The example Datasette plugin authoring skill I used in my article was entirely written by Claude Opus 4.5 - I uploaded a zip file to its the Datasette repo in it (after it failed to clone that itself for some weird environment reason) and had it use its skill-writing skill to create the rest: https://claude.ai/share/0a9b369b-f868-4065-91d1-fd646c5db3f4