fix: empty slices rather than null on the unavailable status snapshot

server/internal/services/statussnapshot.go

@@ -375,6 +375,21 @@ func componentStatus(mon models.Monitor, known, inMaintenance bool, now time.Tim
 
 const statusCacheTTL = 30 * time.Second
 
+// unavailableSnapshot returns a StatusSnapshot with Available: false and all
+// four list fields initialized to empty slices rather than nil, ensuring
+// consistent JSON serialization across the available and unavailable paths.
+func unavailableSnapshot(reason, title string) *StatusSnapshot {
+	return &StatusSnapshot{
+		Available:           false,
+		Reason:              reason,
+		Title:               title,
+		Sections:            []PublicSection{},
+		ActiveIncidents:     []PublicIncident{},
+		UpcomingMaintenance: []PublicIncident{},
+		History:             []PublicIncident{},
+	}
+}
+
 // PublicStatusSnapshot is the whole public read path.
 //
 // A missing page, an unpublished page and a page belonging to another instance
@@ -401,10 +416,10 @@ func PublicStatusSnapshot(instanceID, pageID string) (*StatusSnapshot, error) {
 	// and deserves an explanation rather than a browser error.
 	st := GetLicenseState(instanceID)
 	if !st.Active() {
-		return &StatusSnapshot{Available: false, Reason: "licence_inactive", Title: page.Title}, nil
+		return unavailableSnapshot("licence_inactive", page.Title), nil
 	}
 	if !st.Feature(license.FeatureStatusPages) {
-		return &StatusSnapshot{Available: false, Reason: "feature_unavailable", Title: page.Title}, nil
+		return unavailableSnapshot("feature_unavailable", page.Title), nil
 	}
 
 	in, err := loadSnapshotInput(instanceID, *page)