feat: M2 — 写→审(一致性)→裁决→验收(事务)；未决冲突禁验收

- 续审 Agent 声明(AgentSpec) + 结构化输出契约(ContinuityReview/Conflict 五类)
- LangGraph 并行审子图(可扩四审) + collect 落 chapter_reviews 留痕 + review SSE(section/conflict)
- 验收-side Repository：章节 accepted 版本晋升 + digest append-only + 审稿留痕/裁决
- API：review(SSE) + reviews 历史 + accept(单原子事务：晋升 version + 终稿 digest + 裁决留痕)
- 冲突 gate：未决裁决拦截(CONFLICT_UNRESOLVED)；digest 从终稿提炼(不变量#4)
- 前端：审稿报告页 + 冲突就地标注 + 裁决(采纳/忽略/手改) + 未决禁验收 + 「本次将更新」清单
- M2 E2E：真实 DB + 多档位 mock 网关零 token 走通 写→审→裁决→验收→摘要入库
- 多 agent 协同台账(PROGRESS.md) + 共享记忆(memory/contracts·decisions·gotchas)

apps/web/lib/review/useReviewStream.ts

@@ -0,0 +1,135 @@
+"use client";
+
+import { useCallback, useReducer, useRef } from "react";
+
+import { API_BASE_PUBLIC } from "@/lib/api/config";
+import {
+  ReviewFrameBuffer,
+  initialReviewState,
+  reduceReview,
+  type ReviewConflict,
+  type ReviewStreamState,
+} from "./sse";
+
+type Action =
+  | { type: "start" }
+  | { type: "events"; events: ReturnType<ReviewFrameBuffer["push"]> }
+  | { type: "abort" }
+  | { type: "fail"; code: string; message: string }
+  | { type: "seed"; conflicts: ReviewConflict[] };
+
+function reducer(state: ReviewStreamState, action: Action): ReviewStreamState {
+  switch (action.type) {
+    case "start":
+      return { ...initialReviewState, phase: "reviewing" };
+    case "events":
+      return action.events.reduce(reduceReview, state);
+    case "abort":
+      return { ...state, phase: "aborted" };
+    case "fail":
+      return {
+        ...state,
+        phase: "error",
+        error: { code: action.code, message: action.message },
+      };
+    case "seed":
+      return { ...initialReviewState, conflicts: action.conflicts };
+    default:
+      return state;
+  }
+}
+
+export interface UseReviewStream {
+  state: ReviewStreamState;
+  isReviewing: boolean;
+  // 用当前编辑器草稿重新审稿。
+  start: (projectId: string, chapterNo: number, draft: string) => Promise<void>;
+  stop: () => void;
+  // 进页用历史留痕的冲突种入（无需重审即可裁决）。
+  seed: (conflicts: ReviewConflict[]) => void;
+}
+
+// 消费 POST .../review 的 SSE 流：fetch+ReadableStream（EventSource 不支持 POST）。
+// "停" = abort（已收 section/conflict 留在 state，裁决草稿不丢）。
+// 流前 503 LLM_UNAVAILABLE 是 JSON 信封（非帧）→ 经 !res.ok 检出。
+export function useReviewStream(): UseReviewStream {
+  const [state, dispatch] = useReducer(reducer, initialReviewState);
+  const controllerRef = useRef<AbortController | null>(null);
+
+  const stop = useCallback(() => {
+    controllerRef.current?.abort();
+    controllerRef.current = null;
+    dispatch({ type: "abort" });
+  }, []);
+
+  const seed = useCallback((conflicts: ReviewConflict[]) => {
+    dispatch({ type: "seed", conflicts });
+  }, []);
+
+  const start = useCallback(
+    async (
+      projectId: string,
+      chapterNo: number,
+      draft: string,
+    ): Promise<void> => {
+      const controller = new AbortController();
+      controllerRef.current = controller;
+      dispatch({ type: "start" });
+      try {
+        const res = await fetch(
+          `${API_BASE_PUBLIC}/projects/${projectId}/chapters/${chapterNo}/review`,
+          {
+            method: "POST",
+            headers: {
+              Accept: "text/event-stream",
+              "Content-Type": "application/json",
+            },
+            body: JSON.stringify({ draft }),
+            signal: controller.signal,
+          },
+        );
+        if (!res.ok || !res.body) {
+          let code = "REVIEW_FAILED";
+          let message = `审稿请求失败（${res.status}）`;
+          try {
+            const body = (await res.json()) as {
+              error?: { code?: string; message?: string };
+            };
+            if (body.error?.code) code = body.error.code;
+            if (body.error?.message) message = body.error.message;
+          } catch {
+            // 非 JSON 信封，沿用默认文案。
+          }
+          dispatch({ type: "fail", code, message });
+          return;
+        }
+        const reader = res.body.getReader();
+        const decoder = new TextDecoder();
+        const buffer = new ReviewFrameBuffer();
+        for (;;) {
+          const { value, done } = await reader.read();
+          if (done) break;
+          const events = buffer.push(decoder.decode(value, { stream: true }));
+          if (events.length > 0) dispatch({ type: "events", events });
+        }
+      } catch (err: unknown) {
+        if (err instanceof DOMException && err.name === "AbortError") {
+          return; // 用户主动停止：state 已置 aborted。
+        }
+        const message = err instanceof Error ? err.message : "未知网络错误";
+        dispatch({ type: "fail", code: "NETWORK", message });
+      } finally {
+        controllerRef.current = null;
+      }
+    },
+    [],
+  );
+
+  return {
+    state,
+    isReviewing: state.phase === "reviewing",
+    start,
+    stop,
+    seed,
+  };
+}