How to install DeepSeek Reasonix on Ubuntu

Reasonix is a DeepSeek-native coding agent that runs as a single Go binary in your terminal. It keeps DeepSeek’s prompt prefix stable so long sessions stay cheap. On Ubuntu you can install it three ways; pick the one that matches what your machine already has.

Before you start

You need three things on a stock Ubuntu 24.04 LTS install:

• curl (most installs already have it)
• a DeepSeek API key from platform.deepseek.com
• one of: Node.js + npm, a .deb download, or the Go toolchain

Reasonix itself is a static CGO_ENABLED=0 binary, so once the binary is on $PATH nothing else is required at runtime.

Path A — npm (fastest, works everywhere)

sudo apt update && sudo apt install -y curl ca-certificates
curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
sudo apt install -y nodejs
npm i -g reasonix
reasonix --version

npm i -g reasonix no longer installs a TypeScript runtime; starting with reasonix@1.0.0 the package pulls the prebuilt native Linux binary into npm‘s global bin directory. If reasonix --version is not on $PATH, check npm bin -g and add it to your shell rc.

Path B — .deb from GitHub release (no Node)

Use this when you want a system-wide install without Node. Pick the matching asset from the releases page:

VERSION="1.17.19"   # replace with the current release tag
cd /tmp
curl -fsSLO "https://github.com/esengine/DeepSeek-Reasonix/releases/download/v${VERSION}/reasonix_${VERSION}_amd64.deb"
sudo apt install -y ./reasonix_${VERSION}_amd64.deb
reasonix --version

Verify the checksum against SHA256SUMS in the same release before installing:

grep "reasonix_${VERSION}_amd64.deb" SHA256SUMS | sha256sum -c -

This is the right path for minimal images, CI runners, and any box where adding nodejs is overkill.

Path C — build from source

sudo apt install -y build-essential git
git clone https://github.com/esengine/DeepSeek-Reasonix.git
cd DeepSeek-Reasonix
git checkout main-v2          # the Go 1.0+ branch; v1 is legacy TS
make build                    # -> bin/reasonix
./bin/reasonix --version

make cross cross-compiles to darwin|linux|windows × amd64|arm64 under dist/. Use this when you want the bleeding edge, when you are debugging a bug, or when you intend to send a patch.

Configure the provider

The binary is installed, but Reasonix still does not know which model to call. Run the interactive wizard:

export DEEPSEEK_API_KEY="sk-..."
reasonix setup

The wizard writes ~/.reasonix/config.toml on Linux and saves the API key into ~/.reasonix/.env. If you prefer a hand-written config, create the same two files directly.

A minimal ~/.reasonix/config.toml:

default_model = "deepseek-flash"

[[providers]]
name        = "deepseek-flash"
kind        = "openai"
base_url    = "https://api.deepseek.com"
model       = "deepseek-v4-flash"
api_key_env = "DEEPSEEK_API_KEY"

Resolution order is flag > ./reasonix.toml > ~/.reasonix/config.toml > built-in defaults, so a project-local reasonix.toml overrides the user file when you cd into that project.

First session

reasonix                          # interactive TUI; type /init to generate AGENTS.md
reasonix run "explain the auth flow in main.go"
reasonix run --model deepseek-pro "add unit tests for this function"
echo "refactor the parser" | reasonix run

/init scans the current directory and writes an AGENTS.md so future sessions remember the project layout. /plan on switches the agent to read-only planning. /pro requests a stronger model for hard refactors. /doctor checks API key, config, hooks, and project state when something refuses to start.

Updating and removing

# npm path
npm i -g reasonix@latest

# .deb path
sudo apt install -y --reinstall ./reasonix_<new_version>_amd64.deb

# remove the user config entirely (deep clean)
rm -rf ~/.reasonix

Reasonix stores config in ~/.reasonix/ and nothing else. Uninstalling the binary plus removing that directory is a complete reset.

What changed since Reasonix 1.0

The npm i -g reasonix command has always existed, but what it installs is different now. Pre-1.0 the package shipped a TypeScript runtime and v1 branch still does; from 1.0.0 onward the package is a thin wrapper around a prebuilt Go binary. If you upgraded an old install and something broke, check whether the old v1 branch leftover is still in your $PATH.

Common failure modes

• reasonix: command not found after npm i -g — your shell did not pick up npm bin -g. Restart the shell or add the printed path to ~/.bashrc.
• setup: api_key not set — the wizard reads $DEEPSEEK_API_KEY from the shell or from ~/.reasonix/.env. The key string itself never goes into config.toml.
• The agent edits the wrong file — install a project-local reasonix.toml with permissions = "ask" and approve each tool call interactively.
• git clone of the legacy v1 branch — checkout main-v2 explicitly; the TypeScript build is no longer the supported path.

Sources

• DeepSeek-Reasonix GitHub repository
• Reasonix installation guide
• CLI reference
• Configuration paths
• Migration guide from 0.x
• DeepSeek API keys