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ReasonOS is a rethink of the software development lifecycle. Instead of stitching together a build tool, a package manager, a CI system, an infrastructure tool, and an AI assistant, ReasonOS ships them as one coherent system built around a single binary: rbs.

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The pieces

The build system. rbs is a self-contained build system driven by a Python-like build language. It downloads and manages its own toolchains (Go, Node.js, Python, JVM, .NET, C/C++, and more), resolves external dependencies itself, and caches every action in a content-addressed store shared across all workspaces on your machine. You describe targets in BUILD.rbs files; rbs computes the dependency graph and builds only what changed. Branch nodes. Every active branch gets its own rbs server — a “branch node”. The ReasonOS editor connects to the node for your branch, and switching branches means connecting to a different node, not juggling checkouts. Multiple developers can join the same branch session and collaborate on it. Durable state (chats, plans, tasks) is committed to the branch in the .reasonos/ tree, so it travels through git rather than living on any one machine. The editor. The ReasonOS editor is backed entirely by the rbs server: file APIs, search, terminals, language servers configured from the build graph, and streaming AI assistance all come from the same process that builds your code. The agents. rbs agent is a coding agent that lives inside the build system. It sees the dependency graph, runs builds and tests through the same rules you do, and records its work in the branch’s committed history. Checkpoints let you revert anything it changed.

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Start here

Onboarding your organization

Claim a workspace, bring your team and code, connect AI, and open a first branch.

Quickstart

Install rbs, create a workspace, and build your first target in minutes.

Core concepts

Workspaces, packages, targets, labels, the shared cache, environments, and branch nodes.

Build commands

Build, run, test, query, and watch targets from the command line.

Languages

Hermetic toolchains and built-in rules for Go, JavaScript, Python, JVM, .NET, C/C++, and the web.

Infrastructure

Declare infrastructure in .rbs files and plan, apply, and destroy it with rbs.

Agents

The built-in coding agent: sessions, permissions, checkpoints, and MCP.

The editor

How the ReasonOS editor connects to branch nodes and what the server provides.

CLI reference

Every rbs command, flag by flag.

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Why one system?

Every seam between tools is a place where builds stop being reproducible: the compiler that is a different version on CI, the npm install that resolves differently on a teammate’s laptop, the Terraform state that only one person can apply, the AI assistant that cannot run your tests. ReasonOS removes the seams — one language describes builds, tests, CI workflows, and infrastructure; one cache makes results shareable; one server per branch makes collaboration and tooling converge on the same live state. Read Why ReasonOS for the full positioning, or jump straight to the Quickstart.