Fix jsonargparse ValueError on Windows CI by using custom ArgumentGroup

Refactor jap_wrapper.py to explicitly define a custom ArgumentGroup class instead of relying on jsonargparse's dynamic subclass generation.

jsonargparse attempts to create an ArgumentGroup subclass that inherits add_argument from the parser by reading source code with inspect.getsource(). This mechanism is fragile and can fail on Windows CI (and likely frozen binaries), causing it to fall back to the standard ArgumentGroup.

When falling back, the standard ArgumentGroup lacks our add_argument wrapper that strips type when action is present. This results in ValueError: Providing both type and action not allowed because jsonargparse forbids this combination.

By explicitly defining ArgumentGroup with our mixin and setting self._group_class, we ensure our compatibility logic is always used.

Author: ThomasWaldmann

src/borg/helpers/jap_wrapper.py

@@ -18,6 +18,7 @@
 import argparse
 
 from jsonargparse import ArgumentParser as _JAPArgumentParser
+from jsonargparse._core import ArgumentGroup as _JAPArgumentGroup
 
 
 def _is_highlander_action(action):
@@ -56,8 +57,8 @@ def __call__(self, parser, namespace, values, option_string=None):
     return TypeConvertingAction
 
 
-class ArgumentParser(_JAPArgumentParser):
-    """ArgumentParser bridging Borg's argparse patterns with jsonargparse."""
+class BorgAddArgumentMixin:
+    """Mixin to provide Borg's add_argument logic to ArgumentParser and ArgumentGroup."""
 
     def add_argument(self, *args, **kwargs):
         """Handle type+action combination that jsonargparse forbids.
@@ -108,6 +109,22 @@ class BoundHighlander(action_cls):
         return super().add_argument(*args, **kwargs)
 
 
+class ArgumentGroup(BorgAddArgumentMixin, _JAPArgumentGroup):
+    """ArgumentGroup that supports Borg's add_argument patterns."""
+
+    pass
+
+
+class ArgumentParser(BorgAddArgumentMixin, _JAPArgumentParser):
+    """ArgumentParser bridging Borg's argparse patterns with jsonargparse."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Force jsonargparse to use our ArgumentGroup class instead of trying to
+        # auto-generate one from source code (which is fragile and fails on Windows CI).
+        self._group_class = ArgumentGroup
+
+
 def flatten_namespace(args):
     """Flatten jsonargparse's nested namespace into a flat one.