fix(summarize): 持久化增量蒸馏游标（#229）

[z2Ace0107]

变更

• 新增 distill_cursors SQLite 表，按 session.id 持久化最近成功消费的事件序。
• 宿主重启后恢复游标，避免历史窗口重复蒸馏。
• 记忆写入与游标推进在同一 SQLite 事务中完成。
• LLM、解析、中止、记忆写入或游标写入失败时保留窗口，并正确记录失败审计。
• 补充旧库迁移、重启恢复、失败重试、事务回滚、空数组和混合数组测试。
• 同步 src/ 与 lib/。

验证

• npm test：1247 passed
• node scripts/check-sync.js
• node --check
• git diff --check

Fixes #229

Summary by CodeRabbit

• 新功能
  • 新增蒸馏进度游标的持久化能力，支持按会话保存和恢复最近处理位置。
  • 服务重启后可继续增量蒸馏，减少重复处理。
  • 游标仅向前推进，避免较小序号覆盖已保存进度。
• 错误修复
  • 摘要处理失败或游标写入失败时，相关状态会回滚并记录错误审计信息。
• 测试
  • 补充游标持久化、数据库迁移、回滚及异常场景的测试覆盖。

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: slow-stack/dsh-mneme/.coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: 815d2c8c-b4bc-4429-ada2-89357286f411

📥 Commits

Reviewing files that changed from the base of the PR and between 9089a71 and c08ab76.

📒 Files selected for processing (8)

• dsh-mneme/lib/service.js
• dsh-mneme/lib/store.js
• dsh-mneme/lib/summarize.js
• dsh-mneme/src/service.js
• dsh-mneme/src/store.js
• dsh-mneme/src/summarize.js
• dsh-mneme/test/store.test.js
• dsh-mneme/test/summarize.test.js

Included review availability: Your plan provides up to 2 included reviews per hour; 1 remains after this review.

---

📝 Walkthrough

Walkthrough

本次变更为蒸馏流程新增按会话持久化的游标。存储层提供游标读写和单调更新。服务层透传 API。摘要流程恢复并提交游标，同时补充失败审计和回滚测试。

Changes

蒸馏游标持久化

Layer / File(s)	Summary
游标存储与迁移 dsh-mneme/lib/store.js, dsh-mneme/src/store.js, dsh-mneme/test/store.test.js	新增 distill_cursors 表、getDistillCursor 和 setDistillCursor。写入时保留较大的 last_seq。测试覆盖初始化、旧库迁移和游标不回退。
服务层游标 API dsh-mneme/lib/service.js, dsh-mneme/src/service.js	服务对象新增 getDistillCursor 和 setDistillCursor，并委托给存储层。
摘要流程与回滚验证 dsh-mneme/lib/summarize.js, dsh-mneme/src/summarize.js, dsh-mneme/test/summarize.test.js	摘要流程优先读取持久游标，并在成功消费、空摘要和窗口过小时提交游标。异常时记录 error 审计状态并重新抛出。测试覆盖重启恢复、混合条目、写入失败和游标提交失败。

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~30 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: modusensus

Sequence Diagram(s)

sequenceDiagram
  participant 摘要流程
  participant 服务层
  participant 存储层
  摘要流程->>服务层: 读取会话持久游标
  服务层->>存储层: getDistillCursor(sessionId)
  存储层-->>服务层: 返回 last_seq
  服务层-->>摘要流程: 返回 previousSeq
  摘要流程->>服务层: 提交窗口末尾 nextSeq
  服务层->>存储层: setDistillCursor(sessionId, nextSeq)
  存储层-->>服务层: 返回更新后的游标

Loading

Merge Risk: ⚪ Minimal · up to c08ab

No actionable merge-blocking risk remains. The cursor persistence change can proceed with normal checks.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 29.17% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 24 functions across 8 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	标题准确概括了 PR 的主要变更：为 summarize 持久化增量蒸馏游标，并包含关联 Issue 编号 #229。
Linked Issues check	✅ Passed	PR 实现了 Issue #229 的编码要求。distill_cursors 按 session_id 持久化 last_seq，并在服务重启后读取游标。初始化和旧库测试覆盖表创建，支持幂等结构迁移。游标写入使用单调不回退的 UPSERT。摘要流程在成功写入、空摘要和窗口过小路径推进游标；混合数组推进到窗口末尾，全无效数组不推进。记忆写入或游标写入失败时执行回滚并记录 error…
Out of Scope Changes check	✅ Passed	变更集中在 Issue #229 所需的存储层、服务透传、摘要流程和对应测试。src/ 与 lib/ 同步属于该功能的构建产物一致性要求。未发现与持久化游标、事务语义、迁移或测试无关的变更。

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create a new PR

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[Anans-Ivresse]

审阅通过，实现很稳 👍 游标与记忆写入同事务原子提交（恰一次语义）、旧库迁移幂等、与 summarizeMinWindowChars / summarizePeakHours 的游标消费语义完全兼容、并发下单调不倒退，lib 同步 ✓，全量 1251 测试通过。

非阻塞小建议（可后续优化）：

• src/summarize.js:410 persistCursor 在 setDistillCursor 缺失时硬抛错，建议降级为 warn + 内存态回退（理论场景：第三方宿主用旧版 service 构造时）
• 每轮 turn/end 都先读库取游标，绕过了内存 map 缓存，可改内存优先（每事件少一次 PK 查询）
• 可补「峰值时段 / 最小窗口」与持久化游标的交叉用例

[codecov]

Codecov Report

❌ Patch coverage is 90.27778% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
dsh-mneme/src/store.js	90.24%	4 Missing ⚠️
dsh-mneme/src/summarize.js	89.65%	3 Missing ⚠️

📢 Thoughts on this report? Let us know!