Add detailed validation evidence

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Shared reporting and PromptKit v0.20.0 implementation plan
 
-Status: implementation in progress; Stages 1–19 complete.
+Status: implementation in progress; Stages 1–20 complete.
 
 ## Scope, authority, and execution
 
@@ -709,6 +709,11 @@ add a comparison callback, reload data, or implement list matching.
 
 ## Stage 20: Detailed validation and reached-scope aggregation
 
+**Complete.** Detailed validation filters native findings and reports reached
+scopes after acquisition stops, preserving independent diagnostics and causes.
+Root, ckconfig, and ckprompt workspace suites passed with Go 1.27.0, including
+failure, cancellation, source references, quiet mode, and output failure.
+
 Complete Stage 7's validation aggregation using Stage 14's evidence. Add
 `--details`, repeatable `--severity`, and repeatable `--code` on validation;
 filters require detailed mode. Parse severity using native known severities;