fix(跟价): 失败任务也产出并保留部分结果文件，不再只剩一条失败记录

会话掉线这类「跑到第 N 页才断」的场景，任务本就该是 FAILED，但已经跑出来的行
（哪些 ASIN 真实改价过）必须随任务一起交付，否则用户无从对账、也无法只重跑漏掉的。

- submitResult 的 error / success=false 分支改走 finalizeFailedShop：先按失败落库
  （success=0 + 原因），若合并后仍有可用行就排队组装部分结果文件；一行可用数据都没有时
  才退化成原来的纯失败（并清掉合并缓存）
- markResultFilePending / assembleShopResult 增加 preserveFailure 语义：失败行只挂文件，
  不把 success 洗成 1、也不清 errorMessage
- updateTaskStatusFromLatestRows：失败行正在组装文件时不让任务提前终态，
  否则前端一停轮询、下载按钮永不出现（失败任务的结果文件同样要能下载）

PriceTrackTaskServiceTest 新增 2 条契约测试（部分结果排队 + 组装完成后仍失败且可下载），
跟价模块测试 20/20 通过。

backend-java/src/main/java/com/nanri/aiimage/modules/pricetrack/service/PriceTrackTaskService.java

@@ -653,13 +653,11 @@ public class PriceTrackTaskService {
                 }
                 changed = true;
                 if (payload.getError() != null && !payload.getError().isBlank()) {
-                    markResultFailed(fr, payload.getError());
+                    finalizeFailedShop(fr, shopKey, payload, payload.getError());
-                    priceTrackTaskCacheService.removeShopMergedPayload(taskId, shopKey);
                     continue;
                 }
                 if (Boolean.FALSE.equals(payload.getSuccess())) {
-                    markResultFailed(fr, "shop processing failed");
+                    finalizeFailedShop(fr, shopKey, payload, "shop processing failed");
-                    priceTrackTaskCacheService.removeShopMergedPayload(taskId, shopKey);
                     continue;
                 }
                 handleSkipAsinDeletionSignals(shopKey, payload);
@@ -815,6 +813,39 @@ public class PriceTrackTaskService {
         updateTaskStatusFromLatestRows(task, latest);
     }
 
