Integrate inference smoke diagnostics

docs/roadmap/implementation.md

@@ -622,6 +622,14 @@ Validate: focused use-case/engine tests for text/schema results, retry-default
 isolation, injected generation, required-credential/capacity findings, and evidence
 after cancellation. Stage 17 owns broader facade-level capacity/observer regressions.
 
+**Completed: 2026-10-13.** Integrated private inference cases through the shared
+generation coordinator, preserving attempts, usage, phase timings, last-dispatched
+facts, and local validation findings. Required-credential and logical-capacity
+findings conclude without dispatch. Built-in and injected engines share the
+runner/coordinator while only built-in engines supply HTTP diagnostics.
+Validation passed: `go test -race ./internal/usecase ./internal/generation
+./internal/engine`, `go vet ./...`, `go test ./...`, and `git diff --check`.
+
 ## Stage 16: Expose The Public SmokeTest Facade
 
 Scope: root declarations, GoDoc, conversions, and external-package API tests.