Guides / From Lovable to Claude Code

From Lovable to Claude Code: start the next app on nerdsystem

Lovable is where a lot of people built their first app. This guide is for building the second one with Claude Code, which works in a folder of code you can open, read, and keep. It covers how to start that app on nerdsystem, so the hosting, the sign-in, the database, and a check on Claude's work are settled before the first feature. It ends with what to do with the Lovable app you already have.

Time: about twenty minutes. You need Node 22.12 or newer (it comes with npm; the template's scripts use pnpm, so run npm install -g pnpm once if you don't have it), Claude Code, and a nerdsystem account. Sign in with your email; the first sign-in creates your account. On Windows, run the commands in Git Bash (it comes with Git for Windows) or WSL; PowerShell blocks npm's scripts until you run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once.

Why people leave Lovable for an agent

• Iteration. Claude Code edits the files in your folder, runs the build, reads the error, and tries again. You do not paste anything back into a chat.
• Cost per message. Lovable bills by the message, in credits. Hosting and the database are billed separately from those credits. Claude Code is billed through a Claude subscription or API usage, and the hosting is whatever you choose.
• A codebase of your own. Lovable can sync a project to GitHub, but the project lives in Lovable, and its Cloud functions and database wiring are set up there. With an agent the repository is the project: any editor opens it, and the server is code you can read.

None of this is a complaint about Lovable. It is good at the first screen. The reasons above show up when the app has to keep changing after that.

What Claude Code does not come with

Claude Code writes code. It does not host the app, sign anyone in, keep a database, or check its own work before the app goes live. Left alone, it writes the login and the data access itself, and those are the parts that go wrong. The same mistake is what the Lovable showcase finding was: 170 apps with tables readable by anyone, behind database rules an agent wrote or forgot to write. Any agent writing its own data layer can make it.

nerdsystem supplies those four things, so Claude only writes features:

• Hosting on Cloudflare, with a URL like https://you-myapp.nerdsystem.app and a custom domain on Pro.
• Sign-up, login, logout, password reset, and roles. The login is a service the agent does not write. Protecting a route is one line, requireAuth().
• A SQLite database and a file bucket, provisioned for the project and wired in as bindings. Every query runs on the server with the signed-in user in hand. The browser does not reach the database.
• Gates that run before every deploy and refuse a leaked key, a dependency with a critical or high vulnerability, or a secret in the built bundle. Each finding goes back to Claude with the file, the risk, and the fix.

Fastest path: paste this into Claude Code

Open Claude Code in an empty folder. Put your email and a one-line description in the two boxes below, press Copy for your agent, and paste the prompt into Claude Code. Claude installs the command, signs you in by email, creates the app, builds the first feature, and deploys it, explaining each step.

Describe the app the way you would have described it to Lovable. nerd init writes the description at the top of CLAUDE.md, so Claude starts from your idea. Keep the first feature small enough to finish in one session, open it on the live URL, and say what is wrong in plain words.

The Claude Code guide is the same path done by hand, step by step, with what happens when a gate fires and how previews per pull request work. Everything in it applies here.

If you want to bring the Lovable app

The screens can come with you. The rest is rebuilt, and it is better to know that before you start.

• In Lovable, connect GitHub and sync the project to a repository, then clone it into a folder named lovable-export next to where the new app will live.
• Run nerd init my-app for a fresh project, next to the export rather than inside it; nerd init refuses a folder that already has files in it.
• Open the new folder in Claude Code and say: "Port the UI from the exported repo at ../lovable-export into this app. Replace every Supabase call with a route under /api, filtered by the signed-in user. Keep the design." Claude moves the React screens over and rebuilds the server on createNerdApp().
• Claude runs the gates, takes any key it finds out of the code and asks you to set it with nerd secret set (and to rotate it if it ever reached git), then runs nerd deploy.

What does not carry over: Postgres-only features and Lovable Cloud functions. Each one becomes a route on the new server or a table in SQLite, or it is dropped, and Claude will tell you which ones it hit. Your app's users sign up again on the new login; accounts do not carry over. How long the port takes depends on how much of the app talked to the database from the browser.

The Lovable comparison says what each side does well and what you have to accept.

Things to know

• nerd deploy from the terminal works from the first minute, and git builds work as soon as the repo is linked.
• Free covers 1,000 active users a month and 100 build minutes. Pro is $39 a month for 25,000.
• nerd logs --since 1h shows what the deployed app did, and nerd rollback puts the previous version back without touching the database.
• When a git build is refused by the gates, the findings are posted on the pull request, or as a GitHub issue for a push to production, written for the agent; say "read the nerdsystem issue and fix it". A refused nerd deploy prints the same findings in the terminal, where Claude already sees them.