Fitness tracker on Nuxt 4, MySQL 8 and Better Auth

import { drizzle } from "drizzle-orm/mysql2";
import mysql from "mysql2/promise";

// ponytail: single module-level pool; the runtime + mysql2's pool handle concurrency,
// so no globalThis singleton dance needed.
const pool = mysql.createPool(process.env.DATABASE_URL!);

export const db = drizzle({ client: pool });

import { boolean, mysqlTable, text, timestamp, varchar } from "drizzle-orm/mysql-core";

export const user = mysqlTable("user", {
  id: varchar("id", { length: 255 }).primaryKey(),
  name: text("name").notNull(),
  email: varchar("email", { length: 255 }).notNull().unique(),
  emailVerified: boolean("email_verified").notNull().default(false),
  image: text("image"),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull().defaultNow(),
});

export const session = mysqlTable("session", {
  id: varchar("id", { length: 255 }).primaryKey(),
  expiresAt: timestamp("expires_at").notNull(),
  token: varchar("token", { length: 255 }).notNull().unique(),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull(),
  ipAddress: text("ip_address"),
  userAgent: text("user_agent"),
  userId: varchar("user_id", { length: 255 })
    .notNull()
    .references(() => user.id, { onDelete: "cascade" }),
});

export const account = mysqlTable("account", {
  id: varchar("id", { length: 255 }).primaryKey(),
  accountId: text("account_id").notNull(),
  providerId: text("provider_id").notNull(),
  userId: varchar("user_id", { length: 255 })
    .notNull()
    .references(() => user.id, { onDelete: "cascade" }),
  accessToken: text("access_token"),
  refreshToken: text("refresh_token"),
  idToken: text("id_token"),
  accessTokenExpiresAt: timestamp("access_token_expires_at"),
  refreshTokenExpiresAt: timestamp("refresh_token_expires_at"),
  scope: text("scope"),
  password: text("password"),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull(),
});

export const verification = mysqlTable("verification", {
  id: varchar("id", { length: 255 }).primaryKey(),
  identifier: text("identifier").notNull(),
  value: text("value").notNull(),
  expiresAt: timestamp("expires_at").notNull(),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull().defaultNow(),
});

// Better Auth instance (self-hosted, Nuxt 4).
import { betterAuth } from "better-auth";
import { drizzleAdapter } from "better-auth/adapters/drizzle";
// Reuse the SAME postgres-js/Drizzle client the db slice exported in
// server/lib/db.ts — Better Auth shares the pooled `DATABASE_URL` connection.
// Server code lives under server/ (Nitro); reach it via Nuxt's `~~` rootDir alias.
import { db } from "~~/server/lib/db";
import * as authSchema from "~~/server/db/auth-schema";

export const auth = betterAuth({
  // Drizzle adapter over the shared client. The schema is passed HERE (not into
  // drizzle()) — it is the only consumer that needs it, so the db client stays
  // schema-less. ponytail: do NOT enable experimental.joins; it is the one option
  // that would make the adapter reach into db._.fullSchema.
  // ponytail: usePlural stays false (the default) — with it true Better Auth would
  // look for `sessions`/`accounts` and could bind to the analytics/ledger app-type tables.
  database: drizzleAdapter(db, { provider: "mysql", schema: authSchema }),
  // ponytail: email+password is the shortest real auth that works out of
  // the box — add socialProviders / plugins here when the app needs them.
  emailAndPassword: { enabled: true },
  secret: process.env.BETTER_AUTH_SECRET,
  baseURL: process.env.BETTER_AUTH_URL,
});

export type Session = typeof auth.$Infer.Session;

// Better Auth mounted as a Nitro catch-all route. auth.handler is framework-
// agnostic — (Request) => Promise<Response> — and toWebRequest adapts the H3
// event into a web Request. The `[...all]` param catches every /api/auth/*
// sub-path Better Auth routes internally.
// ponytail: Nuxt AUTO-IMPORTS defineEventHandler/toWebRequest from Nitro/H3 at
// runtime; we import them EXPLICITLY from h3 (Nitro's engine, a nuxt dep) so this
// handler type-checks under standalone tsc — the one idiom trade for verifiability.
import { defineEventHandler, toWebRequest } from "h3";
import { auth } from "~~/lib/auth";

export default defineEventHandler((event) => auth.handler(toWebRequest(event)));

// Vue/Nuxt client binding. better-auth/vue exposes the framework-appropriate client
// (signIn / signUp / useSession as Vue refs) — the Vue analog of the React client.
import { createAuthClient } from "better-auth/vue";

export const authClient = createAuthClient();

