test: cover slot naming and per-system extras

tests/test_e2e.py

@@ -5685,6 +5685,36 @@ struct BurnDriver BurnDrvneogeo = {
         )
         self.assertTrue(checked.issubset(self._names_in(out)))
 
+    def test_extras_group_under_their_system_not_a_shared_bucket(self):
+        """find_undeclared_files reports the display name, the profiles are
+        keyed by slug; a key-only lookup put nearly every core extra in one
+        bucket and lost the per-system grouping both narrowing passes need."""
+        from generate_pack import _emulator_systems_index
+
+        index = _emulator_systems_index(
+            {
+                "beetle_psx": {
+                    "emulator": "Beetle PSX (Mednafen PSX)",
+                    "systems": ["sony-playstation"],
+                },
+                "beebem": {"emulator": "beebem", "systems": ["bbc-micro-b"]},
+            }
+        )
+        self.assertEqual(index["beetle_psx"], ["sony-playstation"])
+        self.assertEqual(
+            index["Beetle PSX (Mednafen PSX)"], ["sony-playstation"]
+        )
+        self.assertEqual(index["beebem"], ["bbc-micro-b"])
+        self.assertNotIn("_extras", index)
+
+    def test_slot_narrowed_pack_gets_its_own_name(self):
+        names = {
+            os.path.basename(self._region_pack()),
+            os.path.basename(self._region_pack(one_per_slot=True)),
+        }
+        self.assertEqual(len(names), 2, names)
+        self.assertTrue(any("OnePerSlot" in n for n in names))
+
     def test_verify_pack_return_matches_its_annotation(self):
         import inspect
         import typing

wiki/advanced-usage.md

@@ -145,9 +145,11 @@ cannot be ordered, so the whole slot is left alone: the North American
 PlayStation slot stays open because `scph101.bin` carries no priority, even
 though `scph5501.bin` would otherwise win at 5.
 
-`--one-per-slot` requires `--platform` or `--all`, and is refused with
-`--manifest`, `--emulator`, `--system` and `--from-md5` rather than silently
-ignored.
+`--one-per-slot` works with or without `--region`, requires `--platform` or
+`--all`, and is refused with `--manifest`, `--emulator`, `--system` and
+`--from-md5` rather than silently ignored. It tags the output name
+(`Recalbox_10.0.8_OnePerSlot_BIOS_Pack.zip`) so a narrowed build never
+overwrites the full one, and the pack README says the pack was narrowed.
 
 
 `--region` composes with `--split`, `--target`, `--required-only`, `--source`,