Key Takeaways React single-page applications are invisible to AI agents by default. Claude's fetch tools do not execute JavaScript, so any content rendered client-side does not exist from the agent's perspective. A plain-text sitemap (sitemap.txt) was the single most impactful artifact. Once provided, Claude could autonomously discover and read every piece of content on a site. Server-side HTML injection works — but edge caching can mask it entirely. A working injection pipeline appeared broken for over an hour because stale cached responses were being served. Markdown endpoints (.md) are the ideal content format for AI agents. Structured front matter, clean hierarchy, and explicit metadata allow an LLM to parse, cite, and reason about content with zero friction. Homepage discovery is the critical gap. If the homepage returns nothing navigable, an AI agent has no starting point — even if every other endpoint works perfectly. MIME types for novel file formats must be explicitly configured. A .toon file served as application/octet-stream is unreadable binary to an AI agent, regardless of how well-designed the format is. The UTMI format (utmi.toon) consolidates robots.txt, sitemaps, llms.txt, metadata, and API tool registration into a single file that Claude could parse immediately once the MIME type was corrected — demonstrating that unified site manifests are viable and useful for AI agents.
