feat: log LLM metadata to question_cache_meta

Made-with: Cursor

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "samreshu_docs"]
+	path = samreshu_docs
+	url = https://git.vakanaut.ru/admin/samreshu_docs.git

src/app.ts

@@ -4,6 +4,10 @@ import databasePlugin from './plugins/database.js';
 import redisPlugin from './plugins/redis.js';
 import securityPlugin from './plugins/security.js';
 import rateLimitPlugin from './plugins/rateLimit.js';
+import authPlugin from './plugins/auth.js';
+import subscriptionPlugin from './plugins/subscription.js';
+import { authRoutes } from './routes/auth.js';
+import { profileRoutes } from './routes/profile.js';
 import { env } from './config/env.js';
 import { randomUUID } from 'node:crypto';
 
@@ -69,6 +73,10 @@ export async function buildApp(): Promise<FastifyInstance> {
   await app.register(databasePlugin);
   await app.register(securityPlugin);
   await app.register(rateLimitPlugin);
+  await app.register(authPlugin);
+  await app.register(subscriptionPlugin);
+  await app.register(authRoutes, { prefix: '/auth' });
+  await app.register(profileRoutes, { prefix: '/profile' });
 
   app.get('/health', async () => ({ status: 'ok', timestamp: new Date().toISOString() }));
 

src/config/env.ts

@@ -14,9 +14,11 @@ const envSchema = z.object({
 
   LLM_BASE_URL: z.string().url().default('http://localhost:11434/v1'),
   LLM_MODEL: z.string().default('qwen2.5:14b'),
+  LLM_FALLBACK_MODEL: z.string().optional(),
   LLM_API_KEY: z.string().optional(),
   LLM_TIMEOUT_MS: z.coerce.number().default(15000),
   LLM_MAX_RETRIES: z.coerce.number().min(0).default(1),
+  LLM_RETRY_DELAY_MS: z.coerce.number().min(0).default(1000),
   LLM_TEMPERATURE: z.coerce.number().min(0).max(2).default(0.7),
   LLM_MAX_TOKENS: z.coerce.number().default(2048),
 

src/plugins/auth.ts

@@ -0,0 +1,42 @@
+import type { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify';
+import fp from 'fastify-plugin';
+import { verifyToken, isAccessPayload } from '../utils/jwt.js';
+import { unauthorized } from '../utils/errors.js';
+
+declare module 'fastify' {
+  interface FastifyInstance {
+    authenticate: (req: FastifyRequest, reply: FastifyReply) => Promise<void>;
+  }
+  interface FastifyRequest {
+    user?: { id: string; email: string };
+  }
+}
+
+export async function authenticate(req: FastifyRequest, _reply: FastifyReply): Promise<void> {
+  const authHeader = req.headers.authorization;
+
+  if (!authHeader?.startsWith('Bearer ')) {
+    throw unauthorized('Missing or invalid authorization header');
+  }
+
+  const token = authHeader.slice(7);
+
+  try {
+    const payload = await verifyToken(token);
+
+    if (!isAccessPayload(payload)) {
+      throw unauthorized('Invalid token type');
+    }
+
+    req.user = { id: payload.sub, email: payload.email };
+  } catch {
+    throw unauthorized('Invalid or expired token');
+  }
+}
+
+const authPlugin = async (app: FastifyInstance) => {
+  app.decorateRequest('user', undefined);
+  app.decorate('authenticate', authenticate);
+};
+
+export default fp(authPlugin, { name: 'auth' });

src/plugins/rateLimit.ts

@@ -29,6 +29,7 @@ const rateLimitPlugin: FastifyPluginAsync = async (app: FastifyInstance) => {
   app.decorate('rateLimitOptions', options);
 
   await app.register(rateLimit, {
+    global: false,
     max: options.apiGuest.max,
     timeWindow: options.apiGuest.timeWindow,
     keyGenerator: (req) => {

