Simon Willison’s Weblog

Most people's mental model of Claude Code is that "it's just a TUI" but it should really be closer to "a small game engine".

For each frame our pipeline constructs a scene graph with React then:

-> layout elements
-> rasterize them to a 2d screen
-> diff that against the previous screen
-> finally use the diff to generate ANSI sequences to draw

We have a ~16ms frame budget so we have roughly ~5ms to go from the React scene graph to ANSI written.

— Chris Lloyd, Claude Code team at Anthropic