Herdr: a terminal multiplexer for coding-agent fleets
The Rust tool groups long-lived terminal sessions and flags which agent is working, blocked or waiting. Omarchy Quattro ships it alongside tmux.
In short
Herdr is an Apache-2.0 terminal multiplexer written in Rust that keeps many long-lived sessions alive and shows, per pane, whether the coding agent inside is working, blocked or waiting for input.
At a glance
- Herdr is written in Rust and licensed under Apache 2.0; the project was first released in March 2026.
- Version 0.9 is the current stable release, out on September 7, 2026; it went from 0.1 to 0.8 in under five months.
- Five agent states: working, blocked, done, idle, unknown - detected via hooks, plugins or terminal output.
- Omarchy Linux ships Herdr next to tmux in its fourth major version, Quattro; the prefix key there is Ctrl+Space.
- Y Combinator accepted the team into its fall 2026 batch, whose standard deal is 500,000 US dollars.
Run half a dozen coding agents at once and the terminal stops telling you anything useful: every pane looks busy, and nothing marks the one that stalled on a question ten minutes ago. Herdr attacks that specific gap by keeping long-lived sessions alive and attaching a state to each running agent. What follows rests on a single report, published by heise online on September 11, 2026; no second independent account was available at the time of writing.
A Rust project at version 0.9
Herdr first appeared in March 2026 and comes from founder Can Celik, whose team works out of Ankara. The code is Rust and the license is Apache 2.0. Version 0.9 is the current stable release and shipped on September 7, 2026, after a run from 0.1 to 0.8 in less than five months. Y Combinator took the team into its fall 2026 batch, whose standard deal puts 500,000 US dollars into each company.
Five states, one per agent
Terminals are arranged into workspaces, tabs and panes, with a sidebar listing the agents currently running. Each entry carries one of five states: working, blocked, done, idle or unknown. Detection happens through hooks, through plugins, or by reading what the terminal prints. The tool ships no model of its own - it launches ordinary processes and watches them.
Sessions outlive the connection
Under the hood Herdr runs as a client and a server, using PTYs on Unix and ConPTY on Windows. Drop the link and the processes keep going; reconnect and workspaces, tabs, splits and working directories come back. Version 0.9.0 added SSH support, letting several clients view different workspaces while sharing one agent list. A command line and a local socket API cover scripting, from creating panes to querying status.
Bundled with Omarchy Quattro
Omarchy Linux added the multiplexer alongside tmux in Quattro, its fourth major version. The prefix key there is Ctrl+Space, matching the distribution's existing tmux binding. David Heinemeier Hansson contributed code as well, covering window titles, pane resizing and moving tabs.
Where plain tmux still wins
Binaries exist for Linux and macOS on x86-64 and ARM64, plus Windows on x86-64, with installs via Homebrew, Nix and mise; a few features are limited on Windows. For one or two sessions you already know by name, SSH and tmux remain the sober option after two decades of hardening and packaging. Herdr earns its place once several distributed agents compete for a single person's attention. Terminal history is off by default because it can hold credentials, tokens or prompts, and the plugin marketplace is not curated - listings are collected automatically.
FAQ
What is Herdr?
A free terminal multiplexer written in Rust and licensed under Apache 2.0. It groups long-lived sessions and shows each coding agent's state: working, blocked, done, idle or unknown.
Is Herdr a tmux replacement?
No. It adds semantic agent states and notifications on top of what a multiplexer normally does. For one or two known sessions, SSH plus tmux is still the sober choice; Herdr targets distributed agent fleets.
How do you install Herdr and which platforms are supported?
Binaries cover Linux and macOS (x86-64, ARM64) and Windows (x86-64), with Homebrew, Nix and mise as install paths. Some features are limited on Windows, and Omarchy Quattro already bundles it.
