outline: Add preview pane to buffer symbols (#61069)

# Objective

- Implement preview pane for buffer symbols, similar to #59863 

## Showcase
### Before 
<img width="4512" height="2980" alt="CleanShot 2026-07-15 at 23 25
19@2x"
src="https://github.com/user-attachments/assets/443f150a-bb67-4bac-ba4a-f8f299554470"
/>

### After
<img width="4512" height="2980" alt="CleanShot 2026-07-15 at 23 19
09@2x"
src="https://github.com/user-attachments/assets/0fd4be89-d25e-4052-8de0-3a9a5a5908f9"
/>


---

Release Notes:

- Added a preview pane to the buffer symbols picker

Cargo.lock

@@ -12560,6 +12560,7 @@ dependencies = [
  "lsp",
  "menu",
  "picker",
+ "picker_preview",
  "project",
  "rope",
  "serde_json",

crates/outline/Cargo.toml

@@ -18,6 +18,7 @@ fuzzy_nucleo.workspace = true
 gpui.workspace = true
 language.workspace = true
 picker.workspace = true
+picker_preview.workspace = true
 settings.workspace = true
 theme.workspace = true
 theme_settings.workspace = true

crates/outline/src/outline.rs

@@ -10,8 +10,8 @@ use gpui::{
     ParentElement, Point, Rems, Render, Styled, StyledText, Task, TextStyle, WeakEntity, Window,
     div, rems,
 };
-use language::{Outline, OutlineItem, OutlineSearchEntry};
-use picker::{Picker, PickerDelegate};
+use language::{OffsetRangeExt, Outline, OutlineItem, OutlineSearchEntry};
+use picker::{MatchLocation, Picker, PickerDelegate, PreviewUpdate};
 use settings::Settings;
 use theme::ActiveTheme;
 use theme_settings::ThemeSettings;
@@ -176,9 +176,16 @@ impl OutlineView {
         window: &mut Window,
         cx: &mut Context<Self>,
     ) -> OutlineView {
+        let project = editor.read(cx).project().cloned();
         let delegate = OutlineViewDelegate::new(cx.entity().downgrade(), outline, editor, cx);
         let picker = cx.new(|cx| {
-            Picker::uniform_list(delegate, window, cx)
+            let picker = if let Some(project) = project {
+                let preview = picker_preview::editor_preview(project, window, cx);
+                Picker::uniform_list_with_preview(delegate, preview, window, cx)
+            } else {
+                Picker::uniform_list(delegate, window, cx)
+            };
+            picker
                 .max_height(Rems::from_pixels(
                     window.viewport_size().height * 0.75,
                     window,
@@ -293,6 +300,30 @@ impl PickerDelegate for OutlineViewDelegate {
         self.set_selected_index(ix, true, cx);
     }
 
+    fn try_get_preview_data_for_match(&self, cx: &App) -> Option<PreviewUpdate> {
+        let selected_match = self.matches.get(self.selected_match_index)?;
+        let outline_item = self.outline.items.get(selected_match.candidate_id())?;
+        let multi_buffer = self.active_editor.read(cx).buffer().clone();
+        let (buffer, start) = multi_buffer
+            .read(cx)
+            .text_anchor_for_position(outline_item.selection_range.start, cx)?;
+        let (end_buffer, end) = multi_buffer
+            .read(cx)
+            .text_anchor_for_position(outline_item.selection_range.end, cx)?;
+        if buffer != end_buffer {
+            return None;
+        }
+
+        let range = (start..end).to_offset(&buffer.read(cx).text_snapshot());
+        Some(PreviewUpdate::from_buffer(
+            buffer,
+            MatchLocation {
+                anchor_range: start..end,
+                range,
+            },
+        ))
+    }
+
     fn update_matches(
         &mut self,
         query: String,