cmux — AI Native Terminal Multiplexer Skill by [ara.so](https://ara.so) — Daily 2026 Skills collection cmux is a terminal multiplexer with a programmable socket API designed for AI coding agents. It provides full Playwright equivalent browser automation, real time terminal split management, sidebar status reporting, and agent team coordination — all via a simple CLI. What cmux Does Terminal splits — create side by side or stacked panes, send commands, capture output Browser automation — full headless Chromium with snapshot based element refs (no CSS selectors) Status sidebar — live progress bars, log messages, and icon badges visible to the user Notifications — native OS notifications from agent workflows Agent teams — coordinate parallel subagents, each with their own visible split Orient Yourself Environment variables set automatically: $CMUX SURFACE ID — your current surface ref $CMUX WORKSPACE ID — your current workspace ref Handles use short refs: surface:N , pane:N , workspace:N , window:N . Terminal Splits Create splits Always capture the returned surface ref : Send commands and read output Golden rule: never steal focus. Always use surface targeting. Worker split pattern Pane management Browser Automation cmux embeds a full headless Chromium engine with a Playwright style API. No external Chrome required. Every command targets a browser surface by ref. Workflow pattern Open and navigate Capture the surface ref: Snapshot and element refs Instead of CSS selectors, snapshot to get stable element refs ( e1 , e2 , ...): Refs are invalidated after DOM mutations — always re snapshot after navigation or clicks. Use snapshot after to auto get a fresh snapshot: Interact with elements Wait for state Read page content Locators (Playwright style) JavaScript evaluation Frames and dialogs Cookies, storage, and state Authentication flow Diagnostics Script and style injection Sidebar Status and Progress Show live status to the user without interrupting their flow: Notifications Agent Teams with cmux Use cmux splits to give each agent teammate a visible workspace. Coordinate via SendMessage and task lists — never via reading each other's terminal output. The pattern 1. Create splits for each teammate 2. Spawn teammates via Agent tool — pass each their cmux surface ref 3. Teammates run commands in their split via cmux send surface 4. Teammates report status via cmux set status and cmux log 5. User sees all work side by side Example: 3 agent team Then in each teammate's prompt: Mixed layout: terminals + browsers Key rules Never spawn claude p in splits — use the Agent tool with team name instead Create splits before spawning teammates — pass refs in their prompts One split per teammate — each owns their visible workspace Coordinate via SendMessage , not by reading each other's terminal output Clean up : cmux close surface surface <ref when done Quick Reference Task Command Where am I? cmux identify json Split right cmux json new split right Split down cmux json new split down Send command cmux send surface surface <ref "cmd\n" Read output cmux capture pane surface <ref Open browser cmux json browser open <url Page snapshot cmux browser <ref snapshot interactive Click element cmux browser <ref click e1 Fill input cmux browser <ref fill e1 "text" Wait for load cmux browser <ref wait load state complete timeout ms 15000 Read page text cmux browser <ref get text body Evaluate JS cmux browser <ref eval "expression" Find by role cmux browser <ref find role button Save auth cmux browser <ref state save ./auth.json Load auth cmux browser <ref state load ./auth.json Set status cmux set status <key "text" icon <name Progress bar cmux set progress 0.5 label "Working..." Log message cmux log "message" Notify cmux notify title "T" body "B" Close split cmux close surface surface <ref Screenshot cmux browser <ref screenshot Common Patterns Run build in background split, tail logs QA test flow Status driven long task

cmux-terminal-multiplexer