// Session gate — the Nuxt analog of Next's Edge proxy / RR8's requireAuth. A Nitro
// server middleware runs on every SSR/API request; guard the app surface and do the
// REAL server-side session check (like RR8 — stronger than Next's cookie-existence peek).
// ponytail: this guards SSR loads + direct hits + API — the true security boundary. For
// client-side SPA navigation add an app/middleware/*.ts route middleware (authored with
// Nuxt auto-imports; NOT tsc-gated, since plain tsc can't resolve them — spec §6).
// Explicit h3 imports so this type-checks standalone (see the handler note above).
import { defineEventHandler, getRequestURL, sendRedirect, toWebRequest } from "h3";
import { auth } from "~~/lib/auth";

export default defineEventHandler(async (event) => {
  const { pathname } = getRequestURL(event);
  // ponytail: guard the SaaS app surface; widen the prefixes per app-type.
  if (!pathname.startsWith("/dashboard") && !pathname.startsWith("/settings")) return;
  const session = await auth.api.getSession({ headers: toWebRequest(event).headers });
  if (!session) return sendRedirect(event, "/sign-in", 302);
});

// === file: server/db/schema.ts ===
import { relations } from "drizzle-orm";
import {
  decimal,
  index,
  int,
  mysqlTable,
  text,
  timestamp,
  varchar,
} from "drizzle-orm/mysql-core";
// Better Auth owns identity; we only reference its `user` table by id.
import { user } from "./auth-schema";

export const workoutPlans = mysqlTable(
  "workout_plans",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    ownerId: varchar("owner_id", { length: 255 }).notNull().references(() => user.id, { onDelete: "cascade" }),
    name: text("name").notNull(),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [index("idx_plan_owner").on(t.ownerId)],
);

// Shared catalog, not user-owned.
export const exercises = mysqlTable("exercises", {
  id: varchar("id", { length: 36 }).primaryKey(),
  name: varchar("name", { length: 255 }).notNull().unique(),
  muscleGroup: text("muscle_group"),
});

export const workoutLogs = mysqlTable(
  "workout_logs",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    userId: varchar("user_id", { length: 255 }).notNull().references(() => user.id, { onDelete: "cascade" }),
    planId: varchar("plan_id", { length: 36 }).references(() => workoutPlans.id, { onDelete: "set null" }),
    performedAt: timestamp("performed_at").notNull(),
  },
  (t) => [index("idx_log_user_time").on(t.userId, t.performedAt)],
);

export const logSets = mysqlTable(
  "log_sets",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    logId: varchar("log_id", { length: 36 }).notNull().references(() => workoutLogs.id, { onDelete: "cascade" }),
    exerciseId: varchar("exercise_id", { length: 36 }).notNull().references(() => exercises.id),
    setNumber: int("set_number").notNull(),
    reps: int("reps").notNull(),
    weightKg: decimal("weight_kg", { precision: 20, scale: 6 }),
  },
  (t) => [index("idx_set_log").on(t.logId)],
);

export const workoutPlansRelations = relations(workoutPlans, ({ one, many }) => ({
  owner: one(user, { fields: [workoutPlans.ownerId], references: [user.id] }),
  logs: many(workoutLogs),
}));
export const workoutLogsRelations = relations(workoutLogs, ({ one, many }) => ({
  user: one(user, { fields: [workoutLogs.userId], references: [user.id] }),
  plan: one(workoutPlans, { fields: [workoutLogs.planId], references: [workoutPlans.id] }),
  sets: many(logSets),
}));
export const logSetsRelations = relations(logSets, ({ one }) => ({
  log: one(workoutLogs, { fields: [logSets.logId], references: [workoutLogs.id] }),
  exercise: one(exercises, { fields: [logSets.exerciseId], references: [exercises.id] }),
}));

import { drizzle } from "drizzle-orm/mysql2";
import mysql from "mysql2/promise";

// Serverless: a small pool per short-lived instance — many instances × a big pool exhausts MySQL.
export const pool = mysql.createPool({ uri: process.env.DATABASE_URL!, connectionLimit: 2 });
export const db = drizzle({ client: pool });

import { drizzle } from "drizzle-orm/mysql2";
import mysql from "mysql2/promise";

// Long-running process: a real, reused pool (mysql2 manages idle recycling).
export const pool = mysql.createPool({ uri: process.env.DATABASE_URL!, connectionLimit: 10 });
export const db = drizzle({ client: pool });

import { drizzle } from "drizzle-orm/planetscale-serverless";
import { Client } from "@planetscale/database";

// Edge/Workers have NO TCP sockets, so mysql2 cannot run here. PlanetScale's HTTP driver
// speaks MySQL over fetch — the client that works on Workers (the MySQL analog of Neon's HTTP driver).
const client = new Client({ url: process.env.DATABASE_URL! });
export const db = drizzle({ client });