Retain PromptKit diagnostics after cancellation

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Implement PromptKit comparison and catalogs
 
-Status: Stage 1 complete; remaining stages are planned.
+Status: Stages 1–2 complete; remaining stages are planned.
 
 ## Scope and authority
 
@@ -154,6 +154,25 @@ warnings. Check ordinary headings and deferred-writer error propagation. Create
 native diagnostic fixtures through public APIs; do not import upstream internals
 or assert exact cancellation polling counts.
 
+**Completion evidence (2026-10-12)**
+
+- Refactored the private engine loader to collect inspection diagnostics before
+  checking cancellation observed after a successful load. Diagnostic headings
+  retain the ordinary scope form and can identify a comparison side. ConfigKit
+  load diagnostics and the original load error remain available.
+- Added adapter coverage for post-load cancellation, ConfigKit load-error identity
+  and diagnostics, ordinary and comparison-side headings, and deferred-writer
+  error propagation. `GOTOOLCHAIN=local go test ./...` passed in
+  `integrations/ckprompt`.
+- PromptKit v0.14.0 provides no public warning callback in engine configuration,
+  and its native configuration path emits no warnings. Therefore a successful
+  engine with inspection warnings cannot be constructed through the public API;
+  native warning retention across cancellation remains unexercised. The ordering
+  change directly retains any diagnostics if a later PromptKit version supplies
+  them. The selected integration evidence is otherwise complete.
+- Full repository and final assembled-state validation remain assigned to
+  Stage 12.
+
 ## Stage 3: Add the bundled PromptKit configuration pair provider
 
 **Outcome:** `ConfigScope` advertises Diff and supplies a native provider usable