Fix disabled Flatpak filesystem permission check

Return all found Steam library paths in `get_steam_lib_paths`, even
those not found in the filesystem.

Due to earlier refactoring, the function checked which directories were
accessible in the filesystem and only returned those. The return value
was used by `prompt_filesystem_access`; any paths were obviously
already accessible in the sandbox, meaning the function would never find
any inaccessible paths and prompt the user.

Also add new regression test that tests this behavior by running an
actual Protontricks command while mocking the Python FS call to hide the
directory. An existing unit test for the Flatpak permission check was
insufficient as it only tested the prompt check in isolation with a
hardcoded list of paths.

Fixes #472

Author: Matoking

CHANGELOG.md

@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
  - Fix Steam installation being prompted twice when using `protontricks-launch`
  - Fix Steam Runtime crash if it's installed under a blacklisted root directory (eg. `/run/<path>` instead of `/run/media/<path>`)
+ - Fix missing filesystem permissions not being detected under Flatpak
 
 ## [1.14.0] - 2026-02-22
 ### Added

src/protontricks/steam.py

@@ -1065,7 +1065,11 @@ def resolve_library_folder(path):
                 "exist",
                 path
             )
-            return None
+            # If the path does not exist, return it anyway; if we're
+            # inside a Flatpak sandbox we'll need the path to perform
+            # a permission check. Missing permission might explain why the
+            # directory appears nonexistent.
+            return Path(path)
 
         # In case of multiple matches, prioritize those that contain
         # a 'steamapps' subdirectory

tests/cli/test_main.py

@@ -1,6 +1,8 @@
 import os
 import sys
 import shutil
+from glob import glob
+
 from pathlib import Path
 
 import pytest
@@ -737,6 +739,7 @@ def test_steam_installation_not_selected(self, cli, gui_provider):
         assert "No Steam installation was selected" in result
 
 
+
 class TestCLIGUI:
     def test_run_gui(
             self, cli, default_proton, steam_app_factory, gui_provider,
@@ -1123,3 +1126,64 @@ def test_cli_enable_logging(cli, parameter, log_levels):
 
         assert "DEBUG" not in stderr
         assert "INFO" not in stderr
+
+
+@pytest.mark.usefixtures("flatpak_sandbox")
+def test_inaccessible_path_prompted(
+        cli, tmp_path, steam_library_factory, monkeypatch, steam_dir,
+        gui_provider):
+    """
+    Test that an inaccessible path is prompted when the user
+    is inside a Flatpak sandbox and the directory does not appear
+    to exist, usually because it's not mounted in the sandbox and
+    requires a permission first.
+
+    Regression test for #472
+    """
+    flatpak_info_path = tmp_path / "flatpak-info"
+
+    flatpak_info_path.write_text(
+        "[Application]\n"
+        "name=fake.flatpak.Protontricks\n"
+        "\n"
+        "[Instance]\n"
+        "flatpak-version=1.12.1\n"
+        "\n"
+        "[Context]\n"
+        f"filesystems={steam_dir}"
+    )
+    monkeypatch.setattr(
+        "protontricks.flatpak.FLATPAK_INFO_PATH", str(flatpak_info_path)
+    )
+    library_dir = steam_library_factory("hidden-library")
+
+    # Mock 'glob' so that it conceals the existence of the library
+    # directory.
+    mock_glob_called = False
+    def mock_glob(path):
+        results = glob(path)
+        results = [
+            path for path in results
+            if path != str(library_dir)
+        ]
+
+        nonlocal mock_glob_called
+        mock_glob_called = True
+
+        return results
+
+    # Mock the user closing the dialog without ignoring the messages
+    gui_provider.returncode = 1
+
+    with monkeypatch.context() as m:
+        m.setattr("glob.glob", mock_glob)
+        cli(["--no-term", "-s", "app"])
+
+    input_ = gui_provider.kwargs["input"].decode("utf-8")
+
+    # Ensure the 'hidden-library' is listed among the directories to enable
+    # and that the mocked glob was actually used
+    assert "does not appear to have access" in input_
+    assert str(library_dir) in input_
+
+    assert mock_glob_called is True

tests/test_steam.py

@@ -665,7 +665,7 @@ def test_get_steam_lib_paths_missing_library_parent(
         lib_paths = get_steam_lib_paths(steam_dir)
 
         assert library_dir_a in lib_paths
-        assert library_dir_b not in lib_paths
+        assert library_dir_b in lib_paths
         assert library_dir_c in lib_paths
 
         assert any(