3 files changed, 31 insertions, 1 deletions
diff --git a/helix-vcs/Cargo.toml b/helix-vcs/Cargo.toml
index 789ee795..58c078b4 100644
--- a/helix-vcs/Cargo.toml
+++ b/helix-vcs/Cargo.toml
@@ -15,6 +15,7 @@ helix-core = { version = "0.6", path = "../helix-core" }
 
 tokio = { version = "1", features = ["rt", "rt-multi-thread", "time", "sync", "parking_lot", "macros"] }
 parking_lot = "0.12"
+arc-swap = { version = "1.6.0" }
 
 gix = { version = "0.39.0", default-features = false , optional = true }
 imara-diff = "0.1.5"
diff --git a/helix-vcs/src/git.rs b/helix-vcs/src/git.rs
index 2a540c8d..1732bdd0 100644
--- a/helix-vcs/src/git.rs
+++ b/helix-vcs/src/git.rs
@@ -1,4 +1,6 @@
+use arc_swap::ArcSwap;
 use std::path::Path;
+use std::sync::Arc;
 
 use gix::objs::tree::EntryMode;
 use gix::sec::trust::DefaultForLevel;
@@ -87,6 +89,21 @@ impl DiffProvider for Git {
         }
         Some(data)
     }
+
+    fn get_current_head_name(&self, file: &Path) -> Option<Arc<ArcSwap<Box<str>>>> {
+        debug_assert!(!file.exists() || file.is_file());
+        debug_assert!(file.is_absolute());
+        let repo = Git::open_repo(file.parent()?, None)?.to_thread_local();
+        let head_ref = repo.head_ref().ok()?;
+        let head_commit = repo.head_commit().ok()?;
+
+        let name = match head_ref {
+            Some(reference) => reference.name().shorten().to_string(),
+            None => head_commit.id.to_hex_with_len(8).to_string(),
+        };
+
+        Some(Arc::new(ArcSwap::from_pointee(name.into_boxed_str())))
+    }
 }
 
 /// Finds the object that contains the contents of a file at a specific commit.
diff --git a/helix-vcs/src/lib.rs b/helix-vcs/src/lib.rs
index 97320d32..6f5e40d0 100644
--- a/helix-vcs/src/lib.rs
+++ b/helix-vcs/src/lib.rs
@@ -1,4 +1,5 @@
-use std::path::Path;
+use arc_swap::ArcSwap;
+use std::{path::Path, sync::Arc};
 
 #[cfg(feature = "git")]
 pub use git::Git;
@@ -18,6 +19,7 @@ pub trait DiffProvider {
     /// The data is returned as raw byte without any decoding or encoding performed
     /// to ensure all file encodings are handled correctly.
     fn get_diff_base(&self, file: &Path) -> Option<Vec<u8>>;
+    fn get_current_head_name(&self, file: &Path) -> Option<Arc<ArcSwap<Box<str>>>>;
 }
 
 #[doc(hidden)]
@@ -26,6 +28,10 @@ impl DiffProvider for Dummy {
     fn get_diff_base(&self, _file: &Path) -> Option<Vec<u8>> {
         None
     }
+
+    fn get_current_head_name(&self, _file: &Path) -> Option<Arc<ArcSwap<Box<str>>>> {
+        None
+    }
 }
 
 pub struct DiffProviderRegistry {
@@ -38,6 +44,12 @@ impl DiffProviderRegistry {
             .iter()
             .find_map(|provider| provider.get_diff_base(file))
     }
+
+    pub fn get_current_head_name(&self, file: &Path) -> Option<Arc<ArcSwap<Box<str>>>> {
+        self.providers
+            .iter()
+            .find_map(|provider| provider.get_current_head_name(file))
+    }
 }
 
 impl Default for DiffProviderRegistry {