Fix UNKNOWN platform fallback & DAT index collisions

core/bin/openrom.dart

@@ -102,6 +102,10 @@ ArgParser buildParser() {
       help: 'output format: CHD, CSO, ECM, ISO, BIN, BIN/CUE, XISO, ZIP, 7Z',
     )
     ..addOption('force-platform', help: 'override automatic platform detection')
+    ..addOption(
+      'media',
+      help: 'media type override for CHD creation: cd or dvd',
+    )
     ..addFlag(
       'list-dats',
       negatable: false,
@@ -760,6 +764,7 @@ Future<int> main(List<String> args) async {
 
   final targetFmt = results['format'] as String?;
   final forcePlat = results['force-platform'] as String?;
+  final mediaVal = results['media'] as String?;
   final compLevel = results['compression'] as String;
   final verifyVal = results['verify'] == true;
   final outputDir = results['output'] as String?;
@@ -774,6 +779,7 @@ Future<int> main(List<String> args) async {
       compression: compLevel,
       verify: verifyVal,
       forcePlatform: forcePlat,
+      media: mediaVal,
     );
     jobs.add(job);
   } else if (folder != null) {
@@ -786,6 +792,7 @@ Future<int> main(List<String> args) async {
         compression: compLevel,
         verify: verifyVal,
         forcePlatform: forcePlat,
+        media: mediaVal,
       );
       jobs.add(job);
     }

core/lib/src/converter.dart

@@ -40,6 +40,7 @@ class ConversionJob {
   final String compression;
   final bool verify;
   final String? forcePlatform;
+  final String? media;
   String status;
   double progress;
   final List<String> logLines;
@@ -54,6 +55,7 @@ class ConversionJob {
     this.compression = 'Normal',
     this.verify = false,
     this.forcePlatform,
+    this.media,
     this.status = 'Queued',
     this.progress = 0.0,
     List<String>? logLines,
@@ -207,16 +209,28 @@ class Converter {
       subCmd = 'createcd';
     } else if (fmt == 'ISO' || fmt == 'IMG') {
       final platform = info['platform'] as String? ?? 'UNKNOWN';
-      if (platform == 'UNKNOWN' ||
+      final mediaOverride = job.media?.trim().toLowerCase();
+
+      if (mediaOverride == 'cd') {
+        subCmd = 'createcd';
+      } else if (mediaOverride == 'dvd') {
+        subCmd = 'createdvd';
+      } else if (platform.toUpperCase() == 'CD') {
+        subCmd = 'createcd';
+      } else if (platform.toUpperCase() == 'DVD') {
+        subCmd = 'createdvd';
+      } else if (cdPlatformKeywords.any((kw) => platform.contains(kw))) {
+        subCmd = 'createcd';
+      } else if (platform == 'UNKNOWN' ||
           platform == 'Unknown Disc' ||
           platform.isEmpty) {
-        _log(
-            '[WARN] Platform is UNKNOWN for . Defaulting safely to createdvd.');
-        subCmd = 'createdvd';
+        final err =
+            'Error: Platform could not be detected. Please specify --media cd or --media dvd.';
+        _log('[ERROR] $err');
+        job.error = err;
+        return false;
       } else {
-        subCmd = cdPlatformKeywords.any((kw) => platform.contains(kw))
-            ? 'createcd'
-            : 'createdvd';
+        subCmd = 'createdvd';
       }
     } else {
       subCmd = 'createcd';

core/lib/src/rom_renamer.dart

@@ -220,15 +220,21 @@ Future<Map<String, Map<String, dynamic>>> loadDatIndex(String datPath) async {
         }
 
         if (crc.isNotEmpty) {
-          index[crc] = {
+          final item = {
             'name': currentGameName,
             'description':
                 currentDesc.isNotEmpty ? currentDesc : currentGameName,
             'rom_name': romName,
             'size': size,
             'md5': md5,
             'sha1': sha1,
+            'crc': crc,
           };
+          final compositeKey = '${crc}_$size';
+          index[compositeKey] = item;
+          if (!index.containsKey(crc)) {
+            index[crc] = item;
+          }
         }
       }
     } else if (event is XmlTextEvent) {
@@ -272,6 +278,29 @@ class RomScanResult {
   }
 }
 
