IDE-style autocomplete for the terminal. Part of Domus.
A sill is the ledge at the bottom of a window or door, the threshold that holds what comes next. As you type a command in Terminal, iTerm2, or VS Code, Sill shows a popup at your cursor with what can come next: subcommands, options, files, branches, each with a short description. ↑↓ choose, Tab or Return inserts, Esc dismisses (and then Return runs your command as usual).
A one-line zsh integration (installed from the app, removable in Settings,
~/.zshrc is backed up first) streams the command line you're editing to
the app over a local socket. Sill parses it against completion definitions
for hundreds of CLIs from the open-source
withfig/autocomplete corpus
(downloaded on first run, refreshed daily), and inserts your choice through
the same shell integration, nothing types keystrokes on your behalf.
Dynamic suggestions (git branches, npm scripts) come from short shell commands the completion definitions specify, run locally in the session's working directory with a timeout.
The upstream corpus stopped updating in 2025, so Sill layers its own
definitions on top (Specs/overrides) and, if you
turn it on in Settings, learns commands the corpus doesn't know from their
own --help output: the program is run once, in the background, with a
quiet environment and a timeout, and what it prints is kept as a local
definition on your Mac. Only real programs are run, a shell script found in
your PATH is never executed for this.
Steering keys (Tab, arrows, Return, Esc) are handled by the same shell integration, as line-editor bindings active only while the popup is on screen, nothing observes the keyboard at the system level, so they work even with Secure Keyboard Entry enabled. Sill needs the Accessibility permission for one thing: finding the caret's position on screen to place the popup.
- zsh only, in Terminal.app, iTerm2, VS Code's integrated terminal, Ghostty and cmux, for now. Ghostty and cmux expose no caret to accessibility, so the popup is placed from the cell grid the terminal reports, a nudge off when the prompt uses glyphs whose width the shell misjudges.
- Over ssh, inside tmux, and in full-screen TUIs Sill stays out of the way automatically.
./Scripts/dev.sh # rebuild-and-relaunch loop
./Scripts/test.sh # unit tests
./Scripts/bundle.sh # assemble build/Sill.app
./Scripts/build-specs.sh # rebuild the completion-spec bundleRequires macOS 26 or later.
MIT, see LICENSE. Bundled third-party software and its licenses are listed in THIRD-PARTY-NOTICES.md.
Completion definitions come from Fig's open-source withfig/autocomplete corpus; see the notices for its license.