The fast
ADE.
An ADE, an agentic development environment, is the place where your coding agents live. Leon runs Claude Code, Codex and opencode in real terminals, keeps every project, worktree and session in one tree, and does it as a native app with no browser engine underneath.
0.1.0 is being releasedall install options
ADE
n. agentic development environment
An IDE is built around the file you edit. An ADE is built around the agents you run.
You still write code, review it and ship it. The difference is where your attention goes: to several agents, on several projects, at once. An ADE gives that work a home.
Start the agents you already use
Claude Code, Codex and opencode, in real terminals, on this computer or over SSH.
Keep them in one tree
Machines, projects, git worktrees and sessions. Found from your agents' history, not set up by hand.
Pick any of them back up
One searchable history of every session, and a resume for each one.
Native, so it answers when you ask.
Leon is written in Rust and draws its own window on the GPU. Terminals, search and the session tree run in one process, on your machine, with nothing to boot behind them.
1–2ms
Full-text history search
Across about 14,700 messages.
~5ms
Re-import with nothing new
About 1 s the first time, for 132 agent sessions.
~6s
The whole test suite
1,400 tests.
~30MB
Release binary
Native Rust. No browser engine inside.
Measured by the developer on one M1 Pro, on real agent history, with the 0.1.0 code. Your machine and your history will differ. These are Leon's own numbers and say nothing about any other product.
One tree for every agent session.
Machine, project, worktree, session. Leon finds your projects from your agents' history and detects each one's logo by framework, so there is nothing to set up first.
Real terminals, split your way.
GPU-rendered terminals with iTerm-style splits and tabs. Agents run inside a real login shell, and the terminal stays when the agent exits.
Every action has a shortcut.
⌘P goes anywhere. ⇧⌘P runs any command. Native menus and a searchable settings screen cover the rest. The palette shows the shortcut next to each command, so you learn them by using it.
Ctrl replaces ⌘ on Linux and Windows
Add a server. It sits next to this computer.
Remote machines over SSH, in the same tree as your own. The connect screen runs a checklist and, when a step fails, says what is wrong and what to type.
Themes are data.
Leon and Zavu ship built in, in light and dark. Yours is a TOML file that extends one of them, and it reloads live as you save. The lion in the header shows what your agents are doing: working, waiting, error.
[ ocean.toml ]
An accent for dark, an accent for light. Everything else is inherited.
id = "ocean"
name = "Ocean"
extends = "leon"
[dark]
accent = "#4DA3FF"
[light]
accent = "#0B5CAD"Claude Code
Anthropic's coding agent.
Codex
OpenAI's coding agent.
opencode
The open source coding agent.
Leon does not ship an agent. It runs the ones you already use, and does not replace them.
What is next.
Planned, not shipped. Nothing here is available today unless it says so.
First public release
BEING RELEASED
Share a machine with a code
IN DEVELOPMENT
Durable sessions
PLANNED
Review loop
PLANNED
Notifications and unread state
PLANNED
+ 1 more
Orchestration
PLANNED
Precise agent state
PLANNED
Remote history import
PLANNED
+ 4 more
Apache-2.0. Read it, build it, send a patch.
Leon is made by Zavu and developed in the open. The repository has the code, the architecture notes and the changelog.
0.1.0 is being releasedall install options
[ 1 STARS ON GITHUB ]
[ STAR ]
Star the repo
It is the cheapest way to say Leon is worth building.
Star on GitHub →
[ REQUEST ]
Request a feature
Say what is missing and why. One idea per issue.
Open a request →
[ REPORT ]
Report a bug
Steps, your OS and the Leon version. That is enough.
Report a bug →
[ CONTRIBUTE ]
Contribute
Read the guide, pick an issue, send a patch.
Contributing guide →
Security problem? Do not open a public issue. Report it privately (see SECURITY.md).