The agent drives your right pane

An agent working in a cell can use the right pane of that cell, the same pane you open with the Files button. It can do two things there:

• Show you a file (showInPane). It opens a file in the Files pane, in the view it chooses and at the line it chooses. You see the change it just made instead of reading a description of it.
• Ask you to check its work (requestCheck). It puts a checklist over the terminal. Each item opens its file in one click, you mark it OK or NG with an optional note, and Send hands every answer back to the agent as your next message. The agent can then fix what was NG.

Both are for the moments where a person has to look: a UI change, a rendered document, a diagram, an output the agent cannot judge by itself.

1. Turning it on
2. Showing a file: showInPane
3. Asking you to check: requestCheck
4. When the agent’s cell is not the one on screen
5. What to ask for
6. Limits

Turning it on

The two tools belong to the Canvas tool group (render), the same group as presentDocument and presentChart. Whoever already has the Canvas tools has these two as well:

• In the workspace, a Claude, Codex or Copilot cell has every GUI tool already. Nothing to do.
• In a project directory, switch on Canvas in the launcher’s MCP toggles before you start the session. The toggle registers the directory, so it reaches the next session started there, not one that is already running.
• Antigravity, Grok, Muse and Cursor get GUI tools only by registering them, in the workspace too. See Which coding agent.

A session that was already running before you updated MulmoTerminal does not have the tools. Start a new one.

You do not have to name the tools. Each tool tells the agent when to use it, so asking in plain words is enough. See What to ask for below.

Showing a file: showInPane

The agent names a file and, optionally, how to show it:

The agent asks for	What you see
editor (the default)	The file’s source in the editor.
preview	The rendered file: Markdown, HTML, CSV as a table.
canvas	The view the Canvas draws the file with: Markdown, HTML, MulmoScript, ShapeScript.
split	For Markdown, the editor on the left and the Canvas view on the right.
a line number	The editor, scrolled to that line, whatever view was asked for.

The Files pane opens on its own if it was closed, with the file tree beside it as usual. If you had unsaved edits in the pane, they are saved first. If the save fails, the pane stays as it was and nothing is lost.

The file must be inside the cell’s working directory. A path outside it is refused, and the agent is told so. The Files pane must also be showing that directory: if you have pointed the pane somewhere else, the file is not opened there.

Asking you to check: requestCheck

The agent writes a short title and a list of items, up to twenty. Each item is one thing to look at and what counts as right (“The formula is drawn, not shown as $…$”), and can name a file to open.

A card appears at the bottom right of the enlarged cell:

1. Open (the arrow icon on an item) shows that item’s file in the pane, in the view the agent chose. The card stays where it is, so you can go through the items one by one.
2. Press OK or NG for each item. A note is optional. Write what is wrong when you press NG, so the agent knows what to fix.
3. Send becomes active once every item has an answer. It types the results into the terminal as one line, as if you had typed it yourself, and the card goes away.

The agent reads that line as your next message and carries on. A line looks like this:

Check results for "Design notes" (1 NG): 1. OK: The diagram is drawn 2. NG: The HTML page says Hello — the page has no title

Other things you can do with the card:

• Fold it (the chevron) to see the terminal underneath. Your answers stay.
• Close it (the cross) to put it away without answering. The agent is told in one line, Check "<title>" was closed without answers., so it does not keep waiting, and it is told not to post the checklist again unless you ask.
• A newer checklist from the same agent replaces the old one.
• Reload the page, or lose the connection, and the card comes back with the same items.

The agent does not wait for you. It ends its turn after posting the checklist. Your results arrive as a new message, whenever you send them.

When the agent’s cell is not the one on screen

• Another cell is enlarged: nothing on your screen changes. The file or the checklist waits, and appears when you enlarge the agent’s cell.
• Nothing is enlarged (the tiled grid): the agent’s cell is enlarged for you, and the file or the checklist is shown there.
• You are on another page, such as Settings: no cell is enlarged for you. The request is there when you come back to the agent’s cell.

What to ask for

Ask in plain words. The tool descriptions do the rest. Some examples:

• “Show me the file you just changed.” The agent opens it, at the line it changed.
• “Open the README in the Canvas view.” The agent asks for canvas.
• “When you are done, give me a checklist to confirm the new page works.” The agent ends with a requestCheck. Each item points at what to look at, and your NG notes become its next task.
• “Check the slides with me one by one.” Each slide or file becomes an item.

The loop that works well: the agent changes something, posts a checklist, you mark it, it fixes the NGs and posts a new checklist for just what it changed.

Limits

• Only files inside the cell’s working directory.
• Up to twenty items per checklist, and an item’s label is cut at a few hundred characters.
• The card appears over an enlarged cell only. In the tiled grid there is no room for it, which is why the cell is enlarged for you.
• Results are typed as one line. Line breaks in your notes become spaces, since a line break would send the message early. Control characters are removed.
• The agent can only reach its own cell’s pane, never another cell’s.

More: Feature reference · Feature list