perf(chain): review 节点并行扇出五审——复用主图 add-only 记账并发范式（CR-M3-6）

packages/core/ww_core/orchestrator/chain/nodes.py

@@ -10,6 +10,7 @@ checkpoint 只存控制流，正文/审稿落领域表——resume 时重读领
 
 from __future__ import annotations
 
+import asyncio
 import uuid
 from collections.abc import Awaitable, Callable, Sequence
 from contextlib import AbstractAsyncContextManager
@@ -210,9 +211,15 @@ async def review_chapter(
             "user_id": user_id,
             "review_context": review_context,
         }
+        # 并行扇出五审（复用主图 write→review 的 add-only 记账并发范式，T3.8）：各 run_review
+        # 共用本节点 session 的网关，其 SqlAlchemyLedgerSink.record 只 add（同步、不 flush），故
+        # 共享 session 并发安全；run_review 自带失败隔离（不抛、返回 incomplete 占位），gather
+        # 无需 return_exceptions。collect_reviews 在 gather 之后**一次**落库（不引入新并发写）。
+        parts = await asyncio.gather(
+            *(run_review(spec, review_state, gateway=gateway) for spec in review_specs)
+        )
         reviews: dict[str, Any] = {}
-        for spec in review_specs:
-            part = await run_review(spec, review_state, gateway=gateway)
+        for part in parts:
             reviews.update(part.get("reviews", {}))
         review_state["reviews"] = reviews
         review_repo = review_repo_factory(session)