Transport structured diagnostics through the pipeline

internal/framework/contracts/diagnostics_test.go

@@ -128,6 +128,24 @@ func TestDiagnosticGroupRejectsRepeatedSampleWithEqualChunkIndex(t *testing.T) {
 	}
 }
 
+func TestCloneDiagnosticCollectionOwnsGroupsAndChunkIndex(t *testing.T) {
+	chunkIndex := 0
+	collection := DiagnosticCollection{Groups: []DiagnosticGroup{{
+		Disposition:     DiagnosticDispositionAdvisory,
+		Category:        DiagnosticCategoryDataQuality,
+		ReasonCode:      "unresolved",
+		Origin:          DiagnosticOrigin{Stage: DiagnosticOriginStageExtract, StepID: "extract", LaneID: "spells", ModuleKey: "dnd/spells"},
+		OccurrenceCount: 1,
+		Samples:         []DiagnosticSample{{Scope: "spells[0]", Message: "Spell was not found", ChunkIndex: &chunkIndex}},
+	}}}
+	cloned := CloneDiagnosticCollection(collection)
+	collection.Groups[0].Samples[0].Message = "changed"
+	*collection.Groups[0].Samples[0].ChunkIndex = 1
+	if got := cloned.Groups[0].Samples[0]; got.Message != "Spell was not found" || got.ChunkIndex == nil || *got.ChunkIndex != 0 {
+		t.Fatalf("cloned sample = %#v, want independently owned original", got)
+	}
+}
+
 func validProducerDiagnostic() ProducerDiagnostic {
 	return ProducerDiagnostic{
 		Disposition:     DiagnosticDispositionWarning,