Preserve alias context in usage errors

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Application-owned aliases implementation plan
 
-Status: in progress; Stages 1–10 completed.
+Status: in progress; Stages 1–11 completed.
 
 ## Authority, baseline, and scope
 
@@ -561,6 +561,15 @@ spellings; wrapped `errors.Is`/`errors.As`; usage paths with canonical annotatio
 unknown routes and flags; cancellation; output and diagnostic failures. Assert
 semantic fragments and identities, not entire backend wording snapshots.
 
+**Completed:** Flag conversion failures now retain the binding, entered
+spelling, occurrence number, and original wrapped cause. Usage diagnostics use
+entered alias paths and identify resolved canonical commands; unresolved routes
+receive no invented canonical label. Successful and failed registration during
+execution preserve the selected route. Verified with root, ckconfig, and
+ckprompt suites under the local workspace, including existing cancellation,
+diagnostic deduplication, writer failure, short-write, and incomplete-report
+coverage.
+
 ## Stage 12: Verify registration and routing interactions end to end
 
 **Work**