The Crossing Charges Nothing: An Obstruction Census for Vacuum-Energy Mechanisms in Einstein–Cartan Cosmology

We ask whether the observed vacuum energy density, ρΛ = 2.9 × 10^-122 M̄P^4, can be a prediction of Einstein–Cartan (EC) bounce cosmology of a specified corpus frame: spin-sourced torsion, an algebraic bounce at a spin-density wall, a two-boundary (pair) construction glued at the bounce surface, and a sterile Weyl species as the frame's silent carrier. The acceptance criterion is fixed in advance and is strict: a construction counts only if it fixes the sterile mass and abundance with zero free continuous parameters and lands within ±2 dex of the observed value. We then execute, at full strength, every construction class the frame offers, and close each with derivations and numbers. The result is a census, not a solution. The conversion map at the bounce, K: (N, s, ρ) ↦ (N, −s, ρ), is derived from the EC bilinear table; its conservation law makes the crossing exactly toll-free, which closes the entire accumulation/retention class in one line. The pairing's fixed-point set in ρ is a continuum under the only reading that does not kill the bounce, and collapses to s ≡ 0 under the other; the sterile mass is free under the frame's symmetry and stated nowhere in the corpus. The one parameter-free mass the corpus supports, m_s = m_e, is falsified by the frame's own residue chains. A species born at the bounce inherits the program's first construction-fixed abundance, n_0 ∈ [3.64 × 10^-12, 1.02 × 10^-11] eV^3, and at that abundance the bounce-carrying channel misses by +29.2 to +30.0 dex at every mass; the inheritance ceiling caps all channels the abundance feeds. Light's helicity clears the wall's spin requirement by +0.25 dex but couples to torsion by exactly zero under minimal coupling, every extension costing an unfixed constant. Three of the census's kill mechanisms — the identity-channel test, the continuum test, and the dial audit — are frame-independent and are stated as portable fences. The gap stands at 121.5 dex, unpriced in every part. We close by stating, as requirements, the four things a successor theory must supply. Nothing in this paper solves the cosmological constant problem; it is a proof-shaped account of why this frame cannot.