DeepSeek-Reasonix: A Coding Agent Designed Around the Cache Bill
DeepSeek-Reasonix is a terminal coding agent at 29.9k stars, adding 800+ a day on GitHub trending. Single static Go binary, config-driven: providers, agents and tools all declared in one reasonix.toml, plugins over JSON-RPC subprocesses, MCP-compatible, works with any OpenAI-compatible endpoint. Install via npm or Homebrew; there's a VS Code extension and a desktop app too.
The design choice worth studying: the whole harness is engineered around DeepSeek's prefix caching. Context maintenance is cache-aware, pruning stale tool output in ways that keep the cached prefix intact, so long sessions stay cheap instead of re-billing the full context every turn. Most agent harnesses treat the model as interchangeable and the token bill as weather. This one treats one model's caching economics as the core constraint and designs backwards from it. With DeepSeek V4 Flash at $0.14 per million input tokens, an agent that also maximizes cache hits gets to near-zero marginal cost for all-day sessions.
Together with antirez's ds4 trending the same day, a DeepSeek-native tool ecosystem is visibly forming: the same pattern that made Claude Code the center of a plugin economy, replaying around an open Chinese model at a fortieth of the price. Harnesses used to chase the smartest model. Now some chase the best cost curve.
Repo: https://github.com/esengine/DeepSeek-Reasonix
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The design choice worth studying: the whole harness is engineered around DeepSeek's prefix caching. Context maintenance is cache-aware, pruning stale tool output in ways that keep the cached prefix intact, so long sessions stay cheap instead of re-billing the full context every turn. Most agent harnesses treat the model as interchangeable and the token bill as weather. This one treats one model's caching economics as the core constraint and designs backwards from it. With DeepSeek V4 Flash at $0.14 per million input tokens, an agent that also maximizes cache hits gets to near-zero marginal cost for all-day sessions.
Together with antirez's ds4 trending the same day, a DeepSeek-native tool ecosystem is visibly forming: the same pattern that made Claude Code the center of a plugin economy, replaying around an open Chinese model at a fortieth of the price. Harnesses used to chase the smartest model. Now some chase the best cost curve.
Repo: https://github.com/esengine/DeepSeek-Reasonix
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