SPINE All phases, positions, seasons, and eclipse times computed from the JPL DE421 ephemeris (Skyfield). Times UT. Regulus gate separations are apparent geocentric ecliptic longitudes; node positions given for the true (osculating) node.1
SCAFFOLD The reckoning rule — Month N opens at the Nth full moon after the vernal equinox; Day 1 is the UT date of the opening full moon — is a construction, not a discovery. Under it, every lunar eclipse is a month-opener and every solar eclipse falls mid-month by definition. Consistent-with is never proven-by.