# prompt-engineering

Prompt caching should save you 90% on token costs — but one obscure bug can silently make you pay 10x more. From DANGEROUS_uncachedSystemPromptSection to the cch=00000 billing trap hidden in Claude Code's DRM, here's why prompt engineers now need to be accountants too.

Ole Lehmann shares a method that applies Karpathy's 'autoresearch' concept to Claude skills — letting an agent test, tweak, and improve your prompts automatically. His landing page copy skill went from 56% to 92% pass rate with almost zero manual work.

Thariq from Anthropic shares what they've learned from running hundreds of Claude Code Skills internally: Skills are folders not just markdown files, they cluster into 9 categories, and the secret sauce is in the gotchas section, progressive disclosure, and writing descriptions for the model — not for humans.

Someone took the Claude Certified Architect exam content and broke it all down — five domains, core concepts, anti-patterns, and hands-on suggestions. The certificate doesn't matter; the knowledge does.

Vishwas shares a complete guide to CLAUDE.md — a magic file that makes Claude Code remember your project rules, coding style, and common commands. No more repeating yourself every session.

klöss's UI/UX Auditor prompt: turns AI into an auditor with Steve Jobs and Jony Ive's design philosophy, checking every pixel on every screen

klöss's complete XML prompt framework: 6 core tags + 11 advanced tags, never copy-paste prompts again