Relationship Charts (Composite & Davison) (關係合盤（組合盤與戴維森盤）)

Relationship charts — two techniques that read a RELATIONSHIP as an entity in its own right, complementing synastry (which compares two separate charts). The COMPOSITE chart sets every point to the circular midpoint of the two people's same point (composite Sun = the midpoint of the two Suns, …) — a symbolic 'third chart' (Robert Hand, Planets in Composite, 1975). The DAVISON chart is a REAL chart cast for the midpoint in TIME (the mean of the two birth instants) and in SPACE (the great-circle midpoint of the two birthplaces), so its angles are unambiguous. From two births it returns the composite planets + Ascendant (BOTH the midpoint method and Hand's derived reference-place method) + Midheaven + internal aspects + a transparent 0–100 ease tally, and the Davison chart's virtual birth moment (UT), midpoint place, planets, real Ascendant/Midheaven and aspects. Tropical, geocentric, 10 planets + North Node, on the shared Meeus ephemeris. Honest: a symbolic reflection on a bond, NOT a predictor of whether it lasts; the composite Ascendant is method-dependent (both given); the Davison angles need both birth times & places. Verified by the defining invariants — composite points equal the independently-computed near-arc midpoints, and the Davison instant is the mean of the two births.

Cost: 6 TIAN Points per call. tRPC procedure composite.chart.