Update diagnostic and observation contracts

docs/roadmap/implementation.md

@@ -774,6 +774,13 @@ boundary fixtures not completed by Stage 10's serialization changes.
 Validation: run these public contract tests offline; diagnostic operations in
 tests use controlled transports, not actual backend endpoints or API keys.
 
+Completion: public diagnostic, scoped-capacity, and observation fixtures use
+identified lists and retain selection, disclosure, and ownership checks without
+prompt labels. Corrected remaining request-validation callers of the migrated
+requirements helper. Focused offline diagnostic and prepared-observation tests
+passed on Go 1.27.0; other observation tests still rely on the shared legacy
+fixture assigned to the next assignment and will be rerun after its conversion.
+
 ## Stage 19: Update Maintained Examples And Benchmarks
 
 Scope: the three `examples/go-library` workflows, their assets, and configuration-