+Map<String, dynamic>? _findInIndex(
+  Map<String, Map<String, dynamic>> indexMap,
+  String crc32,
+  int fileSize,
+) {
+  final compositeKey = '${crc32}_$fileSize';
+  if (indexMap.containsKey(compositeKey)) {
+    return indexMap[compositeKey];
+  }
+  final zeroKey = '${crc32}_0';
+  if (indexMap.containsKey(zeroKey)) {
+    return indexMap[zeroKey];
+  }
+  if (indexMap.containsKey(crc32)) {
+    final item = indexMap[crc32]!;
+    final expectedSize = item['size'] as int? ?? 0;
+    if (expectedSize == 0 || expectedSize == fileSize) {
+      return item;
+    }
+  }
+  return null;
+}
+
 Future<List<RomScanResult>> scanFolder(
   String folder,
   List<String> datPaths, {
@@ -373,8 +402,10 @@ Future<List<RomScanResult>> scanFolder(
         },
       );
 
-      if (globalIndex.containsKey(result.crc32)) {
-        final item = globalIndex[result.crc32]!;
+      final fileSize = File(fpath).lengthSync();
+      final item = _findInIndex(globalIndex, result.crc32, fileSize);
+
+      if (item != null) {
         result.matched = true;
         result.canonicalName = item['name'] as String;
         result.romName = item['rom_name'] as String;

core/test/detector_test.dart

@@ -184,4 +184,66 @@ void main() {
     final xgdtoolPath = getToolPath('xgdtool');
     expect(xgdtoolPath, isNotEmpty);
   });
+  test('unknown_iso_conversion_without_media_fails_safely', () {
+    final tmpDir = Directory.systemTemp.createTempSync('unknown_iso_conv_');
+    try {
+      final isoPath = p.join(tmpDir.path, 'unidentified.iso');
+      File(isoPath).writeAsBytesSync(List<int>.filled(2048, 0));
+
+      final job = ConversionJob(
+        filepath: isoPath,
+        outputDir: tmpDir.path,
+        targetFormat: 'CHD',
+      );
+
+      final converter = Converter();
+      final success = converter.convert(job);
+
+      expect(success, isFalse);
+      expect(job.status, equals('Failed'));
+      expect(
+        job.error,
+        equals(
+          'Error: Platform could not be detected. Please specify --media cd or --media dvd.',
+        ),
+      );
+    } finally {
+      tmpDir.deleteSync(recursive: true);
+    }
+  });
+
+  test('unknown_iso_conversion_with_media_override_routes_correctly', () {
+    final tmpDir = Directory.systemTemp.createTempSync('unknown_iso_override_');
+    try {
+      final isoPath = p.join(tmpDir.path, 'unidentified.iso');
+      File(isoPath).writeAsBytesSync(List<int>.filled(2048, 0));
+
+      saveConfig({'chdman': p.join(tmpDir.path, 'missing_chdman')});
+
+      final jobCd = ConversionJob(
+        filepath: isoPath,
+        outputDir: tmpDir.path,
+        targetFormat: 'CHD',
+        media: 'cd',
+      );
+
+      final converter = Converter();
+      converter.convert(jobCd);
+      expect(jobCd.error, contains('Tool not found'));
+      expect(jobCd.error, isNot(contains('Platform could not be detected')));
+
+      final jobDvd = ConversionJob(
+        filepath: isoPath,
+        outputDir: tmpDir.path,
+        targetFormat: 'CHD',
+        media: 'dvd',
+      );
+      converter.convert(jobDvd);
+      expect(jobDvd.error, contains('Tool not found'));
+      expect(jobDvd.error, isNot(contains('Platform could not be detected')));
+    } finally {
+      saveConfig({});
+      tmpDir.deleteSync(recursive: true);
+    }
+  });
 }

core/test/rom_renamer_test.dart

@@ -69,7 +69,7 @@ void main() {
 	</header>
 	<game name="Super Mario Land">
 		<description>Super Mario Land</description>
-		<rom name="Super Mario Land.gb" size="65536" crc="cbf43926"/>
+		<rom name="Super Mario Land.gb" size="9" crc="cbf43926"/>
 	</game>
 </datafile>''');
 
