feat: 会话 jsonl 时间戳改为上海时间

[jianYanZhiX7]

Summary

会话 jsonl 转录在写入时将顶层 timestamp 序列化为 +08:00 偏移写法，使会话文件可直接读作本地时间，同时保持 ISO-8601 严格性（Date.parse 语义不变）。

改动

• 新增 src/utils/shanghaiTimestamp.ts：toShanghaiISOString / toShanghaiTimestamp / withShanghaiTimestamp / compareTimestamps
• 5 个写入点接入转换：主写入队列、hydrateRemoteSession、CCR v2 前台转录与子代理转录、appendEntryToFile
• 2 处排序改为按真实时刻比较（recoverOrphanedParallelToolResults、loadAllLogsFromSessionFile），修正 ...Z 与 +08:00 混存时的字典序错序
• 嵌套时间戳不改写：toolUseResult / MCP 元数据等不透明载荷保持逐字节 round-trip

变更文件

• 新增：src/utils/shanghaiTimestamp.ts（61 行）、src/utils/__tests__/shanghaiTimestamp.test.ts（10 个用例）
• 修改：src/utils/sessionStorage.ts（17+/9-）

Test plan

• bun run precheck 全绿：typecheck 零错误 + biome 零修复
• 全量 bun test：6032 pass / 10 skip / 0 fail
• 新增 10 个用例：转换语义、非 Z / 非法值兜底、嵌套时间戳不改写、混存偏移按时刻排序

Summary by CodeRabbit

• New Features
  • Transcript timestamps are now consistently displayed using the Shanghai timezone (+08:00).
  • Timestamped transcript entries are normalized across session storage and restored sessions.
• Bug Fixes
  • Transcript entries with mixed timestamp formats are now ordered by their actual time rather than text formatting, improving log and tool-result ordering.
  • Existing timestamps that cannot be converted remain unchanged.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: c3e7545a-ec81-4017-bc66-2f46aa953102

📥 Commits

Reviewing files that changed from the base of the PR and between 77a7934 and 4e8daf7.

📒 Files selected for processing (3)

• src/utils/__tests__/shanghaiTimestamp.test.ts
• src/utils/sessionStorage.ts
• src/utils/shanghaiTimestamp.ts

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📝 Walkthrough

Walkthrough

The change adds Shanghai timestamp utilities and tests. Transcript hydration paths now normalize timestamps before serialization. Transcript recovery and loading now compare mixed-offset timestamps by instant.

Changes

Timestamp handling

Layer / File(s)	Summary
Timestamp utility contracts and tests src/utils/shanghaiTimestamp.ts, src/utils/__tests__/shanghaiTimestamp.test.ts	Adds timestamp conversion, entry normalization, and offset-aware comparison helpers with coverage for valid, invalid, nested, and mixed-offset values.
Transcript write normalization src/utils/sessionStorage.ts	Applies withShanghaiTimestamp to remote session entries and CCRv2 event payloads before serialization.
Offset-aware transcript ordering src/utils/sessionStorage.ts	Uses compareTimestamps when recovering orphaned results and loading trailing session messages.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Feature

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 77.78% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: converting session JSONL timestamps to Shanghai time.
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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