diff --git a/apps/web/components/style/RefineView.tsx b/apps/web/components/style/RefineView.tsx
index b4c0d62..fa1dbf4 100644
--- a/apps/web/components/style/RefineView.tsx
+++ b/apps/web/components/style/RefineView.tsx
@@ -28,15 +28,17 @@ export function RefineView({
   onClose,
 }: RefineViewProps) {
   const refiner = useRefine();
+  const { refine, abort } = refiner;
 
-  // 进入即触发回炉（段非空）。
+  // 进入即触发回炉（段非空）；清理时取消在途请求，避免旧段迟到响应覆盖新段（CR-H12）。
   useEffect(() => {
     if (segment.trim().length > 0) {
-      void refiner.refine(projectId, chapterNo, segment);
+      void refine(projectId, chapterNo, segment);
     }
-    // 仅在段变化时触发。
-    // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [segment, projectId, chapterNo]);
+    return () => {
+      abort();
+    };
+  }, [segment, projectId, chapterNo, refine, abort]);
 
   return (
     <div
diff --git a/apps/web/lib/style/useRefine.test.ts b/apps/web/lib/style/useRefine.test.ts
index 2918ed5..b556d72 100644
--- a/apps/web/lib/style/useRefine.test.ts
+++ b/apps/web/lib/style/useRefine.test.ts
@@ -122,4 +122,40 @@ describe("useRefine", () => {
     expect(result.current.status).toBe("idle");
     expect(result.current.result).toBeNull();
   });
+
+  it("中止后迟到的响应不覆盖状态（段切换竞态）", async () => {
+    // Arrange：post 挂起，手动兑现以模拟在途请求。
+    let resolvePost!: (v: unknown) => void;
+    const pending = new Promise((r) => {
+      resolvePost = r;
+    });
+    post.mockReturnValue(pending);
+
+    const { result } = renderHook(() => useRefine());
+
+    // Act：发起回炉（进入 refining），随后 abort（模拟切段取消在途）。
+    let refinePromise!: Promise<unknown>;
+    act(() => {
+      refinePromise = result.current.refine("p1", 1, "新段");
+    });
+    expect(result.current.status).toBe("refining");
+
+    act(() => {
+      result.current.abort();
+    });
+
+    // 迟到的旧响应兑现——应被丢弃：不写状态、不弹 toast。
+    await act(async () => {
+      resolvePost({
+        data: { original: "旧段", refined: "旧改写" },
+        error: null,
+      });
+      await refinePromise;
+    });
+
+    // Assert：结果仍为空、未落到 done、未误报 toast。
+    expect(result.current.result).toBeNull();
+    expect(result.current.status).not.toBe("done");
+    expect(toast).not.toHaveBeenCalled();
+  });
 });
diff --git a/apps/web/lib/style/useRefine.ts b/apps/web/lib/style/useRefine.ts
index fd0f159..dedeb9a 100644
--- a/apps/web/lib/style/useRefine.ts
+++ b/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 };
 }