Autonomous systems do not fail at a transaction — they fail over time. Privilege creep, compounded deviation, authority decay. Drift Guard enforces containment across time, not just per-action.
Autonomous systems rarely fail at a single transaction. They fail over time — through privilege creep, compounded deviation, and the slow decay of authority into standing permission. Per-action checks do not see this failure mode, because each action, in isolation, still looks valid.
Containment therefore has to be temporal. If authority does not decay alongside the context that granted it, a once-valid action becomes a permanent capability. A Drift Guard enforces constraint across time, halting when behavior diverges before the deviation has a chance to compound.