Fix chat history rendering error after page refresh

[YoungHypo]

Problem description

#24

Cause Analysis

chat_history in app.py has the following structure.

[
    UserContent(
        parts=[
            Part(
                text='<input prompt>',
                video_metadata=None,
                thought=None,
                code_execution_result=None,
                executable_code=None,
                file_data=None,
                function_call=None,
                function_response=None,
                inline_data=None
            )
        ],
        role='user'
    ),
    Content(
        parts=[
            Part(
                text='<output response 1>',
                video_metadata=None,
                thought=None,
                code_execution_result=None,
                executable_code=None,
                file_data=None,
                function_call=None,
                function_response=None,
                inline_data=None
            )
        ],
        role='model'
    ),
    Content(
        parts=[
            Part(
                text='<output response 2>',
                ...
            )
        ],
        role='model'
    )
]

The templates/index.html file does not handle this structure. Also, a model response may be split into multiple Content objects. That's why there are lots of empty pop-ups after refreshing.

Solution

Refactor the Jinja2 template logic to:

• Validate content (filter out empty messages and check whether is User of Model),
• Merge consecutive model responses into a single reply,