Chiral superconductivity has recently been confirmed in rhombohedral tetra- and pentalayer graphene near the BCS–BEC crossover, but no theory tells the experimentalist what thermal Hall response to expect, or why any signal should persist above the phase-coherence temperature T_c. We show that the parity anomaly of (2+1)-dimensional field theory fixes the answer exactly, at all temperatures, with no free parameters: κ_xy/T = (π² k_B²/6h) C_(rm BdG) tanh[Δ(T)/(2k_BT)], where C_(rm BdG) is the BdG Chern number and Δ(T) is the fermionic excitation gap. The BCS–BEC two-gap relation Δ² = Δ_(rm sc)² + Δ_(rm pg)² makes the same formula govern both the condensate and pseudogap regimes, so the signal onsets at the pair-formation temperature T^* rather than at T_c. Coleman–Hill non-renormalization and the c₁ = 0 theorem protect this result against interactions and finite-size artefacts. Three independent numerical validations confirm the topological input at machine precision (FHS Chern numbers, Wilson-loop c₁ = 0 test) and at the many-body level (DMRG on 28 converged ground states, including the real-space p+ip signature argA_y - argAₓ = -π/2 recovered to 10⁻¹⁴). The theory delivers an immediate falsifiable test that requires no new experimental apparatus: the sign of κ_xy/T below T_c must equal the sign of the anomalous Hall resistance R_xy already measured above T_c, and four further predictions accessible by dilution-refrigerator nano-calorimetry on existing devices.