What was done
Claude read the upstream driver, wrote USB probes and found six missing commands, giving a libfprint patch with working login.
lainff got the MicroArray MAFP 3274:8004 fingerprint sensor working on Linux. The upstream libfprint driver attached to it but failed silently. The README says the reverse engineering, patch and probe scripts were produced with Claude in Claude Code, and every finding was confirmed on the sensor.
How it was done
Claude read the upstream driver, formed hypotheses, wrote pyusb probe scripts and interpreted the device's answers. The sensor runs a reduced firmware with six missing commands and some odd behaviour: one command must be called explicitly, and another destroys feature buffers. Several confident explanations proved wrong and are kept in the notes.
Results
The patch against libfprint master gives enrol, verify and fingerprint login through fprintd and PAM, tested on Debian 13 with KDE Plasma. The repo includes a protocol table and the probes. It is LGPL 2.1 or later.