from datetime import date
from pydantic_ai import Agent, RunContext

agent = Agent(
    "openai:gpt-4o",
    instructions="You are a helpful assistant",
)

@agent.instructions
def guardrail_instructions(ctx: RunContext[str]) -> str:
    print(ctx.messages) # []
    print(ctx.prompt)   # None

    result = check_guardrail(ctx.prompt)
    if result.warn:
       return f"Proceed with caution! Input triggered guardrail for due to {result.reason}"
    
    return ""

result = agent.run_sync(
    message_history=[ModelRequest(parts=[UserPromptPart(content="Hello!")])],
)
print(result.output)