The manual code editor

Fullstack Agent Coding isn't chat-only — every app also has a full code editor for when you want to make a change yourself instead of describing it to the agent.

Opening it

In Visual Code view, click the </> icon next to the device switcher. This opens a real editor pane alongside the app preview.

What it can do

• Real code editing — a full Monaco editor (the same engine VS Code uses), with syntax highlighting, multi-cursor, and undo history per file.
• File tree — browse every file in the app, including ones the agent hasn't touched recently.
• Create, rename, and delete files — a + button to add a new file, and hover any file for rename/delete icons. All of this is staged in memory until you save.
• Quick Open (⌘P / Ctrl+P) — fuzzy-jump to any file by typing part of its name.
• Search in files (⌘⇧F / Ctrl+Shift+F) — grep across the whole project; click a result to jump straight to that line.
• Diff view — see exactly what you've changed versus the currently deployed version, with the option to revert a single file.

Saving and deploying

• Save — writes your changes without deploying, so you can keep editing across multiple files before going live.
• Save & Deploy — writes your changes and redeploys the app in one step. The deploy runs the same smoke-test check the agent's own builds do before it's considered live — a change that breaks the app is caught here, not silently shipped.

⌘S / Ctrl+S saves without leaving the editor. If you try to navigate away with unsaved changes, you'll be asked to confirm first.

Editing while the agent is working

The editor is locked (read-only) while the coding agent is actively building or editing the same app, to avoid the two of you racing on the same files. Once the agent's turn finishes, the editor unlocks automatically.

How this fits with chatting

The manual editor and the chat agent share the same underlying app — a change you make by hand shows up immediately if you go back to describing changes in chat, and vice versa. Use whichever is faster for the change in front of you: chat for anything you'd rather describe than type, the editor for a precise one-line fix or when you already know exactly what to change.