preflight gating

workplans/GUIDE-BOARD-WP-0001-bootstrapping.md

@@ -190,6 +190,8 @@ Acceptance:
   runner-emitted raw artifacts.
 - The baseline executor applies expectation and waiver policy refs from
   assessment profiles and reports policy summary counts.
+- Failed extension preflight evidence gates downstream check groups so later
+  runners are not invoked against an invalid target posture.
 
 ## D1.7 - Extension SDK Skeleton