Leo AI — browser-first starter

Leo AI has two modes:

• Leo Chat: general AI chat through OpenRouter.
• Leo Code: ZIP text-file context and code review. The first version proposes edits in chat; it does not yet apply patches back into the ZIP.
• Sandbox proof-of-concept: /api/sandbox runs a short Python snippet in an isolated E2B sandbox. This is NOT yet a full project terminal or build environment.

Requirements

• Node.js 20+
• OpenRouter API key
• Firebase project
• Vercel account for deployment
• E2B API key only if testing the sandbox endpoint

1. Install and run

npm install
cp .env.example .env.local
npm run dev

Open http://localhost:3000.

2. Configure OpenRouter

Add OPENROUTER_API_KEY to .env.local. It is server-only and must never have the NEXT_PUBLIC_ prefix. The model router is in src/lib/model-router.ts. Set MODEL_FAST, MODEL_GENERAL, and MODEL_CODING to model IDs that currently exist in your OpenRouter account. Model names/prices change; verify them in the OpenRouter model directory. The automatic router is a simple keyword-based starter, not a model that independently decides every task.

3. Firebase setup

1. Open Firebase Console and create a project.
2. In Authentication → Sign-in method, enable Anonymous for the starter. You can replace this with email/password later.
3. In Project settings → Your apps, register a Web app.
4. Copy the web config values into NEXT_PUBLIC_FIREBASE_API_KEY, NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN, NEXT_PUBLIC_FIREBASE_PROJECT_ID, and NEXT_PUBLIC_FIREBASE_APP_ID.
5. In Project settings → Service accounts, generate a private key. Put the full JSON on one line into FIREBASE_SERVICE_ACCOUNT_JSON. Treat this as a secret; never commit it.
6. The starter does not yet store chat history in Firestore. Add Firestore rules and user-owned chat collections before implementing persistence.

Firebase Web config is not a substitute for security rules. Keep Firestore rules locked down and verify user identity on server routes.

4. Test authentication locally

The /api/chat route requires a Firebase ID token verified with Firebase Admin. If you haven't configured the service-account JSON, the route will return an auth configuration error. Do not make the API public to bypass this check.

5. Configure E2B sandbox (optional)

Create an E2B account and add E2B_API_KEY. /api/sandbox is a proof-of-concept for executing short Python snippets in an isolated sandbox. It is not wired to ZIP uploads and is not a terminal. Before making this public, add rate limits, per-user quotas, spend caps, job timeouts, logging, and review the sandbox provider's current isolation/network controls.

6. Deploy to Vercel

1. Push this folder to a new private GitHub repository.
2. In Vercel, choose Add New → Project and import that repository.
3. Framework preset: Next.js.
4. Add the same environment variables from .env.example in Vercel → Project → Settings → Environment Variables. Paste JSON service account as a single line.
5. Deploy, then test login and chat.
6. After changing environment variables, redeploy.
7. Never add .env.local or service-account JSON to GitHub.

Security checklist before inviting users

• Add rate limiting and per-account request/token caps.
• Set OpenRouter spend limits.
• Validate upload count, archive size, file count, total uncompressed size, and paths on the server too.
• Do not run project-provided scripts or arbitrary shell commands in the web server.
• Keep project execution in disposable isolated sandboxes with CPU/RAM/time limits and network restrictions.
• Add approval before applying file changes or running risky commands.
• Add content deletion/export and privacy notice.
• Implement Firestore history only with per-user rules and server-side ownership checks.

Current MVP limitations

• ZIP parsing happens in the browser and selected text files are sent as model context.
• Binary assets are skipped; files are not persisted.
• AI suggestions are displayed as text, not automatically applied.
• Sandbox endpoint only runs Python snippets; no arbitrary terminal, package install, or project build yet.
• Chat history is in browser memory and disappears on refresh.
• Firebase Anonymous Auth is enabled by default for easy testing; add a real sign-in option before production.