Remove the redundant DefaultOutputName report definition field

internal/state/filesystem_test.go

@@ -122,6 +122,43 @@ func TestSaveArtifactsAndMetadataRoundTrip(t *testing.T) {
 	if decoded.RenderedReportPath != renderedReportPath {
 		t.Fatalf("RenderedReportPath = %q, want %q", decoded.RenderedReportPath, renderedReportPath)
 	}
+	if strings.Contains(string(data), "MetadataPath") || strings.Contains(string(data), "metadataPath") {
+		t.Fatalf("metadata JSON includes runtime-only MetadataPath:\n%s", string(data))
+	}
+}
+
+func TestSaveMetadataUsesExplicitMetadataPath(t *testing.T) {
+	store := newTestStore(t)
+	resolved := resolveDailyAt(t, "2026-05-29T05:00:00-05:00")
+	briefingPackage := stateBriefingPackage(resolved)
+	paths, err := store.Paths(resolved)
+	if err != nil {
+		t.Fatalf("Paths() error = %v", err)
+	}
+	otherDir := filepath.Join(t.TempDir(), "other-artifacts")
+	otherBriefingPath := filepath.Join(otherDir, resolved.Metadata().RunID+".briefing.json")
+	derivedMetadataPath := filepath.Join(otherDir, resolved.Metadata().RunID+".metadata.json")
+
+	metadata := BuildMetadata(resolved, briefingPackage, ArtifactPaths{
+		Briefing:       otherBriefingPath,
+		Metadata:       paths.Metadata,
+		DataPackage:    paths.DataPackage,
+		Preflight:      paths.Preflight,
+		RenderedReport: paths.RenderedReport,
+	})
+	metadataPath, err := store.SaveMetadata(context.Background(), metadata)
+	if err != nil {
+		t.Fatalf("SaveMetadata() error = %v", err)
+	}
+	if metadataPath != paths.Metadata {
+		t.Fatalf("SaveMetadata() path = %q, want explicit metadata path %q", metadataPath, paths.Metadata)
+	}
+	if _, err := os.Stat(paths.Metadata); err != nil {
+		t.Fatalf("expected explicit metadata path %q: %v", paths.Metadata, err)
+	}
+	if _, err := os.Stat(derivedMetadataPath); !os.IsNotExist(err) {
+		t.Fatalf("derived metadata path stat error = %v, want not exist", err)
+	}
 }
 
 func TestFindPriorSnapshot(t *testing.T) {