fix: diff the truth against the platform's own list

scripts/export_native.py

@@ -26,7 +26,7 @@ from pathlib import Path
 sys.path.insert(0, str(Path(__file__).resolve().parent))
 
 from artifacts import file_lock, write_bytes_atomic, write_text_atomic
-from common import list_registered_platforms, load_platform_config, yaml_load
+from common import list_registered_platforms, load_platform_config, native_layer, yaml_load
 from exporter import discover_exporters
 from exporter.baseline import HASH_FIELDS, _hash_values, _single_size, build_native_model
 
@@ -206,34 +206,7 @@ def load_inputs(
         scraped = load_platform_config(platform, platforms_dir)
     except (FileNotFoundError, OSError):
         scraped = None
-    return truth, _native_layer(scraped)
-
-
-def _native_layer(config: dict | None) -> dict | None:
-    """The platform config without what we add to it.
-
-    A shared group's files join the config for the pack, but the platform's
-    file does not carry them: counted kept, they were written into
-    libretro's System.dat (N88EXT0-3.ROM) as if libretro declared them. What
-    a core needs from a group reaches the export through the truth, as an
-    addition the format's gates apply to. A scraper's mirror of an entry
-    under another system (RomM's tg16 firmware under turbografx-cd), and a
-    file our scraper adds from the cores' source (Dolphin's DSP ROMs in
-    RetroArch's config), are not in the platform's file either.
-    """
-    if config is None:
-        return None
-    systems = {
-        sys_id: {
-            **system,
-            "files": [
-                f for f in system.get("files", [])
-                if not ({"shared_group", "mirror_of", "curated"} & f.keys())
-            ],
-        }
-        for sys_id, system in config.get("systems", {}).items()
-    }
-    return {**config, "systems": systems}
+    return truth, native_layer(scraped)
 
 
 def refresh_cache(