src/plugins/subscription.ts

@@ -0,0 +1,71 @@
+import type { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify';
+import fp from 'fastify-plugin';
+import { eq } from 'drizzle-orm';
+import { subscriptions } from '../db/schema/subscriptions.js';
+import { forbidden } from '../utils/errors.js';
+
+export type SubscriptionInfo = {
+  plan: 'free' | 'pro';
+  status: 'active' | 'trialing' | 'cancelled' | 'expired';
+  isPro: boolean;
+  expiresAt: Date | null;
+};
+
+declare module 'fastify' {
+  interface FastifyRequest {
+    subscription?: SubscriptionInfo | null;
+  }
+  interface FastifyInstance {
+    withSubscription: (req: FastifyRequest, reply: FastifyReply) => Promise<void>;
+    requirePro: (req: FastifyRequest, reply: FastifyReply) => Promise<void>;
+  }
+}
+
+async function loadSubscription(db: FastifyInstance['db'], userId: string): Promise<SubscriptionInfo | null> {
+  const [sub] = await db
+    .select()
+    .from(subscriptions)
+    .where(eq(subscriptions.userId, userId))
+    .limit(1);
+
+  if (!sub) return null;
+
+  const now = new Date();
+  const isExpired = sub.expiresAt && sub.expiresAt < now;
+  const isPro =
+    sub.plan === 'pro' &&
+    (sub.status === 'active' || sub.status === 'trialing') &&
+    !isExpired;
+
+  return {
+    plan: sub.plan as 'free' | 'pro',
+    status: sub.status as SubscriptionInfo['status'],
+    isPro,
+    expiresAt: sub.expiresAt,
+  };
+}
+
+export async function requirePro(req: FastifyRequest, _reply: FastifyReply): Promise<void> {
+  const sub = req.subscription;
+
+  if (!sub?.isPro) {
+    throw forbidden('Pro subscription required');
+  }
+}
+
+const subscriptionPlugin = async (app: FastifyInstance) => {
+  app.decorateRequest('subscription', undefined);
+
+  app.decorate('withSubscription', async (req: FastifyRequest, _reply: FastifyReply) => {
+    if (!req.user?.id) return;
+    const sub = await loadSubscription(app.db, req.user.id);
+    req.subscription = sub;
+  });
+
+  app.decorate('requirePro', requirePro);
+};
+
+export default fp(subscriptionPlugin, {
+  name: 'subscription',
+  dependencies: ['database', 'auth'],
+});

src/routes/auth.ts

@@ -0,0 +1,168 @@
+import type { FastifyInstance } from 'fastify';
+import { AuthService } from '../services/auth/auth.service.js';
+
+const registerSchema = {
+  body: {
+    type: 'object',
+    required: ['email', 'password', 'nickname'],
+    properties: {
+      email: { type: 'string', minLength: 1 },
+      password: { type: 'string', minLength: 8 },
+      nickname: { type: 'string', minLength: 2, maxLength: 30 },
+    },
+  },
+};
+
+const loginSchema = {
+  body: {
+    type: 'object',
+    required: ['email', 'password'],
+    properties: {
+      email: { type: 'string', minLength: 1 },
+      password: { type: 'string' },
+    },
+  },
+};
+
+const refreshTokenSchema = {
+  body: {
+    type: 'object',
+    required: ['refreshToken'],
+    properties: {
+      refreshToken: { type: 'string' },
+    },
+  },
+};
+
+const logoutSchema = refreshTokenSchema;
+
+const verifyEmailSchema = {
+  body: {
+    type: 'object',
+    required: ['userId', 'code'],
+    properties: {
+      userId: { type: 'string', minLength: 1 },
+      code: { type: 'string', minLength: 1, maxLength: 10 },
+    },
+  },
+};
+
+const forgotPasswordSchema = {
+  body: {
+    type: 'object',
+    required: ['email'],
+    properties: {
+      email: { type: 'string', minLength: 1 },
+    },
+  },
+};
+
+const resetPasswordSchema = {
+  body: {
+    type: 'object',
+    required: ['token', 'newPassword'],
+    properties: {
+      token: { type: 'string' },
+      newPassword: { type: 'string', minLength: 8 },
+    },
+  },
+};
+
+export async function authRoutes(app: FastifyInstance) {
+  const authService = new AuthService(app.db);
+  const { rateLimitOptions } = app;
+
+  app.post(
+    '/register',
+    { schema: registerSchema, config: { rateLimit: rateLimitOptions.register } },
+    async (req, reply) => {
+      const body = req.body as { email: string; password: string; nickname: string };
+      const { userId, verificationCode } = await authService.register(body);
+
+      return reply.status(201).send({
+        userId,
+        message: 'Registration successful. Please verify your email.',
+        verificationCode,
+      });
+    },
+  );
+
+  app.post(
+    '/login',
+    { schema: loginSchema, config: { rateLimit: rateLimitOptions.login } },
+    async (req, reply) => {
+      const body = req.body as { email: string; password: string };
+      const userAgent = req.headers['user-agent'];
+      const ipAddress = req.ip;
+
+      const result = await authService.login({
+        email: body.email,
+        password: body.password,
+        userAgent,
+        ipAddress,
+      });
+
+      return reply.send(result);
+    },
+  );
+
+  app.post(
+    '/logout',
+    { schema: logoutSchema, config: { rateLimit: rateLimitOptions.apiGuest } },
+    async (req, reply) => {
+      const body = req.body as { refreshToken: string };
+      await authService.logout(body.refreshToken);
+      return reply.status(204).send();
+    },
+  );
+
+  app.post(
+    '/refresh',
+    { schema: refreshTokenSchema, config: { rateLimit: rateLimitOptions.apiGuest } },
+    async (req, reply) => {
+      const body = req.body as { refreshToken: string };
+      const userAgent = req.headers['user-agent'];
+      const ipAddress = req.ip;
+
+      const result = await authService.refresh({
+        refreshToken: body.refreshToken,
+        userAgent,
+        ipAddress,
+      });
+
+      return reply.send(result);
+    },
+  );
+
+  app.post(
+    '/verify-email',
+    { schema: verifyEmailSchema, config: { rateLimit: rateLimitOptions.verifyEmail } },
+    async (req, reply) => {
+      const body = req.body as { userId: string; code: string };
+      await authService.verifyEmail(body.userId, body.code);
+      return reply.send({ message: 'Email verified successfully' });
+    },
+  );
+
+  app.post(
+    '/forgot-password',
+    { schema: forgotPasswordSchema, config: { rateLimit: rateLimitOptions.forgotPassword } },
+    async (req, reply) => {
+      const body = req.body as { email: string };
+      await authService.forgotPassword(body.email);
+      return reply.send({
+        message: 'If the email exists, a reset link has been sent.',
+      });
+    },
+  );
+
+  app.post(
+    '/reset-password',
+    { schema: resetPasswordSchema, config: { rateLimit: rateLimitOptions.forgotPassword } },
+    async (req, reply) => {
+      const body = req.body as { token: string; newPassword: string };
+      await authService.resetPassword(body.token, body.newPassword);
+      return reply.send({ message: 'Password reset successfully' });
+    },
+  );
+}

