Return generation attempt results as one value

docs/roadmap/implementation.md

@@ -672,6 +672,11 @@ tests pass on Go 1.27.3; the internal source description is updated.
 response/error behavior, timing facts and cancellation; no new event or HTTP fact
 is fabricated for an injected client.
 
+Completion: built-in attempts return a private result containing outcome,
+dispatch, capacity, duration, and start-time facts. Generation, use-case, and
+engine tests pass on Go 1.27.3; permit lifetime and injected dispatch are
+unchanged.
+
 ## Stage 26: Share Generation Accounting Projections
 
 **Catalog:** 25, completion. **Files:** generation accounting/evidence/observer tests.