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Show HN: Yet another minimal and lightweight terminal multiplexer written in Go.

Developer 'hrdx' released a minimal terminal multiplexer written in Go that runs real PTY sessions for AI agent CLIs including Codex CLI, Claude Code, pi, and zot, with workspace sidebar, tabs, and session persistence. The tool supports macOS, Linux, and Windows 10 1809+ via ConPTY, offers a JSON socket API for scripting, and can be installed via curl or PowerShell. It is positioned for the 'agent era' by letting users run multiple coding agents side by side and monitor their progress with animated spinners.

read13 min views2 publishedAug 27, 2026
Show HN: Yet another minimal and lightweight terminal multiplexer written in Go.
Image: Michielbdejong (auto-discovered)

hrdx is a experimental, minimal and lightweight terminal multiplexer built for the agent era: your projects as workspaces in a sidebar, tabs per workspace, and real terminal panes running Codex CLI, Claude Code, pi, zot or plain shells side by side. Kick off an agent in one project, switch to the next, and let the sidebar spinners tell you who is still working.

Real terminals, not wrappers. Every pane is a genuine PTY session with a full terminal emulator behind it. Agent TUIs run exactly as they do standalone: streaming, slash commands, sessions, mouse support, all of it. Panes present a clean terminal identity so capability-sniffing TUIs pick rendering paths that work inside a multiplexer, andHRDX=1

lets tools detect they run inside hrdx.Everything in view. The sidebar shows one hierarchy of workspaces, Git branches, and panes, adding tab rows only when a workspace has multiple tabs. Every pane has a shared status circle: agents become animated braille spinners while working, and an unfocused agent turns orange when it finishes. Focusing the pane acknowledges it and restores green.Feels like your terminal. Scrollback, mouse selection with clipboard copy, drag-to-resize splits, drag-to-reorder workspaces, right-click context menus, and kitty keyboard protocol pass-through so even exotic chords like ctrl+1 reach your agent.Picks up where you left off. Quit and relaunch: shells and agents keep running in a lightweight session holder and reattach exactly where they were, running commands and all. Workspaces, tabs, splits, and ratios come back too, and if a session is truly gone, agents resume their latest conversation from their own session store.Yours to tune. A settings window (ctrl+b ,

or the gear in the sidebar) lets you switch individual agents on or off, pick a notification sound for finished turns (including your own audio files), and change the color theme, with user themes as simple JSON files. All persisted. SeeThemes.Bring your own agent. Register any agent CLI as a custom harness via a small JSON file, including its own busy detection for the sidebar spinner and finish sound. It shows up in pickers, cycling, and settings like the built-ins. SeeCustom harnesses.Scriptable from outside. A JSON socket API lets scripts and editors inspect workspaces and pane states, open projects, spawn panes, type into agents, wait for them to finish, read their screens, and subscribe to live events. SeeSocket API.

curl -fsSL https://www.hrdx.dev/install.sh | bash
irm https://www.hrdx.dev/install.ps1 | iex

macOS, Linux, or Windows (10 1809+ / 11, via ConPTY), plus at least one agent CLI on your PATH: codex

, claude

, pi

or zot

. Update on any supported platform with hrdx update

.

hrdx

Open several projects at once, or pick your default agent:

hrdx --cwd ~/Developer/api --cwd ~/Developer/web
hrdx --agent claude
Flag Purpose
--cwd PATH
Open a project as a workspace, repeatable
--agent ID
Default agent for new panes: zot , pi , claude , codex (default zot )
--provider ID
Pass a provider to every zot pane (zot only)
--model ID
Pass a model to every zot pane (zot only)
--reasoning LEVEL
Set the reasoning level (zot only)
--continue
Resume each project's latest session
--codex-bin PATH
Use a specific codex binary
--claude-bin PATH
Use a specific claude binary
--pi-bin PATH
Use a specific pi binary
--zot-bin PATH
Use a specific zot binary
--shell PATH
Shell for shell panes (default $SHELL ; on Windows only when resolvable, otherwise %COMSPEC% /powershell.exe )
--state PATH
State file for workspace persistence (empty disables)
--fresh
Ignore saved workspaces and start clean
--api
Serve the control API on a unix socket (default on, --api=false disables)
--persist
Keep pane processes alive across restarts via the session holder (default on)

A native Windows hrdx.exe

launched from Git Bash ignores an MSYS-only SHELL

value such as /usr/bin/bash

, which Windows cannot resolve, and falls back to %COMSPEC%

. To use Git Bash for panes, pass a native path explicitly, for example hrdx --shell "C:/Program Files/Git/bin/bash.exe"

.

