During the migration period, the root-level platformio.ini and current root build flow remain authoritative for the Arduino/PlatformIO targets. The directories here define the target structure we are converging toward.

For Linux bring-up:

apps/linux_cardputer_zero is the Cardputer Zero portable Linux device app shell. It owns the cardputerzero product target boundary and selects the cardputer_compact UX pack while framebuffer, evdev, launch, and packaging validation remain pending.
apps/linux_sim_shell is the final simulator and developer-tooling app shell.
apps/linux_uconsole_gtk is the final GTK/uConsole app shell.
removed root linux_sim and removed root linux_uconsole are transitional historical roots that may be reached only through declared compatibility adapters.
removed root linux_rpi remains a historical bring-up root and must not be treated as the Cardputer Zero product app shell.