@@ -99,4 +99,47 @@ void main() {
       tmpDir.deleteSync(recursive: true);
     }
   });
+  test('composite_dat_lookup_prevents_crc32_collisions', () async {
+    final tmpDir = Directory.systemTemp.createTempSync('collision_test_');
+    try {
+      final datPath = p.join(tmpDir.path, 'collision.dat');
+      final xmlContent = '''<?xml version="1.0"?>
+<datafile>
+	<header>
+		<name>Collision DAT</name>
+		<url>http://www.no-intro.org</url>
+	</header>
+	<game name="Game A">
+		<description>Game A</description>
+		<rom name="Game A.gb" size="9" crc="cbf43926"/>
+	</game>
+	<game name="Game B Collision">
+		<description>Game B Collision</description>
+		<rom name="Game B.gb" size="100" crc="cbf43926"/>
+	</game>
+</datafile>''';
+      File(datPath).writeAsStringSync(xmlContent);
+
+      final romDir = p.join(tmpDir.path, 'roms');
+      Directory(romDir).createSync();
+      final romPath = p.join(romDir, 'sample.gb');
+      File(romPath).writeAsStringSync('123456789');
+
+      final results = await scanFolder(romDir, [datPath]);
+      expect(results.length, equals(1));
+      expect(results.first.matched, isTrue);
+      expect(results.first.canonicalName, equals('Game A'));
+      expect(results.first.suggestedFilename, equals('Game A.gb'));
+
+      final mismatchPath = p.join(romDir, 'mismatch.gb');
+      File(mismatchPath).writeAsBytesSync(List<int>.filled(50, 0x31));
+
+      final mismatchResults = await scanFolder(romDir, [datPath]);
+      final mismatchRes =
+          mismatchResults.firstWhere((r) => r.filename == 'mismatch.gb');
+      expect(mismatchRes.matched, isFalse);
+    } finally {
+      tmpDir.deleteSync(recursive: true);
+    }
+  });
 }

gui/lib/app.dart

@@ -77,6 +77,27 @@ class _OpenROMAppState extends State<OpenROMApp> {
       compression: _compression,
       verify: _verify,
       outputDir: _outputDir,
+      onPromptMedia: (job) async {
+        return await showDialog<String>(
+          context: context,
+          builder: (ctx) => AlertDialog(
+            title: const Text('Unrecognized Media Type'),
+            content: Text(
+              'Unrecognized Media Type: Is this game a CD or DVD?\n\nFile: ${job.romFile.filename}',
+            ),
+            actions: [
+              TextButton(
+                onPressed: () => Navigator.of(ctx).pop('cd'),
+                child: const Text('CD'),
+              ),
+              ElevatedButton(
+                onPressed: () => Navigator.of(ctx).pop('dvd'),
+                child: const Text('DVD'),
+              ),
+            ],
+          ),
+        );
+      },
     );
   }
 

gui/lib/controllers/home_controller.dart

@@ -76,6 +76,7 @@ class HomeController extends ChangeNotifier {
     String compression = 'Normal',
     bool verify = false,
     String outputDir = '',
+    Future<String?> Function(ConversionJob job)? onPromptMedia,
     void Function(OpenROMException e)? onError,
   }) async {
     if (_jobs.isEmpty || _isConverting) return;
@@ -100,6 +101,27 @@ class HomeController extends ChangeNotifier {
         job.compression,
       );
 
+      if (job.targetFormat.toUpperCase() == 'CHD' &&
+          (job.romFile.platform == 'UNKNOWN' ||
+              job.romFile.platform == 'Unknown Disc' ||
+              job.romFile.platform == 'ROM File') &&
+          (job.media == null || job.media!.isEmpty)) {
+        if (onPromptMedia != null) {
+          final choice = await onPromptMedia(job);
+          if (choice != null && choice.isNotEmpty) {
+            job.media = choice;
+          } else {
+            job.status = JobStatus.failed;
+            job.errorMessage =
+                'Error: Platform could not be detected. Please specify media type.';
+            job.error = OpenROMError.conversionFailed;
+            _logs.add('[ERROR] ${job.errorMessage}');
+            notifyListeners();
+            continue;
+          }
+        }
+      }
+
       job.status = JobStatus.converting;
       notifyListeners();
 

gui/lib/models/conversion_job.dart

@@ -12,6 +12,7 @@ class ConversionJob {
   String targetFormat;
   String compression;
   bool verify;
+  String? media;
   JobStatus status;
   double progress;
   List<String> logs;
@@ -25,6 +26,7 @@ class ConversionJob {
     required this.targetFormat,
     this.compression = 'Normal',
     this.verify = false,
+    this.media,
     this.status = JobStatus.queued,
     this.progress = 0.0,
     List<String>? logs,

gui/lib/services/core_bridge.dart

@@ -170,6 +170,10 @@ class CoreBridge {
         args.add('--verify');
       }
 
+      if (job.media != null && job.media!.isNotEmpty) {
+        args.addAll(['--media', job.media!]);
+      }
+
       if (outputDir.isNotEmpty) {
         args.addAll(['--output', outputDir]);
       }