A running mistakes log from an agent-built STM32C071 board with USB-C firmware upload: M57, a peg slot keep-out drawn across the slot because the long axis came from the footprint file at rotation 0, not the placed board; M58, a firmware update path no user could reach, since the coin cell never powers the board down and the planned jump would carry a running watchdog into ROM DFU; M59, a CRLF parts catalogue rewritten whole by Python's csv module. Every one is a context gap between layout, firmware and the real device.