> What models and tools did you use to create this?

Opus 4.8.

> What were your biggest challenges in making this?

UI that had to react due to things such as the window size changing, specifically with horizontal and vertical scrolling and getting it to work with mouse drag + text selection via shift and arrow keys. It was a lot of back and forth. In the end after getting it working for the main editor I (Claude) turned it into a with_scrollbars decorator method.

Knowing to splitting god functions before they sprawl / emphasising regression tests, and specifically frame rate regression has helped me a lot so far I think.