esengine · 2026-05-24 · notable
DeepSeek-Reasonix — Terminal Coding Agent Built Around DeepSeek's Prefix Cache Reports a 99.82% Cache Hit Rate, Cutting a 435M-Token Day From ~$61 to ~$12
Open-source terminal coding agent built only for DeepSeek's API. It holds prompt prefixes byte-stable to maximize cache hits, with a reported 99.82% hit rate over 435M input tokens in a day that cut the workload to about $12.
A terminal coding agent that bets on DeepSeek's prefix cache to keep long sessions cheap.
Key specs
| License | MIT |
|---|---|
| GitHub stars | 6,471 |
| Cache hit rate | 99.82% |
| Hn points | 230 |
What is it?
Reasonix is an open-source command-line coding agent that talks directly to DeepSeek's API with no provider-abstraction layer. It runs in your terminal, reads and edits files, and runs tasks, defaulting to DeepSeek-V4-Flash with a per-turn or per-session switch to V4-Pro.
How does it work?
It is engineered around DeepSeek's byte-stable prefix cache: the agent keeps the prompt prefix identical across turns so cached tokens stay valid, using four mechanisms to avoid cache-invalidating edits. A tool-call repair layer fixes malformed tool calls so a turn rarely has to restart. The maintainers report a 99.82% cache hit rate across 435M input tokens in one day.
Why does it matter?
Prefix-cache misses are the main hidden cost of long agent sessions. By holding the prefix stable, the same 435M-token day that would cost about $61 uncached on V4-Flash drops to roughly $12, making always-on agents affordable for solo developers.
Who is it for?
developers using DeepSeek's API
Try it
npx reasonix code