diff --git a/CHANGELOG.md b/CHANGELOG.md
index ed6e23968..5239f8697 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 ## [Unreleased]
 
 ### 修复
+- 本地下载遇到大量同名文件时继续递增编号，避免超过 999 个编号后重复使用进程号文件名并覆盖之前的下载
 - 云端协同对端专家的模型、连接器、知识库和对话模式会显示在本端输入框上方
 - 侧栏 Beta 标记跟随主题色
 - 管理员用量统计里，其他用户创建的专家显示名称而不是 id
diff --git a/src/octop/infra/utils/user_downloads.py b/src/octop/infra/utils/user_downloads.py
index 9dfba0cb9..382617aab 100644
--- a/src/octop/infra/utils/user_downloads.py
+++ b/src/octop/infra/utils/user_downloads.py
@@ -63,14 +63,12 @@ def unique_download_path(filename: str, *, home: Path | None = None) -> Path:
     dest_dir.mkdir(parents=True, exist_ok=True)
     safe = sanitize_download_filename(filename)
     path = dest_dir / safe
-    if not path.exists():
-        return path
     stem, suffix = path.stem, path.suffix
-    for index in range(1, 1000):
-        candidate = dest_dir / f"{stem} ({index}){suffix}"
-        if not candidate.exists():
-            return candidate
-    return dest_dir / f"{stem}-{os.getpid()}{suffix}"
+    index = 1
+    while path.exists():
+        path = dest_dir / f"{stem} ({index}){suffix}"
+        index += 1
+    return path
 
 
 def save_user_download(
diff --git a/tests/unit/utils/test_user_downloads.py b/tests/unit/utils/test_user_downloads.py
index 3d718aaa1..22b69fa1c 100644
--- a/tests/unit/utils/test_user_downloads.py
+++ b/tests/unit/utils/test_user_downloads.py
@@ -45,6 +45,22 @@ def test_save_user_download_writes_bytes(tmp_path: Path) -> None:
     assert path.parent == downloads
 
 
+def test_save_user_download_preserves_files_after_many_collisions(tmp_path: Path) -> None:
+    downloads = tmp_path / "Downloads"
+    downloads.mkdir()
+    (downloads / "note.txt").write_bytes(b"original")
+    for index in range(1, 1000):
+        (downloads / f"note ({index}).txt").touch()
+
+    first = save_user_download("note.txt", b"first", home=tmp_path)
+    second = save_user_download("note.txt", b"second", home=tmp_path)
+
+    assert first != second
+    assert first.read_bytes() == b"first"
+    assert second.read_bytes() == b"second"
+    assert (downloads / "note.txt").read_bytes() == b"original"
+
+
 def test_local_dashboard_request_requires_loopback_host_and_peer() -> None:
     assert is_local_dashboard_request(_Req("127.0.0.1:8088", "127.0.0.1"))
     assert is_local_dashboard_request(_Req("localhost:8088", "127.0.0.1"))