src/routes/profile.ts

@@ -0,0 +1,73 @@
+import type { FastifyInstance } from 'fastify';
+import { UserService } from '../services/user/user.service.js';
+
+const patchProfileSchema = {
+  body: {
+    type: 'object',
+    properties: {
+      nickname: { type: 'string', minLength: 2, maxLength: 30 },
+      avatarUrl: { type: ['string', 'null'], maxLength: 500 },
+      country: { type: ['string', 'null'], maxLength: 100 },
+      city: { type: ['string', 'null'], maxLength: 100 },
+      selfLevel: { type: ['string', 'null'], enum: ['jun', 'mid', 'sen'] },
+      isPublic: { type: 'boolean' },
+    },
+    additionalProperties: false,
+  },
+};
+
+const usernameParamsSchema = {
+  params: {
+    type: 'object',
+    required: ['username'],
+    properties: {
+      username: { type: 'string', minLength: 2, maxLength: 30 },
+    },
+  },
+};
+
+export async function profileRoutes(app: FastifyInstance) {
+  const userService = new UserService(app.db);
+  const { rateLimitOptions } = app;
+
+  app.get(
+    '/',
+    {
+      config: { rateLimit: rateLimitOptions.apiAuthed },
+      preHandler: [app.authenticate, app.withSubscription],
+    },
+    async (req, reply) => {
+      const userId = req.user!.id;
+      const profile = await userService.getPrivateProfile(userId);
+      return reply.send(profile);
+    },
+  );
+
+  app.patch(
+    '/',
+    {
+      schema: patchProfileSchema,
+      config: { rateLimit: rateLimitOptions.apiAuthed },
+      preHandler: [app.authenticate],
+    },
+    async (req, reply) => {
+      const userId = req.user!.id;
+      const body = req.body as Parameters<UserService['updateProfile']>[1];
+      const profile = await userService.updateProfile(userId, body);
+      return reply.send(profile);
+    },
+  );
+
+  app.get(
+    '/:username',
+    {
+      schema: usernameParamsSchema,
+      config: { rateLimit: rateLimitOptions.apiGuest },
+    },
+    async (req, reply) => {
+      const { username } = req.params as { username: string };
+      const profile = await userService.getPublicProfile(username);
+      return reply.send(profile);
+    },
+  );
+}

