Cmux

If you're orchestrating parallel tasks or subagents in Claude Code, this gives you programmatic control over terminal splits, command execution, and output capture. It's a Unix socket CLI for managing panes, surfaces, and workspaces, so you can spawn a split, send commands with `cmux send`, read results with `read-screen`, and clean up when done. The gotcha that'll bite you: `send` doesn't press Enter, and `read-screen` without `--scrollback` only shows what's visible, not what scrolled off. Most useful when you need isolated terminal environments for concurrent operations rather than just running shell commands in your current terminal.