fix(deepseek): prevent incorrect ToolCall merging caused by empty id and name strings

[ggndnn]

Fix tool call merging issue during deepseek stream processing, same as #2589.

[markpollack]

@mxsl-gr thoughts?

[mxsl-gr]

Hi, @ggndnn Thanks for the PR!
I’ve done quite a few tests, and both deepseek-chat and ZhiPuAI in stream mode don’t seem to return an empty string for the tool call id.
It seems like this issue might be specific to OpenAI, If you have a minimal reproducible scenario, that would be even better!

[ggndnn]

@mxsl-gr Hi, In order to obtain the reasoning_content while also utilizing the tool calling feature, I believe the DeepSeekApi is capable of doing so, so I used it to access aliyun models such as qwen3-235b-a22b, then got the issue.

[mxsl-gr]

@mxsl-gr Hi, In order to obtain the reasoning_content while also utilizing the tool calling feature, I believe the DeepSeekApi is capable of doing so, so I used it to access aliyun models such as qwen3-235b-a22b, then got the issue.

You’re right! I tested it with Qwen3 and saw the same issue.
It related to the model’s default return values. From a defensive programming perspective, I think this merge change doesn’t hurt and can be helpful.