+    /**
+     * 失败店铺的收尾：任务照旧标 FAILED（原因回显给用户），但已经把跑出来的行组装成
+     * 部分结果文件随任务交付——否则用户只看到「失败」，却拿不到「哪些 ASIN 实际已被
+     * 跟价/改价」的记录（会话掉线这类"跑了前几页才断"的场景尤其需要）。
+     *
+     * <p>组装出来的行仍是失败态（success=0 + errorMessage），任务状态因此不变，
+     * 只是多了个可下载的文件；只有一行可用数据都没有时才退化成纯失败。
+     */
+    private void finalizeFailedShop(FileResultEntity fr, String shopKey,
+                                    PriceTrackSubmitResultRequest.ShopResult payload, String errorMessage) {
+        String finalMessage = errorMessage;
+        try {
+            PriceTrackSubmitResultRequest.ShopResult merged = mergeShopPayload(fr.getTaskId(), shopKey, payload);
+            int rows = countPayloadRows(merged);
+            if (rows > 0) {
+                markResultFailed(fr, errorMessage);
+                enqueueResultFileAssembly(fr, shopKey, merged, true);
+                priceTrackTaskCacheService.removeShopMergedPayload(fr.getTaskId(), shopKey);
+                log.info("[price-track] 失败店铺仍产出部分结果 taskId={} shop={} rows={} error={}",
+                        fr.getTaskId(), shopKey, rows, errorMessage);
+                return;
+            }
+            log.info("[price-track] 失败店铺无可用行，不产出结果文件 taskId={} shop={} error={}",
+                    fr.getTaskId(), shopKey, errorMessage);
+        } catch (Exception ex) {
+            log.warn("[price-track] 失败店铺部分结果排队失败，仅标记失败 taskId={} shop={} msg={}",
+                    fr.getTaskId(), shopKey, ex.getMessage(), ex);
+            finalMessage = errorMessage + "（部分结果组装排队失败：" + ex.getMessage() + "）";
+        }
+        markResultFailed(fr, finalMessage);
+        priceTrackTaskCacheService.removeShopMergedPayload(fr.getTaskId(), shopKey);
+    }
+
     private void markResultFailed(FileResultEntity fr, String message) {
         fr.setSuccess(0);
         fr.setErrorMessage(message);
@@ -841,11 +872,18 @@ public class PriceTrackTaskService {
         java.io.File workRoot = cn.hutool.core.io.FileUtil.mkdir(
                 cn.hutool.core.io.FileUtil.file(System.getProperty("java.io.tmpdir"), "price-track-result", String.valueOf(result.getTaskId())));
         java.io.File xlsx = cn.hutool.core.io.FileUtil.file(workRoot, stem + ".xlsx");
+        // 失败店铺的部分结果（errorMessage 已写明原因）：组装完成时保留失败态，只挂文件。
+        // 否则组装一落地就把行"洗成成功"，用户再也看不到「这个店铺其实没跑完」。
+        boolean partialFailure = result.getErrorMessage() != null && !result.getErrorMessage().isBlank();
         try {
             excelAssemblyService.writeWorkbook(xlsx, countries);
             String objectKey = ossStorageService.uploadResultFile(xlsx, MODULE_TYPE);
+            if (partialFailure) {
+                result.setSuccess(0);
+            } else {
                 result.setSuccess(1);
                 result.setErrorMessage(null);
+            }
             result.setResultFilename(stem + ".xlsx");
             result.setResultFileUrl(objectKey);
             result.setResultFileSize(xlsx.length());
@@ -885,9 +923,20 @@ public class PriceTrackTaskService {
     private void enqueueResultFileAssembly(FileResultEntity result,
                                            String shopKey,
                                            PriceTrackSubmitResultRequest.ShopResult payload) {
+        enqueueResultFileAssembly(result, shopKey, payload, false);
+    }
+
+    /**
+     * @param preserveFailure 失败店铺的部分结果：保留 success=0 + 失败原因，只把文件挂上去，
+     *                        任务状态不变（仍 FAILED），用户仍能下载已跑出来的行
+     */
+    private void enqueueResultFileAssembly(FileResultEntity result,
+                                           String shopKey,
+                                           PriceTrackSubmitResultRequest.ShopResult payload,
+                                           boolean preserveFailure) {
         applyServerModifyCounts(result.getTaskId(), payload);
         taskResultPayloadService.saveLatest(result.getTaskId(), MODULE_TYPE, shopKey, payload);
-        markResultFilePending(result, shopKey, payload);
+        markResultFilePending(result, shopKey, payload, preserveFailure);
         taskFileJobService.enqueueAssembleResult(result.getTaskId(), MODULE_TYPE, result.getId(), shopKey);
     }
 
