fix: normalize null Responses input content

[u-wlkjyy]

⚠️ 提交说明 / PR Notice

Important

• 请提供人工撰写的简洁摘要，避免直接粘贴未经整理的 AI 输出。

📝 变更描述 / Description

Some OpenAI-compatible clients can send empty assistant messages as content: null. When these requests are converted to, or directly sent through, the Responses API path, Responses-compatible upstreams reject them because each input item's content must be a string or an array.

This change normalizes explicit null content on Responses input items to an empty string before the request is sent upstream. It is applied both to native /v1/responses requests and to the /v1/chat/completions to /v1/responses compatibility conversion path.

🚀 变更类型 / Type of change

• 🐛 Bug 修复 (Bug fix) - 请关联对应 Issue，避免将设计取舍、理解偏差或预期不一致直接归类为 bug
• ✨ 新功能 (New feature) - 重大特性建议先通过 Issue 沟通
• ⚡ 性能优化 / 重构 (Refactor)
• 📝 文档更新 (Documentation)

🔗 关联任务 / Related Issue

• Closes # (N/A)

✅ 提交前检查项 / Checklist

• 人工确认: 我已亲自整理并撰写此描述，没有直接粘贴未经处理的 AI 输出。
• 非重复提交: 我已搜索现有的 Issues 与 PRs，确认不是重复提交。
• Bug fix 说明: 若此 PR 标记为 Bug fix，我已提交或关联对应 Issue，且不会将设计取舍、预期不一致或理解偏差直接归类为 bug。
• 变更理解: 我已理解这些更改的工作原理及可能影响。
• 范围聚焦: 本 PR 未包含任何与当前任务无关的代码改动。
• 本地验证: 已在本地运行并通过测试或手动验证，维护者可以据此复核结果。
• 安全合规: 代码中无敏感凭据，且符合项目代码规范。

📸 运行证明 / Proof of Work

Relevant test passed:

go test ./dto
ok  	github.com/QuantumNous/new-api/dto	0.025s

I also attempted broader local test commands. They are currently blocked in this workspace by unrelated existing/local issues:

go test ./...
FAIL github.com/QuantumNous/new-api [setup failed]
main.go:43:12: pattern web/classic/dist: no matching files found

FAIL github.com/QuantumNous/new-api/output [build failed]
output/analytics_paper_bench.go: undefined symbols from local untracked output files

A targeted relay command also reaches unrelated existing failures in Claude and stream scanner tests, outside the files changed by this PR.

Summary by CodeRabbit

• Bug Fixes

  • Normalize null message content in incoming requests to empty strings, improving robustness and compatibility of API input handling.

• Tests

  • Added tests verifying null content is correctly preserved or converted where appropriate, reducing regressions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 05ac9299-ed5d-43f2-87fd-90c3d3e60e89

📥 Commits

Reviewing files that changed from the base of the PR and between e15435a and 9880498.

📒 Files selected for processing (2)

• dto/openai_request.go
• dto/openai_request_zero_value_test.go

🚧 Files skipped from review as they are similar to previous changes (1)

• dto/openai_request.go

---

Walkthrough

Adds OpenAIResponsesRequest.NormalizeInputNullContent() to rewrite message-like input entries with content: null to "", integrates that normalization into request handling and conversion paths, and adds a unit test validating the behavior.

Changes

Responses API Null Content Normalization

Layer / File(s)	Summary
Data Shape / Import dto/openai_request.go	Adds bytes import to support trimming when reserializing normalized JSON.
Core Normalization Logic dto/openai_request.go	Implements OpenAIResponsesRequest.NormalizeInputNullContent() which unmarshals Input (JSON array), replaces message-like items with content: null to "", and re-marshals/stores trimmed JSON back to Input.
Handler Integration relay/responses_handler.go	After deep-copying the request, ResponsesHelper calls request.NormalizeInputNullContent() and returns an invalid_request error (with skip-retry) if normalization fails.
Conversion Integration service/openaicompat/chat_to_responses.go	ChatCompletionsRequestToResponsesRequest invokes out.NormalizeInputNullContent() after building the responses request and returns any error.
Tests dto/openai_request_zero_value_test.go	Adds TestOpenAIResponsesRequestNormalizeInputNullContent asserting that input[1].content converts from JSON null to "", while other entries remain unchanged as expected.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• QuantumNous/new-api#2876: Modifies ChatCompletionsRequestToResponsesRequest in the same conversion path.

Suggested reviewers

• seefs001
• Calcium-Ion

Poem

🐰 I hopped through JSON, quiet and small,
Turned null to a whisper, no crash nor call,
Empty strings now softly sing,
Requests march on like spring—
A tidy fix, I nibbled and solved it all.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: normalizing null Responses input content to empty strings before sending upstream.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[u-wlkjyy]

trea cn调用会存在这个问题