fix: skip rebase when remote branch does not exist yet

src/forge/workspace/git_ops.py

@@ -131,6 +131,9 @@ def pull_rebase(self, remote: str = "fork") -> None:
         branch = self.workspace.branch_name
         logger.info(f"Syncing with {remote}/{branch} before implementing changes")
         self._run_git("fetch", remote)
+        if not self.remote_branch_exists(branch, remote=remote):
+            logger.info(f"Remote branch {remote}/{branch} does not exist yet; skipping rebase")
+            return
         self._run_git("rebase", f"{remote}/{branch}")
         logger.info(f"Rebase onto {remote}/{branch} complete")
 

tests/unit/workspace/test_pull_rebase.py

@@ -0,0 +1,47 @@
+"""Tests for GitOperations.pull_rebase behavior."""
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+from forge.workspace.git_ops import GitOperations
+from forge.workspace.manager import Workspace
+
+
+def _git_ops(tmp_path: Path) -> GitOperations:
+    settings = MagicMock()
+    settings.github_token.get_secret_value.return_value = "ghp_fake"
+    workspace = Workspace(
+        path=tmp_path / "repo",
+        repo_name="org/repo",
+        branch_name="forge/test-123",
+        ticket_key="TEST-123",
+    )
+    with patch("forge.workspace.git_ops.get_settings", return_value=settings):
+        return GitOperations(workspace)
+
+
+def test_pull_rebase_skips_when_remote_branch_missing(tmp_path):
+    """First implementation run: remote branch doesn't exist yet, rebase must be skipped."""
+    git = _git_ops(tmp_path)
+
+    with (
+        patch.object(git, "_run_git") as run_git,
+        patch.object(git, "remote_branch_exists", return_value=False),
+    ):
+        git.pull_rebase(remote="origin")
+
+    run_git.assert_called_once_with("fetch", "origin")
+
+
+def test_pull_rebase_rebases_when_remote_branch_exists(tmp_path):
+    """Subsequent runs: remote branch exists, rebase must happen."""
+    git = _git_ops(tmp_path)
+
+    with (
+        patch.object(git, "_run_git") as run_git,
+        patch.object(git, "remote_branch_exists", return_value=True),
+    ):
+        git.pull_rebase(remote="origin")
+
+    assert run_git.call_args_list[0].args == ("fetch", "origin")
+    assert run_git.call_args_list[1].args == ("rebase", "origin/forge/test-123")