sequenceDiagram
    participant User
    participant KB as C64KeyboardView
    participant Main as MainActivity
    participant JNI as vice_jni.c
    participant VICE as VICE keyboard matrix

    User->>KB: touch down/up on key
    KB->>Main: onKeyEvent(key, pressed)
    Main->>JNI: engine.injectKey(code, pressed)  (per code, for composites)
    JNI->>VICE: keyboard_set_keyarr(row, col, pressed)