6c47f8231c
Re-derived the other branch's central check with my own code, my own reading of the record and my own control, rather than accepting the number. At base chunk+0x10, with the plane at intra-record +0 and three u16 vertex indices at +32: every one of 133573 faces has all three named vertices satisfying its own plane equation. Random-vertex control 2782/400719 = 0.69%. 100% against 0.69% is not a fit. That also settles the record boundary from my side: the u16s describing a plane sit after it in the same 48-byte record, so my earlier 'four zeros at the start of each record' was those integers seen 16 bytes out of position, one record late. Two implementations, two independent guesses at the intra-record layout, the same 100%.