backend: Filter out invalid message text when generating chat history

[tianjing-li]

Thanks @EugeneLightsOn for pointing out fix area

Right now if a chat stream fails after creating the initial Chatbot response message, it creates an empty chat in chat_history, which the chat model does not accept. This filters them out.

Ideally we go back and delete those previous messages, but I didn't want to introduce potentially janky logic.

AI Description

This PR introduces several changes to the chat functionality, enhancing the user experience and improving the backend logic.

Summary

The create_chat_history function in src/backend/services/chat.py now filters out the user's most recent message and any empty messages when generating chat history. This ensures that only relevant messages are included in the history, providing a more accurate context for the chat SDK call.

Additionally, a new function is_final_event is added to src/backend/chat/custom/custom.py, which appears to be related to event handling. However, the purpose of this function is not entirely clear from the provided code snippet.

Changes

• src/backend/services/chat.py:
  • The create_chat_history function now filters out the user's most recent message and any empty messages.
• src/backend/chat/custom/custom.py:
  • A new function is_final_event is introduced, which seems to be related to event handling.
• src/backend/chat/custom/tool_calls.py:
  • A new function _call_tool_async is added, but its purpose is not evident from the provided code.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.01%. Comparing base (81a6f32) to head (f1f65d6).

Additional details and impacted files

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  Coverage   79.01%   79.01%           
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  Files         257      257           
  Lines       10975    10975           
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  Hits         8672     8672           
  Misses       2303     2303           

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[EugeneLightsOn]

looks good to me