fix(sidecar): re-register a missing origin remote instead of crashing on attach

basic-memory-git-sync/src/basic_memory_git_sync/sync.py

@@ -34,7 +34,7 @@
 from typing import Protocol
 
 import structlog
-from git import Actor, GitCommandError, Repo
+from git import Actor, GitCommandError, Remote, Repo
 
 from basic_memory_git_sync.settings import Settings
 
@@ -98,7 +98,22 @@ def attach(self) -> None:
         if self._vault_dir.exists() and (self._vault_dir / ".git").exists():
             self._repo = Repo(self._vault_dir)
             self._log.info("backstop.attached", dir=str(self._vault_dir))
-            self._repo.remotes.origin.fetch()
+            origin = self._origin()
+            if origin is None:
+                # A previous crashed boot left a .git with no origin remote
+                # (e.g. Repo.init persisted but the create_remote/fetch did
+                # not). Re-register it before fetching so attach converges
+                # instead of crashing on the missing `.origin`.
+                self._log.info("backstop.registering_origin", dir=str(self._vault_dir))
+                origin = self._repo.create_remote("origin", self._clone_url)
+            with self._repo.git.custom_environment(**self._git_env()):
+                origin.fetch()
+                # A bare Repo.init (no remote, no branch) leaves the repo on
+                # the git default branch (often `master`); adopt the branch we
+                # track so polls commit to the right ref.
+                if self._repo.active_branch.name != self._branch:
+                    self._repo.git.checkout("-B", self._branch, f"origin/{self._branch}")
+                    self._log.info("backstop.branch_adopted", branch=self._branch)
             return
 
         self._vault_dir.parent.mkdir(parents=True, exist_ok=True)
@@ -200,6 +215,21 @@ def _require_repo(self) -> Repo:
             raise RuntimeError("VaultGitBackstop.attach() must be called before poll_once()")
         return self._repo
 
+    def _origin(self) -> Remote | None:
+        """Look up the `origin` remote by name, or None if absent.
+
+        GitPython's ``repo.remotes.origin`` attribute raises when no remote
+        named ``origin`` is registered (e.g. after a crashed ``Repo.init``
+        that persisted the repo without the remote). Look it up defensively
+        by name so attach() can re-register it instead of crashing.
+        """
+        if self._repo is None:
+            return None
+        try:
+            return self._repo.remotes["origin"]
+        except IndexError:
+            return None
+
 
 def run_forever(
     settings: Settings,

basic-memory-git-sync/tests/unit/test_sync.py

@@ -89,6 +89,23 @@ def test_attach_adopts_existing_non_git_dir(tmp_path: Path, remote: Path) -> Non
     assert b._repo.remotes.origin.url == str(remote)
 
 
+def test_attach_readds_origin_when_missing(tmp_path: Path, remote: Path) -> None:
+    """A previous crashed boot left a .git with no origin remote.
+
+    Reproduces the production crash: a prior boot did ``Repo.init`` but died
+    before ``create_remote``/fetch persisted, so ``attach()`` sees a real
+    .git but ``repo.remotes.origin`` raises. The new ``_origin()`` look-up
+    must re-register the remote and fetch instead of crashing.
+    """
+    v = tmp_path / "vault"
+    v.mkdir(parents=True)
+    Repo.init(v)
+    b = VaultGitBackstop(clone_url=str(remote), vault_dir=v, push=False)
+    b.attach()  # must not raise
+    assert b._repo.remotes["origin"].url == str(remote)
+    assert b._repo.active_branch.name == "main"
+
+
 def test_poll_commits_nothing_when_clean(backstop: VaultGitBackstop) -> None:
     result = backstop.poll_once()
     assert result.committed is False