Just as an extra note: there are manual testing steps (and automated end-to-end test, and internal alpha test, etc), independent of whether the diff was Piranha- or developer-authored, but all those happen for the continuous delivery internal version of the app, which is after the diff has been landed to master, but before a release is sent to app stores. We would count an issue discovered there as an outage having made past "our tests", even though it could well be caught before it gets to any external users.