remote-helper: List `HEAD`

Report the default branch correctly via the symbolic reference `HEAD`.

CHANGELOG.md

@@ -16,6 +16,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `rad clone` now supports the flag `--bare` which works analoguously to 
   `git clone --bare`.
 - `rad init --setup-signing` now works on bare repositories.
+- `git-remote-rad` now correctly reports the default branch to Git by listing
+  the symbolic reference `HEAD`.
 
 ## Fixed Bugs
 

crates/radicle-cli/examples/git/git-push-converge.md

@@ -35,6 +35,7 @@ pushing to their `rad` remote -- but they won't sync to the network just yet:
 $ git commit -m "Alice's commit" --allow-empty -q
 $ git push rad -o no-sync
 $ git ls-remote rad
+f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	HEAD
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	refs/heads/master
 ```
 
@@ -43,6 +44,7 @@ $ git add README
 $ git commit -m "Bob's commit" -q
 $ git push rad -o no-sync
 $ git ls-remote rad
+f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	HEAD
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	refs/heads/master
 ```
 
@@ -51,6 +53,7 @@ $ git add README
 $ git commit -m "Eve's commit" -q
 $ git push rad -o no-sync
 $ git ls-remote rad
+f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	HEAD
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	refs/heads/master
 ```
 

crates/radicle-cli/examples/git/git-push.md

@@ -54,6 +54,7 @@ List the canonical refs:
 
 ```
 $ git ls-remote rad
+f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	HEAD
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	refs/heads/master
 ```
 

crates/radicle-cli/examples/rad-init-existing-bare.md

@@ -40,7 +40,7 @@ $ git remote show rad
 * remote rad
   Fetch URL: rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji
   Push  URL: rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
-  HEAD branch: (unknown)
+  HEAD branch: master
   Remote branch:
     master new (next fetch will store in remotes/rad)
   Local ref configured for 'git push':

crates/radicle-cli/examples/rad-init-existing.md

@@ -37,7 +37,7 @@ $ git remote show rad
 * remote rad
   Fetch URL: rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji
   Push  URL: rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
-  HEAD branch: (unknown)
+  HEAD branch: master
   Remote branch:
     master new (next fetch will store in remotes/rad)
   Local ref configured for 'git push':

crates/radicle-cli/examples/rad-patch-fetch-2.md

@@ -22,6 +22,7 @@ $ git branch -r
 $ git pull
 Already up to date.
 $ git branch -r
+  rad/HEAD -> rad/master
   rad/master
   rad/patches/5e2dedcc5d515fcbc1cca483d3376609fe889bfb
 ```

crates/radicle-cli/examples/rad-patch-pull-update.md

@@ -112,6 +112,7 @@ $ rad patch show 55b9721
 │ ↑ updated to f91e056da05b2d9a58af1160c76245bc3debf7a8 (cad2666) now │
 ╰─────────────────────────────────────────────────────────────────────╯
 $ git ls-remote rad
+f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	HEAD
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354	refs/heads/master
 cad2666a8a2250e4dee175ed5044be2c251ff08b	refs/heads/patches/55b9721ed7f6bfec38f43729e9b6631c5dc812fb
 ```

crates/radicle-cli/examples/rad-patch-via-push.md

@@ -61,6 +61,7 @@ And let's look at our local and remote refs:
 $ git show-ref
 42d894a83c9c356552a57af09ccdbd5587a99045 refs/heads/feature/1
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354 refs/heads/master
+f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354 refs/remotes/rad/HEAD
 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354 refs/remotes/rad/master
 42d894a83c9c356552a57af09ccdbd5587a99045 refs/remotes/rad/patches/6035d2f582afbe01ff23ea87528ae523d76875b6
 ```

crates/radicle-remote-helper/src/list.rs

@@ -46,8 +46,15 @@ pub fn for_fetch<R: ReadRepository + cob::Store<Namespace = NodeId> + 'static>(
             println!("{oid} {name}");
         }
     } else {
-        // Listing canonical refs.
-        // We skip over `refs/rad/*`, since those are not meant to be fetched into a working copy.
+        // List the symbolic reference `HEAD`, which is interpreted by
+        // Git clients to determine the default branch.
+        match stored.head() {
+            Ok((target, _)) => println!("@{target} HEAD"),
+            Err(err) => eprintln!("remote: error resolving HEAD: {err}"),
+        }
+
+        // List canonical references.
+        // Skip over `refs/rad/*`, since those are not meant to be fetched into a working copy.
         for glob in [
             git::refspec::pattern!("refs/heads/*"),
             git::refspec::pattern!("refs/tags/*"),
@@ -56,8 +63,10 @@ pub fn for_fetch<R: ReadRepository + cob::Store<Namespace = NodeId> + 'static>(
                 println!("{oid} {name}");
             }
         }
-        // List the patch refs, but don't abort if there's an error, as this would break
-        // all fetch behavior. Instead, just output an error to the user.
+
+        // List the patch refs, but do not abort if there is an error,
+        // as this would break all fetch behavior.
+        // Instead, just output an error to the user.
         if let Err(e) = patch_refs(profile, stored) {
             eprintln!("remote: error listing patch refs: {e}");
         }