Einstein + Bridge: Backreaction and H^1_causal

This paper is the first paper after Synthesis II. In 2026a (Ch. 124), we proved no unital map T → E for H = S^1. In 2026b (Ch. 125), we generalized to the triple (dim H^n, dim C^n, 1). In 2026c (Ch. 138), we defined the Bridge Conjecture. In 2026d (Ch. 139), we proved the eraser must be CPTP. In 2026e (Ch. 140), we proved all four follow from one Unifier Axiom: [x,y] = 1. In 2026f (Ch. 141), we categorified H. In 2026g (Ch. 142), we proved the Unifier survives in characteristic p. In 2026h (Ch. 143), we proved it survives for infinite H. In 2026i (Ch. 144), we gave the lab falsifier D^2 + V^2 ≤ 1. In 2026j (Ch. 145), we proved the nine papers are one theorem. In 2026k (Ch. 146), we proved the Unifier survives for any A with [x,y] = 1. In 2026l (Ch. 147), we constructed H(M) for M Lorentzian. In 2026m (Ch. 148), we defined causal homotopy, π1^causal, and H1^causal. In 2026n (Ch. 149), we defined H^n_causal(H(M)) for all n. In 2026o (Ch. 150), we proved the fourteen papers are one theorem. Here we ask the question left open in 2026o: does Einstein backreaction kill a CTC before H^1_causal ≠ 0 can form? We prove: (1) if (M,g) satisfies Einstein G_ab = 8π T_ab with T_ab obeying the null energy condition (NEC), and H^1_causal ≠ 0 is attempted by forming a CTC, then either NEC is violated or the CPTP eraser from 2026d must act, with stress-energy ⟨T_ab⟩ diverging on the chronology horizon, (2) the eraser stress-energy is exactly the Hawking divergence, reinterpreted as CPTP decoherence, (3) if NEC holds and no eraser acts, then H^1_causal = 0 and no CTC forms — this is chronology protection with Einstein, (4) if NEC is violated, H^1_causal ≠ 0 is allowed by Einstein, but Bridge still forces erasure by 2026l/m/n/o. This does not prove NEC holds in nature. It proves: Einstein + NEC + Bridge ⇒ no CTC. Einstein + NEC violation ⇒ Bridge still forces erasure. Tseglin 2026p = Ch. 151. Cites Tseglin 2026a DOI 10.5281/zenodo.23977165, 2026b DOI 10.5281/zenodo.23980498, 2026c DOI 10.5281/zenodo.23980738, 2026d DOI 10.5281/zenodo.23981860, 2026e DOI 10.5281/zenodo.23982063, 2026f DOI 10.5281/zenodo.23982359, 2026g DOI 10.5281/zenodo.23985216, 2026h DOI 10.5281/zenodo.23991367, 2026i DOI 10.5281/zenodo.23991442, 2026j DOI 10.5281/zenodo.23991535, 2026k DOI 10.5281/zenodo.23991603, 2026l DOI 10.5281/zenodo.23991665, 2026m DOI 10.5281/zenodo.23991998, 2026n DOI 10.5281/zenodo.23992083, 2026o DOI 10.5281/zenodo.23992187.