From 33b09da47e210d4b7f38093fad81a881dfaf69fc Mon Sep 17 00:00:00 2001
From: remimd <remimd@github.com>
Date: Mon, 18 May 2026 15:52:21 +0200
Subject: [PATCH] feat: Expose registered message types

---
 cq/__init__.py      | 26 ++++++++++++--------------
 cq/_core/cq.py      | 13 +++++++++++++
 cq/_core/handler.py | 15 ++++++++++++++-
 3 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/cq/__init__.py b/cq/__init__.py
index 5896098..3320ac9 100644
--- a/cq/__init__.py
+++ b/cq/__init__.py
@@ -21,6 +21,7 @@
 from ._core.related_events import AnyIORelatedEvents, RelatedEvents
 
 __all__ = (
+    "__cq__",
     "AnyCommandBus",
     "AnyIORelatedEvents",
     "Bus",
@@ -55,30 +56,27 @@
 )
 
 try:
-    from cq.ext.injection import InjectionAdapter as _InjectionAdapter
+    from .ext.injection import InjectionAdapter as _InjectionAdapter
 
 except ImportError:  # pragma: no cover
-    _default = CQ(_NoDI())
+    __cq__ = CQ(_NoDI())
 
 else:
-    _default = CQ(_InjectionAdapter())
+    __cq__ = CQ(_InjectionAdapter())
 
-_default.register_defaults()
+__cq__.register_defaults()
 
-command_handler = _default.command_handler
-event_handler = _default.event_handler
-query_handler = _default.query_handler
+command_handler = __cq__.command_handler
+event_handler = __cq__.event_handler
+query_handler = __cq__.query_handler
 
-new_command_bus = _default.new_command_bus
-new_event_bus = _default.new_event_bus
-new_query_bus = _default.new_query_bus
+new_command_bus = __cq__.new_command_bus
+new_event_bus = __cq__.new_event_bus
+new_query_bus = __cq__.new_query_bus
 
 
 class ContextCommandPipeline[C: Command](_ContextCommandPipeline[C]):
     __slots__ = ()
 
-    def __init__(self, di: DIAdapter = _default.di) -> None:
+    def __init__(self, di: DIAdapter = __cq__.di) -> None:
         super().__init__(di)
-
-
-del _default
diff --git a/cq/_core/cq.py b/cq/_core/cq.py
index d999455..8a4152f 100644
--- a/cq/_core/cq.py
+++ b/cq/_core/cq.py
@@ -1,3 +1,4 @@
+from collections.abc import KeysView
 from typing import Any, Self
 
 from cq._core.di import DIAdapter
@@ -34,14 +35,26 @@ def di(self) -> DIAdapter:
     def command_handler(self) -> HandlerDecorator[Command, Any]:
         return HandlerDecorator(self.__command_registry, self.__di)
 
+    @property
+    def command_types(self) -> KeysView[type[Command]]:
+        return self.__command_registry.message_types
+
     @property
     def event_handler(self) -> HandlerDecorator[Event, Any]:
         return HandlerDecorator(self.__event_registry, self.__di)
 
+    @property
+    def event_types(self) -> KeysView[type[Event]]:
+        return self.__event_registry.message_types
+
     @property
     def query_handler(self) -> HandlerDecorator[Query, Any]:
         return HandlerDecorator(self.__query_registry, self.__di)
 
+    @property
+    def query_types(self) -> KeysView[type[Query]]:
+        return self.__query_registry.message_types
+
     def new_command_bus(self) -> Bus[Command, Any]:
         bus = SimpleBus(self.__command_registry)
         command_middleware = CommandDispatchScopeMiddleware(self.__di)
diff --git a/cq/_core/handler.py b/cq/_core/handler.py
index ce5f2bc..e032423 100644
--- a/cq/_core/handler.py
+++ b/cq/_core/handler.py
@@ -1,6 +1,6 @@
 from abc import abstractmethod
 from collections import defaultdict
-from collections.abc import Awaitable, Callable, Iterator
+from collections.abc import Awaitable, Callable, Iterator, KeysView
 from dataclasses import dataclass, field
 from functools import partial
 from inspect import Parameter, isclass, unwrap
@@ -49,6 +49,11 @@ def create(
 class HandlerRegistry[I, O](Protocol):
     __slots__ = ()
 
+    @property
+    @abstractmethod
+    def message_types(self) -> KeysView[type[I]]:
+        raise NotImplementedError
+
     @abstractmethod
     def handlers_from(self, message_type: type[I]) -> Iterator[HandleFunction[[I], O]]:
         raise NotImplementedError
@@ -71,6 +76,10 @@ class MultipleHandlerRegistry[I, O](HandlerRegistry[I, O]):
         init=False,
     )
 
+    @property
+    def message_types(self) -> KeysView[type[I]]:
+        return self.__values.keys()
+
     def handlers_from(self, message_type: type[I]) -> Iterator[HandleFunction[[I], O]]:
         for key_type in _iter_key_types(message_type):
             yield from self.__values.get(key_type, ())
@@ -97,6 +106,10 @@ class SingleHandlerRegistry[I, O](HandlerRegistry[I, O]):
         init=False,
     )
 
+    @property
+    def message_types(self) -> KeysView[type[I]]:
+        return self.__values.keys()
+
     def handlers_from(self, message_type: type[I]) -> Iterator[HandleFunction[[I], O]]:
         for key_type in _iter_key_types(message_type):
             function = self.__values.get(key_type, None)