Episode 7 of 11

Codex IDE Extension

Install and use the Codex IDE extension — ghost text predictions, inline chat for modifying code, and sidebar communication with full workspace context.

Installing the Extension

The Codex extension is available for the most popular code editors:

VS Code

Open the Extensions panel (Cmd+Shift+X on Mac, Ctrl+Shift+X on Windows)
Search for "OpenAI Codex"
Click Install
Reload the editor when prompted

JetBrains IDEs

Go to Settings → Plugins → Marketplace
Search for "OpenAI Codex"
Click Install and restart the IDE

After installation, sign in with your OpenAI account when prompted.

Ghost Text — Inline Predictions

As you type, Codex predicts what you're about to write and shows it as grey "ghost text" inline:

// Start typing a function...
function calculateTax(price, taxRate) {
  // Ghost text appears automatically:
  // return price * (taxRate / 100);
}

To interact with ghost text:

Tab — Accept the entire suggestion
Esc — Dismiss the suggestion
Ctrl+→ — Accept word by word
Keep typing — Ghost text updates in real time

💡 Tip: Write a descriptive comment before a function, and Codex will generate the implementation based on your description.

Inline Chat — Modify Selected Code

Highlight a section of code and open the inline prompt to make targeted modifications:

How to Use

Select the code you want to modify
Press Cmd+I (Mac) or Ctrl+I (Windows)
Type your instruction in the prompt bar
Review the diff and accept or reject

Example Prompts

# Select a function, then ask:
"Add error handling with try-catch"
"Add JSDoc comments"
"Convert to TypeScript with proper types"
"Optimize this for performance"
"Add input validation"

The agent modifies only the selected code, preserving everything else in the file.

Sidebar Panel — Full Workspace Chat

Open the Codex sidebar panel for a ChatGPT-like experience with your entire workspace as context:

Ask questions about any file in your project
Use @ mentions to explicitly attach files — e.g., @database.ts or @folder/utils
Request multi-file changes that span across your codebase
Debug errors by pasting stack traces or error messages

The sidebar maintains conversation history, so you can have an ongoing dialogue about your project as you work.

Keyboard Shortcuts Summary

Action	Mac	Windows / Linux
Accept ghost text	`Tab`	`Tab`
Dismiss suggestion	`Esc`	`Esc`
Inline chat	`Cmd+I`	`Ctrl+I`
Open sidebar	`Cmd+Shift+I`	`Ctrl+Shift+I`
Accept word-by-word	`Ctrl+→`	`Ctrl+→`

What's Next

In the next episode, we'll explore how Codex thinks and reasons — context gathering, chain-of-thought planning, and implementation checklists.