diff --git a/apps/worker/video_processing/dedup.py b/apps/worker/video_processing/dedup.py
index a1f57b390..113908dfe 100755
--- a/apps/worker/video_processing/dedup.py
+++ b/apps/worker/video_processing/dedup.py
@@ -1216,9 +1216,17 @@ def check_duplicate_task(self: Task, generated_video_id: str) -> dict:
             raise ValueError(f"Generated video {generated_video_id} not found")
 
         local_path = os.path.join(temp_dir, f"{generated_video_id}.mp4")
-        storage_service.download_file(
-            f"projects/{video.project_id}/generated/{generated_video_id}/{generated_video_id}.mp4", local_path
-        )
+        # Issue #1702: recompute 走的是 OSS 重新下载路径（正常生成流程用本地渲染文件，
+        # 不经此任务）。成片真实 OSS key 是生成时的
+        # generated/projects/{pid}/tasks/{task_id}/rendered_*.mp4（见 generation.py
+        # _upload_and_record），旧代码硬编码 projects/{pid}/generated/{vid}/{vid}.mp4
+        # 这个从不存在的 key，导致所有 recompute 任务下载 404、查重数据永远无法重算。
+        # 优先从 file_url 解析真实 key，旧 key 模式仅作回退。
+        download_key = getattr(video, "file_url", "") or ""
+        if not download_key:
+            download_key = f"projects/{video.project_id}/generated/{generated_video_id}/{generated_video_id}.mp4"
+            logger.warning("video %s has no file_url, falling back to legacy key %s", generated_video_id, download_key)
+        storage_service.download_file(download_key, local_path)
 
         fingerprint = deduplicator.compute_fingerprint(local_path)
 
diff --git a/tests/unit/test_dedup_1702_zero_rate_fix.py b/tests/unit/test_dedup_1702_zero_rate_fix.py
index e8d2fdafd..6ddf8eab6 100644
--- a/tests/unit/test_dedup_1702_zero_rate_fix.py
+++ b/tests/unit/test_dedup_1702_zero_rate_fix.py
@@ -359,3 +359,31 @@ class TestZeroMatchLogging:
             result = _check(ddp, fp, [existing])
         assert result is None
         assert any("no match" in r.message for r in caplog.records)
+
+
+# ── recompute 任务下载路径（#1702 连带修复：旧硬编码 key 404） ─────
+
+
+class TestRecomputeDownloadPath:
+    """recompute-dedup 走 check_duplicate_task，需要从 OSS 重新下载成片。
+
+    旧代码硬编码 projects/{pid}/generated/{vid}/{vid}.mp4（从不存在），
+    真实 key 在 file_url：generated/projects/{pid}/tasks/{tid}/rendered_*.mp4。
+    """
+
+    def test_task_downloads_from_file_url(self):
+        import inspect
+
+        import video_processing.dedup as dedup_mod
+
+        source = inspect.getsource(dedup_mod.check_duplicate_task)
+        # 下载 key 必须来自 video.file_url
+        assert 'getattr(video, "file_url"' in source or "video.file_url" in source
+        # 旧的硬编码 key 只能作为回退存在，不能是主路径
+        assert "falling back to legacy key" in source
+        # download_file 接收的是派生 key 而非硬编码 f-string
+        assert "storage_service.download_file(download_key" in source
+        assert '/generated/{generated_video_id}/{generated_video_id}.mp4"' not in source.replace(
+            'download_key = f"projects/{video.project_id}/generated/{generated_video_id}/{generated_video_id}.mp4"',
+            "",
+        )