When I click on a Stack Exchange site link from within the browser, it automatically opens in the Stack Exchange app, or asks if I want to open the link in the Stack Exchange app. But when I visit http://pt.stackoverflow.com and visit a question, the app doesn't open and the browser navigates normally.
I'm assuming the intent filter is not catching the subdomain of stackoverflow.com? I know Stack Overflow in Portuguese is a beta site. But this functionality does work on the beta sites located at *.stackexchange.com.