Method _write_cached_content

src/services/file_cache.py:166–178

先写临时文件，再原子替换，避免并发读到半截文件。

(self, file_path: Path, content: bytes)

        return headers

    def _write_cached_content(self, file_path: Path, content: bytes):
        """先写临时文件，再原子替换，避免并发读到半截文件。"""
        temp_path = file_path.with_suffix(f"{file_path.suffix}.part")
        try:
            with open(temp_path, "wb") as f:
                f.write(content)
            temp_path.replace(file_path)
        finally:
            if temp_path.exists():
                try:
                    temp_path.unlink()
                except Exception:
                    pass

    async def start_cleanup_task(self):
        """Start background cleanup task"""