KEEP THIS PAGE HANDY
Something not behaving? Start with the situation that looks like yours. You can also return here for prompts, definitions, and the official documentation.
Need to see it?
When you’re stuck
I can’t install the app or sign in.
Check the operating-system and hardware requirements on the official download page. Make sure you’re signing in with the account that has the access your course requires. On a managed computer, ask your instructor or IT for help. If you’re working independently, resolve installation and access before continuing to the build.
My app doesn’t look like these instructions.
Look for the same purpose rather than an identical label: choose Codex, select your local project folder, start a task/chat, and send a message. OpenAI changes the interface. Use the current quickstart linked below if you can’t find a control.
Codex gives me code, but no file.
Confirm that you’re in Codex with your practice folder attached. Ask: “Please create index.html in the selected project folder, rather than only showing code in the chat. Tell me its exact location.” If you are in a discussion or planning mode, return to a mode that can make changes before asking it to build.
I opened the file and see text instead of an app.
Right-click index.html and choose Open With → your browser. If the browser still shows source code, ask Codex to check that it saved a valid HTML document without Markdown fences and that the filename does not end in .txt.
I can’t see the latest change.
Wait for Codex to finish saving, then refresh the browser. Check that you opened index.html from the correct folder, not index-before-changes.html or a downloaded copy. Ask Codex which exact file it edited.
It says it’s fixed. It isn’t.
Repeat the steps and describe the actual result. Include the exact error or a screenshot with private information removed. Ask for the cause and the smallest fix. After two unsuccessful attempts, pause and ask for a diagnosis or get help from your instructor.
It wants to install things or change permissions.
Ask what the action does and why this project needs it. The shared planner is one local HTML file with no external libraries or server. Remind Codex of that scope. Keep required school settings and don’t disable security protections just to move past a prompt.
I reached a usage limit.
Read the limit message and reset time shown in the app. Save your files and continue reviewing or testing what you have. Don’t assume a paid plan means unlimited use. For a class activity, tell your instructor; pairing or finishing after the reset may be appropriate.
My tasks disappeared.
Lesson 4 deliberately starts without saving between visits. If you added saving in Lesson 5, test in the same browser with the same file. Private browsing, cleared browser data, storage restrictions, or moving the file may affect saved data. Keep important work somewhere reliable; this practice app is not your only calendar or task record.
Prompts worth keeping
Select the prompt text, copy it with Command-C (Mac) or Ctrl-C (Windows), and paste it into Codex. Replace the bracketed parts. These are starting points, not magic words.
TRY THIS PROMPT
Before changing anything, inspect [the relevant files or folder]. Explain how it currently works and propose the smallest change that would accomplish [goal].
TRY THIS PROMPT
I tried [steps]. I expected [result], but [actual result] happened. Here is the error: [exact text]. Find the cause, make a focused fix, and tell me how to verify it.
TRY THIS PROMPT
Explain [this part] as if I’m seeing it for the first time. Use one example from my project. Then ask me a short question to check my understanding. Don’t edit the files.
TRY THIS PROMPT
Review the changes you made. Which requirements did you check, how did you check them, and what remains untested? Don’t claim a test passed unless you ran it.
A short glossary
- Local
- On your computer. A local file is not automatically public.
- Repository (repo)
- A project whose files and change history are managed with a tool such as Git.
- Commit
- A saved point in a Git project’s history.
- Diff
- A view showing what changed between file versions.
- Terminal
- A place to run typed commands. You don’t need to learn terminal commands for this module.
- API
- A way for software systems to exchange requests and information. Our shared planner does not need one.
- AGENTS.md
- A project instructions file Codex can read. Useful later for rules you keep repeating, such as how to run checks or which files to leave alone.
- Browser storage
- A way an app can keep data in a browser between visits. It isn’t the same as syncing or backing up your files.
Official guides
- Getting started and choosing Codex
- Desktop app and downloads
- Windows setup
- Current access and usage information
- Projects and local folders
- Permissions
- Prompting, planning, and reviewing work
Product references checked September 24, 2026. These links are for checking current details; you don’t need to read all of them to complete the module.
A simple work log
Copy these lines into your own notes as you work. You can also print this page or save it as a PDF from your browser’s Print menu.
MY CODEX WORK LOG
My goal + audience:
My first prompt:
A change I requested and why:
Test 1 — steps / expected / actual:
Test 2 — steps / expected / actual:
Test 3 — steps / expected / actual:
What I retested after a change:
One thing I can explain:
One limitation or next step:
Tools, sources, and assets I used: