cli: Tell the user when canonical head is updated

This is useful especially in multi-delegate repos, since patches can be
merged without the head being updated.

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

@@ -62,6 +62,7 @@ f2de534 Second commit
 ```
 ``` ~alice RAD_SOCKET=/dev/null (stderr)
 $ git push rad
+✓ Canonical head updated to f6cff86594495e9beccfeda7c20173e55c1dd9fc
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
    f2de534..f6cff86  master -> master
 ```
@@ -79,6 +80,7 @@ We have to use the `allow.rollback` option:
 
 ``` ~alice RAD_SOCKET=/dev/null (stderr)
 $ git push -f -o allow.rollback
+✓ Canonical head updated to 319a7dc3b195368ded4b099f8c90bbb80addccd3
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
  + f6cff86...319a7dc master -> master (forced update)
 ```

radicle-cli/examples/rad-merge-after-update.md

@@ -16,6 +16,7 @@ $ git commit --amend --allow-empty -q -m "Amended change"
 $ git checkout master -q
 $ git merge feature/1 -q
 $ git push rad master
+✓ Canonical head updated to 954bcdb5008447ce294a61a21d7eb87afbe7f4a6
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
    f2de534..954bcdb  master -> master
 ```

radicle-cli/examples/rad-merge-no-ff.md

@@ -37,6 +37,7 @@ Finally, we push master and expect the patch to be merged.
 ``` (stderr) RAD_SOCKET=/dev/null
 $ git push rad master
 ✓ Patch a1207f6e82700e42cc46c9c38c7786b18cbd2040 merged
+✓ Canonical head updated to 737a10cfa29111afeb0d43cf3545cee386b939ec
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
    f2de534..737a10c  master -> master
 ```

radicle-cli/examples/rad-merge-via-push.md

@@ -63,6 +63,7 @@ When we push to `rad/master`, we automatically merge the patches:
 $ git push rad master
 ✓ Patch 8357a9f1d61e80309d314491aa754969d9f47d77 merged
 ✓ Patch a1207f6e82700e42cc46c9c38c7786b18cbd2040 merged
+✓ Canonical head updated to d6399c71702b40bae00825b3c444478d06b4e91c
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
    f2de534..d6399c7  master -> master
 ```

radicle-cli/examples/rad-patch-merge-draft.md

@@ -14,6 +14,7 @@ $ git checkout master -q
 $ git merge feature/1
 $ git push rad master
 ✓ Patch cf29ac6b10141058be66b94a92a81c703b972751 merged
+✓ Canonical head updated to 20aa5dde6210796c3a2f04079b42316a31d02689
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
    f2de534..20aa5dd  master -> master
 ```

radicle-cli/examples/workflow/5-patching-maintainer.md

@@ -90,6 +90,7 @@ Fast-forward
 ``` (stderr)
 $ git push rad master
 ✓ Patch 3581e83ad18f5cdd806ab50fa11cfd5dd4e8ae1c merged at revision abb0360
+✓ Canonical head updated to f567f695d25b4e8fb63b5f5ad2a584529826e908
 ✓ Synced with 1 node(s)
 To rad://z42hL2jL4XNk6K8oHQaSWfMgCL7ji/z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi
    f2de534..f567f69  master -> master

radicle-remote-helper/src/push.rs

@@ -279,8 +279,16 @@ pub fn run(
 
     // Sign refs and sync if at least one ref pushed successfully.
     if !ok.is_empty() {
-        stored.sign_refs(&signer)?;
+        let _ = stored.sign_refs(&signer)?;
-        stored.set_head()?;
+        let head = stored.set_head()?;
+
+        if head.is_updated() {
+            eprintln!(
+                "{} Canonical head updated to {}",
+                cli::format::positive("✓"),
+                cli::format::secondary(head.new),
+            );
+        }
 
         if !opts.no_sync {
             // Connect to local node and announce refs to the network.

radicle-tools/src/rad-push.rs

@@ -21,7 +21,7 @@ fn main() -> anyhow::Result<()> {
 
     radicle::Node::new(profile.socket()).announce_refs(id)?;
 
-    println!("head: {head}");
+    println!("head: {}", head.new);
     println!("ok: {}", sigrefs.signature);
 
     Ok(())

radicle-tools/src/rad-set-canonical-refs.rs

@@ -10,10 +10,10 @@ fn main() -> anyhow::Result<()> {
     let repo = profile.storage.repository_mut(rid)?;
 
     let id_oid = repo.set_identity_head()?;
-    let branch_oid = repo.set_head()?;
+    let branch = repo.set_head()?;
 
     println!("ok: identity: {id_oid}");
-    println!("ok: branch: {branch_oid}");
+    println!("ok: branch: {}", branch.new);
 
     Ok(())
 }

radicle/src/storage.rs

@@ -69,6 +69,21 @@ impl FromIterator<PublicKey> for Namespaces {
     }
 }
 
+/// Output of [`WriteRepository::set_head`].
+pub struct SetHead {
+    /// Old branch head.
+    pub old: Option<Oid>,
+    /// New branch head.
+    pub new: Oid,
+}
+
+impl SetHead {
+    /// Check if the head was updated.
+    pub fn is_updated(&self) -> bool {
+        self.old != Some(self.new)
+    }
+}
+
 /// Repository error.
 #[derive(Error, Debug)]
 pub enum RepositoryError {
@@ -536,7 +551,7 @@ where
 pub trait WriteRepository: ReadRepository + SignRepository {
     /// Set the repository head to the canonical branch.
     /// This computes the head based on the delegate set.
-    fn set_head(&self) -> Result<Oid, RepositoryError>;
+    fn set_head(&self) -> Result<SetHead, RepositoryError>;
     /// Set the repository 'rad/id' to the canonical commit, agreed by quorum.
     fn set_identity_head(&self) -> Result<Oid, RepositoryError> {
         let head = self.canonical_identity_head()?;

radicle/src/storage/git.rs

@@ -19,8 +19,8 @@ use crate::identity::{Identity, Project};
 use crate::storage::refs;
 use crate::storage::refs::{Refs, SignedRefs, SignedRefsAt};
 use crate::storage::{
-    Inventory, ReadRepository, ReadStorage, Remote, Remotes, RepositoryError, SignRepository,
+    Inventory, ReadRepository, ReadStorage, Remote, Remotes, RepositoryError, SetHead,
-    WriteRepository, WriteStorage,
+    SignRepository, WriteRepository, WriteStorage,
 };
 
 pub use crate::git::{
@@ -799,19 +799,27 @@ impl ReadRepository for Repository {
 }
 
 impl WriteRepository for Repository {
-    fn set_head(&self) -> Result<Oid, RepositoryError> {
+    fn set_head(&self) -> Result<SetHead, RepositoryError> {
         let head_ref = refname!("HEAD");
-        let (branch_ref, head) = self.canonical_head()?;
+        let old = self
+            .raw()
+            .refname_to_id(&head_ref)
+            .ok()
+            .map(|oid| oid.into());
+        let (branch_ref, new) = self.canonical_head()?;
 
-        log::debug!(target: "storage", "Setting ref: {} -> {}", &branch_ref, head);
+        if old == Some(new) {
+            return Ok(SetHead { old, new });
+        }
+        log::debug!(target: "storage", "Setting ref: {} -> {}", &branch_ref, new);
         self.raw()
-            .reference(&branch_ref, *head, true, "set-local-branch (radicle)")?;
+            .reference(&branch_ref, *new, true, "set-local-branch (radicle)")?;
 
         log::debug!(target: "storage", "Setting ref: {} -> {}", head_ref, branch_ref);
         self.raw()
             .reference_symbolic(&head_ref, &branch_ref, true, "set-head (radicle)")?;
 
-        Ok(head)
+        Ok(SetHead { old, new })
     }
 
     fn set_identity_head_to(&self, commit: Oid) -> Result<(), RepositoryError> {

radicle/src/test/storage.rs

@@ -288,7 +288,7 @@ impl WriteRepository for MockRepository {
         todo!()
     }
 
-    fn set_head(&self) -> Result<Oid, RepositoryError> {
+    fn set_head(&self) -> Result<SetHead, RepositoryError> {
         todo!()
     }