[Feature]: Show diff before accepting in Supervised mode

[nick-rtmb]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/desktop

Problem or use case

Using Nightly version

When working on a project where it touches pretty sensitive code or create a sensitive feature I would like to be able to see what changes before accepting (like in Claude Code or sometimes for work I use the AI Agent chat for some things). Currently T3 Code in Supervised mode does not show any diff, only a JSON output.

It also does not show up in the diff tab until it has been accepted.

Proposed solution

Add a UX (probably just in the chat screen real quick) before accepting the changes.
If you even want to go deeper, you could add the ability to accept line by line changes or give more context before commiting changes.

Why this matters

This is a faster workflow then refactoring some changes here and there after the fact of accepting it. Right now I accept the changes and make refactors after it myself or ask for another approach.

Smallest useful scope

Show the diff of the changed code before accepting it (preferably in the chat screen itself or the diff tab).

Alternatives considered

As mentioned I currently just accept the changes and make my own refactors later which is a bit time consuming.

Risks or tradeoffs

Considering the diff tab already exists it should not be much work to implement this, however when displaying the diff you should consider where to put it (in a different tab or just in-chat for quick acceptance/changes).

Examples or references

Contribution

• I would be open to helping implement this.