fix(history): stabilize download history pagination

tests/test_history_search.py

@@ -98,3 +98,92 @@ def test_download_history_title_search_is_case_insensitive(tmp_path: Path):
             await engine.dispose()
 
     asyncio.run(run_case())
+
+
+def test_download_history_page_is_newest_first(tmp_path: Path):
+    """下载历史分页应按时间和 ID 倒序稳定返回。"""
+    engine = create_engine(f"sqlite:///{tmp_path / 'download_history_page.db'}")
+    SessionFactory = sessionmaker(bind=engine)
+    Base.metadata.create_all(bind=engine)
+
+    try:
+        with SessionFactory() as db:
+            db.add_all(
+                [
+                    DownloadHistory(
+                        path="/downloads/oldest",
+                        type="电影",
+                        title="Oldest",
+                        date="2026-06-01 00:00:00",
+                    ),
+                    DownloadHistory(
+                        path="/downloads/newer-first",
+                        type="电影",
+                        title="Newer First",
+                        date="2026-06-02 00:00:00",
+                    ),
+                    DownloadHistory(
+                        path="/downloads/newer-second",
+                        type="电影",
+                        title="Newer Second",
+                        date="2026-06-02 00:00:00",
+                    ),
+                ]
+            )
+            db.commit()
+
+            first_page = DownloadHistory.list_by_page(db, page=1, count=2)
+            second_page = DownloadHistory.list_by_page(db, page=2, count=2)
+
+        assert [item.title for item in first_page] == ["Newer Second", "Newer First"]
+        assert [item.title for item in second_page] == ["Oldest"]
+    finally:
+        engine.dispose()
+
+
+def test_async_download_history_page_is_newest_first(tmp_path: Path):
+    """异步下载历史分页应按时间和 ID 倒序稳定返回。"""
+
+    async def run_case():
+        """执行异步分页顺序断言。"""
+        engine = create_async_engine(f"sqlite+aiosqlite:///{tmp_path / 'async_download_history_page.db'}")
+        SessionFactory = async_sessionmaker(bind=engine)
+
+        try:
+            async with engine.begin() as conn:
+                await conn.run_sync(Base.metadata.create_all)
+
+            async with SessionFactory() as db:
+                db.add_all(
+                    [
+                        DownloadHistory(
+                            path="/downloads/oldest",
+                            type="电影",
+                            title="Oldest",
+                            date="2026-06-01 00:00:00",
+                        ),
+                        DownloadHistory(
+                            path="/downloads/newer-first",
+                            type="电影",
+                            title="Newer First",
+                            date="2026-06-02 00:00:00",
+                        ),
+                        DownloadHistory(
+                            path="/downloads/newer-second",
+                            type="电影",
+                            title="Newer Second",
+                            date="2026-06-02 00:00:00",
+                        ),
+                    ]
+                )
+                await db.commit()
+
+                first_page = await DownloadHistory.async_list_by_page(db, page=1, count=2)
+                second_page = await DownloadHistory.async_list_by_page(db, page=2, count=2)
+
+            assert [item.title for item in first_page] == ["Newer Second", "Newer First"]
+            assert [item.title for item in second_page] == ["Oldest"]
+        finally:
+            await engine.dispose()
+
+    asyncio.run(run_case())