src/services/auth/auth.service.ts

@@ -0,0 +1,304 @@
+import { eq, and, gt } from 'drizzle-orm';
+import type { NodePgDatabase } from 'drizzle-orm/node-postgres';
+import type * as schema from '../../db/schema/index.js';
+import { users, sessions, emailVerificationCodes, passwordResetTokens } from '../../db/schema/index.js';
+import { hashPassword, verifyPassword } from '../../utils/password.js';
+import {
+  signAccessToken,
+  signRefreshToken,
+  verifyToken,
+  isRefreshPayload,
+  hashToken,
+} from '../../utils/jwt.js';
+import {
+  AppError,
+  conflict,
+  unauthorized,
+  notFound,
+  ERROR_CODES,
+} from '../../utils/errors.js';
+import { randomBytes, randomUUID } from 'node:crypto';
+
+type Db = NodePgDatabase<typeof schema>;
+
+export interface RegisterInput {
+  email: string;
+  password: string;
+  nickname: string;
+}
+
+export interface LoginInput {
+  email: string;
+  password: string;
+  userAgent?: string;
+  ipAddress?: string;
+}
+
+export interface LoginResult {
+  accessToken: string;
+  refreshToken: string;
+  expiresIn: number;
+}
+
+export interface RefreshInput {
+  refreshToken: string;
+  userAgent?: string;
+  ipAddress?: string;
+}
+
+export interface ForgotPasswordResult {
+  token: string;
+  expiresAt: Date;
+}
+
+const REFRESH_TTL_MS = 7 * 24 * 60 * 60 * 1000;
+const VERIFICATION_CODE_LENGTH = 6;
+const VERIFICATION_CODE_TTL_MS = 15 * 60 * 1000;
+const RESET_TOKEN_TTL_MS = 60 * 60 * 1000;
+
+export class AuthService {
+  constructor(private readonly db: Db) {}
+
+  async register(input: RegisterInput): Promise<{ userId: string; verificationCode: string }> {
+    const [existing] = await this.db
+      .select()
+      .from(users)
+      .where(eq(users.email, input.email.toLowerCase().trim()))
+      .limit(1);
+
+    if (existing) {
+      throw conflict(ERROR_CODES.EMAIL_TAKEN, 'Email already registered');
+    }
+
+    const [nicknameConflict] = await this.db
+      .select()
+      .from(users)
+      .where(eq(users.nickname, input.nickname.trim()))
+      .limit(1);
+
+    if (nicknameConflict) {
+      throw conflict(ERROR_CODES.NICKNAME_TAKEN, 'Nickname already taken');
+    }
+
+    const passwordHash = await hashPassword(input.password);
+
+    const [user] = await this.db
+      .insert(users)
+      .values({
+        email: input.email.toLowerCase().trim(),
+        passwordHash,
+        nickname: input.nickname.trim(),
+      })
+      .returning({ id: users.id });
+
+    if (!user) {
+      throw new AppError(ERROR_CODES.INTERNAL_ERROR, 'Failed to create user', 500);
+    }
+
+    const code = randomBytes(VERIFICATION_CODE_LENGTH)
+      .toString('hex')
+      .slice(0, VERIFICATION_CODE_LENGTH)
+      .toUpperCase();
+    const expiresAt = new Date(Date.now() + VERIFICATION_CODE_TTL_MS);
+
+    await this.db.insert(emailVerificationCodes).values({
+      userId: user.id,
+      code,
+      expiresAt,
+    });
+
+    return { userId: user.id, verificationCode: code };
+  }
+
+  async login(input: LoginInput): Promise<LoginResult> {
+    const [user] = await this.db
+      .select()
+      .from(users)
+      .where(eq(users.email, input.email.toLowerCase().trim()))
+      .limit(1);
+
+    if (!user || !(await verifyPassword(user.passwordHash, input.password))) {
+      throw unauthorized('Invalid email or password');
+    }
+
+    const [accessToken, refreshToken] = await Promise.all([
+      signAccessToken({ sub: user.id, email: user.email }),
+      signRefreshToken({ sub: user.id, sid: randomUUID() }),
+    ]);
+
+    const refreshHash = hashToken(refreshToken);
+    const expiresAt = new Date(Date.now() + REFRESH_TTL_MS);
+
+    await this.db.insert(sessions).values({
+      userId: user.id,
+      refreshTokenHash: refreshHash,
+      userAgent: input.userAgent ?? null,
+      ipAddress: input.ipAddress ?? null,
+      expiresAt,
+    });
+
+    return {
+      accessToken,
+      refreshToken,
+      expiresIn: Math.floor(REFRESH_TTL_MS / 1000),
+    };
+  }
+
+  async logout(refreshToken: string): Promise<void> {
+    const hash = hashToken(refreshToken);
+    await this.db.delete(sessions).where(eq(sessions.refreshTokenHash, hash));
+  }
+
+  async refresh(input: RefreshInput): Promise<LoginResult> {
+    const payload = await verifyToken(input.refreshToken);
+
+    if (!isRefreshPayload(payload)) {
+      throw unauthorized('Invalid refresh token');
