We just shipped support for the ugliest part of HTTP: Vary
Simon Willison's Weblog (LLM / AI engineering) · Sep 23, 2026
Claim: Cloudflare now supports the HTTP Vary header for cache control, enabling content-negotiation patterns (e.g., Accept-based HTML vs JSON) behind Cloudflare's CDN.
Evidence: Anecdotal user comment on HN reporting that Cloudflare previously ignored Vary on non-image assets and now supports it; commenter notes they worked around it by using URL suffixes (.json) instead.
Archive rationale
This is infrastructure/CDN news with no bearing on Claude Code + Codex workflow or token efficiency. No quantified impact. Timothy's stack (Next.js/Supabase/Vercel) does not rely on Cloudflare caching patterns as the critical path. Not applicable to the core build/ship loop. Durability is high (HTTP Vary is structural), but applicability is zero.