llms.txt: a proposed standard no major AI platform has confirmed it uses

A proposed `llms.txt` file—a Markdown document listing a site's most important pages for AI systems—has gained minimal adoption (10% of sites) and lacks support from major AI platforms like Google, despite being recommended as a low-cost, twenty-minute investment. While no AI company has committed to using it and it shows no current evidence of affecting citations, creating one remains worthwhile as an asymmetric bet on future agentic routing and as a useful internal audit tool to identify content gaps and duplicates.