agent: Include active file in recent history (#27914)

This happened because of two reasons:

- `Workspace::recent_navigation_history` didn't include the current file
- The context picker added the current file to a exclude list

The latter was actually intentional because we already show the file in
the suggested context, but now that we actually have mentions, it's just
inconvenient not to have it there.

Release Notes:

- N/A

crates/workspace/src/workspace.rs

@@ -1429,8 +1429,10 @@ impl Workspace {
     ) -> impl Iterator<Item = (ProjectPath, Option<PathBuf>)> {
         let mut abs_paths_opened: HashMap<PathBuf, HashSet<ProjectPath>> = HashMap::default();
         let mut history: HashMap<ProjectPath, (Option<PathBuf>, usize)> = HashMap::default();
+
         for pane in &self.panes {
             let pane = pane.read(cx);
+
             pane.nav_history()
                 .for_each_entry(cx, |entry, (project_path, fs_path)| {
                     if let Some(fs_path) = &fs_path {
@@ -1452,11 +1454,26 @@ impl Workspace {
                         }
                     }
                 });
+
+            if let Some(item) = pane.active_item() {
+                if let Some(project_path) = item.project_path(cx) {
+                    let fs_path = self.project.read(cx).absolute_path(&project_path, cx);
+
+                    if let Some(fs_path) = &fs_path {
+                        abs_paths_opened
+                            .entry(fs_path.clone())
+                            .or_default()
+                            .insert(project_path.clone());
+                    }
+
+                    history.insert(project_path, (fs_path, std::usize::MAX));
+                }
+            }
         }
 
         history
             .into_iter()
-            .sorted_by_key(|(_, (_, timestamp))| *timestamp)
+            .sorted_by_key(|(_, (_, order))| *order)
             .map(|(project_path, (fs_path, _))| (project_path, fs_path))
             .rev()
             .filter(move |(history_path, abs_path)| {