Explain, fix and test code with AI from the editor

Select some code and right-click inside the selection: the DEVUP AI submenu offers these actions.

• Ask DEVUP AI: bring the selection into the chat and ask your own question about it.
• Explain: get an explanation of the selected code.
• Fix: get a fix for the selected code.
• Add Tests: get tests written for the selected code.

1. 1Select the code you want help with in the editor.
2. 2Right-click inside the selection and choose DEVUP AI.
3. 3Choose Ask DEVUP AI, Explain, Fix or Add Tests.
4. 4Follow the answer in the chat. When it suggests a change, Apply shows it as a diff before anything is written.

Take this helper from a sample shop project. It has no tests yet, and the discount handling is easy to get wrong.

// A small shopping cart helper
export function cartTotal(items, discount = 0) {
  const subtotal = items.reduce((sum, item) => sum + item.price * item.quantity, 0);
  return Math.max(0, subtotal - discount);
}

1. 1Select the whole cartTotal function, from export to the closing brace.
2. 2Right-click inside the selection, then choose DEVUP AI → Add Tests.
3. 3The request leaves at once: the selected lines plus a short instruction to write tests, added to the chat you have open.
4. 4Your own instructions and any project rules in use go with it, so an AGENTS.md line that names your test runner reaches the model on every action.
5. 5Watch the reply arrive. If it heads the wrong way, Stop or Esc ends it early.
6. 6Choose New file on the test code block, save it next to cart.js, and run your tests. If one does not pass, select the code involved and choose Fix.

Explaining an unfamiliar function. You inherit a module with a dense parsing routine. Select it and choose Explain: the explanation lands in the current chat, where follow-up questions about the same lines keep their context.

Fixing a compiler error from Quick Fix. A type error underlines a function call. Open Quick Fix on it and pick Fix with DEVUP AI: the code reaches the chat together with the problems the editor reports for it.

Asking your own question about a selection. Press Ctrl+Alt+D with code selected, then type something like "Can this loop run past the end of the array?". Ask DEVUP AI waits for your words and sends nothing on its own.

Cleaning up a block with several warnings. Select the whole block and choose Fix. Along with the code, the request lists the problems the editor reports on those lines, so the model sees them next to the code.

A dedicated model for quick actions. Keep one model in the picker for long design chats, and set devupai.editorActions.model so Explain, Fix, Add Tests and Quick Fix always run on another.

1. 1Put the cursor on code the editor marks with an error or a warning.
2. 2Open Quick Fix and choose Fix with DEVUP AI.
3. 3That code goes to the chat together with the problems the editor reports for it.

With code selected, Ctrl+Alt+D brings it into the chat. With nothing selected, the same key opens the message box.

In Keyboard Shortcuts, the key belongs to DEVUP AI: Ask DEVUP AI and DEVUP AI: Focus Message Box; assign another key there if you prefer.

Editor actions don't have to share the chat's model. Set devupai.editorActions.model to give Explain, Fix, Add Tests and Quick Fix a separate model, or leave them on the model selected in the chat.

See which models are available in the editor, or browse the full model catalog.

• devupai.editor.contextMenu shows or hides the DEVUP AI submenu, and devupai.editor.quickFix does the same for the Quick Fix entry.
• Quick Fix never acts by itself: nothing is sent until you choose the entry.
• Explain, Fix and Add Tests join the chat you have open, so open a new chat before you run one on unrelated code.

Every switch and command for these actions is listed in the editor actions docs.

• Code from a file that may hold secrets, like a .env file or a private key, can't be attached.
• In Restricted Mode you can still chat about the code you attach, but DEVUP AI doesn't write to files.
• With Apply, a suggested change shows as a diff, and nothing is written until you accept it.