I know "minimal terminal email client in golang" sounds like a small feat, but it is not simpler than a webapp, it would be about equivalent, at least.

TUI libraries are more of a PITA than HTML. Also you gotta learn the entire API of a specific TUI library to make it work, this learning will never be useful to you again. With HTML at least you know it is a standard.

And remember, they told me:

> We always have a lot of candidates, some they do the basic, some provide a lot of extra features [...] From hiring point of view, we prefer stronger assessments.

and the instructions mention:

> Do the project in a way that shows off your skills as a developer

The instructions also mention "web app" as a valid solution, literally.

So why should I conclude that making the minimal effort would give me a better chance as an applicant?

There is simply no rhyme or reason to the entire process and communication from the company.