# Reasonix

> A DeepSeek-native AI coding agent for your terminal, engineered around prefix-cache stability to keep token costs low across long sessions.

Reasonix is an open-source, MIT-licensed AI coding agent built specifically for DeepSeek's prefix-cache architecture, available as a CLI/TUI, desktop app, local browser UI, and VS Code extension. It is developed in public on GitHub under the `esengine/DeepSeek-Reasonix` repository, written in Go, and distributed as a single CGO-free static binary that runs on macOS, Linux, Windows, and WSL. The project homepage reports 29,800+ GitHub stars and 98 contributors as of the latest data.

## What It Is

Reasonix is a terminal-first AI coding agent that wraps DeepSeek models in a cache-aware agentic loop. Unlike generic agent frameworks that rebuild the full prompt each turn, Reasonix keeps the conversation history append-only and byte-identical so DeepSeek's prefix cache can replay prior context at a fraction of the cost. The project describes this as achieving 90%+ cache hit rates on long sessions, with input-token costs collapsing to approximately one-fifth of a cold-start equivalent. It supports any OpenAI-compatible endpoint via config, not just DeepSeek, making it a general-purpose but DeepSeek-optimized harness.

## Cache-First Architecture

The core design decision in Reasonix is deterministic, append-only context serialization. Every request replays the exact same byte-for-byte prefix so the model only computes what is new. The project documents that:

- Startup injects a small, stable environment summary
- Stale tool output is snipped/pruned before summary compaction
- Automatic compaction starts at 80% of model context by default (configurable 65–85%)
- Volatile state like timestamps is never injected into the stable prefix

This architecture means sessions get cheaper per turn rather than more expensive, which is the opposite of most agent loops.

## Multi-Surface Deployment

Reasonix runs the same local engine across four surfaces:

- **CLI/TUI** — interactive full-screen terminal interface with Plan, Ask, Auto, and YOLO modes; installable via `npm i -g reasonix` or Homebrew
- **Desktop app** — native app for macOS, Linux, and Windows with visual session management, MCP status, checkpoints, tool approvals, and IM bot connections (Feishu, Lark, WeChat)
- **Browser UI** — `reasonix serve` starts a local web frontend at `127.0.0.1:8787` with optional token or password auth for remote sharing
- **VS Code extension** — connects to `reasonix acp` (Agent Client Protocol) and does not bundle the CLI; available on Visual Studio Marketplace and Open VSX Registry

## MCP and Plugin System

Reasonix is a first-class MCP (Model Context Protocol) client. Plugins are declared in `reasonix.toml` and support `stdio`, SSE, and Streamable HTTP transports. External server tools are merged into a single registry under a prefix (`mcp__<server>__<tool>`). MCP prompts become slash commands and MCP resources are referenceable via `@server:uri`. The project also reads `.mcp.json` files using the Claude Code `mcpServers` schema, making it compatible with existing MCP configurations.

## Subagents, Skills, and Plan Mode

Beyond single-turn coding tasks, Reasonix ships with built-in subagents for explore, research, review, and security-review workflows. Markdown skill scripts with isolated tools extend the agent's capabilities. Plan mode (`/plan`) asks the model to plan before acting, with permissions and the workspace sandbox still governing every tool call. The sandbox enforces file-write boundaries using OS-level backends (Seatbelt on macOS, bubblewrap on Linux) and resolves symlinks to prevent path-traversal escapes.

## Update: Desktop v1.19.5

The current official release is **v1.19.5**, published on 2026-08-03, covering the desktop app, CLI, npm package, and Homebrew tap. The 1.x line is a Go rewrite of the earlier 0.x TypeScript codebase; the 0.x line (`npm i -g reasonix@0.53.2`) is deprecated and no longer maintained. The repository's default branch is `main-v2`, and the project reports 2,871 merged PRs. Windows installers are code-signed through SignPath.io with a certificate provided by the SignPath Foundation.

## Features
- Cache-first append-only context loop for 90%+ DeepSeek prefix-cache hit rates
- Single CGO-free Go binary for macOS, Linux, Windows, and WSL
- Interactive TUI with Plan, Ask, Auto, and YOLO modes
- Desktop app with visual session management, checkpoints, and tool approvals
- Local browser UI via `reasonix serve` with token/password auth
- VS Code extension via Agent Client Protocol (ACP)
- MCP client supporting stdio, SSE, and Streamable HTTP transports
- Built-in subagents: explore, research, review, security-review
- Markdown skill scripts with isolated tools
- Snapshot-based rewind (not git-based) for code and conversation
- Project memory via REASONIX.md or AGENTS.md
- Permissions and sandbox with OS-level enforcement (Seatbelt/bubblewrap)
- Multi-model support via any OpenAI-compatible endpoint
- Optional dual-model executor + planner configuration
- IM bot integration: Feishu, Lark, WeChat
- Headless automation via `reasonix run`
- Automatic context compaction at configurable threshold (65–85%)
- Goal mode with AutoResearch strategy for long-horizon tasks
- Branch and fork conversation history
- Config-driven via reasonix.toml with TOML schema

## Integrations
DeepSeek API, MiMo, Any OpenAI-compatible API endpoint, Model Context Protocol (MCP), Agent Client Protocol (ACP), Visual Studio Code, VSCodium, Eclipse Theia, Feishu, Lark, WeChat, npm, Homebrew, SignPath.io

## Platforms
WINDOWS, MACOS, LINUX, WEB, API, VSC_EXTENSION, CLI

## Pricing
Open Source

## Version
v1.19.5

## Links
- Website: http://reasonix.io/
- Documentation: https://reasonix.io/docs
- Repository: https://github.com/esengine/DeepSeek-Reasonix
- EveryDev.ai: https://www.everydev.ai/tools/reasonix