We made markdown HTML code fences runnable in an isolated sand-box, with access to popular JS libraries for data viz and 3d graphics including D3, Mermaid and Three.js.

Design docs are how we communicate ideas with other people, and increasingly with agents. We got used to code blocks and embedded images, but agents can do amazing things when their canvas is HTML. Interactive visualizations make ideas more persuasive, and help you converge with an agent on what to build before you build it.

Just to see what was possible, we told Fable to make a one-off DOOM inspired raycaster, and it did everything from sprites, textures and audio, with no external assets. Maybe you don't need a first person shooter in your next design review, but think charts, graphs, and interactive mocks.

Other neat concepts:

Black hole: https://strata.space/@strataspace/gargantua

Earthquake data viz: https://strata.space/@strataspace/ring-of-fire

Flappy Bird: https://strata.space/@strataspace/flappy-bird

Also, real DOOM, because why not: https://strata.space/@strataspace/doom-for-real

Docs for the feature and the agent tools:

https://strata.space/documentation#interactive-html

https://strata.space/documentation/mcp

https://strata.space/documentation/cli

Show HN: Sandboxed HTML in Markdown (With Doom, Sort Of)