Track the operation owning internal errors

docs/roadmap/implementation.md

@@ -120,6 +120,11 @@ Go 1.27.3, including nested capture and deferred unsupported/cyclic errors.
 category and matchable cause. Finish facade behavior in Stage 4; do not add
 temporary mapping paths just for this intermediate stage.
 
+Completion: operation errors retain their owning category and original cause,
+including direct prompt/profile lookup categories. Focused use-case tests pass
+on Go 1.27.3. Public projection and built-in preparation classification remain
+for their respective later units.
+
 ## Stage 4: Preserve Categories Through Public Error Projection
 
 **Catalog:** 7, completion. **Files:** `errors.go` and public error contracts/tests.