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Learn how to make widgets on canvas
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| name | build-widgets |
| title | How to build widgets |
| description | Learn how to make widgets on canvas |
| allowed-tools | ["files.*"] |
Here's how you build a widget:
Create a new subdirectory where the app will go. Check to see that this is a new directory.
Write the React app using Opal SDK in that subdirectory. Rules for app crafting
Create or update the surface to include the widget.
Get back to the user with a friendly message notifying them that the widget was added.
How authenticated HTTP calls to the Opal backend work — the host/guest architecture, fetchWithCreds, the fetch allowlist, and the OpalBackendClient migration. Read this before adding, modifying, or debugging any backend call.
Learn how to make widgets on canvas
Produce high-quality React apps from natural language descriptions.
Teaches you how to properly operate in the sandboxed environment you're in.
Learn how to present your work as a structured surface — a curated manifest of artifacts that the user's application renders in real time.
Learn how to use `window.opalSDK` inside your sandboxed React component to read files, call host services, and listen for events from the application.
