git: add workspace coordination forms and conversation trailers

userland/git/src/changes.rs

@@ -173,6 +173,13 @@ fn quote(prefix: &str, path: &[u8]) -> String {
 }
 // Internal byte paths preserve identity even when the RPC display is lossy.
 fn compare(old: &Snapshot, new: &Snapshot) -> Vec<(Vec<u8>, Option<Vec<u8>>, Kind)> {
+    compare_with_renames(old, new, true)
+}
+fn compare_with_renames(
+    old: &Snapshot,
+    new: &Snapshot,
+    renames: bool,
+) -> Vec<(Vec<u8>, Option<Vec<u8>>, Kind)> {
     let mut deleted: BTreeSet<_> = old
         .keys()
         .filter(|p| !new.contains_key(*p))
@@ -187,7 +194,7 @@ fn compare(old: &Snapshot, new: &Snapshot) -> Vec<(Vec<u8>, Option<Vec<u8>>, Kin
                 // Git does not pair empty blobs as renames by default.
                 let empty =
                     gix::objs::compute_hash(entry.id.kind(), gix::objs::Kind::Blob, b"").ok();
-                let source = if Some(entry.id) == empty {
+                let source = if !renames || Some(entry.id) == empty {
                     None
                 } else {
                     deleted.iter().find(|p| old.get(*p) == Some(entry)).cloned()
@@ -383,6 +390,9 @@ fn worktree(repo: &gix::Repository, index: &Snapshot, filter: Option<&str>) -> R
     Ok(snapshot)
 }
 pub fn diff(p: DiffParams) -> Result<Vec<FileDiff>> {
+    diff_with_renames(p, true)
+}
+pub fn diff_with_renames(p: DiffParams, renames: bool) -> Result<Vec<FileDiff>> {
     if let Some(path) = &p.path {
         repo::validate_path(path)?;
     }
@@ -425,7 +435,7 @@ pub fn diff(p: DiffParams) -> Result<Vec<FileDiff>> {
         }
     };
     let mut result = Vec::new();
-    for (path, source, status) in compare(&old, &new) {
+    for (path, source, status) in compare_with_renames(&old, &new, renames) {
         let before_path = source.as_ref().unwrap_or(&path);
         if !matches_path(&path, p.path.as_deref()) && !matches_path(before_path, p.path.as_deref())
         {