fix: split only the systems the target runs

--split --target asked for a part per declared system, and each one
the target drops ended on a refusal naming it unknown (finding 14).

scripts/generate_pack.py

@@ -1940,7 +1940,11 @@ def generate_split_packs(
     split_dir = os.path.join(output_dir, f"{part_prefix}{group_tag}_Split")
     os.makedirs(split_dir, exist_ok=True)
 
-    systems = config.get("systems", {})
+    if emu_profiles is None:
+        emu_profiles = load_emulator_profiles(emulators_dir)
+    # The systems a core of the target runs: a part per declared system sent
+    # each one the target drops to a refusal naming it as unknown.
+    systems = platform_scope_systems(config, emu_profiles, target_cores)
 
     if group_by == "manufacturer":
         groups = _group_systems_by_manufacturer(systems, db, bios_dir)
@@ -1949,8 +1953,6 @@ def generate_split_packs(
 
     # Pre-compute core extras once (expensive: scans 260+ emulator profiles)
     # then distribute per group based on emulator system overlap
-    if emu_profiles is None:
-        emu_profiles = load_emulator_profiles(emulators_dir)
     base_dest = config.get("base_destination", "")
     # Each part cuts the platform's own entries from the full profiles. The
     # extras are collected once here, already without the cores' game data.

tests/test_target_verify.py

@@ -128,5 +128,40 @@ class ASystemTheTargetDropsIsNamedAsSuch(unittest.TestCase):
                       proc.stderr)
 
 
+class ASplitBuildsOnlyTheTargetsSystems(unittest.TestCase):
+    """`--split --target switch` asked for a part per declared system, and
+    each one the target drops ended on 'retroarch has no system matching'."""
+
+    def test_no_part_is_asked_for_a_dropped_system(self):
+        from unittest import mock
+
+        import generate_pack
+        from common import load_emulator_profiles
+
+        platforms = str(REPO_ROOT / "platforms")
+        profiles = load_emulator_profiles(str(REPO_ROOT / "emulators"))
+        asked: list[list[str]] = []
+
+        def record(*_a, **kw):
+            if kw.get("system_filter"):
+                asked.append(kw["system_filter"])
+            return None
+
+        with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as out, \
+                mock.patch.object(generate_pack, "generate_pack", record), \
+                mock.patch.object(generate_pack, "_collect_emulator_extras",
+                                  return_value=[]):
+            generate_pack.generate_split_packs(
+                "retroarch", platforms, {"files": {}}, "bios", out,
+                emu_profiles=profiles,
+                target_cores=_target_cores_for("retroarch", "switch", platforms),
+                target_name="nintendo-switch",
+            )
+        systems = {sid for ids in asked for sid in ids}
+        self.assertTrue(systems)
+        self.assertNotIn("sony-playstation-2", systems)
+        self.assertIn("sony-playstation", systems)
+
+
 if __name__ == "__main__":
     unittest.main()