Add backoff to auth requests, to try handling 400 errors from Kinde

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Version 0.6.1 - 2026-02-23
+
+- Add exponential backoff to calls toward the auth endpoint
+
 ## Version 0.6.0 - 2026-01-27
 
 - Add update_validation method

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "cradl"
-version = "0.6.0"
+version = "0.6.1"
 description = "Python SDK for Cradl"
 authors = [{ name = "Cradl", email = "hello@cradl.ai" }]
 readme = "README.md"

src/cradl/backoff.py

@@ -2,6 +2,15 @@
 import time
 from typing import Optional, Union, Type, Callable
 
+import requests  # type: ignore
+from requests.exceptions import RequestException  # type: ignore
+
+
+def fatal_code(e: RequestException):
+    if isinstance(e.response, requests.Response) and isinstance(e.response.status_code, int):
+        return 400 <= e.response.status_code < 500
+    raise e
+
 
 def exponential_backoff(
     exceptions: Union[tuple[Type[Exception]], Type[Exception]],

src/cradl/client.py

@@ -3,20 +3,18 @@
 from base64 import b64encode
 from datetime import datetime
 from pathlib import Path
-
 from typing import Callable, Dict, List, Optional, Sequence, Union
 from urllib.parse import urlparse, quote
 
 import requests  # type: ignore
 from requests.exceptions import RequestException  # type: ignore
 
-from .credentials import Credentials, guess_credentials
+from .backoff import exponential_backoff, fatal_code
 from .content import parse_content
+from .credentials import Credentials, guess_credentials
 from .log import setup_logging
-from .backoff import exponential_backoff
 from .response import decode_response, TooManyRequestsException, EmptyRequestError
 
-
 logger = setup_logging(__name__)
 Content = Union[bytes, bytearray, str, Path, io.IOBase]
 Queryparam = Union[str, List[str]]
@@ -35,12 +33,6 @@ def dictstrip(d):
     return {k: v for k, v in d.items() if v is not None}
 
 
-def _fatal_code(e: RequestException):
-    if isinstance(e.response, requests.Response) and isinstance(e.response.status_code, int):
-        return 400 <= e.response.status_code < 500
-    raise e
-
-
 class Client:
     """A low level client to invoke api methods from Cradl."""
     def __init__(self, credentials: Optional[Credentials] = None, profile=None):
@@ -49,7 +41,7 @@ def __init__(self, credentials: Optional[Credentials] = None, profile=None):
         self.credentials = credentials or guess_credentials(profile)
 
     @exponential_backoff(TooManyRequestsException, max_tries=4)
-    @exponential_backoff(RequestException, max_tries=3, giveup=_fatal_code)
+    @exponential_backoff(RequestException, max_tries=3, giveup=fatal_code)
     def _make_request(
         self,
         requests_fn: Callable,
@@ -81,7 +73,7 @@ def _make_request(
         return decode_response(response)
 
     @exponential_backoff(TooManyRequestsException, max_tries=4)
-    @exponential_backoff(RequestException, max_tries=3, giveup=_fatal_code)
+    @exponential_backoff(RequestException, max_tries=3, giveup=fatal_code)
     def _make_fileserver_request(
         self,
         requests_fn: Callable,

src/cradl/credentials.py

@@ -7,9 +7,11 @@
 from typing import Optional, Tuple
 
 import requests  # type: ignore
+from requests.exceptions import RequestException  # type: ignore
 
+from .backoff import exponential_backoff, fatal_code
 from .log import setup_logging
-
+from .response import TooManyRequestsException, BadRequest
 
 logger = setup_logging(__name__)
 NULL_TOKEN = '', 0
@@ -82,6 +84,9 @@ def access_token(self) -> str:
 
         return access_token
 
+    # Backoff on BadRequest since Kinde seems to sometimes give bogus 400 responses
+    @exponential_backoff(exceptions=(TooManyRequestsException, BadRequest), max_tries=4)  # type: ignore
+    @exponential_backoff(RequestException, max_tries=3, giveup=fatal_code)
     def _get_client_credentials(self) -> Tuple[str, int]:
         if any(endpoint in self.auth_endpoint for endpoint in ['auth.lucidtech.io', 'auth.cradl.ai', 'kinde.com']):
             data = {