From dda057f45f64da210a6d3b110c1d98bff90b8824 Mon Sep 17 00:00:00 2001
From: Abdessamad Derraz <3028866+Abdess@users.noreply.github.com>
Date: Sun, 18 Oct 2026 13:55:06 +0200
Subject: [PATCH] fix: key cross-reference slots by the build's path

---
 scripts/cross_reference.py    | 20 +++++++++++++-------
 tests/test_standalone_mode.py | 26 ++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/scripts/cross_reference.py b/scripts/cross_reference.py
index 215566b1..1fc0c729 100644
--- a/scripts/cross_reference.py
+++ b/scripts/cross_reference.py
@@ -453,14 +453,19 @@ def _first_hash(entry: dict) -> str:
     return ""
 
 
-def slot_key(f: dict) -> tuple:
+def slot_key(f: dict, standalone: bool = False) -> tuple:
     """The slot a profile entry fills: its entries on one slot are the
-    versions its code accepts there, and holding any of them fills it."""
+    versions its code accepts there, and holding any of them fills it.
+
+    The path is the one the running build reads: b2's standalone build
+    reads MOS 3.20 and 3.50 from two directories, two slots, while the
+    entries share a name and no `path:`."""
     fname = f.get("name", "")
+    where = (f.get("standalone_path") if standalone else None) or f.get("path")
     return (
         fname,
         f.get("archive"),
-        f.get("path") or fname,
+        where or fname,
         f.get("system"),
         f.get("variant_group"),
         f.get("mode", "both"),
@@ -517,8 +522,8 @@ def _cross_reference_profile(
     # accepts there (raze's ten DUKE3D.GRP): holding any of them fills the
     # slot, as verify --emulator credits it.
     versions: dict[tuple, list[dict]] = {}
-    for f in emu_files:
-        versions.setdefault(slot_key(f), []).append(f)
+    for f, is_standalone in layout_files:
+        versions.setdefault(slot_key(f, is_standalone), []).append(f)
 
     for f, is_standalone in layout_files:
         fname = f.get("name", "")
@@ -530,7 +535,8 @@ def _cross_reference_profile(
             effective_path = f.get("standalone_path") or f.get("path") or fname
         else:
             effective_path = f.get("path") or fname
-        seen_key = slot_key(f)
+        slot = slot_key(f, is_standalone)
+        seen_key = slot
         if len(layouts) > 1:
             # One file read at one path by both builds counts once.
             seen_key = (effective_path.casefold(), seen_key)
@@ -613,7 +619,7 @@ def _cross_reference_profile(
         else:
             source = next(
                 (
-                    found for version in versions[seen_key]
+                    found for version in versions[slot]
                     if (found := entry_source(version, index)) is not None
                 ),
                 "missing",
diff --git a/tests/test_standalone_mode.py b/tests/test_standalone_mode.py
index 720a0db8..5e885c2c 100644
--- a/tests/test_standalone_mode.py
+++ b/tests/test_standalone_mode.py
@@ -90,5 +90,31 @@ class CrossReferenceReadsTheBuildThePlatformRuns(unittest.TestCase):
         self.assertEqual(self._gaps(set()), ["both.bin", "libretro.bin"])
 
 
+    def test_a_platform_running_both_builds(self):
+        # The dual layout keyed seen files by (path, slot) and then looked
+        # the pair up in the slot table: KeyError on Batocera's dolphin.
+        from common import DUAL_MODE_PREFIX
+
+        self.assertEqual(
+            self._gaps({"dual", DUAL_MODE_PREFIX + "dual"}),
+            ["both.bin", "libretro.bin", "standalone.bin"],
+        )
+
+    def test_standalone_paths_are_separate_slots(self):
+        # b2 reads MOS 3.20 and 3.50 ROMs under one name from two
+        # directories: two slots, not two versions of one.
+        profile = {
+            "emulator": "B", "type": "standalone", "systems": ["sys"],
+            "files": [
+                {"name": "dfs.rom", "standalone_path": "m128/3.20/dfs.rom"},
+                {"name": "dfs.rom", "standalone_path": "m128/3.50/dfs.rom"},
+            ],
+        }
+        report = cross_reference(
+            {"b": profile}, {}, {"files": {}, "indexes": {}}, standalone_cores={"b"}
+        )
+        self.assertEqual(len(report["b"]["gap_details"]), 2)
+
+
 if __name__ == "__main__":
     unittest.main()