feat(metadata): 元数据引擎第 3 步之一——一致性与冲突感知的状态机

之前只要 confidence>=0.6 且 validation_count>=2 就升级 verified，两次读到不同结果也会被当成"验证通过"，错误标签一旦写入很难纠正。新增 MetadataStability（纯函数，可单测）： - 首次见到 → pending(first_seen)，次数 1 - 与上次记录标题/艺术家冲突 → pending(conflict)，次数重置为 1 - 一致且次数 >= 2、置信度达标 → verified(stable) - 置信度不足 → pending(low_confidence)，次数继续累计 - 字段缺失不算冲突；比较时忽略大小写与首尾空格 metadata_service 改为调用该状态机，并打印判定原因： 🧭 [MetadataService] 状态机: stable → verified（validations=2）测试：新增 test/metadata_stability_test.dart 7 个用例，连同原有 9 个共 16 个，flutter test 全绿。已构建并安装 release 验证。
2026-10-24 20:24:55 +08:00
parent 9f53d1c604
commit b8138ad125
3 changed files with 234 additions and 4 deletions
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+// test/metadata_stability_test.dart
+import 'package:flutter_test/flutter_test.dart';
+import 'package:qingting_player/metadata/metadata_model.dart';
+import 'package:qingting_player/metadata/metadata_stability.dart';
+
+void main() {
+  CandidateMetadata candidate({double confidence = 0.8}) => CandidateMetadata(
+        metadata: const NormalizedMetadata(title: '夜曲', artist: '周杰伦'),
+        confidence: confidence,
+      );
+
+  group('MetadataStability', () {
+    test('首次见到 → pending，次数 1', () {
+      final d = MetadataStability.decide(
+        previous: null,
+        candidate: candidate(),
+        title: '夜曲',
+        artist: '周杰伦',
+      );
+      expect(d.status, 'pending');
+      expect(d.reason, 'first_seen');
+      expect(d.validationCount, 1);
+    });
+
+    test('第二次结果一致且置信度达标 → verified', () {
+      final d = MetadataStability.decide(
+        previous: {
+          'title': '夜曲',
+          'artist': '周杰伦',
+          'confidence': 0.8,
+          'validation_count': 1,
+        },
+        candidate: candidate(),
+        title: '夜曲',
+        artist: '周杰伦',
+      );
+      expect(d.status, 'verified');
+      expect(d.reason, 'stable');
+      expect(d.validationCount, 2);
+    });
+
+    test('标题或艺术家冲突 → 次数重置为 1，保持 pending', () {
+      final d = MetadataStability.decide(
+        previous: {
+          'title': '夜曲',
+          'artist': '周杰伦',
+          'confidence': 0.9,
+          'validation_count': 5,
+        },
+        candidate: candidate(),
+        title: '完全不同的歌',
+        artist: '别的歌手',
+      );
+      expect(d.status, 'pending');
+      expect(d.reason, 'conflict');
+      expect(d.validationCount, 1);
+    });
+
+    test('置信度不足 → pending，但次数继续累计', () {
+      final d = MetadataStability.decide(
+        previous: {
+          'title': '夜曲',
+          'artist': '周杰伦',
+          'confidence': 0.4,
+          'validation_count': 3,
+        },
+        candidate: candidate(confidence: 0.5),
+        title: '夜曲',
+        artist: '周杰伦',
+      );
+      expect(d.status, 'pending');
+      expect(d.reason, 'low_confidence');
+      expect(d.validationCount, 4);
+    });
+
+    test('一致但只验证过一次 → pending', () {
+      final d = MetadataStability.decide(
+        previous: {
+          'title': '夜曲',
+          'artist': '周杰伦',
+          'confidence': 0.8,
+          'validation_count': 0,
+        },
+        candidate: candidate(),
+        title: '夜曲',
+        artist: '周杰伦',
+      );
+      expect(d.status, 'pending');
+      expect(d.reason, 'need_second_validation');
+      expect(d.validationCount, 1);
+    });
+
+    test('字段缺失不算冲突（旧记录没有艺术家）', () {
+      final d = MetadataStability.decide(
+        previous: {
+          'title': '夜曲',
+          'artist': '',
+          'confidence': 0.7,
+          'validation_count': 1,
+        },
+        candidate: candidate(),
+        title: '夜曲',
+        artist: '周杰伦',
+      );
+      expect(d.status, 'verified');
+      expect(d.validationCount, 2);
+    });
+
+    test('大小写与首尾空格不影响一致性判断', () {
+      final d = MetadataStability.decide(
+        previous: {
+          'title': ' Night Song ',
+          'artist': 'JAY',
+          'confidence': 0.8,
+          'validation_count': 1,
+        },
+        candidate: candidate(),
+        title: 'night song',
+        artist: 'jay',
+      );
+      expect(d.status, 'verified');
+    });
+  });
+}