Reasonix - Deepseek: A Terminal Coding Agent Built Around the Thing Everyone Else Ignores
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Reasonix is an open-source terminal coding agent that optimizes DeepSeek API costs by explicitly designing its architecture around prompt prefix caching. Because provider APIs offer substantial discounts when consecutive requests share identical prompt prefix sequences, Reasonix maintains two distinct execution sessions: a planner and an executor. Naive agent implementations interleave planning turns into a single conversation stream, destroying cache stability for both roles; Reasonix preserves stable token sequences by isolating them into separate sessions. For developers working with LLM integrations, this article provides a practical lesson in cost and latency optimization. Understanding how prompt layout impacts provider-level prefix caching empowers engineers to design high-throughput, budget-efficient agentic architectures without sacrificing model reasoning capabilities.