Talk to your shell. Commands run in your shell, and questions go to the AI coding tool you already use.
? what files are here answered by your AI tool
$ ls -la runs in your shell
curl -fsSL https://lacy.sh/install | bashOther methods
npx lacy
brew install lacymorrow/tap/lacyThe installer fetches the latest release and asks at most one question. With one AI tool installed it asks nothing. It asks which to use if you have several, and offers to install lash if you have none. Open a new terminal when it's done.
Lacy runs in zsh, Bash 4+ and fish on macOS, Linux and WSL. It works with lash, claude, opencode, gemini, codex, hermes, copilot, goose, amp, aider, or a command you choose.
Lacy picks a destination when you press Enter. That step doesn't use AI: it checks word lists and whether the first word is a command.
| Input | Goes to | Why |
|---|---|---|
ls -la |
shell | ls is a command |
what files are here |
agent | starts with a question word |
fix the bug |
agent | several words, and fix is not a command |
do we have a way to uninstall? |
agent | do is never a command on its own |
!rm -rf node_modules |
shell | ! sends the line to the shell |
@ make sure the tests pass |
agent | @ sends the line to the agent |
In zsh, a mark after your prompt shows where the line will go as you type: $ for the shell, ? for the agent. In Bash and fish the prompt shows the current mode.
Sometimes a real command gets a sentence for arguments, like make sure the tests pass. It runs in the shell, and if it fails, Lacy suggests @ make sure the tests pass as your next line. zsh shows that as gray text (Right arrow or Tab takes it, Enter sends it). Bash prints it above the prompt. Nothing goes to the agent until you send it.
Questions asked from zsh or Bash carry what changed since your last one: directory, git branch, recent commands, the last exit code, and the visible terminal output in tmux, screen, iTerm2 and Terminal.app.
| Command | What it does |
|---|---|
mode shell|agent|auto |
Send everything to the shell, to the agent, or decide per line (default) |
Ctrl+Space |
Switch mode |
tool set <name> |
Pick the AI tool and save it to the config |
ask "question" |
Send a question to the agent |
/new, /resume |
Start a new conversation, or resume the last one |
quit |
Turn Lacy off. The shell keeps running |
exit |
Exit the shell, as usual |
Fish supports mode, ask, quit and Ctrl+Space.
Outside the shell, the lacy command handles setup and maintenance: lacy doctor, lacy update, lacy setup, lacy logs. Run lacy help for the full list.
Settings live in ~/.lacy/config.yaml:
agent_tools:
active: claude # leave empty to use the first tool found
modes:
default: auto # shell, agent, or autoThe full reference, including the query log, spinner style, terminal context, environment variables and NO_COLOR, is in docs/DOCS.md.
Lacy sends anonymous events on install, update, uninstall and first load (install method, OS, architecture, shell, version). Set DO_NOT_TRACK=1 to turn them off.
lacy uninstallOr npx lacy --uninstall, or curl -fsSL https://lacy.sh/install | bash -s -- --uninstall.
Start with lacy doctor. It checks the install, your shell config and the AI tool, and exits 1 if something is wrong.
- A command went to the agent: start the line with
!, or runmode shell. - A question went to the shell: start the line with
@.
FSL-1.1-MIT. To contribute, see CONTRIBUTING.md.