Herdr

Parent: Integrations.

Herdr is a terminal workspace that hosts agent panes. When Rho runs inside a Herdr pane, integration turns on by itself. You do not install a plugin, run an init command, or edit Rho config.

Herdr support is Unix-only. On other platforms Rho ignores Herdr environment variables.

What you get

Feature	Behavior
Agent state	Rho reports idle, working, and blocked so Herdr can show pane status
Session identity	Rho reports the active session id (and the attach run id in rho attach)
Subagent panes	Click a subagent row in the activity rail to open a sibling pane that runs rho attach <id>
Image paste	A single-line paste of an image path becomes an attachment instead of plain text
Image previews	Kitty placements when Herdr can paint them; halfblock fallback when host cell metrics are missing

Nothing extra is required after you start Rho under Herdr.

How Rho detects Herdr

Rho enables Herdr when all of these are true:

• the process runs on Unix
• HERDR_ENV=1
• HERDR_SOCKET_PATH is a non-empty path to Herdr's local socket
• HERDR_PANE_ID is a non-empty pane id

Herdr sets those variables for processes it launches. You normally do not set them by hand.

Rho talks to Herdr over that Unix socket with short timeouts. Failed or timed-out reports are ignored so a stuck host never blocks the session.

Agent state

Rho keeps Herdr in sync with the session:

State	When
working	A model turn or tool run is in progress, or an attached subagent is still running
blocked	Rho waits on you (approval, questionnaire), auth is missing, a goal is blocked, or an attached run failed
idle	The session is resting and not waiting on user input

On exit, Rho releases the agent marker for the pane.

Interactive sessions and rho run both report state when they detect Herdr. rho attach <id> reports state for the watched run and releases on detach.

Watch a subagent in a sibling pane

Outside Herdr, activating a subagent row copies rho attach <id> so you can paste it elsewhere.

Inside Herdr, the same action opens a sibling pane to the right and submits the attach command there. Rho prefers the current executable path so a cargo-built or downloaded binary still starts when rho is not on PATH. If the pane split fails, Rho falls back to copying the attach command.

Detaching from the attach TUI does not stop the delegated run. See attachment and artifacts.

Images and graphics

Hosts such as Herdr may paste clipboard images as a filesystem path. Rho treats a single-line paste of a PNG, JPEG, GIF, or WebP path as an image attachment. Details: attachments.

For in-feed image previews, Rho probes whether Herdr can paint Kitty placements for the pane:

• paintable host metrics → Kitty placements through Herdr
• missing metrics → halfblock preview so reserved rows are not blank

See documents and images.

Check the integration

In the interactive TUI, run /doctor. The Herdr row reports:

Status	Meaning
not configured	Rho is not running inside Herdr (healthy when you are outside Herdr)
connected	Herdr env is set and the socket accepted a connection
unreachable	Herdr env is set but the socket did not accept a connection
unavailable	Herdr is configured but reachability could not be determined

Related

• Integrations - other built-in integrations
• Interactive TUI - session UI, /doctor, and rho attach
• Subagent attachment - run artifacts and detach behavior
• Attachments - image and document paste
• Documents and images - thumbnail paint paths
• Development - use PTY tests for regressions; use Herdr for exploratory checks