Output custom parameters at the message_end node

[dajianguo]

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1. Is this request related to a challenge you're experiencing? Tell me about your story.

I need to customize the output of some parameters in the streaming interface and non-streaming interface. For example: customized knowledge sources, recommended questions, some flags, etc.

I modified the meesage_end node to output the specified session variable.If allowed I will submit it.

2. Additional context or comments

No response

3. Can you help us with this feature?

• I am interested in contributing to this feature.