Claude Code Costs, Act III — The ecosystem of options for spending less (opens in new tab)

There is a whole open-source ecosystem aimed at cutting LLM cost. The trick to evaluating any of it is to ask which of the three cost lines it attacks — cached input (0.1×), uncached/written input (1×/2×), or output (the priciest, never cached) — and then whether it does so without forfeiting the model-scoped prompt cache. That last clause is the recurring catch, and it's the throughline of this entire guide: Anything that rewrites the request prefix per turn forfeits the model-scoped prompt ...