The #2 audit (BT_CTRLMAP_LOG) proves the Eng-page button->msg-3 route was always
authored (121-mapping L4 ControlMappingsList, ~a dozen EVENT msg 0x3 entries;
weapons via Eng-page aux elem 0x21 mask-gated per ModeMFD page). It was "silently
dead" ONLY for lack of the id-3 handler, which the prior commit wired -- so coolant
priority via the MFD "Display -> Coolant" button now works end-to-end. (The
mask-0xffffffff msg-3 entries at 0x12/0x14 go to ThermalSight/Searchlight on the
PowerWatcher branch -- separate, untouched, no collision.)
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>