cherry-pick: #54575 to preview (#54577)

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- git: Fix remote branch picker

crates/collab/src/db/queries/projects.rs

@@ -886,6 +886,7 @@ impl Database {
                         current_merge_conflicts,
                         branch_summary,
                         head_commit_details,
+                        branch_list: Vec::new(),
                         scan_id: db_repository_entry.scan_id as u64,
                         is_last_update: true,
                         merge_message: db_repository_entry.merge_message,

crates/collab/src/db/queries/rooms.rs

@@ -790,6 +790,7 @@ impl Database {
                             current_merge_conflicts,
                             branch_summary,
                             head_commit_details,
+                            branch_list: Vec::new(),
                             project_id: project_id.to_proto(),
                             id: db_repository.id as u64,
                             abs_path: db_repository.abs_path.clone(),

crates/collab/tests/integration/git_tests.rs

@@ -91,6 +91,29 @@ fn collect_diff_stats<C: gpui::AppContext>(
     })
 }
 
+fn branch_list_snapshot(
+    project: &gpui::Entity<project::Project>,
+    cx: &mut TestAppContext,
+) -> (Option<String>, Vec<String>) {
+    project.read_with(cx, |project, cx| {
+        let repos = project.repositories(cx);
+        assert_eq!(repos.len(), 1, "project should have exactly 1 repository");
+        let repo = repos.values().next().unwrap();
+        let snapshot = repo.read(cx).snapshot();
+        (
+            snapshot
+                .branch
+                .as_ref()
+                .map(|branch| branch.name().to_string()),
+            snapshot
+                .branch_list
+                .iter()
+                .map(|branch| branch.ref_name.to_string())
+                .collect(),
+        )
+    })
+}
+
 #[gpui::test]
 async fn test_project_diff(cx_a: &mut TestAppContext, cx_b: &mut TestAppContext) {
     let mut server = TestServer::start(cx_a.background_executor.clone()).await;
@@ -480,6 +503,95 @@ async fn test_remote_git_head_sha(
     assert_eq!(remote_head_sha.unwrap(), local_head_sha);
 }
 
+#[gpui::test]
+async fn test_branch_list_sync(
+    executor: BackgroundExecutor,
+    cx_a: &mut TestAppContext,
+    cx_b: &mut TestAppContext,
+) {
+    let mut server = TestServer::start(executor.clone()).await;
+    let client_a = server.create_client(cx_a, "user_a").await;
+    let client_b = server.create_client(cx_b, "user_b").await;
+    server
+        .create_room(&mut [(&client_a, cx_a), (&client_b, cx_b)])
+        .await;
+    let active_call_a = cx_a.read(ActiveCall::global);
+
+    client_a
+        .fs()
+        .insert_tree(
+            path!("/project"),
+            json!({ ".git": {}, "file.txt": "content" }),
+        )
+        .await;
+    client_a.fs().insert_branches(
+        Path::new(path!("/project/.git")),
+        &["main", "feature-1", "feature-2"],
+    );
+
+    let (project_a, _) = client_a.build_local_project(path!("/project"), cx_a).await;
+    executor.run_until_parked();
+
+    let host_snapshot = branch_list_snapshot(&project_a, cx_a);
+    assert_eq!(host_snapshot.0.as_deref(), Some("main"));
+    assert_eq!(
+        host_snapshot.1,
+        vec![
+            "refs/heads/feature-1".to_string(),
+            "refs/heads/feature-2".to_string(),
+            "refs/heads/main".to_string(),
+        ]
+    );
+
+    let project_id = active_call_a
+        .update(cx_a, |call, cx| call.share_project(project_a.clone(), cx))
+        .await
+        .unwrap();
+    let project_b = client_b.join_remote_project(project_id, cx_b).await;
+
+    executor.run_until_parked();
+
+    let repo_b = cx_b.update(|cx| project_b.read(cx).active_repository(cx).unwrap());
+
+    cx_b.update(|cx| {
+        repo_b.update(cx, |repository, _cx| {
+            repository.create_branch("totally-new-branch".to_string(), None)
+        })
+    })
+    .await
+    .unwrap()
+    .unwrap();
+
+    cx_b.update(|cx| {
+        repo_b.update(cx, |repository, _cx| {
+            repository.change_branch("totally-new-branch".to_string())
+        })
+    })
+    .await
+    .unwrap()
+    .unwrap();
+
+    executor.run_until_parked();
+
+    let host_snapshot_after_update = branch_list_snapshot(&project_a, cx_a);
+    assert_eq!(
+        host_snapshot_after_update.0.as_deref(),
+        Some("totally-new-branch")
+    );
+    assert_eq!(
+        host_snapshot_after_update.1,
+        vec![
+            "refs/heads/feature-1".to_string(),
+            "refs/heads/feature-2".to_string(),
+            "refs/heads/main".to_string(),
+            "refs/heads/totally-new-branch".to_string(),
+        ]
+    );
+
+    let guest_snapshot_after_update = branch_list_snapshot(&project_b, cx_b);
+    assert_eq!(guest_snapshot_after_update, host_snapshot_after_update);
+}
+
 #[gpui::test]
 async fn test_linked_worktrees_sync(
     executor: BackgroundExecutor,

