refactor: split this round's fixes into small helpers

scripts/exporter/baseline.py

@@ -38,6 +38,10 @@ def _is_placeholder(name: str) -> bool:
     return "<" in name or ">" in name or "*" in name
 
 
+def _field_sets(entry: dict | None) -> dict[str, set[str]]:
+    return {f: set(_hash_values(entry or {}, f)) for f in HASH_FIELDS}
+
+
 @dataclass
 class NativeFile:
     """One file as the platform will read it, after correction."""
@@ -67,8 +71,7 @@ class NativeFile:
         truth's crc32 beside Batocera's md5 for bios7.bin is one dump, and
         reading it as a contradiction emptied the md5 the frontend checks.
         """
-        truth = {f: set(_hash_values(self.truth or {}, f)) for f in HASH_FIELDS}
-        plat = {f: set(_hash_values(self.platform or {}, f)) for f in HASH_FIELDS}
+        truth, plat = _field_sets(self.truth), _field_sets(self.platform)
         if not any(truth.values()):
             return "platform"
         if not any(plat.values()):
@@ -76,10 +79,12 @@ class NativeFile:
         shared = [f for f in HASH_FIELDS if truth[f] and plat[f]]
         if any(truth[f] & plat[f] for f in shared):
             return "both"
+        return "truth" if shared or self._sizes_differ() else "both"
+
+    def _sizes_differ(self) -> bool:
         t_size = (self.truth or {}).get("size")
         p_size = (self.platform or {}).get("size")
-        sizes_differ = isinstance(t_size, int) and isinstance(p_size, int) and t_size != p_size
-        return "truth" if shared or sizes_differ else "both"
+        return isinstance(t_size, int) and isinstance(p_size, int) and t_size != p_size
 
     def hashes(self, field_name: str) -> list[str]:
         """Accepted values for a hash, truth first when it has an opinion.

scripts/exporter/emudeck_exporter.py

@@ -95,6 +95,14 @@ class Exporter(BaseExporter):
             return False
         return super().states(fe, field_name)
 
+    def _expected_md5s(
+        self, systems: dict[str, NativeSystem], name: str, system_id: str
+    ) -> list[str]:
+        """What a check must now hold; a refused rewrite keeps EmuDeck's own array."""
+        if name in getattr(self, "_withdrawn", {}):
+            return []
+        return self._md5s(systems, system_id)
+
     def _refused_systems(self) -> set[str]:
         withdrawn = getattr(self, "_withdrawn", {})
         return {FUNCTION_HASH_MAP[name] for name in withdrawn if name in FUNCTION_HASH_MAP}
@@ -200,9 +208,8 @@ class Exporter(BaseExporter):
             if name not in defined:
                 issues.append(f"check absent from the output: {name}")
                 continue
-            md5s = self._md5s(systems, system_id)
-            if not md5s or name in getattr(self, "_withdrawn", {}):
-                # A refused rewrite keeps EmuDeck's own array, by design.
+            md5s = self._expected_md5s(systems, name, system_id)
+            if not md5s:
                 continue
             body = next(
                 content[start:end]

scripts/exporter/romm_exporter.py

@@ -64,7 +64,7 @@ class Exporter(BaseExporter):
         """
         return native_id in SLUG_MAP
 
-    def writable(self, fe: NativeFile, require: str = "") -> bool:
+    def writable(self, fe: NativeFile, require: str = "") -> bool:  # noqa: ARG002
         """What RomM already ships stays; the conditions gate additions.
 
         An entry of theirs that could never verify is still theirs, and the