amux vs GNU Screen

amux is a terminal multiplexer for shared workflows in which people use keybindings and agents use CLI commands in the same panes. Users can create and arrange panes, manage windows, zoom panes, and broadcast keystrokes to multiple panes. Its CLI offers structured JSON session capture, blocking waits, and push-based events without requiring an SDK or language-specific library. Pane history stays on the server and can survive detach and reattach, server reload, and crash recovery; the default scrollback is 5,000 lines per pane. A built-in mailbox lets panes send, read, reply to, and acknowledge messages, with recipients checking an inbox instead of receiving automatic PTY input. An optional local MCP server over stdio exposes mailbox tools. Remote panes and windows can be mirrored over SSH, forwarding input and streaming remote PTY output. The repository documents Claude Code and Codex integrations, including mailbox-drain hook recipes. amux is MIT licensed and free, with installation through a shell script, Homebrew, or go install. The first server start installs a terminfo entry and requires ncurses tic. It runs on Linux and macOS, but does not implement every tmux feature, including session groups and advanced hooks.

GNU Screen has no write-up on Specifiction yet; its figures are above.