XContext

AI-powered interview platform for a given codebase — run contests, upload/inspect code, and generate targeted JS/TS interview questions.

Tech stack

• Frontend: Next.js (App Router) + React + Tailwind + shadcn/ui
• Backend: Bun + Express
• Auth: Better Auth (Google provider enabled)
• DB: Postgres (Neon) via Drizzle ORM
• LLM: Vercel AI Gateway (via ai)

Repo structure

• frontend/: Next.js app (UI)
• backend/: Bun + Express API

Prerequisites

• Bun installed (backend and scripts use Bun)
• A Postgres database URL (local Postgres or hosted Neon)
• Optional: Google OAuth credentials (for Better Auth social login)
• Optional: Vercel AI Gateway API key (required for question generation endpoint)

Environment variables

Backend (backend/.env)

Required:

• DATABASE_URL: Postgres connection string
• BETTER_AUTH_SECRET: Better Auth secret
• BETTER_AUTH_URL: Public backend base URL (e.g. http://localhost:3000)
• FRONTEND_URL: Frontend URL used for redirects (e.g. http://localhost:7000)
• AI_GATEWAY_API_KEY: Vercel AI Gateway API key (required for AI question generation)

Auth providers:

• GOOGLE_CLIENT_ID
• GOOGLE_CLIENT_SECRET

Optional:

• PORT: API port (defaults to 3000)

Frontend (frontend/.env.local)

Required:

• NEXT_PUBLIC_BACKEND_URL: Backend base URL (e.g. http://localhost:3000)

Setup

Install dependencies (each package has its own package.json):

cd backend && bun install
cd ../frontend && bun install

Run locally

Because the backend defaults to port 3000, it’s easiest to run the frontend on 7000.

1) Start the backend API

cd backend
bun run dev

The API serves:

• GET / → welcome message
• GET /api/v1/health → health check
• POST /api/v1/ai-question → generate a single JS/TS question (requires AI_GATEWAY_API_KEY)
• Better Auth routes under GET|POST /api/auth/*

2) Start the frontend

cd frontend
bun run dev -- -p 7000

Database migrations (Drizzle)

The backend includes Drizzle Kit scripts:

cd backend
bun run gen
bun run migrate

Other available commands:

cd backend
bun run push
bun run pull
bun run studio

Formatting & linting

From each package:

cd frontend && bun run format && bun run lint
cd ../backend && bun run format

Or from the repo root:

bun run format
bun run format:check

Notes

• Cross-origin isolation headers are enabled in frontend/next.config.ts to support @webcontainer/api (SharedArrayBuffer).
• The frontend also includes a rewrite for /api/auth/* to the backend when NEXT_PUBLIC_BACKEND_URL is set, but Better Auth client requests should still be configured to preserve cookies correctly.