M1 R3: current_branch via gix referent_name (qwen2.5-coder:32b)

src/python.rs

@@ -57,8 +57,9 @@ fn is_clean(_path: String) -> PyResult<bool> {
 }
 
 #[pyfunction]
-fn current_branch(_path: String) -> PyResult<Option<String>> {
-    todo!("repo::current_branch (None if detached)")
+fn current_branch(path: String) -> PyResult<Option<String>> {
+    // soft-fail: any error -> None (API.md)
+    Ok(crate::repo::current_branch(std::path::Path::new(&path)).unwrap_or(None))
 }
 
 #[pyfunction]

src/repo/current_branch.rs

@@ -0,0 +1,38 @@
+use crate::error::GitxtendError;
+use crate::repo::Result;
+use std::path::Path;
+
+/// Short name of the current branch (e.g. "main"); `Ok(None)` when HEAD is
+/// detached (mirrors `git rev-parse --abbrev-ref HEAD`, which prints "HEAD"
+/// when detached — we return None in that case).
+pub fn current_branch(path: &Path) -> Result<Option<String>> {
+    let repo = gix::open(path).map_err(GitxtendError::from_err)?;
+    let head = repo.head().map_err(GitxtendError::from_err)?;
+    Ok(head.referent_name().map(|n| n.shorten().to_string()))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::repo::fixtures;
+
+    #[test]
+    fn test_current_branch_on_main() {
+        let td = fixtures::repo();
+        let p = td.path();
+        assert_eq!(current_branch(p).unwrap(), Some("main".into()));
+        assert_eq!(
+            current_branch(p).unwrap(),
+            Some(fixtures::git(p, &["rev-parse", "--abbrev-ref", "HEAD"]))
+        );
+    }
+
+    #[test]
+    fn test_current_branch_detached_head() {
+        let td = fixtures::repo();
+        let p = td.path();
+        let sha = fixtures::git(p, &["rev-parse", "HEAD"]);
+        fixtures::git(p, &["checkout", "--detach", &sha]);
+        assert_eq!(current_branch(p).unwrap(), None);
+    }
+}

src/repo/mod.rs

@@ -26,6 +26,9 @@ pub use is_git_repo::is_git_repo;
 mod head_sha;
 pub use head_sha::head_sha;
 
+mod current_branch;
+pub use current_branch::current_branch;
+
 /// Temp-dir git fixtures shared by the per-method parity tests.
 ///
 /// Fixtures are built with the real `git` CLI, so each parity test asserts