fix(session): refresh updated_at timestamp on session and event mutations

handlers/session_handler.go

@@ -154,6 +154,12 @@ func (h *SessionHandler) CreateSession(c *gin.Context) {
 			}
 		}
 
+		// Events belong to the session's sync unit, so advance its timestamp
+		// after all event upserts/deletions have completed.
+		if err := tx.Model(&session).Update("updated_at", gorm.Expr("NOW()")).Error; err != nil {
+			return err
+		}
+
 		return nil
 	})
 	if isConflict {
@@ -240,7 +246,10 @@ func (h *SessionHandler) AddEventToSession(c *gin.Context) {
 		respondError(c, http.StatusInternalServerError, 500, "failed to add event")
 		return
 	}
-	h.DB.Model(&session).Updates(map[string]interface{}{"revision": gorm.Expr("revision + 1")})
+	h.DB.Model(&session).Updates(map[string]interface{}{
+		"revision":   gorm.Expr("revision + 1"),
+		"updated_at": gorm.Expr("NOW()"),
+	})
 	respondSuccess(c, event)
 }
 
@@ -251,7 +260,11 @@ func (h *SessionHandler) DeleteSession(c *gin.Context) {
 	now := time.Now().UTC()
 	result := h.DB.Model(&models.CelestiaSession{}).
 		Where("id = ? AND user_id = ? AND deleted_at IS NULL", sessionID, userID).
-		Updates(map[string]interface{}{"deleted_at": &now, "revision": gorm.Expr("revision + 1")})
+		Updates(map[string]interface{}{
+			"deleted_at": &now,
+			"revision":   gorm.Expr("revision + 1"),
+			"updated_at": gorm.Expr("NOW()"),
+		})
 	if result.Error != nil {
 		respondError(c, http.StatusInternalServerError, 500, "failed to delete record")
 		return