How generation works

One modelCopy Anchor Link

Your four files compile to one model, and every output reads it. Nothing is copied into your repo, so no generated code drifts from the definition.

1. Parse. The engine reads each file's frontmatter, its $type and its $id.
2. Check. It refuses any key, name or input outside the shape, and the refusal names the fix.
3. Compile. It builds your Startup's model on the platform's own Nouns and stamps it as a dated Version.
4. Generate. The API routes, the typed $, the MCP tools, the CLI, the schemas, the App screens and the Docs each read that model.
5. Serve. Every request reads the current Version, so an improvement to a default reaches you on the next request.

Change one lineCopy Anchor Link

Add rent to Lease:

  rent: { type: money, currency: USD }

Send the field in try, which stores nothing:

curl -X PATCH "https://api.sb/<your-domain>/nouns/Lease" -H 'Prefer: mode=try' \
  -H "authorization: Bearer $SB_TOKEN" -H 'content-type: application/json' \
  -d '{"fields":{"rent":{"type":"money","currency":"USD"}}}'
# "mode": "try", "major": false, "stored": false,
# with the Version it would become and every Interface it touches

The answer arrives before you commit, and it covers every Interface at once:

Money has one form everywhere: an amount and a currency, as the Offer writes its price. Removing renter answers "major": true, because records hold it. A rename of renter is refused once records exist, and the refusal says to change its label instead.

The defaultsCopy Anchor Link

Every SaaS answers the same questions. The platform answers each one once, for every Startup on it.

The two script rows apply to $ and MCP. On REST, a record write without Prefer: mode=try commits.

OverridesCopy Anchor Link

The defaults are the product. An override replaces one output, never the definition, and everything else stays generated.

A Startup with no theme file renders in the default theme, on its Site and in every App screen. Three lines restyle Leaseclock's Site, Admin and SaaS App:

{
  "fonts": ["Libre Caslon Text:wght@700"],
  "light": { "accent": "#8A4B0F" }
}

A printed-form face and a brass clock-hand accent, Leaseclock's own. Every primary button takes the accent. A value that could end a CSS declaration is refused, never emitted.

A page of your own returns catalog blocks with computed props, and writes no markup and no CSS:

const block = (name: string, props: object) => <sb-block data-block={name} data-props={JSON.stringify(props)} />

export default function NoticeBy({ endsOn, days = 60 }: { endsOn: string; days?: number }) {
  const by = new Date(Date.parse(endsOn) - days * 86_400_000).toISOString().slice(0, 10)
  return block('facts', { title: 'Renewal notice', items: [
    { label: 'Lease ends', value: endsOn },
    { label: `Give notice by (${days} days)`, value: by },
  ] })
}

The renderer applies the theme and checks the props, and you maintain that one component. A screen you add to the App reads and writes through the generated API, so Access levels, try and revert still apply.

An API route of your own is refused. New behaviour is a declared Verb, which gets its URL, preview, undo, button and agent call from one block.

The constraintsCopy Anchor Link

The engine refuses what it cannot generate from. Each refusal buys something every output relies on:

The same refusals let an agent write the definition and fix its own mistakes before anything is stored:

What you write as does: is what your agent reads on the method. The platform's own Startup Noun takes the same shape, and its types need no key:

curl -s 'https://api.sb/$.d.ts?nouns=Startup' | grep -A1 'Sell it'
# /** Sell it, with its Customers, to another party · Live|Dormant → Sold · modes try|send · a legal Decision */
# sell(target: string, input: StartupSellInput, o?: { mode?: 'try' | 'send' }): Promise<Action>

Why the constraintsCopy Anchor Link

Made by hand, screens multiply: 2 audiences, 4 views plus 1 per Verb with input, 3 states, 2 themes and 2 widths.

The platform carries that count while you stay inside the constraints.

What fitsCopy Anchor Link

Made for products that are records and the actions people take on them. A Lease and its renewal fit; so does a Unit and its building. Inside that shape, an agent writes the definition and one person checks it.

Blog and changelogCopy Anchor Link

Every Startup gets a blog at /blog, under its own theme, and a changelog. Each changelog entry is a dated Version of the definition, so the day Lease gained rent is an entry with no post to write.