All keys go to the focused terminal, except the ctrl+b

prefix (tmux style):

After ctrl+b | Action | |---|---| c or C | Split right / below (opens a picker: installed agents or shell) | a or A | Split right / below with the default agent directly | s or S | Split with a new shell pane directly (right / below), also % /\" and | /- | w | New workspace (directory prompt with tab completion, then agent/shell picker) | t | New tab in the current workspace (opens the agent/shell picker) | n or p | Next / previous tab | ] or [ | Next / previous workspace | tab or shift+tab | Next / previous pane; stays in prefix mode for repeated jumps, esc exits | / | Fuzzy finder over every workspace, tab, and pane: type to filter, arrows select, enter jumps | r | Rename the focused pane | m | Open the pane context menu | = | Equalize all splits | u or d (or pgup /pgdown ) | Scroll the focused pane's history | esc / G | Back to live output, clear selection | , | Settings window: enable / disable agents, notifications | x | Close pane (sibling takes its room) | X | Close workspace | ctrl+b | Send a literal ctrl+b to the pane | q | Quit | left / right | Scroll the hint row in the footer (narrow terminals) |

Panes whose process exits (for example exit

in a shell) close automatically; the sibling pane takes the room. Panes that fail to start stay visible with the error.

Prefix keys are remappable via a keys.json

next to the state file (~/Library/Application Support/hrdx/keys.json

on macOS, $XDG_CONFIG_HOME/hrdx/keys.json

on Linux, %AppData%\hrdx\keys.json

on Windows). It maps action names to a single key; an override replaces that action's default keys. The prefix

action remaps the ctrl+b

trigger itself, not just an action inside it:

{
  "find": "f",
  "quit": "Q",
  "agent-cycle": "g"
}

Actions: prefix

, literal

, quit

, picker-right

, picker-down

, agent-right

, agent-down

, agent-cycle

(unbound by default), shell-right

, shell-down

, workspace

, tab-new

, tab-next

, tab-prev

, space-next

, space-prev

, pane-next

, pane-prev

, find

, close-pane

, close-space

, equalize

, rename

, menu

, settings

, scroll-up

, scroll-down

, live

.

Everything is clickable: workspace, tab, and pane rows in the sidebar, the main tab bar, menus, and the settings entry at the bottom. Drag workspaces to reorder them, drag pane borders to resize, right-click for context menus, and drag with the left button to select text (copied straight to your clipboard). Wheel events go to the pane under the cursor: agent TUIs scroll themselves, shells scroll their local history, and shift+pgup

/ shift+pgdn

do the same from the keyboard.

Every pane is a real PTY, so a shell pane can connect to a remote host, Docker container, or Kubernetes workload. For an interactive shell:

ssh user@host
docker exec -it -w /workspace container-name sh
kubectl exec -it -n namespace deploy/app -- sh

An agent installed at the target can be launched directly instead:

ssh -tt user@host 'cd /path/to/project && exec codex'
docker exec -it -w /workspace container-name codex
kubectl exec -it -n namespace deploy/app -- codex

Use the same pattern for any supported or custom agent. Authentication and the agent executable, configuration, credentials, and project files must be available at the target.

