fix: unmark files of standalone-only profiles

tests/test_standalone_mode.py

@@ -0,0 +1,59 @@
+"""A standalone-only profile does not mark its files standalone.
+
+Per-file mode separates the two builds of a dual profile. ares, clk,
+primehack, jgenesis and five Switch emulators repeated `mode: standalone`
+on all 226 of their files: the gap analysis skips such a file, so
+cross_reference reported 0 undeclared files where verify --standalone
+counted 118 for clk alone, and a platform listing the emulator without
+standalone_cores dropped them from its pack.
+"""
+
+from __future__ import annotations
+
+import json
+import unittest
+from pathlib import Path
+
+import yaml
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+
+
+class StandaloneProfilesCarryNoFileMode(unittest.TestCase):
+    def test_every_profile_follows_it(self):
+        offenders = []
+        for path in sorted((REPO_ROOT / "emulators").glob("*.yml")):
+            document = yaml.safe_load(path.read_text(encoding="utf-8")) or {}
+            if document.get("type") != "standalone":
+                continue
+            marked = sum(
+                1 for entry in document.get("files") or []
+                if isinstance(entry, dict) and entry.get("mode") == "standalone"
+            )
+            if marked:
+                offenders.append(f"{path.stem}: {marked}")
+        self.assertEqual(offenders, [])
+
+    def test_the_schema_refuses_it(self):
+        try:
+            from jsonschema import Draft202012Validator
+        except ImportError:
+            self.skipTest("jsonschema is not installed")
+        schema = json.loads((REPO_ROOT / "schemas" / "emulator.schema.json").read_text())
+        validator = Draft202012Validator(schema)
+        profile = {
+            "emulator": "X",
+            "type": "standalone",
+            "systems": ["x"],
+            "files": [{"name": "a.bin", "mode": "standalone"}],
+        }
+        self.assertTrue(list(validator.iter_errors(profile)))
+        profile["type"] = "standalone + libretro"
+        self.assertEqual(
+            [e.message for e in validator.iter_errors(profile) if "mode" in e.message],
+            [],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()