vellum-terminal-sessions

name	vellum-terminal-sessions
description	Manage persistent tmux terminal sessions: create, read, write to, list, and close named shell sessions. For Claude Code or Codex, use the ACP skill instead.
compatibility	Sandbox mode works without any host dependencies. Host mode requires tmux installed on the user's machine. Works on macOS and Linux.
metadata	{"emoji":"🖥️","author":"vellum-ai","version":"0.2","vellum":{"category":"system","display-name":"Terminal Sessions","activation-hints":["User asks about their running terminal sessions or processes","User wants to monitor a long-running command or run something in a persistent shell","User mentions tmux or terminal management","User wants to orchestrate multiple CLI processes in parallel"],"avoid-when":["Setting up, authenticating, or running Claude Code or Codex: the ACP skill owns those agents","A simple one-shot command that host_bash handles fine","The user is asking about shell scripting in general, not session management"]}}

Overview

This skill manages persistent terminal sessions via tmux. Two modes:

	Sandbox Mode	Host Mode
Where tmux runs	In the assistant's sandbox	On the user's host machine
How user connects	vellum terminal attach <session-name>	User opens their own terminal
Assistant access	Direct (bash tool)	Via host_bash
Best for	Long-running builds, servers, always-on tasks	Work needing host access (e.g. SwiftUI builds, host-local services)

Default: Use Sandbox Mode unless the task specifically requires host access. Details: sandbox-sessions.md · host-sessions.md · tmux-best-practices.md

Prerequisites

Sandbox Mode: No setup needed — tmux is available in the sandbox.

Host Mode: Requires tmux on the host — see host-sessions.md.

Workflow: Orchestrating Multiple Sessions

• List all sessions: tmux list-sessions to get names and current commands
• Read each: tmux capture-pane -t NAME -p -S -50 (30-50 lines is usually enough)
• Summarize before acting: "Build done, tests at 73%, deploy waiting for confirmation"
• Act on the user's instructions