@@ -993,15 +1042,24 @@ public class PriceTrackTaskService {
 
     private void markResultFilePending(FileResultEntity result,
                                        String shopKey,
-                                       PriceTrackSubmitResultRequest.ShopResult payload) {
+                                       PriceTrackSubmitResultRequest.ShopResult payload,
+                                       boolean preserveFailure) {
         Map<String, List<PriceTrackSubmitResultRequest.AsinResult>> countries =
                 excelAssemblyService.normalizeCountriesMap(payload.getCountries());
         String displayName = payload.getShopName() != null && !payload.getShopName().isBlank()
                 ? payload.getShopName().trim()
                 : shopKey;
         String stem = safeFileStem(displayName);
+        if (preserveFailure) {
+            // 失败店铺的部分结果：成功态与失败原因都不能动，只标「文件名已定、文件待组装」
+            result.setSuccess(0);
+            if (result.getErrorMessage() == null || result.getErrorMessage().isBlank()) {
+                result.setErrorMessage("店铺未跑完，仅产出部分结果");
+            }
+        } else {
             result.setSuccess(1);
             result.setErrorMessage(null);
+        }
         result.setResultFilename(stem + ".xlsx");
         result.setResultFileUrl(null);
         result.setResultFileSize(0L);
@@ -2164,6 +2222,12 @@ public class PriceTrackTaskService {
                 }
                 ok++;
             } else if (failed) {
+                // 失败行也可能正在组装"部分结果"文件：文件没落地前不能让任务提前终态，
+                // 否则前端一停轮询，下载按钮永远不出现（失败任务的结果文件同样要能下载）
+                if (isResultAwaitingFileAssembly(fr, jobMap.get(fr.getId()))) {
+                    allDone = false;
+                    continue;
+                }
                 fail++;
                 allErrors.add(fr.getSourceFilename() + ": " + fr.getErrorMessage());
             } else {

backend-java/src/test/java/com/nanri/aiimage/modules/pricetrack/service/PriceTrackTaskServiceTest.java

@@ -10,6 +10,7 @@ import com.nanri.aiimage.modules.task.mapper.FileResultMapper;
 import com.nanri.aiimage.modules.task.mapper.FileTaskMapper;
 import com.nanri.aiimage.modules.task.model.entity.FileResultEntity;
 import com.nanri.aiimage.modules.task.model.entity.FileTaskEntity;
+import com.nanri.aiimage.modules.task.model.entity.TaskFileJobEntity;
 import com.nanri.aiimage.modules.task.service.TaskDistributedLockService;
 import com.nanri.aiimage.modules.task.service.TaskFileJobService;
 import com.nanri.aiimage.modules.task.service.TaskResultPayloadService;
@@ -28,6 +29,7 @@ import java.util.Map;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.anyString;
@@ -255,6 +257,101 @@ class PriceTrackTaskServiceTest {
         verify(lock, times(2)).close();
     }
 
