How the agent works: approvals, undo, models

The agent is the AI teammate built into every Prototyper workspace. You ask for something in the chat; it builds apps, edits files and draws on the canvas, and shows each step as it goes. It asks before anything destructive, and you can undo a whole turn with one click.

Try it

Prototyper is an AI prototyping tool for anything visual: your agents build running apps, wireframes and slide decks on a shared canvas with your team, from real design rules, not AI slop.

The agent in the chat is one of those agents. You can also bring your own: Claude Code, Codex, Cursor or another MCP client can work in the same workspace. See Connect your agent.

Ask for something

1. Open a workspace. The chat is in the agent panel: press / to jump to it from anywhere you aren't typing.

2. Type what you want, in plain words: "Build a pricing page with three plans" or "Make the header sticky".

3. Send it.

The box says Ask the agent to build, edit, or debug the app… before your first message, and Send a follow-up — ask the agent to refine, fix, or extend… after it.

Watch it work

While the agent works, the box says Agent is working — press stop to interrupt…. To stop it, press stop, or Esc while you're in the box. You see:

• Thinking: what the agent is reasoning about, folded once it moves on.
• Its steps: every file read, edit, command and canvas change, grouped into one list. While the agent works, the list stays open and its header names the current step. When the turn ends it folds to one line, for example Ran 5 tools. Click it to open it again.
• Its answer: plain text, plus diagrams or tables when they help.
• Changed files: when the turn is over, a card lists the files it changed, for example 3 files changed, with how many lines were added and removed.

Each request has a step budget. On a new build the agent pauses after 20 steps, and after 16 on a change, to sum up where it is. Reply "continue" to keep going. One request stops at 25 steps.

Tool calls

Every step is a tool call: read a file, edit it, run a command, add a shape. Each one shows its state:

• Running: the step is happening now, and the list header names it.
• Done: it worked. Open it to see what went in and what came out.
• Failed: it didn't work. The step shows the error, and the list header counts it, for example 1 failed. The agent sees the error too, and can fix it in the next step.

A step you refused shows You denied this, so nothing changed.

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When it asks first

Most work runs without asking. The agent stops and asks you before it:

• deletes a file;
• runs a command that removes, moves or truncates files;
• types into a terminal;
• writes to a connected GitHub repository.

Google Drive folders are read-only: the agent can read them but not change them.

Ordinary edits inside the workspace never ask.

When it asks, you see what it wants to do, and the change itself when there is one. Choose:

• Approve (or Delete, when it wants to delete a file): do it this once.
• Always allow: do it, and stop asking in this workspace.
• Deny: don't do it. Nothing changes, and the agent carries on without it.

Try it

To turn asking back on, or off:

1. Click Workspace settings (the gear in the workspace header).

2. Open Agent.

3. Switch Ask before destructive actions on or off.

It's on for every new workspace, and it applies to everyone in the workspace. You need edit access to change it.

Undo a turn

When a turn changed files, its Changed files card has an Undo button. Click it to put back everything that turn changed: files, and shapes on the canvas, as they were before the turn. The chat itself stays. The card then says Undone.

Try it

Undo can't always run. It tells you why:

Subagents

For a bigger job, the agent can hand parts of it to subagents. Each subagent takes one task, and they work at the same time. You don't set them up. The agent starts them when the work splits well, or when you ask, for example "use a subagent for the settings page".

• Each subagent shows as a card in the chat, with its name and what it's doing right now.
• When it finishes, the card says Done, Stopped or Failed. Open the card to see its steps.
• Each subagent has its own avatar and cursor on the canvas, so you can watch it work.

Up to 4 subagents run at once. A subagent can start subagents of its own, one level deeper and no further.

Try it

Answers with diagrams and charts

Ask for a diagram or a chart and the agent draws it right in its answer: "Draw the signup flow as a diagram", "Chart signups per month".

• It can draw flowcharts, state diagrams, sequence diagrams, class diagrams, entity-relationship diagrams, bar and line charts, pie charts, Gantt charts and mind maps.
• It can also answer with a table.
• A wide diagram fits the chat, then scrolls sideways. To see it bigger, use the expand button on the diagram, then zoom in, zoom out or fit it to the window.
• If a diagram can't be drawn, the answer says This diagram couldn't be drawn. Here is its source. and shows the text it was made from.

Try it

Models and context

Under the message box:

• On the left, the model. Click it to pick one. Auto uses the default model, named under it. Each model has a tier: Fast, Balanced or Most capable. Models your plan doesn't include show a lock. Choosing one opens the upgrade options.
• On the right, the context. For example 42% of 1000k: how full the model's memory of this chat is. It turns amber at 70% and red at 90%.

Try it

When the context is nearly full, start a fresh chat. Your canvas and files stay; only the conversation starts over.

• New chat: ⇧⌘OCtrl+Shift+O, or New chat in the chat menu.
• History: go back to an earlier chat.
• Clear chat…: clear this chat for everyone in the workspace.

Availability

Each request you send counts as one message. When the agent starts subagents, each one also counts as a message. For example, a request that starts 3 subagents uses 4 messages. On Free, the box shows how many messages you have left this week.

On Free, the weekly messages and MCP calls are yours, not each account's: they're shared across your personal account and every free team you work in. The team's plan decides, so in a free team you get the free allowance even if you're on Premium.

Troubleshooting

"You've used your 5 free AI messages this week across your free teams." You've sent this week's free messages, across your personal account and your free teams. Upgrade this team, or connect your own agent (Claude Code, Codex, Cursor or another MCP client) and keep working through it.

The agent stopped with "Paused at the step budget". The request took more steps than one request gets, so the agent summed up where it is. Reply "continue".

The agent stopped with "Stopped at the turn limit". The request reached 25 steps. Send a follow-up that picks up from where it stopped, or split the job into smaller asks.

Undo says "Edited since — can't undo". Someone (you, a teammate or another agent) changed the same files or shapes after that turn. Undo won't overwrite their work. Change it back by hand, or ask the agent to.

The agent is waiting and nothing happens. It's asking first. Scroll the chat to the approval and choose Approve, Always allow or Deny.