How to build flet app named something other than "main.py" (with solution)

[gcutt]

I can create a flet app using

flet create
which produces the expected directory structure and a subdirectory "src" containing "main.py" which runs using
flet run.

I can build a windows app using

flet build windows
and it creates appdir\build\site-packages and appdir\build\windows which contains appdir.exe that runs.

I then rename "main.py" to "myapp.py" and it runs using

flet run myapp.py

However, when I try to build it using e.g.:

flet build windows [NAME]
where [NAME] is myapp, myapp.py, "C:\mypath...\appdir\src\myapp.py", or ""C:\mypath...\appdir" for example.

All of these failed with errors.

As I was writing this post, I got a set of errors that led me to the correct syntax for building a flet app for windows where the app does not use "main.py":

flet build windows --module-name myapp.py

I post this now in case that others have encountered this problem, or if I forget and need to find in in the future.

Thanks