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

https://echo-wiki.win/index.php/What%E2%80%99s_inside_SKILL.md_for_html-artifacts_-_any_good_heuristics%3F

Anthropic switched to HTML artifacts from Markdown for internal planning, code reviews, design systems, and reports to speed up workflows and improve clarity. HTML cut output costs by $0.08 per document and slashed latency 5x, making reviews smoother