+    }
+
+    const hash = hashToken(input.refreshToken);
+
+    const [session] = await this.db
+      .select()
+      .from(sessions)
+      .where(and(eq(sessions.refreshTokenHash, hash), gt(sessions.expiresAt, new Date())))
+      .limit(1);
+
+    if (!session) {
+      throw new AppError(ERROR_CODES.INVALID_REFRESH_TOKEN, 'Invalid or expired refresh token', 401);
+    }
+
+    await this.db.delete(sessions).where(eq(sessions.id, session.id));
+
+    const [user] = await this.db.select().from(users).where(eq(users.id, session.userId)).limit(1);
+
+    if (!user) {
+      throw notFound('User not found');
+    }
+
+    const [accessToken, newRefreshToken] = await Promise.all([
+      signAccessToken({ sub: user.id, email: user.email }),
+      signRefreshToken({ sub: user.id, sid: randomUUID() }),
+    ]);
+
+    const newHash = hashToken(newRefreshToken);
+    const expiresAt = new Date(Date.now() + REFRESH_TTL_MS);
+
+    await this.db.insert(sessions).values({
+      userId: user.id,
+      refreshTokenHash: newHash,
+      userAgent: input.userAgent ?? session.userAgent,
+      ipAddress: input.ipAddress ?? session.ipAddress,
+      expiresAt,
+    });
+
+    return {
+      accessToken,
+      refreshToken: newRefreshToken,
+      expiresIn: Math.floor(REFRESH_TTL_MS / 1000),
+    };
+  }
+
+  async verifyEmail(userId: string, verificationCode: string): Promise<void> {
+    const codeUpper = verificationCode.toUpperCase();
+    const [record] = await this.db
+      .select()
+      .from(emailVerificationCodes)
+      .where(
+        and(
+          eq(emailVerificationCodes.userId, userId),
+          eq(emailVerificationCodes.code, codeUpper),
+        ),
+      )
+      .limit(1);
+
+    if (!record) {
+      throw new AppError(ERROR_CODES.INVALID_CODE, 'Invalid or expired verification code', 400);
+    }
+
+    if (record.expiresAt < new Date()) {
+      await this.db
+        .delete(emailVerificationCodes)
+        .where(eq(emailVerificationCodes.id, record.id));
+      throw new AppError(ERROR_CODES.INVALID_CODE, 'Verification code expired', 400);
+    }
+
+    const [user] = await this.db.select().from(users).where(eq(users.id, userId)).limit(1);
+
+    if (!user) {
+      throw notFound('User not found');
+    }
+
+    if (user.emailVerifiedAt) {
+      throw new AppError(ERROR_CODES.ALREADY_VERIFIED, 'Email already verified', 400);
+    }
+
+    await this.db
+      .update(users)
+      .set({ emailVerifiedAt: new Date(), updatedAt: new Date() })
+      .where(eq(users.id, userId));
+
+    await this.db
+      .delete(emailVerificationCodes)
+      .where(eq(emailVerificationCodes.userId, userId));
+  }
+
+  async forgotPassword(email: string): Promise<ForgotPasswordResult> {
+    const [user] = await this.db
+      .select()
+      .from(users)
+      .where(eq(users.email, email.toLowerCase().trim()))
+      .limit(1);
+
+    if (!user) {
+      return {
+        token: '',
+        expiresAt: new Date(Date.now() + RESET_TOKEN_TTL_MS),
+      };
+    }
+
+    const token = randomBytes(32).toString('hex');
+    const tokenHash = hashToken(token);
+    const expiresAt = new Date(Date.now() + RESET_TOKEN_TTL_MS);
+
+    await this.db.insert(passwordResetTokens).values({
+      userId: user.id,
+      tokenHash,
+      expiresAt,
+    });
+
+    return { token, expiresAt };
+  }
+
+  async resetPassword(token: string, newPassword: string): Promise<void> {
+    const tokenHash = hashToken(token);
+
+    const [record] = await this.db
+      .select()
+      .from(passwordResetTokens)
+      .where(eq(passwordResetTokens.tokenHash, tokenHash))
+      .limit(1);
+
+    if (!record) {
+      throw new AppError(ERROR_CODES.INVALID_RESET_TOKEN, 'Invalid or expired reset token', 400);
+    }
+
+    if (record.expiresAt < new Date()) {
+      await this.db
+        .delete(passwordResetTokens)
+        .where(eq(passwordResetTokens.id, record.id));
+      throw new AppError(ERROR_CODES.INVALID_RESET_TOKEN, 'Reset token expired', 400);
+    }
+
+    const passwordHash = await hashPassword(newPassword);
+
+    await this.db
+      .update(users)
+      .set({ passwordHash, updatedAt: new Date() })
+      .where(eq(users.id, record.userId));
+
+    await this.db
+      .delete(passwordResetTokens)
+      .where(eq(passwordResetTokens.id, record.id));
+  }
+}

