Chamber Specification
Invariant: F(H) = XOR-SAT over GF(2) on node-local observed bits o(H) (boolean)
Falsifier: Utility realized while SAT is false (unsatisfiable prefix at t_utility)
Expected Signature: Feasibility cliff (B_u) — abrupt collapse at first violated parity check
Coupling Rule: τ admissible iff F.feasible == true (irreversible)
Utility: Shared EMA threshold (k=8 consecutive steps above U_crit)