实现附件处理链路的统一引用化与可检索增强，避免大文件/多模态内容直接撑爆上下文并提升工具可用性。

本次补齐 text/image/video/archive 的标准化处理、会话级工具守卫、回放压缩、配置与文档对齐，并修复表格与流式输出相关体验问题。

Made-with: Cursor

platform/__init__.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+import importlib.util
+import sysconfig
+from pathlib import Path
+
+
+def _load_stdlib_platform() -> object | None:
+    stdlib_dir = Path(sysconfig.get_paths().get("stdlib") or "")
+    platform_py = (stdlib_dir / "platform.py").resolve()
+    if not platform_py.exists():
+        return None
+    spec = importlib.util.spec_from_file_location("_stdlib_platform", str(platform_py))
+    if spec is None or spec.loader is None:
+        return None
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+_stdlib = _load_stdlib_platform()
+if _stdlib is not None:
+    for _name in dir(_stdlib):
+        if _name in {"__name__", "__package__", "__loader__", "__spec__", "__file__", "__cached__"}:
+            continue
+        globals()[_name] = getattr(_stdlib, _name)
+    __all__ = list(getattr(_stdlib, "__all__", []))
+else:
+    __all__ = []
+