Python: During Dapr step activation, perform model validate internally (microsoft#10841)

### Motivation and Context

In the current Dapr step activation code, we know what state (if it
exists) is to be activated, but we're forcing the step to perform that
operation. We can perform the validation internally to remove the burden
from the dev to have to do this (making it less error prone).

<!-- Thank you for your contribution to the semantic-kernel repo!
Please help reviewers and future users, providing the following
information:
  1. Why is this change required?
  2. What problem does it solve?
  3. What scenario does it contribute to?
  4. If it fixes an open issue, please link to the issue here.
-->

### Description

Perform model validation internally, removing the need to do it from
each step.

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

Author: moonbox3

python/samples/demos/process_with_dapr/process/steps.py

@@ -6,8 +6,8 @@
 
 from pydantic import Field
 
-from semantic_kernel.agents.chat_completion.chat_completion_agent import ChatCompletionAgent
-from semantic_kernel.connectors.ai.open_ai.services.azure_chat_completion import AzureChatCompletion
+from semantic_kernel.agents import ChatCompletionAgent
+from semantic_kernel.connectors.ai.open_ai import AzureChatCompletion
 from semantic_kernel.contents.chat_history import ChatHistory
 from semantic_kernel.functions import kernel_function
 from semantic_kernel.kernel import Kernel
@@ -107,9 +107,6 @@ class CStep(KernelProcessStep[CStepState]):
     # The activate method overrides the base class method to set the state in the step.
     async def activate(self, state: KernelProcessStepState[CStepState]):
         """Activates the step and sets the state."""
-        # If validation is necessary, overwrite the original reference
-        # Overwriting the state object is crucial to link back to the original state
-        state.state = state.state if isinstance(state.state, CStepState) else CStepState.model_validate(state.state)
         self.state = state.state
         print(f"##### CStep activated with Cycle = '{self.state.current_cycle}'.")
 

python/semantic_kernel/processes/dapr_runtime/actors/step_actor.py

@@ -207,10 +207,10 @@ async def activate_step(self):
         t_state = get_generic_state_type(step_cls)
 
         if t_state is not None:
-            # Create state_type as KernelProcessStepState[TState].
             state_type = KernelProcessStepState[t_state]
 
             if state_object is None:
+                # Create a fresh step state object if none is provided.
                 state_object = state_type(
                     name=step_cls.__name__,
                     id=step_cls.__name__,
@@ -219,7 +219,7 @@ async def activate_step(self):
             else:
                 # Ensure that state_object is an instance of the expected type.
                 if not isinstance(state_object, KernelProcessStepState):
-                    error_message = "State object is not of the expected type."
+                    error_message = "State object is not of the expected KernelProcessStepState type."
                     raise KernelException(error_message)
 
                 await self._state_manager.try_add_state(
@@ -232,13 +232,21 @@ async def activate_step(self):
                 )
                 await self._state_manager.save_state()
 
-            # Initialize state_object.state if it is not already set.
+            # If state is None, instantiate it. If it exists but is not the right type, validate it.
             if state_object.state is None:
                 try:
                     state_object.state = t_state()
                 except Exception as e:
                     error_message = f"Cannot instantiate state of type {t_state}: {e}"
                     raise KernelException(error_message)
+            else:
+                # Convert the existing state if it's not already an instance of t_state
+                if not isinstance(state_object.state, t_state):
+                    try:
+                        state_object.state = t_state.model_validate(state_object.state)
+                    except Exception as e:
+                        error_message = f"Cannot validate state of type {t_state}: {e}"
+                        raise KernelException(error_message)
         else:
             # The step has no user-defined state; use the base KernelProcessStepState.
             state_type = KernelProcessStepState