babysit

Wrap a command in a PTY and control it from another terminal. The command runs
in the background under a worker that owns the PTY and records its output. From
anywhere you can read the output, screenshot the screen, send input, wait for
exit, or attach interactively.

Useful for scripts and coding agents that need to drive a command they didn't
start.

$ babysit run -d --json -- make local-ci   # {"id":"ab12"}
$ babysit log -s ab12 --tail 20
$ babysit screenshot -s ab12
$ babysit wait -s ab12

babysit -- make local-ci is the interactive shorthand. For scripting, use
run -d --json and capture the id.

How it works

The command runs under a background worker that owns the PTY, logs all output,
and serves a Unix control socket. Your terminal is just attached to it, so you
can detach, re-attach, and query from other terminals.

State lives in ~/.babysit/sessions/<id>/. Set $BABYSIT_DIR (absolute path) to
change the root. status, log, and screenshot work after the worker exits;
send, key, restart, and kill need it alive.

-s <id> selects a session; there is no "most recent" fallback. Inside the
wrapped command the id is exported as $BABYSIT_SESSION_ID.

Library use (embedding)

babysit is also a library. Everything is reached through a Babysit context — an
explicit handle to a state root. The library never reads the environment to find
its root; you pass it in. ($BABYSIT_DIR is consulted only by the babysit
binary, via Babysit::from_env.)

use babysit::Babysit;

# async fn demo() -> anyhow::Result<()> {
let bs = Babysit::new("/path/to/state"); // explicit root, no env
let id = /* spawn */ "job".to_string();
for s in bs.list_sessions().await? {
    println!("{} {}", s.id, s.state);
}
bs.kill(Some(id), false).await?;
# Ok(()) }

Embedders (e.g. looop) compute their own
root and call Babysit::new, so a babysit-backed tool never has to touch
$BABYSIT_DIR or share the global ~/.babysit.

Install

Pick one.

From crates.io:

cargo install babysit

With Nix flakes:

nix profile install github:yusukeshib/babysit

Prebuilt binary via the install script:

curl -fsSL https://raw.githubusercontent.com/yusukeshib/babysit/main/install.sh | sh

The install script drops a prebuilt binary in ~/.local/bin (override with
BABYSIT_INSTALL_DIR, pin with BABYSIT_VERSION). babysit upgrade
self-updates cargo/binary installs; Nix installs are managed by Nix.

Run without installing: nix run github:yusukeshib/babysit -- -- make local-ci.

Subcommands

Each command documents its own flags and gotchas: babysit help <command>.
babysit --help covers the model and the typical agent loop.

Build from source

cargo build --release   # target/release/babysit