The mode chip on the composer decides what kind of turn your prompt starts. Pick per message — a chat can mix modes freely.
Agent
Makes real changes to your codebase.
The default and the workhorse. The agent edits real code in your workspace, runs it, and shows the result in the live preview. Changes are versioned (Rollbacks) and checked against your guardrails.
Use it when you know what you want built or changed.
Design
Prototypes it first as clickable mock screens.
Nothing touches your codebase — Vision generates a clickable, multi-screen prototype with mock data instead. Explore direction cheaply, share screens with teammates, then press Build to hand the winner to Agent mode. Full guide: Design mode.
Use it when you’re still deciding what to build. The green palette icon tells you at a glance you’re in prototype land.
Prompt Builder
Asks a few questions, then builds a winning prompt.
Instead of building immediately, Vision interviews you — a handful of quick questions about goals, data, and edge cases — then shows you the assembled prompt for review. From there, Preview opens it as a quick design mockup, or Build runs it as a full Agent turn. It’s the default mode when you launch a brand-new blank project.
Use it when the task is large or fuzzy and you want the agent set up to succeed on the first try.
The Manager
One more mode you’ll meet: Mission Control, each project’s Manager chat. You don’t pick it from the composer — it lives in its own tab, takes goals rather than single changes, and farms work out to parallel sessions. See Building in parallel.
Switching modes
The chip sits next to the prompt box (in the workspace composer and on the home page hero). Your last choice per chat is remembered, and each message in the thread is badged with the mode it ran in, so a mixed conversation stays readable.