fix: use AsyncHTTPDigestAuth instead of HTTPDigestAuth for niquests async client

When using niquests in async mode, digest auth must use AsyncHTTPDigestAuth.
The sync HTTPDigestAuth.handle_401() calls r.connection.send() which returns
a coroutine in async context, causing "AttributeError: 'coroutine' object has
no attribute 'history'".

Reported at jawah/niquests#387 (comment)

prompt: Please check jawah/niquests#387 (comment), the last comment hints that the problem is in the caldav library

AI Prompts:
claude-sonnet-4-6: Please check jawah/niquests#387 (comment), the last comment hints that the problem is in the caldav library

Author: tobixen

caldav/async_davclient.py

@@ -835,9 +835,9 @@ def build_auth_object(self, auth_types: list[str] | None = None) -> None:
             if _USE_HTTPX:
                 self.auth = httpx.DigestAuth(self.username, self.password)
             else:
-                from niquests.auth import HTTPDigestAuth
+                from niquests.auth import AsyncHTTPDigestAuth
 
-                self.auth = HTTPDigestAuth(self.username, self.password)
+                self.auth = AsyncHTTPDigestAuth(self.username, self.password)
         elif auth_type == "basic":
             if _USE_HTTPX:
                 self.auth = httpx.BasicAuth(self.username, self.password)

docs/source/v3-migration.rst

@@ -38,11 +38,11 @@ replace it with:
     from caldav import Event, Todo, Calendar           # OK
 
 All public symbols that were in ``caldav.objects`` should remain available directly
-from the ``caldav`` namespace
+from the ``caldav`` namespace.  Exceptions may apply.
 
 Wildcard import into caldav.* removed
 -------------------------------------
-Earlier a wildcard import ``from caldav.objects import *`` was done into the ``caldav`` namespace.  This has been removed.  In normal circumstances, your imports should continue to work - but there are no guarantees that all imports will continue working.  If you have any issues, see :doc:`contact`.
+Earlier a wildcard import ``from caldav.objects import *`` was done into the ``caldav`` namespace.  This has been removed.  Imports should work, but corner cases may exists.  If you have any issues, see :doc:`contact`.
 
 Config-file parse errors now raise exceptions
 ---------------------------------------------
@@ -308,9 +308,7 @@ context-manager "borrow" methods that give exclusive, safe write access.
 
 While inside the ``with`` block, the borrowed representation is the
 single source of truth.  Attempting to borrow a *different*
-representation raises ``RuntimeError``.  This means the current
-pattern is not completely thread-safe as of v3.x - but an explicit
-error is often better than updates silently being dropped.
+representation raises ``RuntimeError``.
 
 **The data representation remains the same:**
 

examples/basic_usage_examples.py

@@ -113,9 +113,6 @@ def find_delete_calendar_demo(my_principal, calendar_name):
 def add_stuff_to_calendar_demo(calendar):
     """
     This demo adds some stuff to the calendar
-
-    Unfortunately the arguments that it's possible to pass to save_* is poorly documented.
-    https://github.com/python-caldav/caldav/issues/253
     """
     ## Add an event with some certain attributes
     print("Saving an event")