request when username or password is empty', async () => {
+    const deps = buildDeps();
+    const r1 = await attemptLogin(deps, { username: '', password: 'x', ip: '1', userAgent: 'ua' });
+    expect(r1.kind).toBe('bad_request');
+    const r2 = await attemptLogin(deps, { username: 'alice', password: '', ip: '1', userAgent: 'ua' });
+    expect(r2.kind).toBe('bad_request');
+  });
+
+  it('triggers lockout at threshold and logs AUTH_LOCKOUT_TRIGGERED', async () => {
+    const deps = buildDeps();
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1.1.1.1', userAgent: 'ua' });
+    const second = await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1.1.1.1', userAgent: 'ua' });
+    expect(second.kind).toBe('bad_credentials');
+    const log = readFileSync(logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_LOCKOUT_TRIGGERED/);
+    expect(log).toMatch(/duration_seconds=60/);
+  });
+
+  it('returns locked + retry-after on subsequent attempt; correct password still rejected', async () => {
+    const deps = buildDeps();
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1.1.1.1', userAgent: 'ua' });
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1.1.1.1', userAgent: 'ua' });
+
+    const blocked = await attemptLogin(deps, {
+      username: 'alice',
+      password: 'correct-pw',
+      ip: '1.1.1.1',
+      userAgent: 'ua',
+    });
+    expect(blocked.kind).toBe('locked');
+    if (blocked.kind === 'locked') {
+      expect(blocked.retryAfterSeconds).toBeGreaterThan(0);
+      expect(blocked.retryAfterSeconds).toBeLessThanOrEqual(60);
+    }
+
+    const log = readFileSync(logFile, 'utf-8');
+    expect(log).toMatch(/AUTH_LOCKED_ATTEMPT/);
+    // Even though password was correct, no AUTH_SUCCESS for this attempt.
+    const successCount = (log.match(/AUTH_SUCCESS/g) ?? []).length;
+    expect(successCount).toBe(0);
+  });
+
+  it('does NOT call bcrypt when account is locked (short-circuits)', async () => {
+    const deps = buildDeps();
+    // Lock the account.
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1', userAgent: 'ua' });
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1', userAgent: 'ua' });
+
+    // Locked attempt with constant-time clamp at 50ms — should be roughly clamp duration,
+    // not bcrypt time (250ms+).
+    const start = Date.now();
+    await attemptLogin(deps, { username: 'alice', password: 'correct-pw', ip: '1', userAgent: 'ua' });
+    const elapsed = Date.now() - start;
+    // Clamp is 50ms; allow generous slack but assert well under bcrypt cost.
+    expect(elapsed).toBeLessThan(150);
+  });
+
+  it('respects loginMinResponseMs clamp on bad_credentials', async () => {
+    config = makeConfig({ logFile, loginMinResponseMs: 200 });
+    const deps = buildDeps();
+    const start = Date.now();
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1', userAgent: 'ua' });
+    const elapsed = Date.now() - start;
+    expect(elapsed).toBeGreaterThanOrEqual(190);
+  }, 10_000);
+
+  it('successful login between failures resets the counter', async () => {
+    const deps = buildDeps();
+    await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1', userAgent: 'ua' });
+    await attemptLogin(deps, { username: 'alice', password: 'correct-pw', ip: '1', userAgent: 'ua' });
+    const r = await attemptLogin(deps, { username: 'alice', password: 'wrong', ip: '1', userAgent: 'ua' });
+    // After reset, this is failure #1 — well under threshold of 2, so no lock yet.
+    expect(r.kind).toBe('bad_credentials');
+    // No AUTH_LOCKOUT_TRIGGERED in log.
+    const log = readFileSync(logFile, 'utf-8');
+    expect(log).not.toMatch(/AUTH_LOCKOUT_TRIGGERED/);
+  });
+
+  it('unknown username also accumulates lockout', async () => {
+    const deps = buildDeps();
+    await attemptLogin(deps, { username: 'ghost', password: 'x', ip: '1', userAgent: 'ua' });
+    await attemptLogin(deps, { username: 'ghost', password: 'x', ip: '1', userAgent: 'ua' });
+    const r = await attemptLogin(deps, { username: 'ghost', password: 'x', ip: '1', userAgent: 'ua' });
+    expect(r.kind).toBe('locked');
+  }, 10_000);
+
+  // Cleanup
+  beforeEach(() => {
+    return () => rmSync(logDir, { recursive: true, force: true });
+  });
+});