diff --git a/src/melobot/plugin/imp.py b/src/melobot/plugin/imp.py
index 6491504e..7abec7b0 100644
--- a/src/melobot/plugin/imp.py
+++ b/src/melobot/plugin/imp.py
@@ -1,16 +1,27 @@
 import sys
-from importlib._bootstrap_external import _get_supported_file_loaders
+from importlib._bootstrap_external import PathFinder as _PathFinder
+from importlib._bootstrap_external import (
+    _get_supported_file_loaders,
+    _NamespaceLoader,
+    _NamespacePath,
+)
 from importlib.abc import Loader, MetaPathFinder
-from importlib.machinery import ModuleSpec
+from importlib.machinery import ModuleSpec, all_suffixes
 from importlib.util import module_from_spec, spec_from_file_location
 from os import PathLike
 from pathlib import Path
 from types import ModuleType
-from typing import Any, Sequence
+from typing import Any, Sequence, cast
 
 from ..exceptions import DynamicImpError
 from ..utils import singleton
 
+ALL_EXTS = tuple(all_suffixes())
+NAMESPACE_PKG_TAG = "__melobot_namespace__"
+
+
+class _NestedQuickExit(BaseException): ...
+
 
 @singleton
 class SpecFinder(MetaPathFinder):
@@ -32,30 +43,66 @@ def find_spec(
         else:
             name = fullname
 
-        for entry in paths:
-            mod_path = Path(entry).joinpath(name)
-            if mod_path.is_dir():
-                file = mod_path.joinpath("__init__.py")
-                submodule_locations = [str(mod_path)]
-                if not mod_path.exists():
-                    continue
-            else:
-                file = Path(entry).joinpath(f"{name}.py")
-                submodule_locations = None
-                if not file.exists():
-                    continue
-
-            file = file.resolve()
-            return spec_from_file_location(
-                fullname,
-                file,
-                loader=ModuleLoader(
-                    fullname, file, sys_cache, load_cache, pre_sys_len, pre_cache_len
-                ),
-                submodule_search_locations=submodule_locations,
-            )
+        mod_path: Path | None = None
+        submod_locs: list[str] | None = None
+        # The spec finding according PEP420: https://peps.python.org/pep-0420/#specification
+        try:
+            for entry in paths:
+                dir_path = Path(entry).joinpath(name)
+                pkg_init_path = dir_path.joinpath("__init__.py")
+                if pkg_init_path.exists():
+                    mod_path = pkg_init_path
+                    submod_locs = [str(dir_path)]
+                    raise _NestedQuickExit
+
+                for ext in ALL_EXTS:
+                    _mod_path = Path(entry).joinpath(f"{name}{ext}")
+                    if _mod_path.exists():
+                        mod_path = _mod_path
+                        submod_locs = None
+                        raise _NestedQuickExit
+
+                if dir_path.exists() and dir_path.is_dir():
+                    submod_locs = _NamespacePath(
+                        fullname,
+                        [str(dir_path)],
+                        _PathFinder()._get_spec,  # pylint: disable=protected-access
+                    )
+                    spec = spec_from_file_location(
+                        fullname,
+                        dir_path,
+                        loader=ModuleLoader(
+                            fullname,
+                            dir_path,
+                            sys_cache,
+                            load_cache,
+                            pre_sys_len,
+                            pre_cache_len,
+                            _NamespaceLoader(fullname, dir_path, submod_locs),
+                        ),
+                        submodule_search_locations=submod_locs,
+                    )
+                    assert spec is not None
+                    spec.has_location = False
+                    spec.origin = None
+                    setattr(spec, NAMESPACE_PKG_TAG, True)
+                    return spec
+
+        except _NestedQuickExit:
+            pass
 
-        return None
+        if mod_path is None and submod_locs is None:
+            return None
+
+        mod_path = cast(Path, mod_path).resolve()
+        return spec_from_file_location(
+            fullname,
+            mod_path,
+            loader=ModuleLoader(
+                fullname, mod_path, sys_cache, load_cache, pre_sys_len, pre_cache_len
+            ),
+            submodule_search_locations=submod_locs,
+        )
 
 
 sys.meta_path.insert(0, SpecFinder())
@@ -74,6 +121,7 @@ def has_cache(self, mod: ModuleType) -> bool:
         return mod in self._caches.values()
 
     def get_cache(self, path: Path) -> ModuleType | None:
+        # 对应有 __init__.py 的包模块
         if path.parts[-1] == "__init__.py":
             path = path.parent
         return self._caches.get(path)
@@ -86,7 +134,7 @@ def set_cache(self, name: str, mod: ModuleType) -> None:
         ):
             return
 
-        # __file__ 存在且不为空，可能包或文件，包对应 __init__.py，应该转换为不包含 __init__.py 后缀的形式
+        # __file__ 存在且不为空，可能包或任意可被加载的文件，包对应 __init__.py，应该转换为不包含 __init__.py 后缀的形式
         if mod.__file__ is not None:
             fp = Path(mod.__file__)
             if fp.parts[-1] == "__init__.py":
@@ -120,6 +168,7 @@ def __init__(
         load_cache: bool,
         pre_sys_len: int = -1,
         pre_cache_len: int = -1,
+        inner_loader: Loader | None = None,
     ) -> None:
         super().__init__()
         self.cacher = ModuleCacher()
@@ -130,7 +179,10 @@ def __init__(
         self.pre_sys_len = pre_sys_len
         self.pre_cache_len = pre_cache_len
 
-        self.inner_loader: Loader | None = None
+        self.inner_loader: Loader | None = inner_loader
+        if inner_loader is not None:
+            return
+
         for loader_class, suffixes in _get_supported_file_loaders():
             if str(fp).endswith(tuple(suffixes)):
                 loader = loader_class(fullname, str(fp))  # pylint: disable=not-callable
@@ -146,11 +198,13 @@ def create_module(self, spec: ModuleSpec) -> ModuleType | None:
         return mod
 
     def exec_module(self, mod: ModuleType) -> None:
-        if self.cacher.has_cache(mod) or not self.fp.exists():
+        if self.cacher.has_cache(mod):
             pass
         else:
             if self.inner_loader is not None:
                 self.inner_loader.exec_module(mod)
+                if hasattr(mod.__spec__, NAMESPACE_PKG_TAG):
+                    mod.__file__ = None
 
         if self.use_load_cache:
             self.cacher.set_cache(self.fullname, mod)