Fix branch refresh.

src/review/Server.zig

@@ -783,7 +783,16 @@ fn handleRevision(
             else => "git could not produce that diff — check the base ref",
         },
     );
-    return writeJson(a, request, .ok, .{ .revision = rev });
+    // The branch rides along with the digest so the page can notice that the
+    // work tree moved to another branch — which the digest alone cannot always
+    // say. `digest` hashes HEAD's *sha*, so branching off the commit you are
+    // already on (`git switch -c`) leaves it identical while the name in the
+    // review's header is now wrong. One `rev-parse` next to the `git diff` this
+    // endpoint already runs is not a cost worth avoiding.
+    return writeJson(a, request, .ok, .{
+        .revision = rev,
+        .branch = git.currentBranch(repo, a, self.io),
+    });
 }
 
 fn handleFile(