[Python] Pluggy hook function not receiving keyword arguments - always using defaults

I'm using Pluggy to build a plugin system for a Python application. Everything works fine for most hooks, but I'm having a persistent issue where keyword arguments (kwargs) passed from my call_hook() function are not showing up in the plugin function.

Here’s a simplified version of the code:

Hook specification (plugin_hooks.py):

@hookspec
def discover_files(directory: str, recursive: bool, reprocess: bool) -> list:
"""Discover files in the given directory."""


Hook implementation (file_discovery_plugin.py):

@hookimpl
def discover_files(directory: str, recursive: bool = False, reprocess: bool = False) -> list:
print("recursive:", recursive) # Always prints: False
print("reprocess:", reprocess) # Always prints: False


Plugin invocation:

logger.debug("Calling hook '%s' with args=%s, kwargs=%s", hook_name, args, kwargs)
result = hook(*args, **kwargs)
return result


Logging Output:

[DEBUG] __main__: Reprocess flag passed to discover_files: True
[DEBUG] core.plugin_manager: Calling hook 'discover_files' with args=(), kwargs={'directory': 'C:\\input', 'recursive': False, 'reprocess': True}
[DEBUG] file_discovery_plugin: reprocess flag in discover_files: False


Despite clearly passing reprocess=True, the plugin function always receives the default False.

What I’ve tried:

• Confirmed the hook is correctly registered
• Confirmed the parameters match between @hookspec and @hookimpl
• Printed kwargs in the plugin and verified that it's empty ({})
• Tried Python 3.10 and 3.11 — same behavior
• Manually invoking the plugin bypassing Pluggy works as expected

Workaround:

As a workaround, I'm bypassing Pluggy for this hook and manually calling plugin.discover_files(...) from my plugin_manager. That works, but I’d prefer to use Pluggy’s dispatch model if possible.

Question:

Is there a known issue with Pluggy not forwarding kwargs to plugin implementations? Or is there a subtle requirement in how @hookimpl functions are defined that I’m missing?

I've been scratching my head over this for a while and any help or insight would be appreciated!

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