Anthropic switched from Markdown to HTML artifacts for internal planning, code...

https://echo-wiki.win/index.php/How_do_I_avoid_rewriting_structure_when_I_want_Claude_to_iterate_on_the_same_report%3F

Anthropic switched from Markdown to HTML artifacts for internal planning, code reviews, design systems, and reports because HTML lets them deliver richer, more interactive content without extra effort. This change cut output costs to just $0