[Bug] dspy.ReAct doesn't format/use dspy.History OutputFields

[nickthegroot]

What happened?

When using dspy.ReAct and passing dspy.History as a InputField, none of the included OutputFields are used in the LLM chain.

Steps to reproduce

from dspy import ReAct, History, Signature, InputField, OutputField

class GenerateAnswer(Signature):
    question: str = InputField(desc="The question to answer")
    history: History = InputField(desc="The conversation history")

    answer: str = OutputField(desc="The answer to the question")

react = ReAct(GenerateAnswer, tools=[])
history = History(messages=[{"question": "What's the capital of Germany?", "answer": "The capital of Germany is Berlin"}])

react.forward(question="What is the capital of France?", history=history)

Checking the LLM call chain reveals that the user portion is correctly passed, but the assistant portion is not.

lm.history

[
    {'role': 'system', 'content': '...'}, # omitted for brevity
    {'role': 'user', 'content': "[[ ## question ## ]]\nWhat's the capital of Germany?"}, # InputField correctly passed
    {'role': 'assistant', 'content': '[[ ## next_thought ## ]]\nNone\n\n[[ ## next_tool_name ## ]]\nNone\n\n[[ ## next_tool_args ## ]]\nNone'}, # OutputField not passed
    {'role': 'user', 'content': """[[ ## question ## ]]\nWhat is the capital of France?\n\n[[ ## trajectory ## ]]\n\n\nRespond with the correspondi
ng output fields, starting with the field `[[ ## next_thought ## ]]`, then `[[ ## next_tool_name ## ]]` (must be formatted as a 
valid Python Literal['finish']), then `[[ ## next_tool_args ## ]]` (must be formatted as a valid Python dict[str, Any]), and the
n ending with the marker for `[[ ## completed ## ]]`."""}
]

[chenmoneygithub]

@nickthegroot Thanks for reporting the issue, I will take a look