src/services/llm/llm.service.ts

@@ -0,0 +1,237 @@
+import { z } from 'zod';
+import { createHash } from 'node:crypto';
+import { env } from '../../config/env.js';
+import type { Stack, Level, QuestionType } from '../../db/schema/enums.js';
+
+export interface LlmConfig {
+  baseUrl: string;
+  model: string;
+  fallbackModel?: string;
+  apiKey?: string;
+  timeoutMs: number;
+  temperature: number;
+  maxTokens: number;
+  maxRetries: number;
+  retryDelayMs: number;
+}
+
+export interface ChatMessage {
+  role: 'system' | 'user' | 'assistant';
+  content: string;
+}
+
+export interface ChatCompletionResponse {
+  choices: Array<{
+    message?: { content: string };
+    text?: string;
+  }>;
+}
+
+const QUESTION_TYPES: QuestionType[] = ['single_choice', 'multiple_select', 'true_false', 'short_text'];
+
+const optionSchema = z.object({
+  key: z.string().min(1),
+  text: z.string().min(1),
+});
+
+const generatedQuestionSchema = z.object({
+  questionText: z.string().min(1),
+  type: z.enum(QUESTION_TYPES as [string, ...string[]]),
+  options: z.array(optionSchema).optional(),
+  correctAnswer: z.union([z.string(), z.array(z.string())]),
+  explanation: z.string().min(1),
+});
+
+const generateQuestionsResponseSchema = z.object({
+  questions: z.array(generatedQuestionSchema),
+});
+
+export type GeneratedQuestion = z.infer<typeof generatedQuestionSchema> & {
+  stack: Stack;
+  level: Level;
+};
+
+export interface GenerateQuestionsInput {
+  stack: Stack;
+  level: Level;
+  count: number;
+  types?: QuestionType[];
+}
+
+/** Metadata for persisting to question_cache_meta (used by QuestionService) */
+export interface LlmGenerationMeta {
+  llmModel: string;
+  promptHash: string;
+  generationTimeMs: number;
+  rawResponse: unknown;
+}
+
+export interface GenerateQuestionsResult {
+  questions: GeneratedQuestion[];
+  meta: LlmGenerationMeta;
+}
+
+export class LlmService {
+  private readonly config: LlmConfig;
+
+  constructor(config?: Partial<LlmConfig>) {
+    this.config = {
+      baseUrl: config?.baseUrl ?? env.LLM_BASE_URL,
+      model: config?.model ?? env.LLM_MODEL,
+      fallbackModel: config?.fallbackModel ?? env.LLM_FALLBACK_MODEL,
+      apiKey: config?.apiKey ?? env.LLM_API_KEY,
+      timeoutMs: config?.timeoutMs ?? env.LLM_TIMEOUT_MS,
+      temperature: config?.temperature ?? env.LLM_TEMPERATURE,
+      maxTokens: config?.maxTokens ?? env.LLM_MAX_TOKENS,
+      maxRetries: config?.maxRetries ?? env.LLM_MAX_RETRIES,
+      retryDelayMs: config?.retryDelayMs ?? env.LLM_RETRY_DELAY_MS,
+    };
+  }
+
+  async chat(messages: ChatMessage[]): Promise<string> {
+    const { content } = await this.chatWithMeta(messages);
+    return content;
+  }
+
+  /** Returns content and model used (for logging to question_cache_meta) */
+  async chatWithMeta(messages: ChatMessage[]): Promise<{ content: string; model: string }> {
+    let lastError: Error | null = null;
+
+    const modelsToTry = [this.config.model];
+    if (this.config.fallbackModel) {
+      modelsToTry.push(this.config.fallbackModel);
+    }
+
+    for (const model of modelsToTry) {
+      for (let attempt = 0; attempt <= this.config.maxRetries; attempt++) {
+        try {
+          const content = await this.executeChat(messages, model);
+          return { content, model };
+        } catch (err) {
+          lastError = err instanceof Error ? err : new Error('LLM request failed');
+          if (attempt < this.config.maxRetries) {
+            const delayMs = this.config.retryDelayMs * Math.pow(2, attempt);
+            await sleep(delayMs);
+          }
+        }
+      }
+    }
+
+    throw lastError ?? new Error('LLM request failed');
+  }
+
+  private async executeChat(messages: ChatMessage[], model: string): Promise<string> {
+    const url = `${this.config.baseUrl.replace(/\/$/, '')}/chat/completions`;
+
+    const headers: Record<string, string> = {
+      'Content-Type': 'application/json',
+    };
+    if (this.config.apiKey) {
+      headers['Authorization'] = `Bearer ${this.config.apiKey}`;
+    }
+
+    const body = {
+      model,
+      messages: messages.map((m) => ({ role: m.role, content: m.content })),
+      temperature: this.config.temperature,
+      max_tokens: this.config.maxTokens,
+    };
+
+    const controller = new AbortController();
+    const timeoutId = setTimeout(() => controller.abort(), this.config.timeoutMs);
+
+    try {
+      const res = await fetch(url, {
+        method: 'POST',
+        headers,
+        body: JSON.stringify(body),
+        signal: controller.signal,
+      });
+
+      clearTimeout(timeoutId);
+
+      if (!res.ok) {
+        const text = await res.text();
+        throw new Error(`LLM request failed: ${res.status} ${res.statusText} - ${text}`);
+      }
+
+      const data = (await res.json()) as ChatCompletionResponse;
+
+      const choice = data.choices?.[0];
+      const content = choice?.message?.content ?? choice?.text ?? '';
+
+      return content.trim();
+    } catch (err) {
+      clearTimeout(timeoutId);
+      if (err instanceof Error) {
+        throw err;
+      }
+      throw new Error('LLM request failed');
+    }
+  }
+
+  async generateQuestions(input: GenerateQuestionsInput): Promise<GenerateQuestionsResult> {
+    const { stack, level, count, types = QUESTION_TYPES } = input;
+
+    const typeList = types.join(', ');
+    const systemPrompt = `You are a technical interview question generator. Generate exactly ${count} programming/tech questions.
+Return ONLY valid JSON in this exact format (no markdown, no code blocks):
+{"questions":[{"questionText":"...","type":"single_choice|multiple_select|true_false|short_text","options":[{"key":"a","text":"..."}],"correctAnswer":"a" or ["a","b"],"explanation":"..."}]}
+Rules: type must be one of: ${typeList}. For single_choice/multiple_select: options array required with key (a,b,c,d). For true_false: options [{"key":"true","text":"True"},{"key":"false","text":"False"}]. For short_text: options omitted, correctAnswer is string.`;
+
+    const userPrompt = `Generate ${count} questions for stack="${stack}", level="${level}". Use types: ${typeList}.`;
+
+    const promptForHash = systemPrompt + '\n---\n' + userPrompt;
+    const promptHash = createHash('sha256').update(promptForHash).digest('hex');
+
+    const start = Date.now();
+    const { content: raw, model } = await this.chatWithMeta([
+      { role: 'system', content: systemPrompt },
+      { role: 'user', content: userPrompt },
+    ]);
+    const generationTimeMs = Date.now() - start;
+
+    const jsonStr = extractJson(raw);
+    const parsed = JSON.parse(jsonStr) as unknown;
+
+    const result = generateQuestionsResponseSchema.safeParse(parsed);
+    if (!result.success) {
+      throw new Error(`LLM response validation failed: ${result.error.message}`);
+    }
+
+    const questions: GeneratedQuestion[] = result.data.questions.map((q) => ({
+      ...q,
+      stack,
+      level,
+    }));
+
+    for (const q of questions) {
+      if ((q.type === 'single_choice' || q.type === 'multiple_select') && (!q.options || q.options.length === 0)) {
+        throw new Error(`Question validation failed: ${q.type} requires options`);
+      }
+      if (q.type === 'true_false' && (!q.options || q.options.length < 2)) {
+        throw new Error(`Question validation failed: true_false requires true/false options`);
+      }
+    }
+
+    return {
+      questions,
+      meta: {
+        llmModel: model,
+        promptHash,
+        generationTimeMs,
+        rawResponse: parsed,
+      },
+    };
+  }
+}
+
+function sleep(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+function extractJson(text: string): string {
+  const trimmed = text.trim();
+  const match = trimmed.match(/\{[\s\S]*\}/);
+  return match ? match[0]! : trimmed;
+}

