fix(proxy): recognize DeepSeek reasoning stream content

[ding113]

Fixes #1394

Summary

• Classify non-empty choices[].delta.reasoning_content as valid OpenAI Chat stream content.
• Preserve empty reasoning chunks as neutral and keep existing error/content precedence unchanged.
• Cover the 65-frame DeepSeek reasoning stream and the Request Replay owner path that still gates streams while STREAM_GATE_MODE=off.

Validation

• bunx vitest run tests/unit/proxy/stream-gate-frame-classifier.test.ts tests/unit/proxy/stream-gate-content-gate.test.ts tests/unit/proxy/stream-gate-forwarder-integration.test.ts (79 passed)
• bun run typecheck
• bun run lint
• bun run lint:fix
• bun run build
• bun run test
• bun run test:coverage

Review

• Local Standards review: no actionable findings.
• Local Spec review against 0.9.1版本，在Pi中使用DeepSeek compatible端口 100%报错 #1394: no actionable findings.

Greptile Summary

This PR updates the OpenAI Chat stream classifier so non-empty DeepSeek reasoning_content deltas count as valid content while empty deltas remain neutral.

• Adds choices.#.delta.reasoning_content to the existing OpenAI Chat content paths.
• Adds classifier coverage for non-empty and empty reasoning deltas.
• Adds content-gate and replay-owner integration coverage for a 65-frame reasoning stream.

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The new path uses the classifier’s existing non-empty-value semantics, preserves error-before-content precedence, and is covered at classifier, gate, and forwarding integration levels.

Important Files Changed

Filename	Overview
src/app/v1/_lib/proxy/stream-gate/frame-classifier.ts	Adds DeepSeek reasoning deltas to the established OpenAI Chat content classification without changing error precedence or empty-value semantics.
tests/unit/proxy/stream-gate-frame-classifier.test.ts	Verifies non-empty reasoning deltas classify as content and empty reasoning deltas remain neutral.
tests/unit/proxy/stream-gate-content-gate.test.ts	Verifies a reasoning-only stream commits immediately rather than reaching the event cap.
tests/unit/proxy/stream-gate-forwarder-integration.test.ts	Verifies the replay-owner forwarding path accepts and returns a reasoning-only DeepSeek stream without failover.

_{Reviews (1): Last reviewed commit: "fix(proxy): recognize DeepSeek reasoning..." | Re-trigger Greptile}

Context used:

• Knowledge Base — Proxy request pipeline

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.

[coderabbitai]

📝 Walkthrough

Walkthrough

OpenAI Chat 内容帧规则新增 delta.reasoning_content。测试覆盖非空与空 reasoning 内容，以及 DeepSeek 流的提交、完整透传和单次转发行为。

Changes

DeepSeek reasoning 内容支持

Layer / File(s)	Summary
内容帧分类规则 src/app/v1/_lib/proxy/stream-gate/frame-classifier.ts, tests/unit/proxy/stream-gate-frame-classifier.test.ts	非空 reasoning_content 被分类为 content。空字符串仍被分类为 neutral。
流式提交与转发验证 tests/unit/proxy/stream-gate-content-gate.test.ts, tests/unit/proxy/stream-gate-forwarder-integration.test.ts	测试验证 65 个 reasoning 帧可提交并完整透传，且不触发 failover 或失败记录。

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

Possibly related PRs

• ding113/claude-code-hub#1373：同样修改 frame-classifier.ts 和 OpenAI Chat 内容帧分类规则。

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	变更将非空 reasoning_content 识别为有效内容，并覆盖 DeepSeek 流场景，符合问题 #1394 的修复目标。
Out of Scope Changes check	✅ Passed	代码和测试变更均围绕 DeepSeek reasoning 流处理及其验证，没有发现无关改动。
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Title check	✅ Passed	标题准确概括了修复 DeepSeek reasoning stream 内容识别的主要变更。
Description check	✅ Passed	描述与变更内容直接相关，并说明了实现、测试范围和验证结果。

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/deepseek-reasoning-stream-gate

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[github-actions]

🧪 测试结果

测试类型	状态
代码质量	✅
单元测试	✅
集成测试	✅
API 测试	✅

总体结果: ✅ 所有测试通过

[github-actions]

Code Review Summary

No significant issues identified in this PR.

PR Size: S

• Lines changed: 60
• Files changed: 4

Review Coverage

• Logic and correctness - Clean
• Security (OWASP Top 10) - Clean
• Error handling - Clean
• Type safety - Clean
• Documentation accuracy - Clean
• Test coverage - Adequate
• Code clarity - Good

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Automated review by Codex AI

[github-actions]

• Completed the PR review for #1395 and posted the GitHub review summary as a comment.
• Applied the size label size/S.
• I did not find any diff-scoped issue that cleared the reporting threshold after validating the new classifier change and the added coverage in src/app/v1/_lib/proxy/stream-gate/frame-classifier.ts, tests/unit/proxy/stream-gate-frame-classifier.test.ts, tests/unit/proxy/stream-gate-content-gate.test.ts, and tests/unit/proxy/stream-gate-forwarder-integration.test.ts.
• I also attempted targeted test execution, but this runner does not have bun/bunx installed, so runtime validation could not be rerun locally here.