The AI assistant is set to deepseek-v4-pro or deepseek-v4-flash, but cannot output the corresponding response.

The AI assistant is set to deepseek-v4-pro or deepseek-v4-flash, but cannot output the corresponding response.Output the error message: 'Error: Failed to create AI stream'

But when I set the AI assistant to deepseek-chat, it can output content, but it can only search for the question and cannot effectively retrieve the corresponding answer.

Reproduce the failure using deepseek-v4-pro and deepseek-v4-flash, then compare it with deepseek-chat while observing the reported “Failed to create AI stream” error. Trace the AI assistant's stream-creation entry point and provider handling; done means both listed models produce responses without that error and the reported retrieval behavior is understood.

Written by the indexing model from the issue text.