Add Daily recent changes comparison

internal/state/filesystem_test.go

@@ -88,6 +88,13 @@ func TestSaveArtifactsAndMetadataRoundTrip(t *testing.T) {
 			t.Fatalf("expected artifact %q: %v", path, err)
 		}
 	}
+	loadedBriefing, err := store.LoadBriefing(context.Background(), briefingPath)
+	if err != nil {
+		t.Fatalf("LoadBriefing() error = %v", err)
+	}
+	if loadedBriefing.Metadata.RunID != resolved.Metadata().RunID {
+		t.Fatalf("loaded briefing RunID = %q, want %q", loadedBriefing.Metadata.RunID, resolved.Metadata().RunID)
+	}
 	var decoded Metadata
 	data, err := os.ReadFile(metadataPath)
 	if err != nil {
@@ -146,6 +153,39 @@ func TestFindPriorDailySnapshot(t *testing.T) {
 	}
 }
 
+func TestFindPriorDailySnapshotUsesValidDate(t *testing.T) {
+	store := newTestStore(t)
+	previousDate := resolveDailyAt(t, "2026-05-28T05:00:00-05:00")
+	currentDate := resolveDailyAt(t, "2026-05-29T05:00:00-05:00")
+	briefingPackage := stateBriefingPackage(previousDate)
+	briefingPath, err := store.SaveBriefing(context.Background(), previousDate, briefingPackage)
+	if err != nil {
+		t.Fatalf("SaveBriefing() error = %v", err)
+	}
+	paths, err := store.Paths(previousDate)
+	if err != nil {
+		t.Fatalf("Paths() error = %v", err)
+	}
+	_, err = store.SaveMetadata(context.Background(), BuildMetadata(previousDate, briefingPackage, ArtifactPaths{
+		Briefing:       briefingPath,
+		Metadata:       paths.Metadata,
+		DataPackage:    paths.DataPackage,
+		Preflight:      paths.Preflight,
+		RenderedReport: paths.RenderedReport,
+	}))
+	if err != nil {
+		t.Fatalf("SaveMetadata() error = %v", err)
+	}
+
+	prior, err := store.FindPriorDailySnapshot(context.Background(), currentDate)
+	if err != nil {
+		t.Fatalf("FindPriorDailySnapshot() error = %v", err)
+	}
+	if prior != nil {
+		t.Fatalf("FindPriorDailySnapshot() = %#v, want nil for different valid date", prior)
+	}
+}
+
 func TestFilesystemStoreRejectsUnsafeDirs(t *testing.T) {
 	cfg := config.Defaults().Workspace
 	cfg.Root = t.TempDir()