src/services/user/user.service.ts

@@ -0,0 +1,175 @@
+import { eq } from 'drizzle-orm';
+import type { NodePgDatabase } from 'drizzle-orm/node-postgres';
+import type * as schema from '../../db/schema/index.js';
+import { users, userStats } from '../../db/schema/index.js';
+import { notFound, conflict, ERROR_CODES } from '../../utils/errors.js';
+import type { User } from '../../db/schema/users.js';
+import type { SelfLevel } from '../../db/schema/index.js';
+
+type Db = NodePgDatabase<typeof schema>;
+
+export type UserStatItem = {
+  stack: string;
+  level: string;
+  totalQuestions: number;
+  correctAnswers: number;
+  testsTaken: number;
+  lastTestAt: string | null;
+};
+
+export type ProfileStats = {
+  byStack: UserStatItem[];
+  totalTestsTaken: number;
+  totalQuestions: number;
+  correctAnswers: number;
+  accuracy: number | null;
+};
+
+export type ProfileUpdateInput = {
+  nickname?: string;
+  avatarUrl?: string | null;
+  country?: string | null;
+  city?: string | null;
+  selfLevel?: SelfLevel | null;
+  isPublic?: boolean;
+};
+
+export type PublicProfile = {
+  id: string;
+  nickname: string;
+  avatarUrl: string | null;
+  country: string | null;
+  city: string | null;
+  selfLevel: string | null;
+  isPublic: boolean;
+  stats: ProfileStats;
+};
+
+export type PrivateProfile = PublicProfile & {
+  email: string;
+  emailVerifiedAt: string | null;
+  createdAt: string;
+  updatedAt: string;
+};
+
+async function getStatsForUser(db: Db, userId: string): Promise<ProfileStats> {
+  const rows = await db
+    .select()
+    .from(userStats)
+    .where(eq(userStats.userId, userId));
+
+  const byStack: UserStatItem[] = rows.map((r) => ({
+    stack: r.stack,
+    level: r.level,
+    totalQuestions: r.totalQuestions,
+    correctAnswers: r.correctAnswers,
+    testsTaken: r.testsTaken,
+    lastTestAt: r.lastTestAt?.toISOString() ?? null,
+  }));
+
+  const totalTestsTaken = rows.reduce((sum, r) => sum + r.testsTaken, 0);
+  const totalQuestions = rows.reduce((sum, r) => sum + r.totalQuestions, 0);
+  const correctAnswers = rows.reduce((sum, r) => sum + r.correctAnswers, 0);
+  const accuracy = totalQuestions > 0 ? correctAnswers / totalQuestions : null;
+
+  return { byStack, totalTestsTaken, totalQuestions, correctAnswers, accuracy };
+}
+
+function toPublicProfile(user: User, stats: ProfileStats): PublicProfile {
+  return {
+    id: user.id,
+    nickname: user.nickname,
+    avatarUrl: user.avatarUrl,
+    country: user.country,
+    city: user.city,
+    selfLevel: user.selfLevel,
+    isPublic: user.isPublic,
+    stats,
+  };
+}
+
+function toPrivateProfile(user: User, stats: ProfileStats): PrivateProfile {
+  return {
+    ...toPublicProfile(user, stats),
+    email: user.email,
+    emailVerifiedAt: user.emailVerifiedAt?.toISOString() ?? null,
+    createdAt: user.createdAt.toISOString(),
+    updatedAt: user.updatedAt.toISOString(),
+  };
+}
+
+export class UserService {
+  constructor(private readonly db: Db) {}
+
+  async getById(userId: string): Promise<User | null> {
+    const [user] = await this.db.select().from(users).where(eq(users.id, userId)).limit(1);
+    return user ?? null;
+  }
+
+  async getByNickname(nickname: string): Promise<User | null> {
+    const [user] = await this.db
+      .select()
+      .from(users)
+      .where(eq(users.nickname, nickname.trim()))
+      .limit(1);
+    return user ?? null;
+  }
+
+  async getPrivateProfile(userId: string): Promise<PrivateProfile> {
+    const [user, stats] = await Promise.all([this.getById(userId), getStatsForUser(this.db, userId)]);
+    if (!user) {
+      throw notFound('User not found');
+    }
+    return toPrivateProfile(user, stats);
+  }
+
+  async getPublicProfile(username: string): Promise<PublicProfile> {
+    const user = await this.getByNickname(username);
+    if (!user) {
+      throw notFound('User not found');
+    }
+    if (!user.isPublic) {
+      throw notFound('User not found');
+    }
+    const stats = await getStatsForUser(this.db, user.id);
+    return toPublicProfile(user, stats);
+  }
+
+  async updateProfile(userId: string, input: ProfileUpdateInput): Promise<PrivateProfile> {
+    const updateData: Partial<typeof users.$inferInsert> = {
+      updatedAt: new Date(),
+    };
+
+    if (input.nickname !== undefined) {
+      const trimmed = input.nickname.trim();
+      const [existing] = await this.db
+        .select({ id: users.id })
+        .from(users)
+        .where(eq(users.nickname, trimmed))
+        .limit(1);
+
+      if (existing && existing.id !== userId) {
+        throw conflict(ERROR_CODES.NICKNAME_TAKEN, 'Nickname already taken');
+      }
+      updateData.nickname = trimmed;
+    }
+    if (input.avatarUrl !== undefined) updateData.avatarUrl = input.avatarUrl;
+    if (input.country !== undefined) updateData.country = input.country;
+    if (input.city !== undefined) updateData.city = input.city;
+    if (input.selfLevel !== undefined) updateData.selfLevel = input.selfLevel;
+    if (input.isPublic !== undefined) updateData.isPublic = input.isPublic;
+
+    const [updated] = await this.db
+      .update(users)
+      .set(updateData)
+      .where(eq(users.id, userId))
+      .returning();
+
+    if (!updated) {
+      throw notFound('User not found');
+    }
+
+    const stats = await getStatsForUser(this.db, userId);
+    return toPrivateProfile(updated, stats);
+  }
+}

