She replayed the trip in her head: user-space pushes data -> kernel constructs buffer -> checksum appended -> DMA queued to controller -> controller executes write to flash -> readback verification. At which point in that elegant pipeline could bits change their minds?
Simple. Precise. Absolutely lethal.
The log told the story in one cold line, repeated every few seconds like a heartbeat out of rhythm: checksum error writing buffer kess v2