Add typed spell validation strategies

internal/modules/generic/merge/appendorder/merger_test.go

@@ -174,6 +174,30 @@ func TestMergeRejectsInvalidJSONAndNonJSONMediaTypes(t *testing.T) {
 	}
 }
 
+func TestTypedMergeUsesRequestOrderForReusableValueType(t *testing.T) {
+	type notes struct{ Values []string }
+	merger, err := NewTyped(func(values []notes) (notes, error) {
+		var combined notes
+		for _, value := range values {
+			combined.Values = append(combined.Values, value.Values...)
+		}
+		return combined, nil
+	})
+	if err != nil {
+		t.Fatalf("NewTyped() error = %v", err)
+	}
+	result, err := merger.Merge(context.Background(), contracts.TypedMergeRequest[notes]{ExtractOutputs: []contracts.ExtractArtifact[notes]{
+		{ChunkIndex: 4, Value: notes{Values: []string{"first"}}},
+		{ChunkIndex: 1, Value: notes{Values: []string{"second"}}},
+	}})
+	if err != nil {
+		t.Fatalf("Merge() error = %v", err)
+	}
+	if got := result.Value.Values; !reflect.DeepEqual(got, []string{"first", "second"}) {
+		t.Fatalf("Values = %#v", got)
+	}
+}
+
 func extractOutput(chunkID string, chunkIndex int, content string) contracts.ExtractOutput {
 	return contracts.ExtractOutput{
 		LaneID:       "events",