fix(frontend): RefineView 取消在途 refine——AbortController 防段切换竞态（CR-H12）

apps/web/lib/style/useRefine.ts

@@ -1,6 +1,6 @@
 "use client";
 
-import { useCallback, useState } from "react";
+import { useCallback, useRef, useState } from "react";
 
 import { api } from "@/lib/api/client";
 import { useToast } from "@/components/Toast";
@@ -24,6 +24,8 @@ export interface UseRefine {
     segment: string,
     instruction?: string,
   ) => Promise<RefineResult | null>;
+  // 取消在途回炉（段切换/卸载时调用）——不触碰 state，安全用于 effect 清理。
+  abort: () => void;
   reset: () => void;
 }
 
@@ -32,10 +34,15 @@ export interface UseRefine {
 export function useRefine(): UseRefine {
   const [status, setStatus] = useState<RefineStatus>("idle");
   const [result, setResult] = useState<RefineResult | null>(null);
+  const controllerRef = useRef<AbortController | null>(null);
   const toast = useToast();
 
   const refine = useCallback<UseRefine["refine"]>(
     async (projectId, chapterNo, segment, instruction) => {
+      // 取消上一次在途请求，换新 controller（段切换竞态防护，CR-H12）。
+      controllerRef.current?.abort();
+      const controller = new AbortController();
+      controllerRef.current = controller;
       setStatus("refining");
       setResult(null);
       try {
@@ -46,8 +53,11 @@ export function useRefine(): UseRefine {
               path: { project_id: projectId, chapter_no: chapterNo },
             },
             body: buildRefineRequest(segment, instruction),
+            signal: controller.signal,
           },
         );
+        // 已被后续请求/卸载中止：丢弃迟到响应，不写状态。
+        if (controller.signal.aborted) return null;
         if (error || !data) {
           setStatus("error");
           const code = errorCode(error);
@@ -67,6 +77,8 @@ export function useRefine(): UseRefine {
         setStatus("done");
         return outcome;
       } catch {
+        // 主动中止（abort）触发的异常不该报错 toast。
+        if (controller.signal.aborted) return null;
         setStatus("error");
         toast("回炉请求异常，请检查网络。", "error");
         return null;
@@ -75,10 +87,18 @@ export function useRefine(): UseRefine {
     [toast],
   );
 
+  // 仅取消在途请求，不触碰 state——可安全用于 effect 清理 / 卸载。
+  const abort = useCallback((): void => {
+    controllerRef.current?.abort();
+    controllerRef.current = null;
+  }, []);
+
   const reset = useCallback((): void => {
+    controllerRef.current?.abort();
+    controllerRef.current = null;
     setStatus("idle");
     setResult(null);
   }, []);
 
-  return { status, result, refine, reset };
+  return { status, result, refine, abort, reset };
 }