feat(kb): daily feeds brief — sweep, classify, personalized rank, dual-write (K-H)

[oratis]

Part of the knowledge-base v2.0 stack (plan: #278, handoff: #281). Stacked on #285 (K-G) — merge order: #278 → … → #285 → this.

差距

需求 ①（信息日报）完全缺位：没有订阅、没有分类、没有"跟用户相关"的排序，也没有让日报进入知识系统的通道。

做了什么

新目录 src/kb/feeds/，整体照抄 mail 模块的形状（交接文档指定）：

部件	对应 mail	说明
isBriefDue	isDigestDue	同签名纯函数
定时	server.ts mail 块	30 分钟 setInterval + 20 秒重启补跑，unref()
classify.ts	mail/classify.ts	批量小模型 → {category, importance 0-3, oneLine}，同样的注入防护（数据围栏 + 封闭类目校验 + 启发式兜底）
buildBrief/formatBriefText	buildDigest/formatDigestText	纯函数
投递	onMailDigest	新增 pushBridge.onKbBrief（新 brief push 偏好，默认开）+ broadcast({type:'idle_message', source:'kb'})

三条不能省的，逐条落实：

1. 完全惰性（D4）——feeds.json 不存在/为空时，任何入口直接 return null：不碰网络、不调模型；文件的存在即同意，不新增 consent signal。文件每次读取 chmod 0600 并确保进 kb/.gitignore（可能含 SESSDATA）。
2. 日报写两份（D7）——kb/feeds/<date>.json 给 UI（配 GET /api/kb/brief），sources/brief-<date>.md 走 addSource 进 Layer 1（可搜、可链、可蒸馏；K-G 的 lisa kb brief 直接读到）。
3. 预算闸门——budgetTokens 默认 120k/天，分类批次到顶即停并打日志，剩余条目降级为中性评级而不是被丢；Top-N 全文摄取 N=3（走 K-E 引擎，feed 即用户自己的 watchlist，D3 语义自洽）。

个性化排序（相对通用 RSS 阅读器的差异点）：(1+importance) × watchlist 权重 × (1 + 兴趣/wiki 词重叠)——兴趣项来自 MEMORY.md/USER.md 分词，wiki 项来自已有页面标题+标签，重叠计数饱和封顶防关键词堆砌刷分。

增量抓取：按 feed 记 seen-id 环（封顶 300）；单 feed 失败降级为该 feed 无新条目；全部 feed 失败不烧掉当天（下个 tick 重试）；成功但无新条目才算完成当天。

测了什么

13 例全离线：RSS2（CDATA/guid/content:encoded）与 Atom 解析、isBriefDue 四态、评分三信号各自抬升、buildBrief 排序 + 文本渲染（含 ingested 反链）、分类校验（未知类目拒收/importance 钳位/空 oneLine 兜底）、模型失败兜底、预算闸门批次截停、端到端（sweep→classify→rank→topN ingest→两份产物+gitignore+0600）、当天去重、全失败不烧天、pickNewItems 去重封顶。

npm run typecheck 干净；npm test 1268 pass / 0 fail。

🤖 Generated with Claude Code

[oratis]

Reviewed as the penultimate PR of the KB v2 stack. The shape (mail-module mirror), the injection stance in classify.ts, and the offline test suite are solid — but a few things should land before this merges.

Blocking

• No CI has run on this PR (gh pr checks 286 → "no checks reported"). This is a stacked infra change that merges bottom-up; it needs a green run. I verified every cross-module import typechecks against the branch APIs, so I expect it's clean — but that must be confirmed by CI, not asserted.
• Untested new paths: feeds.test.ts covers the pure logic + offline runDailyBrief well, but the server.ts timer/reentrancy guard, onKbBrief push, the idle_message/kb_brief_update broadcasts, and GET /api/kb/brief have no coverage.

Bugs

• service.ts:108-110 — lastBriefDate = today + saveFeedsState run before classify/rank/ingest/dual-write. Any throw in that tail (caught upstream) marks the day done and items seen, permanently losing that brief. You explicitly guard "all feeds failing doesn't burn the day" — please extend the same care to the write pipeline: advance lastBriefDate only after both writes succeed.
• service.ts:90 — (await res.text()).slice(0, FETCH_CAP_BYTES) buffers the whole body before truncating, and the safe-fetch helper has no size cap, so the 2 MB limit doesn't bound memory. A hostile/huge feed on the unattended timer can OOM the backend. Cap during streaming.
• classify.ts:148 — the budget check is at batch start, so the daily ceiling can overshoot by one batch. Fine, but it's a soft cap, not the hard gate the description implies.

Security

• The top-3 auto-ingest fetches attacker-controlled feed links unattended. fetchFollowingSafeRedirects guards redirects, but isPrivateHost matches only literal IPs — no DNS resolution — so a public host resolving to 127.0.0.1/169.254.169.254 slips through. The guard predates this PR, but automating the fetch raises the stakes; worth a resolve-then-validate (or a documented accept).

Nits: service.ts:162 re-sorts items already sorted by buildBrief; rss.ts:33 recompiles a RegExp per tag per item.

Personalization-by-overlap-count (no memory text in the output), the 0600 + gitignore handling of a SESSDATA-bearing feeds.json, and inert-by-default are all done right. Happy to re-approve once CI is green and the two write/read fixes land.

[oratis]

Reconciled onto main + landed the review blockers: (1) brief-loss fixed — lastBriefDate is no longer advanced before classify/rank/ingest/write; it is persisted only after the dual-write succeeds, so a throw in that tail no longer permanently burns the day (a successful-but-empty sweep still marks it done); (2) OOM fixed — the feed fetch now streams through a bounded readBodyCapped instead of (await res.text()).slice(), so a hostile/oversized feed on the unattended timer can't exhaust memory; (3) CI now runs (this PR had none). typecheck + 171 tests green locally. Waiting for CI before merge. Deferred follow-ups (noted): dual-write atomicity, DNS-resolving SSRF, soft-vs-hard budget, server/push/API path tests.