Handle duplicate Gmail label creation

Author: lucaomul

inboxanchor/api/v1/routers/frontend.py

@@ -271,6 +271,11 @@ def _provider_runtime_error_message(provider_name: str, exc: Exception) -> str:
             "backend, so the unread scan never completed. Check the backend machine's "
             "internet/DNS access, then retry Refresh unread scan."
         )
+    if "gmail.googleapis.com" in lowered and "/labels" in lowered and "409" in lowered:
+        return (
+            "Gmail rejected a duplicate label create request. InboxAnchor should refresh its "
+            "provider label cache and retry instead of failing the workflow."
+        )
     if provider_name == "gmail":
         return f"Gmail connected, but InboxAnchor could not fetch unread mail: {message}"
     if provider_name in {"imap", "yahoo", "outlook"}:

inboxanchor/connectors/gmail_transport.py

@@ -595,28 +595,36 @@ def _label_name_to_id(self, label_name: str) -> str:
         if label_name in self._label_cache:
             return self._label_cache[label_name]
 
-        if self._service is not None:
-            service = self._build_service()
-            created = self._execute_legacy(
-                service.users().labels().create(
-                    userId=self.user_id,
-                    body={
+        try:
+            if self._service is not None:
+                service = self._build_service()
+                created = self._execute_legacy(
+                    service.users().labels().create(
+                        userId=self.user_id,
+                        body={
+                            "name": label_name,
+                            "messageListVisibility": "show",
+                            "labelListVisibility": "labelShow",
+                        },
+                    )
+                )
+            else:
+                created = self._request_json(
+                    "POST",
+                    "labels",
+                    json_body={
                         "name": label_name,
                         "messageListVisibility": "show",
                         "labelListVisibility": "labelShow",
                     },
                 )
-            )
-        else:
-            created = self._request_json(
-                "POST",
-                "labels",
-                json_body={
-                    "name": label_name,
-                    "messageListVisibility": "show",
-                    "labelListVisibility": "labelShow",
-                },
-            )
+        except Exception as exc:
+            if self._is_label_conflict_error(exc):
+                self._refresh_label_cache()
+                existing_id = self._label_cache.get(label_name)
+                if existing_id:
+                    return existing_id
+            raise
         self._label_cache[label_name] = created["id"]
         return created["id"]
 
@@ -655,6 +663,17 @@ def _is_missing_label_error(exc: Exception) -> bool:
             return True
         return "404" in str(exc)
 
+    @staticmethod
+    def _is_label_conflict_error(exc: Exception) -> bool:
+        status_code = getattr(getattr(exc, "response", None), "status_code", None)
+        if status_code == 409:
+            return True
+        legacy_status = getattr(getattr(exc, "resp", None), "status", None)
+        if legacy_status == 409:
+            return True
+        lowered = str(exc).lower()
+        return "409" in lowered
+
     def apply_labels(self, email_ids: list[str], labels: list[str]) -> None:
         if not labels:
             return

tests/test_gmail_transport.py

@@ -631,6 +631,32 @@ def test_google_api_transport_apply_labels_uses_batch_modify_endpoint():
     assert session.calls[1][3]["addLabelIds"] == ["Label_1"]
 
 
+def test_google_api_transport_reuses_existing_label_after_conflict():
+    session = StubSession(
+        [
+            StubResponse({"labels": []}),
+            StubResponse({}, status_code=409),
+            StubResponse({"labels": [{"id": "Label_1", "name": "work"}]}),
+            StubResponse({}),
+        ]
+    )
+    transport = GoogleAPITransport(
+        credentials_path="~/credentials.json",
+        token_path="~/token.json",
+        session=session,
+    )
+
+    transport.apply_labels(["msg-1"], ["work"])
+
+    assert session.calls[0][0] == "GET"
+    assert session.calls[1][0] == "POST"
+    assert session.calls[1][1].endswith("/users/me/labels")
+    assert session.calls[2][0] == "GET"
+    assert session.calls[3][0] == "POST"
+    assert session.calls[3][1].endswith("/users/me/messages/batchModify")
+    assert session.calls[3][3]["addLabelIds"] == ["Label_1"]
+
+
 def test_google_api_transport_can_delete_labels_from_gmail():
     session = StubSession(
         [