fix(branch): block checkout of remote HEAD symbolic refs (#2681)

Hide remote `*/HEAD` entries from the branch list and reject checkout
attempts so gitui no longer creates a local `HEAD` branch.

Co-authored-by: Cursor <cursoragent@cursor.com>

asyncgit/src/sync/branch/mod.rs

@@ -372,6 +372,23 @@ pub fn checkout_commit(
 	}
 }
 
+/// Whether `name` refers to a remote symbolic `HEAD` ref (e.g. `origin/HEAD`).
+pub fn is_remote_head_ref(name: &str) -> bool {
+	name == "HEAD"
+		|| name
+			.split_once('/')
+			.is_some_and(|(_, local)| local == "HEAD")
+}
+
+fn local_branch_name_from_remote(remote_name: &str) -> Option<String> {
+	if is_remote_head_ref(remote_name) {
+		return None;
+	}
+
+	let local = remote_name.split_once('/')?.1;
+	Some(local.to_string())
+}
+
 ///
 pub fn checkout_remote_branch(
 	repo_path: &RepoPath,
@@ -391,10 +408,11 @@ pub fn checkout_remote_branch(
 		return Err(Error::UncommittedChanges);
 	}
 
-	let name = branch.name.find('/').map_or_else(
+	let name = local_branch_name_from_remote(&branch.name).ok_or_else(|| {
-		|| branch.name.clone(),
+		Error::Generic(
-		|pos| branch.name[pos..].to_string(),
+			"cannot checkout remote HEAD reference".to_string(),
-	);
+		)
+	})?;
 
 	let commit = repo.find_commit(branch.top_commit.into())?;
 	let mut new_branch = repo.branch(&name, &commit, false)?;
@@ -1021,6 +1039,40 @@ mod test_remote_branches {
 		);
 	}
 
+	#[test]
+	fn test_checkout_remote_head_fails() {
+		let (r1_dir, _repo) = repo_init_bare().unwrap();
+
+		let (clone1_dir, clone1) =
+			repo_clone(r1_dir.path().to_str().unwrap()).unwrap();
+		let clone1_dir = clone1_dir.path().to_str().unwrap();
+
+		write_commit_file(&clone1, "test.txt", "test", "commit1");
+		push_branch(
+			&clone1_dir.into(),
+			"origin",
+			"master",
+			false,
+			false,
+			None,
+			None,
+		)
+		.unwrap();
+
+		let (clone2_dir, _clone2) =
+			repo_clone(r1_dir.path().to_str().unwrap()).unwrap();
+		let clone2_dir = clone2_dir.path().to_str().unwrap();
+
+		let branches =
+			get_branches_info(&clone2_dir.into(), false).unwrap();
+		let head = branches
+			.iter()
+			.find(|b| b.name == "origin/HEAD")
+			.expect("origin/HEAD");
+
+		assert!(checkout_remote_branch(&clone2_dir.into(), head).is_err());
+	}
+
 	#[test]
 	fn test_checkout_remote_branch_hierarchical() {
 		let (r1_dir, _repo) = repo_init_bare().unwrap();

src/popups/branchlist.rs

@@ -17,7 +17,8 @@ use asyncgit::{
 	sync::{
 		self,
 		branch::{
-			checkout_remote_branch, BranchDetails, LocalBranch,
+			checkout_remote_branch, is_remote_head_ref, BranchDetails,
+			LocalBranch,
 			RemoteBranch,
 		},
 		checkout_branch, get_branches_info,
@@ -317,12 +318,9 @@ impl BranchListPopup {
 			self.check_remotes();
 			self.branches =
 				get_branches_info(&self.repo.borrow(), self.local)?;
-			//remove remote branch called `HEAD`
 			if !self.local {
 				self.branches
-					.iter()
+					.retain(|b| !is_remote_head_ref(&b.name));
-					.position(|b| b.name.ends_with("/HEAD"))
-					.map(|idx| self.branches.remove(idx));
 			}
 			self.set_selection(self.selection)?;
 		}