1. Locate current position

All cmux commands need --socket /tmp/cmux.sock and dangerouslyDisableSandbox: true.

1. Locate current position

cmux --socket /tmp/cmux.sock identify    # note workspace:N

2. Open panes

cmux --socket /tmp/cmux.sock new-pane right --workspace workspace:N
# → OK surface:X pane:Y workspace:N

Save surface:X — that's the ref for all send/read/close commands. Open all panes before starting Claude in any of them.

3. Start Claude

cmux --socket /tmp/cmux.sock send --surface surface:X "claude"
cmux --socket /tmp/cmux.sock send-key --surface surface:X "Return"
sleep 6
cmux --socket /tmp/cmux.sock read-screen --surface surface:X --lines 4

Confirm ❯ prompt before sending tasks. Never put \n in send strings — always use a separate send-key Return.

4. Write prompts to temp files

cat > /tmp/agent1.txt << 'END'
Task description here. No escaping needed.
END

Always use temp files — inline strings break on backticks, $, and special chars.

5. Send prompts

cmux --socket /tmp/cmux.sock send --surface surface:X "$(cat /tmp/agent1.txt)"
cmux --socket /tmp/cmux.sock send-key --surface surface:X "Return"

Send all agents before polling — they run in parallel.

6. Poll and unblock

cmux --socket /tmp/cmux.sock read-screen --surface surface:X --lines 12

Poll early, then regularly: Agents often hit permission prompts within the first 15–30 seconds of running (e.g., reading from /tmp/, shell command warnings). Poll at ~15s after sending the prompt, then again at 30s if needed, before settling into 60–120s intervals. Missing early prompts stalls all agents simultaneously.

Poll every 60–120s after the initial burst. Agents pause on file-write permission prompts:

 Do you want to create file.py?
 ❯ 1. Yes
   2. Yes, allow all edits during this session

Unblock with send "2" — not send-key "2" (send-key fails on menu selections):

cmux --socket /tmp/cmux.sock send --surface surface:X "2"

Done when screen shows Worked for Xm Xs or idle ❯ with no spinner.

7. Verify and close

ls path/to/expected/output/
cmux --socket /tmp/cmux.sock close-surface --surface surface:X

---

For agent isolation decisions → /cmux-agents-isolation For writing effective subagent prompts → /cmux-agents-prompts