Day 07 of 21
Week 1 build day - one safe homepage change from start to finish
Goal: Today you use everything from Days 1 to 6 together on one real task. You will pick one small visible change, ask Codex to plan it, approve only what you understand, preview it in your browser, check the diff, and save only when it looks right.
What to do
Open a terminal in your project folder
Find your project folder in Finder (Mac) or File Explorer (Windows). On Mac, right-click the folder and choose "New Terminal at Folder." On Windows, hold Shift, right-click the folder, and choose "Open PowerShell window here" or "Open Command Prompt here." The terminal should open showing your project folder name in the prompt.
Start Codex and ask it to inspect only
In the terminal, type "codex" and press Enter to start Codex. Once it opens, give it a read-only task first. Do not ask it to change anything yet — ask it to look and report only.
codexAsk Codex to describe your project without changing anything
Type this exact prompt into Codex and press Enter. Read the response carefully. You want to confirm Codex can see the right files before you ask it to change anything.
Describe this project to me in plain English. Tell me: what files exist, what the homepage file is called, and what the current homepage heading says. Do not change any files. Inspect only.Give Codex the exact change prompt
Now you will ask Codex to make your one small change. Use this structure exactly — fill in your specific change where indicated. The key rules are: ask for a plan first, name the exact file if you know it, say what not to change.
I want to change one thing on the homepage. Here is the exact change: [DESCRIBE YOUR EXACT CHANGE — for example: change the main heading from "Welcome" to "Build without coding"]. Before you touch any file, write me a plan: tell me which file you will edit, which line or section you will change, and what you will leave alone. Do not make any changes until I say "go ahead."Approve and let Codex make the change
If the plan looks right — it names only the homepage file, describes only your requested change, and does not mention unrelated files — type "go ahead" and press Enter. Watch what Codex does. If it starts changing things you did not ask for, type "stop" immediately.
go aheadPreview the change in your browser
Open your project in a browser to check the change looks right. How to preview depends on your project type: (A) Plain HTML files — open your project folder in File Explorer or Finder, find the HTML file (usually index.html), and double-click it to open it in your browser. (B) Next.js, React, or similar projects — open a second terminal window in your project folder and run: npm run dev — then open your browser and go to http://localhost:3000. Leave that terminal open while you check. If you are not sure which type your project is, ask Codex: "Is this a plain HTML project or does it need a development server, Give me the exact command to preview it in my browser."
Review the diff and save if correct — or recover if broken
Before you commit or save anything, ask Codex to show you a diff — a line-by-line list of exactly what changed. Read it and check: did only the one thing change, If yes, commit or save. If something looks wrong, ask Codex to undo the change before saving anything.
Show me a diff of every change you made. List which files changed and exactly which lines were added or removed. Flag anything that looks unrelated to my request.Expected result
One small homepage change is planned, approved, made, previewed in the browser, checked with a diff, and saved. You used Codex safely from start to finish without breaking anything.
Key takeaway
- The safe Codex build cycle is: inspect first, plan before editing, approve the plan, preview the result, check the diff, save only if correct. That order protects you every single time.