fix: Immediately clear data state on resolution or station ID changes to prevent UI blocking and stale data rendering.

server.R

@@ -500,6 +500,28 @@ server <- function(input, output, session) {
     fetch_current_token <- reactiveVal(NULL) # To invalidate stale sessions
     fetch_temp_file <- reactiveVal(NULL)
 
+    # --- Immediate State Clearing to Prevent Main Thread Blocking ---
+    # When inputs change, clear data IMMEDIATELY to prevent plots from
+    # rendering old data with new settings (e.g. Daily data -> Hourly plots = 3000+ traces)
+    # This covers the 500ms debounce gap.
+    observeEvent(input$data_resolution,
+        {
+            loading_status(TRUE)
+            station_data(NULL)
+            parsed_data_list(list())
+        },
+        priority = 1000
+    )
+
+    observeEvent(current_station_id(),
+        {
+            loading_status(TRUE)
+            station_data(NULL)
+            parsed_data_list(list())
+        },
+        priority = 1000
+    )
+
     # Initial Trigger (Debounced Window)
     window_reactive <- reactive({
         req(input$date_range)