Added in Thiago fix

src/crewai/flow/flow.py

@@ -137,6 +137,12 @@ class Flow(Generic[T], metaclass=FlowMeta):
     _routers: Dict[str, str] = {}
     initial_state: Union[Type[T], T, None] = None
 
+    def __class_getitem__(cls, item):
+        class _FlowGeneric(cls):
+            _initial_state_T = item
+
+        return _FlowGeneric
+
     def __init__(self):
         print("[Flow.__init__] Initializing Flow")
         self._methods: Dict[str, Callable] = {}
@@ -152,6 +158,8 @@ class Flow(Generic[T], metaclass=FlowMeta):
 
     def _create_initial_state(self) -> T:
         print("[Flow._create_initial_state] Creating initial state")
+        if self.initial_state is None and hasattr(self, "_initial_state_T"):
+            return self._initial_state_T()  # type: ignore
         if self.initial_state is None:
             return {}  # type: ignore
         elif isinstance(self.initial_state, type):

src/crewai/flow/structured_test_flow.py

@@ -9,8 +9,7 @@ class ExampleState(BaseModel):
     message: str = ""
 
 
-class StructuredExampleFlow(Flow):
-    initial_state = ExampleState
+class StructuredExampleFlow(Flow[ExampleState]):
 
     @start()
     async def start_method(self):
@@ -21,8 +20,7 @@ class StructuredExampleFlow(Flow):
         return "Start result"
 
     @listen(start_method)
-    async def second_method(self, result):
-        print(f"Second method, received: {result}")
+    async def second_method(self):
         print(f"State before increment: {self.state}")
         self.state.counter += 1
         self.state.message += " - updated"
@@ -30,8 +28,7 @@ class StructuredExampleFlow(Flow):
         return "Second result"
 
     @listen(start_method)
-    async def third_method(self, result):
-        print(f"Third method, received: {result}")
+    async def third_method(self):
         print(f"State before increment: {self.state}")
         self.state.counter += 1
         self.state.message += " - updated"

src/crewai/flow/structured_test_flow_or.py

@@ -10,7 +10,6 @@ class ExampleState(BaseModel):
 
 
 class StructuredExampleFlow(Flow[ExampleState]):
-    initial_state = ExampleState
 
     @start()
     async def start_method(self):

src/crewai/flow/unstructured_test_flow.py

@@ -11,15 +11,15 @@ class FlexibleExampleFlow(Flow):
         return "Start result"
 
     @listen(start_method)
-    def second_method(self, result):
-        print(f"Second method, received: {result}")
+    def second_method(self):
+        print("Second method")
         self.state["counter"] += 1
         self.state["message"] = "Hello from flexible flow"
         return "Second result"
 
     @listen(second_method)
-    def third_method(self, result):
-        print(f"Third method, received: {result}")
+    def third_method(self):
+        print("Third method")
         print(f"Final counter value: {self.state["counter"]}")
         print(f"Final message: {self.state["message"]}")
         return "Third result"