I will be using Subplot to document the requirements and acceptance criteria for sshca, and for automating the verification that they are met. The approach in Subplot is to write semi-formal scenarios that get translated into code, using functions that implement each scenario step. I can choose between the Python and Rust languages for writing those scenarios. I choose Rust, because it allows more concurrency when the verification code is running, and also I find I can write correct code more easily in Rust than in Python.

The only reason to choose Python would be to make the step functions be more easily audited by people other than me, but I think Rust has already become sufficiently popular that Rust will not be a problem. It's more important that the actual requirements, acceptance criteria, and the scenarios are understood by anyone interested.

The actual code for sshca will be written in Rust in any case.