fix: finalize Claude streams after upstream EOF

[kuangzhenfeng]

📝 变更描述 / Description

修复 OpenAI 兼容流在发送 [DONE] 或直接 EOF、但没有可转换的终止 chunk 时，Claude Messages 流缺少结束事件的问题。

此前 HandleFinalResponse 处理最后一个普通 chunk 后会直接将转换状态标记为完成。若上游没有提供 finish_reason 终止 chunk，当前 content block 不会关闭，message_delta 和 message_stop 也不会发送，Claude Code 等等待 Anthropic SSE 结束事件的客户端会一直停留在生成状态。

本次改动在处理最后一个 chunk 后调用现有的 Claude 流 finalizer，由转换状态统一补齐仍未发送的 content_block_stop、message_delta 和 message_stop。正常已完成的流会由 Done 状态阻止重复结束事件。

同时在 relayconvert 兼容入口中暴露 finalizer，供 OpenAI relay 的 EOF 收尾路径调用。

本 PR 仅修改两个源码文件，不包含测试文件。

与 #5345 的区别：该 PR 修改的是重构前的 service/convert.go 路径；本 PR 针对当前 relaykit 架构下无 finish_reason 终止 chunk 的 [DONE]/EOF 收尾路径，不改变正常终止 chunk 的 usage 处理逻辑。

🚀 变更类型 / Type of change

• 🐛 Bug 修复 (Bug fix)
• ✨ 新功能 (New feature)
• ⚡ 性能优化 / 重构 (Refactor)
• 📝 文档更新 (Documentation)

🔗 关联任务 / Related Issue

• Related to Bug: /v1/messages streaming for qwen3.6-plus lacks content_block_stop/message_delta/message_stop, causing Claude Code to hang #4697

✅ 提交前检查项 / Checklist

• 非重复提交: 已检索现有 Issues 与 PRs，并在变更描述中说明与相近 PR 的差异。
• Bug fix 说明: 已关联相同结束事件缺失症状的 Issue。
• 变更理解: 已确认 EOF 收尾路径通过现有 finalizer 生成完整 Claude SSE 生命周期。
• 范围聚焦: 本 PR 仅包含两个相关源码文件的修改。
• 本地验证: 已通过包级编译检查。
• 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

$ GOWORK=off go test -vet=off ./relay/channel/openai -run '^$' -count=1
ok  github.com/QuantumNous/new-api/relay/channel/openai  0.686s [no tests to run]

Summary by CodeRabbit

• Bug Fixes
  • Improved Claude response handling when using OpenAI-compatible streaming.
  • Ensured final streamed responses are emitted correctly after conversion completes.

[coderabbitai]

Walkthrough

The change adds an exported OpenAI-to-Claude stream finalization wrapper. Claude final-response handling now invokes the wrapper after processing converted stream responses and emits the finalized responses.

Changes

OpenAI-to-Claude stream finalization

Layer / File(s)	Summary
Finalize converted Claude responses relaykit/relayconvert/response_compat.go, relay/channel/openai/helper.go	The compatibility layer exposes FinalizeStreamResponseOpenAI2Claude. Claude final-response handling invokes it after converted responses and removes the previous completion-state assignment.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• QuantumNous/new-api#6394: Both changes modify the OpenAI-to-Claude stream conversion lifecycle.
• QuantumNous/new-api#6629: Both changes modify OpenAI-to-Claude stream finalization.
• QuantumNous/new-api#6714: Both changes modify the finalization flow and wrapper for Claude stream termination events.

Suggested reviewers: calcium-ion

Poem

A rabbit hops through streams of light,
Claude responses finish right.
A wrapper opens the final gate,
Converted words no longer wait.
The final signal joins the flow—
Hop, hop, done! Off we go.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: finalizing Claude streams after upstream EOF.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

relay/channel/openai/helper.go (1)

197-199: 🗄️ Data Integrity & Integration | 🔵 Trivial | ⚡ Quick win

Add regression coverage for the final SSE sequence.

Test a final normal chunk without finish_reason, followed by finalization. Assert content_block_stop, message_delta, and message_stop.

Also test a chunk that already completes conversion. Assert that the finalizer emits no duplicate events after Done is set. The PR adds no tests. (github.com)

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@relay/channel/openai/helper.go` around lines 197 - 199, Add regression tests
covering FinalizeStreamResponseOpenAI2Claude and the helper.ClaudeData flow:
verify a final normal chunk without finish_reason followed by finalization emits
content_block_stop, message_delta, and message_stop, and verify an
already-completed chunk causes no duplicate events after Done is set.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@relay/channel/openai/helper.go`:
- Around line 197-199: Add regression tests covering
FinalizeStreamResponseOpenAI2Claude and the helper.ClaudeData flow: verify a
final normal chunk without finish_reason followed by finalization emits
content_block_stop, message_delta, and message_stop, and verify an
already-completed chunk causes no duplicate events after Done is set.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 88f13e74-68bb-414c-be3b-4764cfd98469

📥 Commits

Reviewing files that changed from the base of the PR and between 823e263 and 72b4def.

📒 Files selected for processing (2)

• relay/channel/openai/helper.go
• relaykit/relayconvert/response_compat.go