`HidD_GetFeature`/`HidD_SetFeature` reject any buffer shorter than the
collection's `FeatureReportByteLength`, and the proof hardcoded 64. That held
only because every pad enumerated with the DualSense descriptor; a Deck that
enumerates as a Deck reports 65 (its one feature report is unnumbered and 64
bytes wide, plus the report-id slot Windows always reserves), so both calls
would have failed, the proof with them, and — the gate being fail-closed — the
pad would never receive its DATA section at all.
Take the length from the descriptor, and accept the Deck's reply at either
offset 0 or 1: one driver binary serves four identities and Windows places an
unnumbered report's payload behind the report-id slot.
An answer must also VALIDATE, not merely parse. `from_feature_report`
reinterprets any 17 bytes, and a Deck serves its one unnumbered feature report
for *any* requested id — so it answers the PS `0x85` probe with Steam attribute
bytes that parse into a proof and fail on magic. Returning that first answer
stopped the search while the real proof sat one transport away.
enricobuehler
98147fb89c