5 22 min

Developer: build the site

Role
Developer
Outcome
Your site, running on your laptop, with its legal page
Time box
22 minutes

The Developer builds your site from your content file and your design brief. Before it writes code, it reads current guidance on how to build for today's web. At the end it writes your legal page from a template.

Get ready 2:00 min

The Developer works for several minutes, and you mostly wait. Two things before you start:

Work with the Developer 14:00 min

The Developer leads you through this Block in the chat and says when it is done. Read this part first, then start the Developer at its end, under Now start the Developer. Keep this page open next to the chat.

While it builds

The Developer builds your site in your style, with your fonts and your signature move. That takes a few minutes. Meanwhile:

Now start the Developer

  1. In Antigravity IDE, start a new chat: click the + at the top right of the agent panel, not the one in the chat box.
  2. Check the model name at the bottom of the chat box: it says Gemini 3.8 Flash. If not, click it and pick Gemini 3.8 Flash.

Then type:

Agent chat

Start the Developer step.

You know it worked when it names the Modern Web Guidance guides it read, and one thing it builds differently because of them.

When the Developer says it is done, look at your site in Look and accept below.

Look and accept 6:00 min

When the Developer is done, open the preview (your site on your own laptop) at the address it gives you, such as http://localhost:8000, in Chrome. You see your content in your style, for the first time. Look for your signature move too.

Part of your face outside the square of your photo? Crop the photo. Then start a fresh chat, attach the cropped photo with the + in the chat box and Media, and type: "Replace my photo with this one."

Then switch your computer between light and dark mode. Your site follows it:

Apple menu → System Settings → Appearance → Light or Dark.

Read it back

The Developer's read-back ends with the result of the Check (the script that tests your site). All five items pass, the legal page among them.

What the Check prints (the end of it)

  PASS             Content file matches the schema
  PASS             Accessibility (the axe rules Lighthouse scores)
  PASS             No errors in the browser console
  PASS             What an agent sees: your content without JavaScript
  PASS             Legal page written

5 of 5 items pass.
This Check only reports. It never stops you from publishing.

Read your legal page

Today there is no QA Block, so you read your legal page now: it goes public with your site at Ops. In the preview, click Legal notice & privacy at the bottom of your site (Note legali e privacy on an Italian site). It is not legal advice: for a site that sells services, have it checked by someone who knows the law in your country.

  • Are your name and email address right? And the address, VAT number and phone number, if you gave them to the Analyst? Check the phone number digit by digit.
  • Anything on the page you do not want there? Tell the Developer in one sentence. A missing email address belongs to the Analyst, in a fresh chat.

If something goes wrong

Ask your agent first. In a fresh chat, type the question below: it reads your repo and tells you what is done and what comes next. Got an error message? Paste it into the chat.

Agent chat

Where am I?
The preview address does not open

Fix: the preview runs only while its terminal runs. Ask the agent: "Start the preview again." If port 8000 is taken, it prints another address.

The preview says "Your site could not be built"

Cause: something in site/ is broken, so the build stops. The page names what is wrong.

Fix: copy that message into the Developer's chat; it fixes its own files. A problem in site/content.json belongs to the Analyst, in a fresh chat. After the fix, a reload shows your site again.

The page looks unstyled, or the cards sit in one long column

Fix: reload the page in Chrome. Still wrong? Tell the Developer what you see, in one sentence.

The agent wants to change site/content.json

Fix: say no. Content changes belong to the Analyst, in a fresh chat.

Fell behind?

The Developer Block's time is up and you are not done? Run its checkpoint. It brings your repo to where the room is, and keeps your own content file, design brief and spec.

  1. Stop the agent in your old chat if it is still working: click the round button with the red square in the chat box.
  2. In Antigravity IDE, open a terminal with the menu Terminal → New Terminal. Paste this command (Cmd+V on a Mac, Ctrl+V on Windows, Ctrl+Shift+V on Linux) and press Enter:

Terminal · same on Mac, Windows and Linux

node tools/checkpoint.mjs developer

Use the Block that has just ended, not the one that starts now.

It lists what it kept and what it changed, and ends with what to do next. Nothing to change means you were already there. Two Blocks behind? This one checkpoint includes the earlier Blocks.

Or start a fresh chat and let the agent run it:

Agent chat

Catch me up: the room just finished the Developer block.

The checkpoint adds the Developer's finished page, in the colours and fonts of your brief.