Validate Level 21 overlay system.

PR Details:
- Full system validation for advanced overlays

Author: DavidQ

docs/dev/CODEX_COMMANDS.md

@@ -2,7 +2,7 @@ MODEL: GPT-5.4
 REASONING: medium
 
 COMMAND:
-Optimize overlay performance:
-- Reduce overhead
-- Improve event efficiency
+Run full Level 21 validation:
+- Validate all features
+- Confirm stability
 - Update roadmap status only

docs/dev/COMMIT_COMMENT.txt

@@ -1,4 +1,4 @@
-Optimize overlay performance.
+Validate Level 21 overlay system.
 
 PR Details:
-- Improves efficiency and scalability
+- Full system validation for advanced overlays

docs/dev/reports/validation_checklist.txt

@@ -1,4 +1,4 @@
-[ ] Performance improved
+[ ] All features validated
 [ ] No regressions
-[ ] Stable behavior
+[ ] Stable
 [ ] Roadmap updated

docs/dev/roadmaps/MASTER_ROADMAP_HIGH_LEVEL.md

@@ -824,7 +824,7 @@
 - [x] ensure future phases can build cleanly
 
 ### Track H — Final Stability Gate
-- [.] full-repo validation sweep
+- [x] full-repo validation sweep
 - [x] zero regression requirement
 - [x] contract freeze readiness
 - [x] readiness for long-term maintenance mode

docs/pr/BUILD_PR.md

@@ -1,21 +1,20 @@
-# BUILD_PR_LEVEL_21_5_OVERLAY_PERFORMANCE_OPTIMIZATION
+# BUILD_PR_LEVEL_21_6_OVERLAY_SYSTEM_VALIDATION
 
 ## Purpose
-Optimize overlay system performance under advanced usage.
+Perform full validation of Level 21 overlay system.
 
 ## Roadmap Improvement
-Enhances efficiency and scalability of Level 21 overlays.
+Confirms stability and readiness of advanced overlay features.
 
 ## Scope
-- Reduce render overhead
-- Optimize event handling
-- Validate performance gains
+- Validate all Level 21 features
+- Ensure no regressions
 
 ## Test Steps
-1. Run multiple overlays
-2. Measure performance
-3. Compare before/after
+1. Run all advanced overlays
+2. Stress test system
+3. Validate performance and behavior
 
 ## Expected
-- Improved performance
+- Stable system
 - No regressions