fix: refresh file tree when reopening cached file viewer

The cached FileViewer entity scanned files once at creation and never
rescanned, so added/removed files wouldn't appear in the sidebar.
Now refresh_file_tree() runs on every reopen and can be triggered
manually with the 'r' key.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: matej21

crates/okena-files/src/file_viewer/mod.rs

@@ -316,12 +316,15 @@ impl FileViewer {
     }
 
     /// Update configuration (font size and dark mode) from the host app.
-    /// Also refreshes all tabs that were modified externally.
+    /// Also refreshes the file tree and all tabs that were modified externally.
     pub fn update_config(&mut self, font_size: f32, is_dark: bool) {
         let rehighlight = is_dark != self.is_dark;
         self.file_font_size = font_size;
         self.is_dark = is_dark;
 
+        // Rescan project files so the sidebar reflects added/removed files
+        self.refresh_file_tree();
+
         for tab in &mut self.tabs {
             if tab.is_empty() {
                 continue;
@@ -341,6 +344,28 @@ impl FileViewer {
         }
     }
 
+    /// Rescan the project directory and rebuild the file tree.
+    /// Preserves expanded folders and updates file indices on open tabs.
+    fn refresh_file_tree(&mut self) {
+        let files = FileSearchDialog::scan_files(&self.project_path);
+        let file_tree = build_file_tree(
+            files
+                .iter()
+                .enumerate()
+                .map(|(i, f)| (i, f.relative_path.as_str())),
+        );
+
+        // Update file indices on open tabs to match the new file list
+        for tab in &mut self.tabs {
+            if !tab.is_empty() {
+                tab.selected_file_index = files.iter().position(|f| f.path == tab.file_path);
+            }
+        }
+
+        self.files = files;
+        self.file_tree = file_tree;
+    }
+
     /// Check if the active tab's file was modified externally and reload if so.
     /// Throttled to at most once per second.
     pub(super) fn check_active_tab_freshness(&mut self) {

crates/okena-files/src/file_viewer/render.rs

@@ -638,6 +638,10 @@ impl Render for FileViewer {
                     "w" if modifiers.platform || modifiers.control => {
                         this.close_active_tab(cx);
                     }
+                    "r" if !modifiers.platform && !modifiers.control => {
+                        this.refresh_file_tree();
+                        cx.notify();
+                    }
                     "left" if modifiers.alt => {
                         this.go_back(cx);
                     }