spawn

Spawn — New Claude Session in cmux Tab

Spawn a new Claude Code session as a terminal tab within the current cmux workspace. Useful for side tasks unrelated to the current conversation.

Prerequisites Check

Before spawning, verify the cmux environment with a single Bash call:

[ -S "${CMUX_SOCKET_PATH:-/tmp/cmux.sock}" ] && [ -n "${CMUX_WORKSPACE_ID}" ] && echo "OK" || echo "FAIL"

If the check fails, report the error in the user's language and stop:

• No socket → "cmux가 실행 중이 아닙니다. cmux를 먼저 시작하세요."
• No CMUX_WORKSPACE_ID → "cmux 워크스페이스 환경이 아닙니다. cmux 터미널에서 실행하세요."

Execution Flow

The argument string passed to this skill is the prompt for the new session. If no argument is provided, open a blank Claude session.

Step 1: Create a new terminal tab

cmux new-surface --type terminal --workspace "$CMUX_WORKSPACE_ID"

Capture the surface ID from stdout for use in the next step.

Step 2: Send the launch command

cmux send interprets \\n as a newline (Enter key). Use this to submit the command.

Without prompt:

cmux send --surface "<surface-id>" "cd $PWD && claude\\n"

With prompt:

Escape single quotes in the user's prompt as '\\'' before interpolation:

cmux send --surface "<surface-id>" "cd $PWD && claude --prompt '<escaped-prompt>'\\n"

Argument Parsing

The full argument string is treated as the prompt. No flags in v0.1.

Future versions may support flags like --split, --model, --workspace — parse these before the prompt string when added.

Output

After successful spawn, report:

• 새 탭이 생성되었음을 확인
• surface ID 표시
• 프롬프트가 전달되었으면 해당 내용 언급

Error Handling

• cmux new-surface 실패 시: cmux 에러 메시지를 그대로 전달
• cmux send 실패 시: 탭은 생성되었으나 명령어 전송에 실패했음을 알리고, 직접 입력을 안내