PromptCaching

Recap: The Cache Mismatch Problem In our previous post, we explained why pairing OpenCode / ClaudeCode with DeepSeek destroys your cache hit rate: DeepSeek uses strict full-prefix matching — a cache hit only fires when every byte from position 0 is identical to the previous request. Agent loops insert tool messages in the middle of the message array, breaking the prefix hash every turn. Anthropic-style cache_control segment markers are silently ignored. Result: near-zero cache hit rate, even though DeepSeek’s billing dashboard shows caching is “enabled.” The problem is not DeepSeek. The problem is that generic agent frameworks were designed for a fundamentally different caching mechanic. ...

Introduction DeepSeek’s disk-based automatic context caching is famous for near 90% input token savings: cached prefix tokens cost just a tiny fraction of standard input pricing, with zero manual configuration required. Thousands of developers switch to DeepSeek chasing this aggressive discount for long system prompts, code rules, and repeated tool definitions. But a costly reality hits teams running ClaudeCode / OpenCode (code agent runtimes built for Anthropic-style cache_control) against the DeepSeek API: ...