The #765 guard against shutdown-time data wipes skipped any AMS update
with power_on_flag=False, but some X1C firmware emits power_on_flag=False
while idle with tray_exist_bits still reflecting the real slot inventory.
Older firmware (01.08.02.00) doesn't emit per-tray state=9/10 events, so
the bitfield path is the only signal — muting it left spool removals
undetected until a manual reconnect.
Narrow the skip to the exact shutdown pattern: zero bits AND
power_on_flag=False. Non-zero bits with power_on_flag=False are now
applied. The #765 shutdown protection is preserved (its regression test
uses tray_exist_bits='0' and still passes); newer firmwares are
unaffected because their per-tray state path catches the removal first.
maziggy
7aa5ff0156