From 4ca4592f655c0dc7495bc23f9dfaee3d8b1dbc9f Mon Sep 17 00:00:00 2001
From: Abdessamad Derraz <3028866+Abdess@users.noreply.github.com>
Date: Tue, 6 Oct 2026 00:26:36 +0200
Subject: [PATCH] fix: group variant slots across their systems

---
 emulators/picodrive.yml | 12 ++++++++++++
 scripts/packextras.py   | 11 +++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/emulators/picodrive.yml b/emulators/picodrive.yml
index 96c0eff0..08d60eb5 100644
--- a/emulators/picodrive.yml
+++ b/emulators/picodrive.yml
@@ -64,6 +64,7 @@ files:
   # -------------------------------------------------------
   - name: "us_scd2_9306.bin"
     system: sega-segacd
+    variant_group: "mega-cd-bios"
     region: [north-america]
     priority: 1
     required: true
@@ -73,6 +74,7 @@ files:
 
   - name: "SegaCDBIOS9303.bin"
     system: sega-segacd
+    variant_group: "mega-cd-bios"
     region: [north-america]
     priority: 2
     required: false
@@ -82,6 +84,7 @@ files:
 
   - name: "us_scd1_9210.bin"
     system: sega-segacd
+    variant_group: "mega-cd-bios"
     region: [north-america]
     priority: 3
     required: false
@@ -91,6 +94,7 @@ files:
 
   - name: "bios_CD_U.bin"
     system: sega-segacd
+    variant_group: "mega-cd-bios"
     region: [north-america]
     priority: 4
     required: false
@@ -103,6 +107,7 @@ files:
   # -------------------------------------------------------
   - name: "eu_mcd2_9306.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [europe]
     priority: 1
     required: true
@@ -112,6 +117,7 @@ files:
 
   - name: "eu_mcd2_9303.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [europe]
     priority: 2
     required: false
@@ -121,6 +127,7 @@ files:
 
   - name: "eu_mcd1_9210.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [europe]
     priority: 3
     required: false
@@ -130,6 +137,7 @@ files:
 
   - name: "bios_CD_E.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [europe]
     priority: 4
     required: false
@@ -142,6 +150,7 @@ files:
   # -------------------------------------------------------
   - name: "jp_mcd2_921222.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [japan]
     priority: 1
     required: true
@@ -151,6 +160,7 @@ files:
 
   - name: "jp_mcd1_9112.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [japan]
     priority: 2
     required: false
@@ -160,6 +170,7 @@ files:
 
   - name: "jp_mcd1_9111.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [japan]
     priority: 3
     required: false
@@ -169,6 +180,7 @@ files:
 
   - name: "bios_CD_J.bin"
     system: sega-megacd
+    variant_group: "mega-cd-bios"
     region: [japan]
     priority: 4
     required: false
diff --git a/scripts/packextras.py b/scripts/packextras.py
index 1e4d1f86..239d9a7d 100644
--- a/scripts/packextras.py
+++ b/scripts/packextras.py
@@ -611,8 +611,15 @@ def platform_region_groups(
             )
         ] = dest
         variant = extra.get("variant_group")
-        for sys_id in _extra_system_ids(extra) or ["_extras"]:
-            group_id = f"{sys_id}:variant:{variant}" if variant else sys_id
+        if variant:
+            # A variant group is one slot of one core, whatever system each
+            # member is filed under: PicoDrive files its US Mega CD BIOS under
+            # sega-segacd and the EU/JP ones under sega-megacd, and find_bios
+            # picks one of the twelve. Keyed as emulator mode keys it.
+            group_ids = [f"{extra.get('source_emulator', '')}:variant:{variant}"]
+        else:
+            group_ids = _extra_system_ids(extra) or ["_extras"]
+        for group_id in group_ids:
             groups.setdefault(group_id, []).append((dest, name))
     return groups, extra_dests