Custom reporter with test metadata

[gorru]

Hi all.
I'm trying to create a custom reporter that generate an xml with some metadata retrieved from tests.
It seems that the Allure reporter do something similar to what I need so I tried to implement the same solution, adding to global an object instance with some method to input metadata from tests code.

It doesn't work: reporter global seems different then testsuite global during test execution (cypress run command from command line)
After reading a lot of issues I found this issue
that refers to the cypress open execution style.
Trying the same approach I get an error (window is not defined in the reporter code.

Which is the best way to share data between reporters and tests?
I also noticed that reports are not available in cypress open execution mode, Is this correct?