fix: handle missing symbolic-ref for default branch detection (fixes #3)

src/__tests__/git-operations.test.ts

@@ -31,7 +31,7 @@ describe('GitOperations', () => {
       mockExecSync
         .mockReturnValueOnce('') // rev-parse --git-dir
         .mockReturnValueOnce('git@github.com:synctree/releasebot.git\n') // remote get-url origin
-        .mockReturnValueOnce('refs/remotes/origin/main\n'); // symbolic-ref
+        .mockReturnValueOnce('main\n'); // rev-parse --abbrev-ref HEAD
 
       const result = gitOps.validateRepository();
 
@@ -51,14 +51,42 @@ describe('GitOperations', () => {
       mockExecSync
         .mockReturnValueOnce('') // rev-parse --git-dir
         .mockReturnValueOnce('https://github.com/synctree/releasebot.git\n') // remote get-url origin
-        .mockReturnValueOnce('refs/remotes/origin/main\n'); // symbolic-ref
+        .mockReturnValueOnce('main\n'); // rev-parse --abbrev-ref HEAD
 
       const result = gitOps.validateRepository();
 
       expect(result.owner).toBe('synctree');
       expect(result.name).toBe('releasebot');
     });
 
+    it('should fallback to "main" when current branch detection fails', () => {
+      mockExecSync
+        .mockReturnValueOnce('') // rev-parse --git-dir
+        .mockReturnValueOnce('git@github.com:synctree/releasebot.git\n') // remote get-url origin
+        .mockImplementationOnce(() => {
+          // rev-parse --abbrev-ref HEAD fails
+          throw new Error('Unable to get current branch');
+        });
+
+      const result = gitOps.validateRepository();
+
+      expect(result.defaultBranch).toBe('main');
+      expect(mockCore.debug).toHaveBeenCalledWith(
+        'Could not determine current branch, using "main" as default'
+      );
+    });
+
+    it('should fallback to "main" when current branch is HEAD', () => {
+      mockExecSync
+        .mockReturnValueOnce('') // rev-parse --git-dir
+        .mockReturnValueOnce('git@github.com:synctree/releasebot.git\n') // remote get-url origin
+        .mockReturnValueOnce('HEAD\n'); // rev-parse --abbrev-ref HEAD returns HEAD (detached)
+
+      const result = gitOps.validateRepository();
+
+      expect(result.defaultBranch).toBe('main');
+    });
+
     it('should throw error if not in git repository', () => {
       mockExecSync.mockImplementation(() => {
         throw new Error('Not a git repository');

src/git-operations.ts

@@ -41,9 +41,20 @@ export class GitOperations {
 
       // Get repository information
       const remoteUrl = this.executeGitCommand('remote get-url origin').trim();
-      const defaultBranch = this.executeGitCommand('symbolic-ref refs/remotes/origin/HEAD')
-        .replace('refs/remotes/origin/', '')
-        .trim();
+
+      // For the default branch, we'll use a simple fallback approach
+      // since the exact default branch isn't critical for most operations
+      let defaultBranch = 'main'; // Safe fallback
+      try {
+        // Try to get the current branch if available
+        const currentBranch = this.executeGitCommand('rev-parse --abbrev-ref HEAD').trim();
+        if (currentBranch !== '' && currentBranch !== 'HEAD') {
+          defaultBranch = currentBranch;
+        }
+      } catch {
+        // If we can't get current branch, stick with 'main' fallback
+        core.debug('Could not determine current branch, using "main" as default');
+      }
 
       // Parse repository info from remote URL
       const repoInfo = this.parseRepositoryUrl(remoteUrl);