fix(walkthrough): use remote default branch

packages/web/server/lib/git/service.js

@@ -3367,6 +3367,7 @@ export async function getBranches(directory) {
     const allBranches = result.all;
     const remoteBranches = allBranches.filter(branch => branch.startsWith('remotes/'));
     const activeRemoteBranches = await filterActiveRemoteBranches(git, remoteBranches);
+    const defaultBranches = await getRemoteDefaultBranches(git);
 
     const filteredAll = [
       ...allBranches.filter(branch => !branch.startsWith('remotes/')),
@@ -3376,7 +3377,8 @@ export async function getBranches(directory) {
     return {
       all: filteredAll,
       current: result.current,
-      branches: result.branches
+      branches: result.branches,
+      defaultBranches,
     };
   } catch (error) {
     console.error('Failed to get branches:', error);
@@ -3384,6 +3386,28 @@ export async function getBranches(directory) {
   }
 }
 
+async function getRemoteDefaultBranches(git) {
+  try {
+    const refs = await git.raw([
+      'for-each-ref',
+      '--format=%(refname) %(symref)',
+      'refs/remotes',
+    ]);
+    return Object.fromEntries(
+      refs.trim().split('\n').flatMap((line) => {
+        const [ref, symbolicRef] = line.split(' ');
+        const match = ref.match(/^refs\/remotes\/([^/]+)\/HEAD$/);
+        const prefix = match ? `refs/remotes/${match[1]}/` : '';
+        return match && typeof symbolicRef === 'string' && symbolicRef.startsWith(prefix)
+          ? [[match[1], symbolicRef.slice(prefix.length)]]
+          : [];
+      })
+    );
+  } catch {
+    return {};
+  }
+}
+
 async function filterActiveRemoteBranches(git, remoteBranches) {
   try {
     const remotes = await git.getRemotes();