assistant2: Make context pill names work like editor tabs (#22741)

Context pills for files will now only display the basename of the file.
If two files have the same base name, we will also show their parent
directories, mimicking the behavior of editor tabs.


https://github.com/user-attachments/assets/ee88ee3b-80ff-4115-9ff9-8fe4845a67d8

Note: The double `/` in the file picker is a known separate issue.

Release Notes:

- N/A

---------

Co-authored-by: Danilo <danilo@zed.dev>
Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

crates/assistant2/src/context_store.rs

@@ -1,7 +1,7 @@
 use std::fmt::Write as _;
 use std::path::{Path, PathBuf};
 
-use collections::HashMap;
+use collections::{HashMap, HashSet};
 use gpui::SharedString;
 use language::Buffer;
 
@@ -60,7 +60,17 @@ impl ContextStore {
         let id = self.next_context_id.post_inc();
         self.files.insert(path.to_path_buf(), id);
 
-        let name = path.to_string_lossy().into_owned().into();
+        let full_path: SharedString = path.to_string_lossy().into_owned().into();
+
+        let name = match path.file_name() {
+            Some(name) => name.to_string_lossy().into_owned().into(),
+            None => full_path.clone(),
+        };
+
+        let parent = path
+            .parent()
+            .and_then(|p| p.file_name())
+            .map(|p| p.to_string_lossy().into_owned().into());
 
         let mut text = String::new();
         push_fenced_codeblock(path, buffer.text(), &mut text);
@@ -68,6 +78,8 @@ impl ContextStore {
         self.context.push(Context {
             id,
             name,
+            parent,
+            tooltip: Some(full_path),
             kind: ContextKind::File,
             text: text.into(),
         });
@@ -77,11 +89,23 @@ impl ContextStore {
         let id = self.next_context_id.post_inc();
         self.directories.insert(path.to_path_buf(), id);
 
-        let name = path.to_string_lossy().into_owned().into();
+        let full_path: SharedString = path.to_string_lossy().into_owned().into();
+
+        let name = match path.file_name() {
+            Some(name) => name.to_string_lossy().into_owned().into(),
+            None => full_path.clone(),
+        };
+
+        let parent = path
+            .parent()
+            .and_then(|p| p.file_name())
+            .map(|p| p.to_string_lossy().into_owned().into());
 
         self.context.push(Context {
             id,
             name,
+            parent,
+            tooltip: Some(full_path),
             kind: ContextKind::Directory,
             text: text.into(),
         });
@@ -94,6 +118,8 @@ impl ContextStore {
         self.context.push(Context {
             id: context_id,
             name: thread.summary().unwrap_or("New thread".into()),
+            parent: None,
+            tooltip: None,
             kind: ContextKind::Thread,
             text: thread.text().into(),
         });
@@ -106,6 +132,8 @@ impl ContextStore {
         self.context.push(Context {
             id: context_id,
             name: url.into(),
+            parent: None,
+            tooltip: None,
             kind: ContextKind::FetchedUrl,
             text: text.into(),
         });
@@ -163,6 +191,19 @@ impl ContextStore {
     pub fn included_url(&self, url: &str) -> Option<ContextId> {
         self.fetched_urls.get(url).copied()
     }
+
+    pub fn duplicated_names(&self) -> HashSet<SharedString> {
+        let mut seen = HashSet::default();
+        let mut dupes = HashSet::default();
+
+        for context in self.context().iter() {
+            if !seen.insert(&context.name) {
+                dupes.insert(context.name.clone());
+            }
+        }
+
+        dupes
+    }
 }
 
 pub enum IncludedFile {