To make remote and container agents appear in pickers, agent cycling, settings, and the sidebar, register their client command as a custom harness:

[
  {
    "kind": "remote-codex",
    "binary": "ssh",
    "args": ["-tt", "user@host", "cd /path/to/project && exec codex"]
  },
  {
    "kind": "docker-codex",
    "binary": "docker",
    "args": ["exec", "-it", "-w", "/workspace", "container-name", "codex"]
  },
  {
    "kind": "k8s-codex",
    "binary": "kubectl",
    "args": ["exec", "-it", "-n", "namespace", "deploy/app", "--", "codex"]
  }
]

Wrapper scripts are useful when the host, container, namespace, pod, working directory, or authentication setup is dynamic. Set the harness binary

to the wrapper path and put any fixed parameters in args

.

The session holder keeps the local SSH, Docker, or Kubernetes client process alive when hrdx restarts. It cannot keep an agent alive when its remote host, container, pod, or network connection ends, and it does not automatically reconnect. Workspace Git details are read from the local workspace path, not from the remote filesystem.

Any agent CLI beyond the built-ins can be registered by dropping a harness.json

next to the state file (~/Library/Application Support/hrdx/

on macOS, $XDG_CONFIG_HOME/hrdx/

on Linux, %AppData%\hrdx\

on Windows). Registered harnesses appear everywhere the built-ins do: in the pickers, in agent cycling, as agent panes in the sidebar hierarchy, and in the settings window for enabling and disabling.

[
  {
    "kind": "aider",
    "binary": "aider",
    "args": ["--no-auto-commits"],
    "resume": ["--restore-chat-history"],
    "busy": "Waiting for the model"
  },
  {
    "kind": "goose",
    "idle_title": "goose idle",
    "attention_title": "goose waiting"
  }
]
Field Purpose
kind
Identifier used in pickers and pane names (required, must not collide with built-ins)
binary
Executable to launch (default: same as kind )
args
Extra arguments passed on every launch
resume
Arguments that resume the latest session when a restored pane relaunches
resume_first
Put the resume args before args (for subcommands like resume --last )
busy
A substring visible on screen only while the harness is working; drives the busy spinner and the finish sound. Empty: braille spinner detection, like the built-ins
idle_title
Terminal-title substring emitted when the harness is idle; overrides a stale visible spinner
attention_title
Terminal-title substring emitted while waiting for user input; overrides the spinner and shows an orange dot when unfocused

Both title fields are optional and have no defaults, since every harness publishes its own markers. Leave them out and the harness is detected purely from the screen, exactly as busy

describes. Set them when the harness keeps a spinner on screen while it is really idle or blocked on a prompt: a matching title always outranks the screen scrape. Check what your harness emits with printf '\e]2;...\a'

-style OSC titles before picking a substring.

While hrdx runs it serves a control API on a unix socket next to the state file (hrdx.sock

), so scripts, editors, and coding agents can inspect and drive a running session. Disable with --api=false

.

The protocol is newline-delimited JSON: send one request per line, receive one response line with the same id

.

SOCK="$HOME/Library/Application Support/hrdx/hrdx.sock"   # macOS

echo '{"id": "1", "method": "status"}' | nc -U "$SOCK"
echo '{"id": "2", "method": "workspace.create", "params": {"path": "~/Developer/api", "agent": "claude"}}' | nc -U "$SOCK"
echo '{"id": "3", "method": "pane.create", "params": {"workspace": "api", "kind": "shell", "split": "down"}}' | nc -U "$SOCK"
echo '{"id": "4", "method": "pane.send_text", "params": {"pane_id": 3, "text": "run the tests", "enter": true}}' | nc -U "$SOCK"
echo '{"id": "5", "method": "pane.wait", "params": {"pane_id": 3, "until": "idle"}}' | nc -U "$SOCK"
echo '{"id": "6", "method": "pane.read", "params": {"pane_id": 3}}' | nc -U "$SOCK"
Method Effect
ping
Liveness check, returns pong
status
Workspaces, tabs, and panes with id, kind, running, and busy state
workspace.create
Open a directory as a workspace (path , optional agent )
workspace.close
Close a workspace by name or path
pane.create
Add a pane (workspace name or path, kind , split : right , down , tab )
pane.send_text
Type into a pane (pane_id , text , optional enter )
pane.read
The pane's visible screen as plain text
pane.wait
Block until a pane's agent is idle or busy (until , optional timeout_ms )
pane.close
Close a pane by id
events.subscribe
Keep the connection open and push events

Successful responses are {"id": "...", "result": {...}}

; failures are {"id": "...", "error": {"code": "not_found", "message": "..."}}

with codes not_found

, invalid_params

, unknown_method

, timeout

, and error

.

