Per-call authorization checks structurally cannot see workflow-level drift.

Runtime Authorization Consistency Checking names the failure where each MCP step is individually legal while the accumulated sequence exceeds what the session was granted. RAC treats authorization as runtime state carried by accepted steps, reconstructs a trusted authorization event from controller-observed metadata at the tool-call boundary, and admits a call only if it's no more permissive than the basis inherited through accepted lineage, with rejected steps dropped from lineage. On the 1,248-workflow TraceBench suite RAC had zero missed blocks where the strongest Static+History baseline missed 509 of 1,008, reached 92.8% block recall on blind LLM-generated plans against 68.8%, and ran at sub-millisecond p99. (arXiv 2609.23498)