As agent autonomy grows, security is moving to external boundaries: sandbox containment, network observation, protocol-aware policy, constrained credentials, and independent receipts.
New Runtime reading: Incidents and defensive controls across several layers point to the same architecture: safety cannot depend on a compliant prompt when action can be contained and audited outside the model.
Evidence boundary: this item uses the listed public sources and keeps vendor, author, or reporter claims attributed. The queued page is an editorial synthesis, not an independent validation of every reported metric.