Build modes

Two choices sit in the menu behind the Build button, next to the box where you write. The top one is how the work starts. The bar under it, Agent mode, is how much gets built.

Build or Plan

Plan builds too, at the end, in the agent mode you chose. The two choices work together.

Once an app exists, the same menu adds Chat, which answers questions about your app and never changes its code.

The three agent modes

The Build icon shows the mode you are on: one cube filled for Seth, two for Power Seth, all three for Max Seth. A mode your plan does not include carries the name of the plan that opens it.

Seth, the plain Build, has no line under the box. Each message in the chat shows what it cost in its menu. When Power Seth or Max Seth is chosen, a line under the box says what it costs, for a new app or for a change to this one, and which model it runs on, for example "Runs on Opus 5.5." A button beside it, Pick another model (or Change model once you have picked one), opens the model menu. The figure depends on the model, so the line under the box is the one to trust: see AI models.

What the modes cost, as an example

On Claude Opus 5.5, the model Power Seth and Max Seth use when the model is left on Auto, today's figures in credits are:

Mode	A new app	A change	When a change adds a screen
Seth	125	40	40
Power Seth	185	45	45
Max Seth	245	45	45 and 30 more for the polish pass

Seth on Auto on Pro runs on Claude Sonnet 5.5, which is 50 for a new app and 15 for a change. On the fast model Free builds with, it is 25 and 10. Power Seth costs about one and a half times Seth for a new app and about one and a fifth for a change. Max Seth costs about twice Seth for a new app, polish pass included.

A change is priced at what it costs to make, not at the price of a rebuild.

Seth

Seth builds what you ask for, on every plan. Everything you name gets built and works; what you leave out is a reasonable guess. This is how every app was built before the modes existed, at the same price.

It suits most changes, small apps, and anything where you would rather add parts one request at a time.

Power Seth

Power Seth builds the app a real company of its kind would launch, not only the parts you named.

• The parts a product cannot do without. A list gets search, filters that really filter, sorting and a page for each item. Anything people sign in to gets a settings screen that saves. A shop gets product pages, a cart and filters by category and price. A tool gets real screens behind its menu, never "coming soon". A game gets a title screen, settings, pause and a game over screen that keeps the best score.
• The states nobody asks for. Every list, table and form says something useful when it is empty, while it loads and when something fails.
• Content in quantity. Lists come with 8 to 12 real looking items in the app's language, not three placeholders.
• Motion with a purpose. Sections and cards ease in as they scroll into view, buttons answer a hover and a press, and all of it switches off for people who ask their device for less motion.
• Three new looks at once. Before the first build you get three looks to choose from, drawn from a set of bolder layouts (a two banner hero, a shop with its categories on the left, a bento grid, a game title screen and more). The two looks your account got last are left out, so your apps do not end up looking alike.

With the model left on Auto, Power Seth builds on Claude Opus 5.5, the best model Pro includes. A model you picked by name stays the one that builds.

Max Seth

With the model left on Auto, Max Seth builds on Claude Opus 5.5, like Power Seth. Claude Fable 5.1 builds only when you pick it by name, and the line under the box shows its price first.

Max Seth is Power Seth followed by a completion pass: the finished app is read once more and held against the list of what a product of its kind cannot do without, the same list Power Seth builds to. Search, filters, a detail page for each item, a settings screen that saves, a cart, a game's title and game over screens: whatever the first pass skipped is built now and wired into the navigation. What was built then gets its finish: motion, spacing, the empty and error states, and the wording of buttons and headings.

The completion pass only adds. It never changes what the app does, its pictures, or the prices, names and dates on it, and it never adds a package. If its version of a file comes out shorter or broken, that file stays exactly as it was built, and a screen it adds is kept only when the app can reach it. The hidden test that opens every app before you see it opens the completed one.

On a new app the completion pass is included in the price. On a change, it runs only when the change adds a screen, and the line under the box says how much it adds before you send.

The mode belongs to the app

An app keeps the mode it was built in, and every change to it follows that mode. A Power Seth app stays a Power Seth app three changes later: what you add gets the same design, the same states and works on a phone.

You can change an app's mode from the same menu in the editor. New apps start in the mode you used last on that browser.

Apps made from an import or a spreadsheet are built in Seth, the price their window shows.

Power up and Polish this screen

Type / in the box to see them.