feat: M3 — 伏笔账本 + 节奏引擎 + 大纲（含并发记账 bugfix）

- 伏笔账本：纯函数状态机(OPEN/PARTIAL/CLOSED/OVERDUE) + ForeshadowLedger repo；验收后到期扫描(BackgroundTask 自建 session 置 OVERDUE)；登记/状态变更端点
- 节奏 + 三审齐：foreshadow-analyst + pace-checker 并入 LangGraph 并行审(REVIEW_SPECS)，collect 分列落 chapter_reviews(conflicts/foreshadow_sug/pace)，review SSE 加 foreshadow/pace 事件
- 大纲：outliner Agent 产 OutlineResult(含 foreshadow_windows)，POST /outline 逐章 upsert outline 表；GET /foreshadow?status= 看板
- 前端：伏笔四泳道看板(OVERDUE 琥珀) + 大纲编辑器(窗口徽标) + 节奏节拍图(▁▃▅) + 审稿页消费 foreshadow/pace SSE
- bugfix(T3.8)：并行三审共用请求 session 记账触发 'Session is already flushing' → foreshadow/pace 静默丢失；SqlAlchemyLedgerSink.record 改 add-only(靠端点/事务 commit)，加并发回归测试
- M3 E2E：真实 DB + mock 网关零 token 走通 埋设→进展→验收后扫描 OVERDUE→看板 + 大纲含窗口 + 三审齐 SSE/留痕；E2E 暴露并钉住上述 bug
- 门禁绿：mypy 111 / pytest 228(0 xfailed) / alembic 无漂移；前端 gen:api/lint/tsc/vitest 69/build

apps/api/ww_api/services/project_deps.py

@@ -16,13 +16,15 @@ from openai import AsyncOpenAI
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from ww_config import get_settings
+from ww_core.domain import ForeshadowLedgerRepo, SqlForeshadowLedgerRepo
 from ww_core.domain.chapter_repo import ChapterRepo, SqlChapterRepo
 from ww_core.domain.digest_repo import DigestAppendRepo, SqlDigestAppendRepo
+from ww_core.domain.outline_write_repo import OutlineWriteRepo, SqlOutlineWriteRepo
 from ww_core.domain.project_repo import ProjectRepo, SqlProjectRepo
 from ww_core.domain.repositories import MemoryRepos
 from ww_core.domain.review_repo import ReviewRepo, SqlReviewRepo
 from ww_core.memory.sql_repositories import sql_memory_repos
-from ww_db import get_session
+from ww_db import get_session, get_sessionmaker
 from ww_db.models import User
 from ww_llm_gateway import (
     Gateway,
@@ -42,6 +44,7 @@ from ww_api.services.credentials import (
     CredentialStore,
     SqlCredentialStore,
 )
+from ww_api.services.foreshadow_scan import SessionFactory
 from ww_api.services.provider_deps import _PROVIDER_BASE_URLS
 
 # 单用户 stub 的占位邮箱（多租户化时由真实主体替换）。
@@ -95,6 +98,30 @@ def get_digest_append_repo(
     return SqlDigestAppendRepo(session)
 
 
+def get_foreshadow_repo(
+    session: Annotated[AsyncSession, Depends(get_session)],
+) -> ForeshadowLedgerRepo:
+    """伏笔账本写侧 repo（登记/状态变更端点；只 flush，端点提交）。测试经 override 注 fake。"""
+    return SqlForeshadowLedgerRepo(session)
+
+
+def get_outline_write_repo(
+    session: Annotated[AsyncSession, Depends(get_session)],
+) -> OutlineWriteRepo:
+    """大纲写侧 repo（大纲生成端点逐章 upsert；只 flush，端点提交）。测试经 override 注 fake。"""
+    return SqlOutlineWriteRepo(session)
+
+
+def get_session_factory() -> SessionFactory:
+    """验收后到期扫描的**独立 session 工厂**缝。
+
+    BackgroundTask 在请求 session 关闭后才跑，必须自建 session（不复用 `get_session`）。
+    返回的工厂 `()` → `async with` 得一个新 `AsyncSession`。测试经 `app.dependency_overrides`
+    注入 fake 工厂（避免真起后台线程/真连 DB）。
+    """
+    return get_sessionmaker()
+
+
 async def build_gateway_for_tier(
     session: AsyncSession, store: CredentialStore, tier: Tier
 ) -> Gateway:
@@ -160,3 +187,11 @@ async def get_digest_gateway(
     """验收终稿 digest 提炼（light 档位）的可注入网关缝。测试经 override 注 mock。"""
     store = SqlCredentialStore(session)
     return await build_gateway_for_tier(session, store, "light")
+
+
+async def get_outline_gateway(
+    session: Annotated[AsyncSession, Depends(get_session)],
+) -> Gateway:
+    """大纲生成（analyst 档位）的可注入网关缝。测试经 override 注 mock（产 OutlineResult）。"""
+    store = SqlCredentialStore(session)
+    return await build_gateway_for_tier(session, store, "analyst")