guidance_calc.dll (current, v3, correct) guidance_calc_legacy.dll (v2, timestamped yesterday at 3:17 AM)

The wrong DLL was physically present. The loader, following its ancient, stubborn rules, found a file matching the requested name and loaded it without checking version or content. The v2 DLL exported guidance.calc , yes—but with different parameter alignment and a fatal overflow bug in the horizon sensor fusion routine.

Loaded C:\sys\lib\guidance_calc_legacy.dll — Version 2.1.4 (Build 0)

She had less than ten minutes.