fix: list systems the way --system selects

scripts/common.py

@@ -1709,17 +1709,24 @@ def list_emulator_profiles(emulators_dir: str, skip_aliases: bool = True) -> Non
 
 
 def list_system_ids(emulators_dir: str) -> None:
-    """Print available system IDs with emulator count."""
+    """Print available system IDs with emulator count.
+
+    Counted on the normalized id, as --system selects: listed per spelling,
+    3do showed two emulators and panasonic-3do six for one system.
+    """
     profiles = load_emulator_profiles(emulators_dir)
-    system_emus: dict[str, list[str]] = {}
-    for name, p in profiles.items():
+    system_emus: dict[str, set[str]] = {}
+    spelling: dict[str, str] = {}
+    for name, p in sorted(profiles.items()):
         if p.get("type") in ("alias", "test", "launcher"):
             continue
         for sys_id in p.get("systems", []):
-            system_emus.setdefault(sys_id, []).append(name)
-    for sys_id in sorted(system_emus):
-        count = len(system_emus[sys_id])
-        print(f"  {sys_id:35s} ({count} emulator{'s' if count > 1 else ''})")
+            key = _norm_system_id(sys_id)
+            system_emus.setdefault(key, set()).add(name)
+            spelling.setdefault(key, sys_id)
+    for key in sorted(system_emus, key=lambda k: spelling[k]):
+        count = len(system_emus[key])
+        print(f"  {spelling[key]:35s} ({count} emulator{'s' if count > 1 else ''})")
 
 
 def list_platform_system_ids(platform_name: str, platforms_dir: str) -> None:

tests/test_system_selection.py

@@ -40,6 +40,23 @@ class SpellingsAgree(unittest.TestCase):
         self.assertEqual(builder._system_display_name("msxturboR"), builder._system_display_name("msxturbor"))
 
 
+class TheListingCountsLikeTheSelection(unittest.TestCase):
+    def test_one_system_is_listed_once_with_every_profile(self):
+        import contextlib  # noqa: PLC0415
+        import io  # noqa: PLC0415
+
+        out = io.StringIO()
+        with contextlib.redirect_stdout(out):
+            common.list_system_ids(str(REPO_ROOT / "emulators"))
+        lines = {line.split()[0]: line for line in out.getvalue().splitlines() if line.strip()}
+        profiles = common.load_emulator_profiles(str(REPO_ROOT / "emulators"))
+        for spellings in (("3do", "panasonic-3do"), ("atari-2600", "atari_2600")):
+            listed = [s for s in spellings if s in lines]
+            self.assertEqual(len(listed), 1, f"{spellings}: one line per system")
+            count = len(common.profiles_for_systems(profiles, [spellings[0]]))
+            self.assertIn(f"({count} emulator", lines[listed[0]])
+
+
 class StandaloneNeedsAStandaloneBuild(unittest.TestCase):
     def test_a_custom_pack_refuses_it_for_a_libretro_core(self):
         with tempfile.TemporaryDirectory() as tmp: