fix: read recalbox mandatory per named core

An element lists its cores. Its mandatory flag now follows whether those
cores need the file, and stays as written where none of them reads it.
cdi/cdibios.zip keeps mandatory=false (same_cdi does not read it), the
two amiberry kickstarts keep theirs, saturn_bios.bin becomes optional
for the three HLE cores it names.

scripts/exporter/base_exporter.py

@@ -200,6 +200,14 @@ class BaseExporter(ABC):
             return self.single_value(fe, field_name)
         return ",".join(fe.hashes(field_name))
 
+    def required_value(self, fe: NativeFile) -> bool:
+        """The requirement the render writes for an entry.
+
+        The model's flag is true when any core needs the file. A format
+        that names the cores of each entry narrows it to those cores.
+        """
+        return fe.required
+
     def states(self, fe: NativeFile, field_name: str) -> bool:
         """Whether the written file carries this entry's corrected field.
 

scripts/exporter/recalbox_exporter.py

@@ -20,7 +20,7 @@ from xml.sax.saxutils import quoteattr
 
 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
 
-from common import parse_untrusted_xml
+from common import load_emulator_profiles, parse_untrusted_xml
 
 from .base_exporter import BaseExporter
 from .baseline import NativeFile, NativeSystem, Report
@@ -29,6 +29,8 @@ SOURCE_URL = (
     "https://gitlab.com/recalbox/recalbox/-/raw/master/board/recalbox/fsoverlay"
     "/recalbox/share_init/system/.emulationstation/es_bios.xml"
 )
+# Resolved from the file: the profiles say which names each core answers to.
+EMULATORS_DIR = Path(__file__).resolve().parents[2] / "emulators"
 SCHEMA_URL = (
     "https://gitlab.com/recalbox/recalbox/-/raw/master/board/recalbox/fsoverlay"
     "/recalbox/share_init/system/.emulationstation/es_bios.xsd"
@@ -149,12 +151,48 @@ class Exporter(BaseExporter):
             return path
         return fe.destination or fe.name
 
+    def _profile_keys(self) -> dict[str, str]:
+        """Each name a core answers to, as Recalbox writes it, to its profile."""
+        index = getattr(self, "_keys", None)
+        if index is None:
+            index = {}
+            for key, profile in load_emulator_profiles(str(EMULATORS_DIR)).items():
+                for name in (key, *(str(c) for c in profile.get("cores") or [])):
+                    index.setdefault(name.replace("-", "_").lower(), key)
+            self._keys = index
+        return index
+
+    def required_value(self, fe: NativeFile) -> bool:
+        """Whether the cores the element names need the file.
+
+        An element lists its cores, and the merged flag is true when any
+        core needs the file: cdi/cdibios.zip names libretro/same_cdi, whose
+        driver declares no such set, and became mandatory because MAME
+        requires it. Where none of the element's cores reads the file, the
+        truth says nothing about it and the platform's value stands.
+        """
+        truth = fe.truth or {}
+        required_by = truth.get("_required_by")
+        readers = truth.get("_cores")
+        if required_by is None or not readers:
+            return fe.required
+        index = self._profile_keys()
+        named = {
+            index.get(core.rsplit("/", 1)[-1].replace("-", "_").lower(), "")
+            for core in fe.cores()
+        } & set(readers)
+        if not named:
+            if fe.platform is not None and fe.platform.get("required") is not None:
+                return bool(fe.platform["required"])
+            return fe.required
+        return bool(named & set(required_by))
+
     def _bios_element(self, fe: NativeFile, native_id: str) -> str:
         attrs = [f"path={quoteattr(self._path(fe))}"]
         attrs.append(f'md5={quoteattr(",".join(fe.hashes("md5")))}')
         attrs.append(f'core={quoteattr(",".join(fe.cores()))}')
 
-        if not fe.required:
+        if not self.required_value(fe):
             attrs.append('mandatory="false"')
         elif fe.native("mandatory_declared", None) is True:
             attrs.append('mandatory="true"')