+    /**
+     * 跟价 28443 场景：店铺跑到第 2 页会话掉线（955 件在售只跟了 20 件），
+     * 客户端收尾回传带 error。失败归失败，但已经跑出来的行必须组装成部分结果文件，
+     * 否则用户只看到「失败」，拿不到「哪些 ASIN 实际已被改价」的记录。
+     */
+    @Test
+    void failedShopWithPartialRowsStillQueuesResultFile() throws Exception {
+        long taskId = 28443L;
+        String shopName = "林芳";
+        String error = "国家 英国 未跑完：会话失效：页面已跳转到登录页，商品列表为空";
+
+        FileTaskEntity task = runningTask(taskId);
+        FileResultEntity result = pendingResult(taskId, shopName);
+
+        PriceTrackSubmitResultRequest.ShopResult shopResult = shopResult(
+                shopName,
+                Map.of("UK", List.of(asinRow("B0DWX8WJF8", "改价成功", "改价成功"))));
+        shopResult.setError(error);
+        PriceTrackSubmitResultRequest request = new PriceTrackSubmitResultRequest();
+        request.setShops(List.of(shopResult));
+
+        TaskFileJobEntity pendingJob = new TaskFileJobEntity();
+        pendingJob.setTaskId(taskId);
+        pendingJob.setResultId(result.getId());
+        pendingJob.setScopeKey(shopName);
+        pendingJob.setStatus("PENDING");
+
+        TaskDistributedLockService.LockHandle lock = mock(TaskDistributedLockService.LockHandle.class);
+        when(taskDistributedLockService.acquire("PRICE_TRACK", taskId)).thenReturn(lock);
+        when(priceTrackTaskCacheService.getTaskCacheBatch(List.of(taskId))).thenReturn(Map.of(taskId, task));
+        when(fileResultMapper.selectList(any())).thenReturn(List.of(result));
+        when(ziniaoShopSwitchService.normalizeShopName(shopName)).thenReturn(shopName);
+        when(excelAssemblyService.normalizeCountriesMap(any())).thenAnswer(invocation -> invocation.getArgument(0));
+        when(excelAssemblyService.countRows(any())).thenReturn(1);
+        when(taskFileJobService.findAssembleJobsByResultIds(anyString(), any()))
+                .thenReturn(Map.of(result.getId(), pendingJob));
+        when(objectMapper.writeValueAsString(any())).thenReturn("[]");
+
+        service.submitResult(taskId, request);
+
+        // 部分结果文件已排队，且失败态没被"洗成成功"
+        verify(taskFileJobService).enqueueAssembleResult(taskId, "PRICE_TRACK", result.getId(), shopName);
+        assertEquals(0, result.getSuccess());
+        assertEquals(error, result.getErrorMessage());
+        assertEquals(shopName + ".xlsx", result.getResultFilename());
+        assertNull(result.getResultFileUrl(), "文件还没组装完，URL 由组装任务回填");
+
+        // 文件还没落地前任务必须留在 RUNNING：提前终态会让前端停轮询、下载按钮永不出现
+        assertEquals("RUNNING", task.getStatus());
+        assertNull(task.getFinishedAt());
+    }
+
+    /**
+     * 部分结果文件组装完成后：文件挂上去了，但行/任务仍是失败态，
+     * 用户既能看到"没跑完"，也能下载已跑出来的部分。
+     */
+    @Test
+    void assembledPartialResultKeepsFailedStateAndStaysDownloadable() throws Exception {
+        long taskId = 28444L;
+        String shopName = "林芳";
+        String error = "国家 英国 未跑完：会话失效";
+        String objectKey = "result/price_track/abc/林芳.xlsx";
+
+        FileTaskEntity task = runningTask(taskId);
+        FileResultEntity result = pendingResult(taskId, shopName);
+        result.setErrorMessage(error);
+        result.setResultFilename(shopName + ".xlsx");
+
+        TaskFileJobEntity job = new TaskFileJobEntity();
+        job.setTaskId(taskId);
+        job.setResultId(result.getId());
+        job.setScopeKey(shopName);
+        job.setStatus("PENDING");
+
+        when(priceTrackTaskCacheService.getTaskCacheBatch(List.of(taskId))).thenReturn(Map.of(taskId, task));
+        when(fileResultMapper.selectById(result.getId())).thenReturn(result);
+        when(fileResultMapper.selectList(any())).thenReturn(List.of(result));
+        when(taskResultPayloadService.getLatest(eq(taskId), eq("PRICE_TRACK"), eq(shopName),
+                eq(PriceTrackSubmitResultRequest.ShopResult.class)))
+                .thenReturn(shopResult(shopName,
+                        Map.of("UK", List.of(asinRow("B0DWX8WJF8", "改价成功", "改价成功")))));
+        when(excelAssemblyService.normalizeCountriesMap(any())).thenAnswer(invocation -> invocation.getArgument(0));
+        when(excelAssemblyService.countRows(any())).thenReturn(1);
+        when(ossStorageService.uploadResultFile(any(), eq("PRICE_TRACK"))).thenReturn(objectKey);
+        when(objectMapper.writeValueAsString(any())).thenReturn("[]");
+
+        service.processResultFileJob(job);
+
+        assertEquals(0, result.getSuccess(), "部分结果不改变失败态");
+        assertEquals(error, result.getErrorMessage(), "失败原因不能被组装洗掉");
+        assertEquals(objectKey, result.getResultFileUrl(), "文件挂上去，失败任务也能下载");
+        assertEquals("FAILED", task.getStatus());
+        assertTrue(task.getErrorMessage() != null && task.getErrorMessage().contains("未跑完"));
+    }
+
     private FileTaskEntity runningTask(long taskId) {
         FileTaskEntity task = new FileTaskEntity();
         task.setId(taskId);