# The code editor

> Vaulter apps are real code, and you can edit it directly. When that helps and the one big caveat.

Vaulter apps are real code, not a locked black box. The **Code** tab in the build workspace shows every file behind your app in a full editor, the same one that powers VS Code, with a file tree to move around. Most people never need it, and there is one important caveat.

## When editing code helps

Direct editing is useful if you are comfortable with code and want to:

- Make a precise change faster than describing it.
- Adjust something specific that is easier to express in code than in words.
- Read how a part of your app actually works. The Code tab is worth opening even if you never type in it; watching what the agent wrote is the fastest way to learn your own app.

## The one big caveat

Editing code by hand can break your app in ways the agent did not intend. When the agent works, it keeps the whole app consistent: data, pages, and logic move together. A hand edit can quietly conflict with that. If you are not sure what a change will do, it is safer to describe what you want in chat and let the agent make the change.

> A good default: use chat and Edit Mode for almost everything. Reach into the code only when you specifically want to, and know that you are taking the wheel when you do.

## After editing

Vaulter still rebuilds and checks your app after manual changes, and the [self-repair layers](/docs/building/auto-fix) catch runtime errors and blank screens the same as always. But auto-fix repairs what is broken, not what is misunderstood; it cannot know your intent. Test your change in the preview before publishing.

## A note on database changes

Schema changes are special: they run as migrations with their own [guardrails](/docs/data/database). If you write one by hand, destructive operations like dropping a table require explicit confirmation, and a failed migration shows up in the Database panel with its error rather than silently breaking your app.

Where things live in the code is covered in [Project structure](/docs/developer/project-structure).