Authority Gate, Immutable Receipts, Drift Guard, Gated Substrate. Four layers forming a deterministic enforcement cascade — each necessary, none sufficient alone.
Runtime governance is a cascade of four layers: an Authority Gate that decides admissibility before execution, Immutable Receipts that prove what was admitted, a Drift Guard that constrains behavior across time, and a Gated Substrate that removes forbidden capability at the execution environment. Each is necessary; none is sufficient alone.
Remove any one and the cascade has a bypass: authority without proof, proof without temporal constraint, or constraint layered over a substrate that still exposes the forbidden capability. The layers are designed to be composed, because each closes a gap the others cannot reach.