Add reasoning content support (for DeepSeek format API)

[PasserbyAlpha]

For customAPI, try to load delta.reasoning_content and message.reasoning_content if it exists.

For DeepSeek-R1

For GPT-4o

Currently only delta part (streaming) has been tested (I don't know how to trigger a single-request chat completion with the repo).

I'm not familiar with nodejs. Please help me to improve it if possible, thank you!

[PeterDaveHello]

/review

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PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Logic Flow The streaming handling logic may have an issue where delta content is only added when reasoning content exists. Check if this could cause regular content to be missed when no reasoning is present. if (delta) { if (with_reasoning && !has_reasoning_end) { answer += REASONING_END_SIGN has_reasoning_end = true } answer += delta } Edge Case The code doesn't handle the case where reasoning_content exists but is empty. This could lead to unnecessary reasoning markers being added to the output. if (delta_reasoning) { with_reasoning = true if (!has_reasoning_start) { answer += REASONING_START_SIGN has_reasoning_start = true } answer += delta_reasoning

[PeterDaveHello]

/improve

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PR Code Suggestions ✨

Category	Suggestion	Impact
Possible issue	Fix reasoning marker logic The current implementation adds the reasoning end sign for every delta chunk when reasoning is present, but it should only be added once before transitioning to the actual response. Add a check to ensure the reasoning end marker is only added when transitioning from reasoning to response content. src/services/apis/custom-api.mjs [91-107] if (delta !== undefined) { // streaming handling if (delta_reasoning) { with_reasoning = true if (!has_reasoning_start) { answer += REASONING_START_SIGN has_reasoning_start = true } answer += delta_reasoning } if (delta) { - if (with_reasoning && !has_reasoning_end) { + if (with_reasoning && !has_reasoning_end && delta_reasoning === undefined) { answer += REASONING_END_SIGN has_reasoning_end = true } answer += delta } } [ ] Apply / Chat Suggestion importance[1-10]: 7 __ Why: The suggestion correctly identifies a logical issue where the REASONING_END_SIGN could be added prematurely if both delta_reasoning and delta are present in the same chunk. Adding the delta_reasoning === undefined condition ensures the end marker is only added when transitioning from reasoning to response content.	Medium
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