preview.ts feeds the local View editor. It is dev-only and never ships in production.

Add preview.ts beside your tool:

get-forecast/preview.ts

export default { city: "San Francisco" };

pnpm dev

The preview host loads the default fixture, calls your tool with that input, and renders the View iframe.

delete-rows/preview.ts

export default { query: "beta" };

export const empty = { query: "" };

Switch cases in the dev UI. Each named export becomes a selectable fixture.

pnpm build

preview.ts is not included in dist/manifest.json or the production tool registry.

Fixtures also drive MRTR previews. Export input that matches your tool schema, for example export default { query: "beta" }.

Reference

Rule	Detail
Location	`src/tools/<name>/preview.ts` only
Default export	Primary fixture case
Named exports	Additional cases in the dev UI
Production	Never bundled or registered

Use bitmcp dev --csp-widget to edit CSP allowlists from the preview host.

Preview fixtures