fix: reset selected stage type when switching tabs

src/gui/app.rs

@@ -513,6 +513,7 @@ impl AmplifierApp {
         match message {
             Message::TabSelected(tab) => {
                 self.active_tab = tab;
+                self.sync_stage_type_with_tab(tab);
             }
             Message::SetStages(stages) => {
                 if let Some(preset_name) = self.settings.selected_preset.as_deref() {
@@ -604,13 +605,7 @@ impl AmplifierApp {
             }
             Message::ToggleAllStagesCollapse => {
                 // Only affect stages of the current tab's category
-                let category = match self.active_tab {
-                    Tab::Amp => Some(StageCategory::Amp),
-                    Tab::Effects => Some(StageCategory::Effect),
-                    _ => None,
-                };
-
-                if let Some(cat) = category {
+                if let Some(cat) = self.active_tab.stage_category() {
                     let category_indices: Vec<usize> = self
                         .stages
                         .iter()
@@ -805,6 +800,25 @@ impl AmplifierApp {
         Task::none()
     }
 
+    /// Reset `selected_stage_type` to the first stage of the new tab's category.
+    fn sync_stage_type_with_tab(&mut self, tab: Tab) {
+        let Some(category) = tab.stage_category() else {
+            return;
+        };
+
+        if self.selected_stage_type.category() == category {
+            return;
+        }
+
+        if let Some(first) = StageType::ALL
+            .iter()
+            .copied()
+            .find(|s| s.category() == category)
+        {
+            self.selected_stage_type = first;
+        }
+    }
+
     /// Find the index after the last stage of the given category.
     fn category_end_index(&self, category: StageCategory) -> usize {
         match category {

src/gui/tabs.rs

@@ -1,3 +1,5 @@
+use crate::gui::stages::StageCategory;
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub enum Tab {
     #[default]
@@ -6,3 +8,13 @@ pub enum Tab {
     Cabinet,
     Io,
 }
+
+impl Tab {
+    pub const fn stage_category(self) -> Option<StageCategory> {
+        match self {
+            Self::Amp => Some(StageCategory::Amp),
+            Self::Effects => Some(StageCategory::Effect),
+            _ => None,
+        }
+    }
+}