After events.subscribe

the connection stays open and hrdx pushes lines like {"event": "pane.busy_changed", "data": {"pane_id": 3, "busy": false}}

. Events: workspace.created

, workspace.closed

, pane.created

, pane.closed

, and pane.busy_changed

, so a script can react the moment an agent finishes instead of polling.

Every request is answered by the TUI's own update loop, so the API always sees exactly what is on screen. pane.wait

plus pane.send_text

is enough to build simple agent pipelines: prompt an agent, wait until it is idle, read the screen, move on.

hrdx themes are JSON files that override any subset of the built-in colors; missing values inherit the default look. Drop them into a themes/

directory next to the state file (~/Library/Application Support/hrdx/themes/

on macOS, $XDG_CONFIG_HOME/hrdx/themes/

on Linux, %AppData%\hrdx\themes\

on Windows) and pick them in the settings window's theme section. The change applies immediately and persists.

{
  "name": "neon",
  "description": "Pink accent, near-black bars.",
  "colors": {
    "accent": 201,
    "bar_bg": "#101010"
  }
}

Values are ANSI 256 color numbers or "#rrggbb"

strings.

Color Used for
accent
Focused pane frames, highlights, logo, selected items
alt
Prefix badge, behind-count in the sidebar
muted
Secondary text, hints, idle pane names
faint
Inactive pane borders, sidebar divider
good
Running dots, input badge
busy
Busy spinner and completed-work attention dot
bad
Errors, exited dots
bar_bg / bar_fg
Header and footer bars
ink
Text on accent backgrounds, tab bar strip

See examples/themes/

for a full example.

The notification section of the settings window has two independent toggles for finished agent turns: play a sound (built-in ding

and chime

, or your own audio files) and a system notification, which rings the terminal bell so your platform's native attention indicator fires: dock badge and bounce on macOS, the window manager's urgency hint on Linux, the taskbar/window attention flash on Windows Terminal (depends on its bellStyle

setting). No notification daemon or permission required. Add custom sounds with a sounds.json

next to the state file; they appear as choices and are previewed when selected:

[
  { "name": "sheep", "file": "~/sounds/maehhh.wav" },
  { "name": "gong", "file": "/Users/me/sounds/gong.aiff" }
]

name

is the label in settings (must not collide with built-ins), file

any audio file your OS player understands (afplay

on macOS, paplay

/aplay

on Linux, PowerShell's SoundPlayer

on Windows — WAV only there). Missing files are reported in the footer and skipped.

Quitting hrdx does not kill your sessions. Pane processes live in a small background process (the session holder) that hrdx starts on demand and talks to over a local socket. Close the TUI, reopen it, and every shell and agent reattaches exactly where it was: running commands keep running, scrollback and screen state are replayed, nothing restarts. The holder is the same hrdx

binary, uses no resources worth mentioning, and goes away when you kill its sessions.

Workspaces, panes, split layout, ratios, selection, and holder session ids are saved automatically (default: ~/Library/Application Support/hrdx/state.json

on macOS, $XDG_CONFIG_HOME/hrdx/state.json

on Linux, %AppData%\hrdx\state.json

on Windows). On the next launch the layout is restored and each pane reattaches to its held session. When a held session is gone (rebooted machine, killed holder), the pane starts fresh instead: shell panes get a new shell, and agent panes relaunch resuming their latest session for that directory via the agent's own session store.

--persist=false

disables the holder (panes die with the TUI, like a plain terminal). --fresh

skips restoring and cleans up now-unreferenced held sessions; --state ""

disables persistence entirely.

make check

Windows without make

on PATH

: go vet ./... && gofmt -l . && go test ./...

.

MIT

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