Introducing CesiumJS Sandcastle Copilot

We’re excited to introduce Sandcastle Copilot, an AI-assisted chat panel built into Sandcastle that helps developers create, edit, and debug CesiumJS sandcastles.

CesiumJS Sandcastle has been a cornerstone of the CesiumJS community for years. It's where developers learn the API, prototype scenes, test ideas, validate fixes, and share working examples with one another. Sandcastle Copilot builds on that workflow by helping developers move from a natural-language idea to code they can read, run, and adapt without leaving Sandcastle. By turning natural-language prompts into working code, it lowers the barrier to entry for everyone who wants to build with CesiumJS, regardless of coding ability.

The initial release is Bring-Your-Own-Key (BYOK). Before starting a chat, connect Sandcastle Copilot to an LLM provider you already use, and your requests will be handled by that provider, not by Cesium. This keeps the first version lightweight and gives you control over the model, key, and account behind your conversations. Because requests go directly to your provider, Cesium does not collect or store your prompts, keys, or conversations.

What you can do with Sandcastle Copilot

Sandcastle Copilot is built to shorten the loop between idea and working code, whether you're exploring a new API, visualizing a dataset, or prototyping an app against your own data. Here are some things you can do with it:

Ask questions about CesiumJS or the active sample

Ask about a CesiumJS API or the sample you’re currently in, and get answers grounded in the editor and console context rather than generic documentation.

Request scene changes in plain language

Describe what you want in plain language, and Copilot proposes the code. Proposed changes appear as diffs in the chat panel, so you review and apply each edit before it touches the editor.

Diagnose runtime errors in context

When something throws, Copilot reads the current editor and console state to help you find and fix the cause, without leaving Sandcastle.

Sandcastle Copilot has taken shape with input from the CesiumJS community, including the discussion that began in our native AI Copilot feedback thread earlier this year. It follows an AI-driven semantic search, which we rolled out last quarter, as the next piece of AI-assisted tooling inside Sandcastle.

This initial release lays the groundwork for a broader AI-assisted development experience in Sandcastle. BYOK keeps the first version lightweight and flexible. Looking ahead, we're exploring ways to streamline access and setup, expand the Cesium-aware skills available to Sandcastle Copilot, and use community feedback to guide where the experience should go next.

Try Sandcastle Copilot and use the Feedback & Issues link in the app to let us know what you think.