Cmux

@luisurrutia/opencode-cmux is an OpenCode plugin that shows OpenCode activity in the current cmux workspace. It updates the cmux sidebar with session status, progress, tool activity, file edits, todos, questions, permission waits, notifications, and git branch state.

The plugin is quiet outside cmux. If CMUX_WORKSPACE_ID is missing, it returns no hooks and does nothing.

At a glance

Package	@luisurrutia/opencode-cmux
Runtime	OpenCode plugin loaded by Bun
Target	Current cmux workspace/sidebar
Transport	Auto-selects cmux socket, falls back to CLI
Main signals	waiting, question, working, error, done
Extras	Tool activity, subagents, todos, file edits, git branch state

Requirements

• OpenCode with plugin support.
• cmux installed and available as cmux, unless OPENCODE_CMUX_BIN points somewhere else.
• OpenCode running inside a cmux managed terminal, so CMUX_WORKSPACE_ID is set.
• Bun >=1.3.4 for local development.

Install from npm

Add the package to your OpenCode config:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["@luisurrutia/opencode-cmux"]
}

The npm package is @luisurrutia/opencode-cmux. Its module entry is dist/index.js, and the published files include dist, README.md, LICENSE, and docs/assets.

Local development install

Build the plugin first:

bun run build

Then point OpenCode at the built file with an absolute file:// URL:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["file:///absolute/path/to/opencode-cmux/dist/index.js"]
}

Rebuild after changing src/* files.

How it works

The core flow is:

OpenCode hooks -> normalizeEvent() -> CmuxStateCoordinator -> cmux socket/CLI

OpenCode emits hook events. The plugin normalizes those raw events, updates a small state machine, then renders the current state to cmux.

The main sidebar status uses this priority order:

1. Permission request pending: waiting
2. Question pending: question
3. Primary session busy: working
4. Primary session error: error
5. Primary session idle: done

Only one main status wins at a time per OpenCode surface. Tool and subagent counts are folded into that surface's working status instead of rendering separate pills.

Progress is an estimate based on tool calls, elapsed time, and todos. It is throttled, never moves backward during a session, and never reaches 1.0 until the primary session goes idle. Sidebar renders are throttled, so updates are near live but not every raw event becomes a separate cmux call.

cmux status pills are keyed per OpenCode surface, so multiple OpenCode terminals in one cmux workspace can show separate working or done pills. Progress, logs, and git branch metadata are workspace-level cmux resources, so they are shared by all OpenCode terminals in that workspace. To avoid wiping another terminal's live progress, the plugin does not clear the shared progress bar during local cleanup; it only clears after rendering primary completion at 100%.

When git integration is enabled, the plugin reports branch and dirty state during initialization and after OpenCode runs git commands through the bash tool.

Transport behavior

OPENCODE_CMUX_TRANSPORT controls how the plugin talks to cmux:

• auto, the default, uses the socket when available and falls back to the cmux CLI when it is not.
• socket uses the socket when it exists. If no socket exists, it logs a warning and falls back to the CLI.
• cli always calls the cmux binary.

Socket discovery checks CMUX_SOCKET_PATH, then CMUX_SOCKET, then platform and user candidates such as the cmux app socket and /tmp/cmux.sock.

The socket path uses two protocols because cmux exposes two command shapes. Sidebar commands use the text socket protocol. Notification writes use JSON requests with method and params, such as notification.create.

Configuration

All configuration uses environment variables.

Boolean values accept 1, true, yes, and on for true. They accept 0, false, no, and off for false. Invalid values fall back to the default.

