Simon Willison used Claude Artifacts on his phone to build interactive animated demonstrations of common sorting algorithms (bubble sort, selection sort, insertion sort, merge sort, quick sort, heap sort). He then prompted Claude to add Python's Timsort by cloning the CPython repo from GitHub and consulting the source files. A 'run all' button was added to display all algorithms simultaneously in a grid. Notably, when GPT-5.4 Thinking reviewed Claude's Timsort implementation, it found it to be a simplified, Timsort-inspired adaptive mergesort rather than a true Timsort.