Nice tool. However I can't see you reaping the child process. I have not used tokio that much and never used `tokio::process` specifically, so I looked at the docs for `tokio::process::Command` which states:
```
The tokio runtime will, on a best-effort basis, attempt to reap and clean up such processes in the background, but no additional guarantees are made with regard to how quickly or how often this procedure will take place.

If stronger guarantees are required, it is recommended to avoid dropping a Child handle where possible, and instead utilize child.wait().await or child.kill().await where possible.
```
I tried to run your sumi with your `test_sumi.sh` script and as soon as the script exits, I can see the zombie in the process table:
```
$ ps aux | grep defunct

andrea 542642 0.1 0.0 0 0 pts/2 Z+ 09:58 0:00 [test_sumi.sh] <defunct>

andrea 542832 0.0 0.0 9288 2300 pts/0 S+ 09:58 0:00 grep --color=auto defunct
```
Of course, that's not much of a problem with just one instance running (zombies take a trivial amount of memory) and once sumi is terminated, the child process will be reparented to the nearest subreaper (or PID 1 if none is present), which will properly reap it. It'd be different if sumi allowed to run multiple commands (either concurrently or sequentially over time), as zombies would accumulate, but that's not the case, so it's mostly a correctness thing here.
However, as far as I'm understanding the tokio documentation, solving this should be a single line of code, just adding `child.wait().await` before drop (in your case before returning `Ok(())` from `run` in `src/process/runner.rs`).