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_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 until a final Linux device app shell owns the product path.