| 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
