diff --git a/tests/test_profile_paths.py b/tests/test_profile_paths.py
new file mode 100644
index 00000000..3df44b9c
--- /dev/null
+++ b/tests/test_profile_paths.py
@@ -0,0 +1,77 @@
+"""A standalone app's paths are the folders its code opens below data_root.
+
+The site prints data_root joined to each entry's standalone destination, so a
+frontend's layout written there (Batocera's bios/switch/) sends the reader to a
+folder the app never reads. A frontend folder name is allowed only where the
+app's own code joins that folder to its data root.
+"""
+
+from __future__ import annotations
+
+import unittest
+from pathlib import Path
+
+import yaml
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+
+FRONTEND_FOLDERS = ("bios/", "switch/", "system/")
+
+# Profiles whose code reads one of those folders below its data root.
+CODE_READS = {
+    # BIOS folder of the data directory, the PCSX2 layout it carries
+    # (aethersx2 profile notes, AetherSX2-release MacOS/AetherSX2).
+    "aethersx2": {"bios/"},
+    # BIOS_FOLDER under gui_data_folder() (src/core/fds.c:305, src/core/cheat.c:105).
+    "punes": {"bios/"},
+    # KeysDir "system" under BaseDirPath
+    # (src/Ryujinx.Common/Configuration/AppDataManager.cs:17, 229).
+    "ryujinx": {"system/"},
+    "kenji-nx": {"system/"},
+    # PathSystem is the system folder beside DOSBoxPure.cfg (main.cpp:2032-2039).
+    "dosbox-pure-unleashed": {"system/"},
+}
+
+
+def _standalone_profiles() -> dict[str, dict]:
+    profiles = {}
+    for path in sorted((REPO_ROOT / "emulators").glob("*.yml")):
+        with path.open(encoding="utf-8") as fh:
+            profile = yaml.safe_load(fh)
+        if isinstance(profile, dict) and profile.get("data_root") \
+                and profile.get("type") == "standalone":
+            profiles[path.stem] = profile
+    return profiles
+
+
+def _destination(entry: dict) -> str:
+    return str(entry.get("standalone_path") or entry.get("path") or "")
+
+
+class StandaloneDestinations(unittest.TestCase):
+    def test_no_frontend_folder_below_data_root(self):
+        wrong = []
+        for name, profile in _standalone_profiles().items():
+            allowed = CODE_READS.get(name, set())
+            for entry in profile.get("files") or []:
+                if not isinstance(entry, dict):
+                    continue
+                dest = _destination(entry)
+                for folder in FRONTEND_FOLDERS:
+                    if dest.startswith(folder) and folder not in allowed:
+                        wrong.append(f"{name}: {entry.get('name')} at {dest}")
+        self.assertEqual(wrong, [])
+
+    def test_every_allowed_folder_is_read(self):
+        profiles = _standalone_profiles()
+        unused = []
+        for name, folders in CODE_READS.items():
+            dests = [_destination(e) for e in profiles.get(name, {}).get("files") or []
+                     if isinstance(e, dict)]
+            unused += [f"{name}: {folder}" for folder in sorted(folders)
+                       if not any(d.startswith(folder) for d in dests)]
+        self.assertEqual(unused, [])
+
+
+if __name__ == "__main__":
+    unittest.main()