Complete resource inspection validation and coverage

docs/roadmap/implementation.md

@@ -6,11 +6,11 @@ Implement the accepted [resource inspection roadmap](inspect-backend.md). That
 document owns intent, scope, and product decisions; this plan owns the concrete
 steps and representation choices needed to deliver them.
 
-Baseline: `951739e`. ConfigKit v1.1.0 composes and resolves definitions once.
-Promptkit captures executable prompts and backend-completed profile targets.
-`InspectPrompt` currently exposes limited metadata; `InspectProfile` exposes an
-execution target. There is no `InspectBackend` or typed `PromptSource`, and
-`BackendConfig` lacks `Extends`. Existing inspection values do not have the
+At baseline `951739e`, ConfigKit v1.1.0 composed and resolved definitions once.
+Promptkit captured executable prompts and backend-completed profile targets.
+`InspectPrompt` exposed limited metadata; `InspectProfile` exposed an
+execution target. There was no `InspectBackend` or typed `PromptSource`, and
+`BackendConfig` lacked `Extends`. Existing inspection values did not have the
 selected generic JSON/YAML contract.
 
 Each numbered stage is intended for one Luna implementation prompt, in order.
@@ -571,6 +571,13 @@ ConfigKit composition contracts intact.
 
 ## Stage 12: Validate And Close The Sprint
 
+**Completed:** Audited the selected resource, encoding, source, ownership, and
+null-migration boundaries; added coverage for inherited diagnostics and explicit
+serialization values. With Go 1.27.3, `GOTOOLCHAIN=local`, and `GOWORK=off`,
+`go test -race ./...`, `go vet ./...`, and module tidy verification pass. Changed
+Go files are formatted, local documentation targets and whitespace are checked,
+and the feature roadmap and plan are retained for review.
+
 **Scope:** Combined verification and final cleanup of this feature only.
 
 1. Confirm that all three inspection operations, every selected result field,