zero2codex
OpenAI Codex workflow course

Course goal: ship your personal brand site

Build a personal brand site with Codex

Keep improving one project from an empty folder to a responsive one-page site with an introduction, projects, and contact details. Every lesson adds a visible result or a check toward that finish line.

Curriculum

Personal brand site build path

01

Start With Codex

Set up Codex and build the hero section of your personal brand site.

0/4
02

Prompt Like A Builder

Map the site, plan its sections, and turn rough ideas into clear changes.

0/3
Find the Files to ChangeAsk Codex to show which files control each part of the site before you edit anything.Plan Before CodingPlan the site's theme control before editing, including risks and browser checks.Define Done WhenDefine visible completion checks, then implement the site's light and dark themes.
8 minReady

Define Done When

Make completion measurable before work starts.

acceptance criteriaverification evidencefinal report
15-minute lab

Hands-on lab

Implement the approved theme switch only after defining visible, checkable completion criteria. This closes the plan-to-proof loop from the previous lesson.

Before you start

  • Open the approved theme-switch plan from the previous task.
  • Preview index.html and confirm the Projects button still moves to the right section before editing.

Do it now

Good prompt

Codex, implement the approved accessible light/dark theme switch in index.html. Keep one file, add no packages, and preserve the existing Projects button. Done when: (1) the theme control has a clear accessible label, (2) switching twice visibly returns to the starting theme, (3) the Projects button works in both themes, (4) wide and narrow layouts have no horizontal overflow, and (5) you report the changed file plus the result of every check.

What success looks like

  • A clearly labeled control switches the page between light and dark themes.
  • The Projects button still works in both themes.
  • The page works at wide and narrow widths, and the final report lists each check separately.
Stuck? Try this
  • If Codex says “done” without evidence, paste the checklist again and ask for one result per condition.
  • If the original button breaks, ask Codex to reproduce that regression before making the smallest fix.

Plain-language explanation

“Done” should mean more than “Codex stopped editing.” A good done condition says what behavior changed and what evidence proves it.

Done-when criteria can include passing tests, a successful build, a screenshot, a browser check, or a clear explanation of remaining risk.

Why it matters

Completion criteria protect you from vague success. Codex can report exact evidence instead of asking you to trust that the change worked.

Common beginner mistake

The common mistake is accepting a confident final message without a command, output, or manual check you can verify.

Step-by-step

  1. State the expected behavior in plain language.
  2. Choose at least two checks that prove the behavior.
  3. Tell Codex to report exact command output or manual evidence.
  4. Do not mark the task complete until the evidence matches the criteria.

Try this

Take a task and add two done-when bullets: one automated check and one human-readable behavior check.

Completion checklist

  • Your request includes at least two done conditions.
  • The final evidence can be checked without reading every edited line.

Sources

08

Finish And Deliver The Site

Polish independent tasks in parallel, then complete one final acceptance review.

0/3

Practice lab

Copyable Codex prompts

Plan before coding

Codex, inspect the relevant files first, then propose a plan. Do not edit until the plan names tests and verification steps.

Verification checklist

  • Relevant files are named before edits begin.
  • The plan includes tests and verification commands.

Verify a UI change

Codex, start the dev server, open the route in the browser, check desktop and mobile layouts, then report the exact evidence.

Verification checklist

  • Desktop and mobile states are checked in the browser.
  • The final note includes exact evidence.

Review focused risk

Codex, review the uncommitted diff. Focus on behavioral regressions, missing tests, and accessibility issues. Do not modify files.

Verification checklist

  • Findings lead with severity and file references.
  • Unchanged files are left untouched.
Every good Codex request says what to change, what to preserve, and how to prove it worked.

Reference

Codex concepts to keep nearby