Avoid retaining hidden simple deferred messages

docs/roadmap/remediation.md

@@ -1,6 +1,6 @@
 # Invocation reporting audit remediation
 
-Status: remediation in progress; 5 of 7 findings complete.
+Status: remediation in progress; 6 of 7 findings complete.
 
 ## Review scope
 
@@ -381,7 +381,13 @@ owners.
 
 ## 6. Avoid retaining deferred messages that need no presentation work
 
-Priority: P3. Status: for consideration.
+Priority: P3. Status: complete.
+
+- [x] Completed: renderer-free hidden deferred messages record suppression
+  without queue retention. Finalization detaches the queue without an array
+  copy and delivers captured callback lists without recopying them. Hidden rich
+  callbacks, FIFO order, no-content handling, capture, and closure remain covered.
+  Validation: root module suite and focused reporter race checks pass.
 
 ### Finding and complexity