Show HN: Boo – screen-style terminal multiplexer built on libghostty

Coder has released Boo, a GNU Screen-style terminal multiplexer built on libghostty that parses every session's output through Ghostty's terminal emulation core to maintain exact screen state. The tool enables sessions to survive disconnects, provides a full-screen session manager, and offers agent-friendly automation primitives including send, peek, wait, and JSON output that work without a TTY.

A GNU screen style terminal multiplexer built on libghostty https://github.com/ghostty-org/ghostty libghostty-vt , written in Zig. Every session's output is parsed through Ghostty's terminal emulation core, so boo always knows the exact screen state of every session: contents, styles, cursor, scrollback, and terminal modes. That state is used to rehydrate your terminal on attach, to answer terminal queries for detached sessions, and to let scripts and AI agents read the screen exactly as a human would see it. - Sessions that survive disconnects: detach with Ctrl-A d , reattach with boo attach . - A full-screen session manager: boo ui lists sessions in a sidebar. - Faithful redraws from libghostty terminal state, including SGR styles, cursor position, scrolling regions, window title, and terminal modes. - Agent-friendly automation primitives: send , peek , wait , and --json output, all usable without a TTY. demo.mp4 For Linux and macOS: curl -fsSL https://raw.githubusercontent.com/coder/boo/main/install.sh | sh Pre-built binaries are published on the releases page https://github.com/coder/boo/releases . Set BOO VERSION to pin a release and BOO INSTALL DIR to change the install location default: /usr/local/bin when writable, otherwise ~/.local/bin . boo new new session running $SHELL, attached boo new work named session boo new work -d -- make create detached, running a command boo ui manage sessions in a full-screen UI alias: i boo ls list sessions boo attach work reattach alias: at, a boo rename work api rename a session boo kill work end a session boo kill --all end every session With no name, boo new names the session after the current directory, falling back to the process id when that name is taken or unusable. Run boo help for the full overview, boo help <command for flags and examples, and boo help --all to print every help page at once. Bindings follow GNU screen's defaults, including the C-x variants C-a C-d detaches just like C-a d . | Keys | Action | |---|---| C-a d , C-a C-d | detach | C-a l , C-a C-l | redraw | C-a a | send a literal C-a | boo ui adds additional keybinds for switching, resizing, creating sessions, and killing them. Everything except attach works without a terminal, which makes boo a natural sandbox for scripts and AI agents driving interactive programs. The canonical loop: boo new build -d -- bash 1. headless session boo send build --text 'make' --enter 2. type into it boo wait build --idle 3. let output settle boo peek build --scrollback 4. read the screen boo kill build 5. clean up Reading state : peek prints the rendered screen reconstructed from terminal state, not a raw byte log: ordered, fully redrawn, and stable. --scrollback includes history; --json adds size, cursor, and title. Waiting : wait --text <text blocks until the screen contains the text; wait --idle until output has been quiet for 2 seconds; --timeout <dur exits 4 instead of hanging forever durations: 500ms , 2s , 1m , 4h , 1d . No more sleep-and-poll loops. Sending input : send --text is literal: no escape processing, no implicit newline, no quoting layer to fight. --enter submits, --key Enter,C-c,Up names control keys, and stdin mode is binary safe. Machine-readable output : ls --json and peek --json . Exit codes : 0 success, 1 error, 2 usage error, 3 no such session, 4 wait timed out. See boo help automation for the full page. Requires Zig https://ziglang.org 0.15.2. zig build binary in zig-out/bin/boo zig build test unit tests zig build test-integration end-to-end tests on a real PTY zig build test-all everything The libghostty dependency is fetched and built from source automatically pinned in build.zig.zon . With Nix, nix develop opens a shell with the right Zig version, and nix build builds the package to ./result/bin/boo . php your terminal <- raw tty - boo client <- unix socket - session daemon - PTY + ghostty-vt Terminal - The client puts your TTY in raw mode and shuttles bytes over a framed Unix-socket protocol src/protocol.zig . - The daemon forked on session creation owns the session's command: a PTY-attached child whose output feeds a persistent ghostty-vt TerminalStream src/window.zig . - While attached, output is passed through to your terminal byte for byte. On attach the daemon sanitizes your terminal and replays the screen from libghostty state using its VT TerminalFormatter . - Terminal queries DSR, DA, XTWINOPS, ... while detached are answered by libghostty's stream handler; while attached your real terminal answers, avoiding double replies. This is a young project, not a drop-in GNU screen replacement: - One attached client per session attaching steals ; no -x sharing. - One window per session: no splits or tabs inside a session. Run one session per task and juggle them with boo ui . - The C-a prefix is not yet configurable, and pasted bytes containing 0x01 are interpreted as the prefix GNU screen has the same quirk; boo ui is immune thanks to bracketed paste . - Sessions run with TERM=xterm-256color . Feel free to open an issue https://github.com/coder/boo/issues/new if you have questions, run into bugs, or have a feature request. MIT /coder/boo/blob/main/LICENSE . Ghostty itself is MIT licensed.