fix: write no platform size beside a truth hash

scripts/exporter/baseline.py

@@ -153,9 +153,15 @@ class NativeFile:
         truth's size is only taken when the truth also speaks for the hash:
         a name-matched 480-byte fbneo boot.bin turned RomM's Dreamcast
         boot.bin into size 480 beside its 2 MB md5, which never verifies.
+        When the truth contradicts the platform's hash, the platform's size
+        describes the dump the truth rejects: geolith's neocdz.zip md5 went
+        out beside System.dat's 953078 bytes, a record no file satisfies.
         """
         source = self._identity_source()
-        order = (self.platform, self.truth) if source == "platform" else (self.truth, self.platform)
+        order = {
+            "platform": (self.platform, self.truth),
+            "truth": (self.truth,),
+        }.get(source, (self.truth, self.platform))
         for entry in order:
             if entry and entry.get("size"):
                 return _single_size(entry["size"])

tests/test_exporters.py

@@ -136,6 +136,21 @@ class Reconciliation(unittest.TestCase):
         self.assertIsNone(platform_entry.truth)
         self.assertEqual(report.hashes_corrected, [])
 
+    def test_a_contradicted_hash_takes_no_platform_size(self):
+        """geolith's neocdz.zip md5 contradicts System.dat's: the export
+        wrote that md5 beside System.dat's 953078 bytes."""
+        entry = NativeFile(
+            "neocdz.zip", "neocdz.zip", "neocd",
+            platform={"md5": "a" * 32, "size": 953078},
+            truth={"md5": "b" * 32},
+        )
+        self.assertEqual((entry.hash("md5"), entry.size()), ("b" * 32, None))
+        agreeing = NativeFile(
+            "neocdz.zip", "neocdz.zip", "neocd",
+            platform={"md5": "b" * 32, "size": 955352}, truth={"md5": "b" * 32},
+        )
+        self.assertEqual(agreeing.size(), 955352)
+
     def test_a_file_the_truth_says_nothing_about_is_kept(self):
         systems, _ = model()
         names = {fe.name for fe in systems["psx"].files}