Implement final fixes and close out the implemetation roadmap

internal/framework/pipeline/runner_chunk_plan_test.go

@@ -438,6 +438,20 @@ func TestRunnerStoresProducerProvenanceAndProducerWarnings(t *testing.T) {
 	}
 }
 
+func TestRunnerRejectsUncloneableModuleManifestMetadata(t *testing.T) {
+	prepared, plan := preparedTerminalDebugPipeline(t)
+	cyclic := make(map[string]any)
+	cyclic["self"] = cyclic
+	prepared.chunker = manifestChunker{
+		terminalChunker: terminalChunker{key: prepared.resolved.Chunk.Module, plan: plan},
+		metadata:        map[string]any{"cyclic": cyclic},
+	}
+	_, err := New().Run(context.Background(), RunInput{Prepared: prepared, RawInput: []byte("input")})
+	if err == nil || !strings.Contains(err.Error(), `clone manifest metadata for module "chunker": metadata.cyclic.self contains a cycle`) {
+		t.Fatalf("Run() error = %v, want contextual module metadata clone failure", err)
+	}
+}
+
 func TestRunnerOmitsProducerProfileForDeterministicChunker(t *testing.T) {
 	prepared, plan := preparedTerminalDebugPipeline(t)
 	prepared.resolved.Chunk.LLMProfile = "configured-but-unused"