Variable	Default	Description
OPENCODE_CMUX_BIN	cmux	cmux executable used by CLI transport.
OPENCODE_CMUX_STATUS_KEY	opencode	Base sidebar status key. Per-surface statuses and legacy cleanup keys use this as a prefix.
OPENCODE_CMUX_TRANSPORT	auto	auto, socket, or cli.
OPENCODE_CMUX_NOTIFY_SUBAGENTS	false	Send desktop notifications for subagent completion and errors.
OPENCODE_CMUX_LOG_SUBAGENTS	true	Log subagent lifecycle events in the sidebar.
OPENCODE_CMUX_PROGRESS	true	Show the cmux progress bar while work is active or waiting.
OPENCODE_CMUX_KEEP_DONE_STATUS	true	Keep the done status visible when the primary session goes idle.
OPENCODE_CMUX_NOTIFY_QUESTIONS	true	Send desktop notifications when OpenCode asks a question.
OPENCODE_CMUX_NOTIFY_PERMISSIONS	true	Send desktop notifications when OpenCode asks for permission.
OPENCODE_CMUX_LOG_TOOLS	true	Log tool start and finish events in the sidebar.
OPENCODE_CMUX_LOG_TOOLS_VERBOSE	false	Include tool arguments in sidebar tool logs.
OPENCODE_CMUX_LOG_FILE_EDITS	true	Log edited files in the sidebar.
OPENCODE_CMUX_LOG_SESSION_LIFECYCLE	true	Log session start, delete, and compaction events.
OPENCODE_CMUX_LOG_TODOS	true	Log todo completion counts.
OPENCODE_CMUX_GIT	true	Report git branch and dirty state to cmux.
OPENCODE_CMUX_STALE_TIMEOUT	0	Milliseconds before a stuck working state is cleared. 0 disables it.
OPENCODE_CMUX_DONE_TIMEOUT	10000	Milliseconds before the done status auto clears when KEEP_DONE_STATUS=true. 0 disables auto clear.

Troubleshooting

Nothing shows up in cmux

Check that OpenCode is running inside cmux and that CMUX_WORKSPACE_ID is set. Without that variable, the plugin disables itself and returns no hooks.

The socket is not used

Use OPENCODE_CMUX_TRANSPORT=auto unless you are debugging. In auto, the plugin silently uses the CLI when no socket is found. If you force socket and no socket exists, the plugin warns and falls back to the CLI.

If needed, set CMUX_SOCKET_PATH or CMUX_SOCKET to the socket path exposed by your cmux session.

Sidebar updates affect the wrong tab

Socket mode targets the cmux workspace for sidebar metadata and uses CMUX_SURFACE_ID in the status key so separate OpenCode terminals do not overwrite each other's status pill. If cmux does not expose CMUX_SURFACE_ID, the plugin falls back to project/session/process details, but stale status cleanup is less precise.

Status stays on working

OpenCode normally sends an idle event when a primary session ends. If that event is missed, set OPENCODE_CMUX_STALE_TIMEOUT to a positive number of milliseconds so the plugin can clear a stuck working state after no events arrive.

Done disappears too quickly or never clears

OPENCODE_CMUX_KEEP_DONE_STATUS=true keeps done visible after idle. OPENCODE_CMUX_DONE_TIMEOUT=10000 clears it after 10 seconds by default. Set OPENCODE_CMUX_DONE_TIMEOUT=0 to keep it until the next session or cleanup.

Too many sidebar logs

Turn off specific log groups with OPENCODE_CMUX_LOG_TOOLS=false, OPENCODE_CMUX_LOG_FILE_EDITS=false, OPENCODE_CMUX_LOG_SUBAGENTS=false, OPENCODE_CMUX_LOG_SESSION_LIFECYCLE=false, or OPENCODE_CMUX_LOG_TODOS=false.

Development

Useful commands:

bun test
bun run build
bun run check
npm pack --dry-run

Package scripts:

• bun run build builds src/index.ts into dist/index.js.
• bun test runs the test suite.
• bun run check runs tests and then builds.

Before release work, run bun test, bun run build, and npm pack --dry-run to confirm the package contains the built entrypoint and published files.

Attribution

This project is forked from Attamusc/opencode-cmux. This fork keeps the same core idea and extends the package for the workflow documented above.