src/utils/jwt.ts

@@ -0,0 +1,52 @@
+import { createHash } from 'node:crypto';
+import * as jose from 'jose';
+import { env } from '../config/env.js';
+
+export function hashToken(token: string): string {
+  return createHash('sha256').update(token).digest('hex');
+}
+
+export interface AccessPayload {
+  sub: string;
+  email: string;
+  type: 'access';
+}
+
+export interface RefreshPayload {
+  sub: string;
+  sid: string;
+  type: 'refresh';
+}
+
+type JwtPayload = AccessPayload | RefreshPayload;
+
+const secret = new TextEncoder().encode(env.JWT_SECRET);
+
+export async function signAccessToken(payload: Omit<AccessPayload, 'type'>): Promise<string> {
+  return new jose.SignJWT({ ...payload, type: 'access' })
+    .setProtectedHeader({ alg: 'HS256' })
+    .setIssuedAt()
+    .setExpirationTime(env.JWT_ACCESS_TTL)
+    .sign(secret);
+}
+
+export async function signRefreshToken(payload: Omit<RefreshPayload, 'type'>): Promise<string> {
+  return new jose.SignJWT({ ...payload, type: 'refresh' })
+    .setProtectedHeader({ alg: 'HS256' })
+    .setIssuedAt()
+    .setExpirationTime(env.JWT_REFRESH_TTL)
+    .sign(secret);
+}
+
+export async function verifyToken(token: string): Promise<JwtPayload> {
+  const { payload } = await jose.jwtVerify(token, secret);
+  return payload as unknown as JwtPayload;
+}
+
+export function isAccessPayload(p: JwtPayload): p is AccessPayload {
+  return p.type === 'access';
+}
+
+export function isRefreshPayload(p: JwtPayload): p is RefreshPayload {
+  return p.type === 'refresh';
+}

src/utils/password.ts

@@ -0,0 +1,15 @@
+import * as argon2 from 'argon2';
+
+const HASH_OPTIONS: argon2.Options = {
+  type: argon2.argon2id,
+  memoryCost: 19456,
+  timeCost: 2,
+};
+
+export async function hashPassword(plain: string): Promise<string> {
+  return argon2.hash(plain, HASH_OPTIONS);
+}
+
+export async function verifyPassword(hash: string, plain: string): Promise<boolean> {
+  return argon2.verify(hash, plain);
+}