Preserve telescope picker size on reopens (#60093)

Before:


https://github.com/user-attachments/assets/b95f3317-669a-462d-bbe8-ba80ede3e496

After:


https://github.com/user-attachments/assets/16536d14-fc91-4d68-ac0d-6b7c382dd298


Release Notes:

- Fixed telescope picker being overly small on consequent reopens

crates/file_finder/src/file_finder_tests.rs

@@ -4380,6 +4380,41 @@ async fn test_open_without_dismiss_then_confirm_closes_finder(cx: &mut TestAppCo
     });
 }
 
+#[gpui::test]
+async fn test_reopen_with_preview_keeps_results_width(cx: &mut TestAppContext) {
+    let app_state = init_test(cx);
+    app_state
+        .fs
+        .as_fake()
+        .insert_tree(path!("/root"), json!({ "a.txt": "", "b.txt": "" }))
+        .await;
+    let project = Project::test(app_state.fs.clone(), [path!("/root").as_ref()], cx).await;
+    let (picker, workspace, cx) = build_find_picker(project, cx);
+
+    cx.dispatch_action(picker::SetPreviewRight);
+    cx.run_until_parked();
+    let in_session_width = picker.update_in(cx, |picker, window, _| picker.results_width(window));
+
+    cx.dispatch_action(Cancel);
+    cx.run_until_parked();
+
+    let picker = open_file_picker(&workspace, cx);
+    cx.run_until_parked();
+    let reopened_width = picker.update_in(cx, |picker, window, _| picker.results_width(window));
+
+    assert_eq!(
+        in_session_width, reopened_width,
+        "reopening with the side preview must keep the same results width as the in-session toggle"
+    );
+
+    // The preview layout is persisted in the key-value store, and tests in a
+    // process share one in-memory fallback store (no per-App `AppDatabase` is
+    // set in tests, so `AppDatabase::global` falls back to the shared static).
+    // Reset to the default layout so this write doesn't leak into other tests.
+    cx.dispatch_action(picker::SetPreviewHidden);
+    cx.run_until_parked();
+}
+
 async fn open_close_queried_buffer(
     input: &str,
     expected_matches: usize,

crates/picker/src/picker.rs

@@ -571,7 +571,7 @@ impl<D: PickerDelegate> Picker<D> {
     pub fn initial_width(mut self, width: impl Into<RelativeWidth>) -> Self {
         let width = width.into();
         self.default_shape.width = width;
-        if !self.shape_loaded_from_persistence {
+        if self.live_shape_is_hidden_default() {
             self.shape.set_initial_width(width);
         }
         // A plain picker's whole-picker minimum tracks its opening width. Preview
@@ -591,12 +591,23 @@ impl<D: PickerDelegate> Picker<D> {
     pub fn max_height(mut self, height: impl Into<RelativeHeight>) -> Self {
         let height = height.into();
         self.default_shape.height = height;
-        if !self.shape_loaded_from_persistence {
+        if self.live_shape_is_hidden_default() {
             self.shape.set_initial_height(height);
         }
         self
     }
 
+    /// Whether the live shape still reflects the hidden-layout default, i.e. it
+    /// was not restored from a persisted size and currently opens with no
+    /// preview. Only then may `initial_width`/`max_height` push their
+    /// hidden/no-preview defaults onto it; a picker reopened in a preview layout
+    /// keeps the larger telescope default, which those (smaller) no-preview
+    /// values must not shrink.
+    fn live_shape_is_hidden_default(&self) -> bool {
+        !self.shape_loaded_from_persistence
+            && self.preview_layout().unwrap_or(preview::Layout::Hidden) == preview::Layout::Hidden
+    }
+
     /// Whether the picker fills its full height (preview visible) or shrinks to
     /// fit its content, treating the height as a maximum (no preview visible).
     fn fill_height(&self) -> bool {
@@ -1242,6 +1253,15 @@ impl<D: PickerDelegate> Picker<D> {
         self.preview.as_ref().map(|p| p.layout)
     }
 
+    #[cfg(any(test, feature = "test-support"))]
+    pub fn results_width(&self, window: &Window) -> gpui::Pixels {
+        let layout = self.preview_layout().unwrap_or(preview::Layout::Hidden);
+        let pos = self
+            .shape
+            .results_position_and_size(layout, &self.size_bounds, window);
+        pos.right - pos.left
+    }
+
     fn toggle_preview(&mut self, _: &TogglePreview, window: &mut Window, cx: &mut Context<Self>) {
         self.toggle_preview_visible(window, cx);
     }