Add a core reporting example

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Invocation reporting implementation plan
 
-Status: Stages 1–15 complete. Stage 16 is next.
+Status: Stages 1–16 complete. Stage 17 is next.
 
 ## Objective and authority
 
@@ -610,7 +610,7 @@ module-wide `go test ./...` reaches and passes that package but cannot compile
 
 ## Stage 16: Maintain a core reporting consumer
 
-Status: pending.
+Status: complete.
 
 Primary files: [examples/core/main.go](../../examples/core/main.go) and its
 existing example tests.
@@ -632,6 +632,14 @@ Validation: keep the example runnable offline and cover representative modes
 and failure paths with its owning suite. Use package tests for detailed cause
 identity and delivery states rather than expanding the example into a framework.
 
+Completion: migrated the core example command to the invocation reporter and
+added a deterministic reporting command with result, warning, info, progress,
+debug, recovery, failure, and partial-output scenarios. Its tests cover ordinary,
+progress, verbose, debug, and quiet output, plus cause identity and terminal
+explanations. `GOTOOLCHAIN=local go test -count=1 ./examples/core` and the debug
+demo pass; the partial-output demo prints its completed section and terminal
+explanation, then exits with status 1 as expected.
+
 ## Stage 17: Migrate maintained integration consumers
 
 Status: pending.