--- contrib/python/Jinja2/py3/jinja2/loaders.py	(index)
+++ contrib/python/Jinja2/py3/jinja2/loaders.py	(working tree)
@@ -4,6 +4,7 @@ sources.
 import importlib.util
 import os
 import sys
+import pkgutil
 import typing as t
 import weakref
 import zipimport
@@ -20,6 +21,8 @@ if t.TYPE_CHECKING:
     from .environment import Environment
     from .environment import Template
 
+import __res as arcadia_res
+
 
 def split_template_path(template: str) -> t.List[str]:
     """Split a path into segments and perform a sanity check.  If it detects
@@ -284,19 +287,22 @@ class PackageLoader(BaseLoader):
 
         # Make sure the package exists. This also makes namespace
         # packages work, otherwise get_loader returns None.
-        import_module(package_name)
+        package = import_module(package_name)
         spec = importlib.util.find_spec(package_name)
         assert spec is not None, "An import spec was not found for the package."
         loader = spec.loader
         assert loader is not None, "A loader was not found for the package."
         self._loader = loader
         self._archive = None
+        self._package = package
         template_root = None
 
         if isinstance(loader, zipimport.zipimporter):
             self._archive = loader.archive
             pkgdir = next(iter(spec.submodule_search_locations))  # type: ignore
             template_root = os.path.join(pkgdir, package_path)
+        elif hasattr(loader, "arcadia_source_finder"):
+            template_root = os.path.dirname(package.__file__)
         else:
             roots: t.List[str] = []
 
@@ -329,7 +335,16 @@ class PackageLoader(BaseLoader):
         p = os.path.join(self._template_root, *split_template_path(template))
         up_to_date: t.Optional[t.Callable[[], bool]]
 
-        if self._archive is None:
+        if self._archive is None and hasattr(self, "_package"):
+            try:
+                source = pkgutil.get_data(self.package_name, os.path.join(self.package_path, *split_template_path(template)))
+            except OSError:
+                raise TemplateNotFound(template)
+
+            def up_to_date() -> bool:
+                return True
+
+        elif self._archive is None:
             # Package is a directory.
             if not os.path.isfile(p):
                 raise TemplateNotFound(template)
@@ -359,7 +374,12 @@ class PackageLoader(BaseLoader):
     def list_templates(self) -> t.List[str]:
         results: t.List[str] = []
 
-        if self._archive is None:
+        if self._archive is None and hasattr(self, "_package"):
+            prefix = os.path.join(self._template_root, self.package_path).encode() + b"/"
+            for name in arcadia_res.resfs_files(prefix):
+                results.append(name.removeprefix(prefix).decode())
+
+        elif self._archive is None:
             # Package is a directory.
             offset = len(self._template_root)