crates/project/src/git_store.rs

@@ -3856,6 +3856,7 @@ impl RepositorySnapshot {
     fn initial_update(&self, project_id: u64) -> proto::UpdateRepository {
         proto::UpdateRepository {
             branch_summary: self.branch.as_ref().map(branch_to_proto),
+            branch_list: self.branch_list.iter().map(branch_to_proto).collect(),
             head_commit_details: self.head_commit.as_ref().map(commit_details_to_proto),
             updated_statuses: self
                 .statuses_by_path
@@ -3941,6 +3942,7 @@ impl RepositorySnapshot {
 
         proto::UpdateRepository {
             branch_summary: self.branch.as_ref().map(branch_to_proto),
+            branch_list: self.branch_list.iter().map(branch_to_proto).collect(),
             head_commit_details: self.head_commit.as_ref().map(commit_details_to_proto),
             updated_statuses,
             removed_statuses,
@@ -6785,6 +6787,15 @@ impl Repository {
         self.snapshot.branch = new_branch;
         self.snapshot.head_commit = new_head_commit;
 
+        if update.is_last_update {
+            let new_branch_list: Arc<[Branch]> =
+                update.branch_list.iter().map(proto_to_branch).collect();
+            if *self.snapshot.branch_list != *new_branch_list {
+                cx.emit(RepositoryEvent::BranchListChanged);
+            }
+            self.snapshot.branch_list = new_branch_list;
+        }
+
         // We don't store any merge head state for downstream projects; the upstream
         // will track it and we will just get the updated conflicts
         let new_merge_heads = TreeMap::from_ordered_entries(

crates/proto/proto/git.proto

@@ -127,6 +127,7 @@ message UpdateRepository {
   optional string remote_origin_url = 15;
   optional string original_repo_abs_path = 16;
   repeated Worktree linked_worktrees = 17;
+  repeated Branch branch_list = 18;
 }
 
 message RemoveRepository {

crates/proto/src/proto.rs

@@ -917,6 +917,7 @@ pub fn split_repository_update(
 ) -> impl Iterator<Item = UpdateRepository> {
     let mut updated_statuses_iter = mem::take(&mut update.updated_statuses).into_iter().fuse();
     let mut removed_statuses_iter = mem::take(&mut update.removed_statuses).into_iter().fuse();
+    let branch_list = mem::take(&mut update.branch_list);
     std::iter::from_fn({
         let update = update.clone();
         move || {
@@ -934,6 +935,7 @@ pub fn split_repository_update(
             Some(UpdateRepository {
                 updated_statuses,
                 removed_statuses,
+                branch_list: Vec::new(),
                 is_last_update: false,
                 ..update.clone()
             })
@@ -942,6 +944,7 @@ pub fn split_repository_update(
     .chain([UpdateRepository {
         updated_statuses: Vec::new(),
         removed_statuses: Vec::new(),
+        branch_list,
         is_last_update: true,
         ..update
     }])
@@ -999,4 +1002,31 @@ mod tests {
         };
         assert_eq!(PeerId::from_u64(peer_id.as_u64()), peer_id);
     }
+
+    #[test]
+    fn test_split_repository_update_keeps_branch_list_on_final_chunk() {
+        let update = UpdateRepository {
+            updated_statuses: vec![
+                StatusEntry::default(),
+                StatusEntry::default(),
+                StatusEntry::default(),
+            ],
+            branch_list: vec![Branch {
+                ref_name: "refs/heads/main".into(),
+                ..Default::default()
+            }],
+            ..Default::default()
+        };
+
+        let chunks = split_repository_update(update).collect::<Vec<_>>();
+
+        assert_eq!(chunks.len(), 3);
+        assert!(chunks[0].branch_list.is_empty());
+        assert!(chunks[1].branch_list.is_empty());
+        assert_eq!(chunks[2].branch_list.len(), 1);
+        assert_eq!(chunks[2].branch_list[0].ref_name, "refs/heads/main");
+        assert!(!chunks[0].is_last_update);
+        assert!(!chunks[1].is_last_update);
+        assert!(chunks[2].is_last_update);
+    }
 }