THIS GUY FOUND WHY YOUR CLAUDE CODE COSTS ARE 10-20X HIGHER THAN THEY SHOULD BE
he reverse engineered the entire Claude Code binary. found two hidden bugs that silently break your prompt cache.
BUG 1: if your conversation mentions billing, tokens, or Claude Code internals, the cache breaks on every single request.
there's a hidden string replacement baked into the binary that targets billing attribution codes.
if that string appears anywhere in your conversation history, it replaces the wrong one and your entire cache rebuilds from scratch.
you get charged full price instead of cached price.
fix: run Claude Code via npx instead of the standalone binary.
BUG 2: every time you use --resume, your entire conversation cache rebuilds from scratch. one resume on a large conversation costs $0.15 that should cost near zero.
the system injects tool attachments in a different position on resume vs fresh sessions. this changes the cache prefix and forces a full rebuild. every single resume costs you a one-time hit on your entire context.
fix: no clean fix yet, as it was introduced in v2.1.69. downgrading to v2.1.30 works but you lose months of features.
on a 500K token conversation these two bugs combined can cost you $0.20+ per request.
if your usage has been burning way faster than expected, this is probably why.