fix(dataset): 展示并切换三路数据切分

frontend/scripts/regression-dataset-preview.mjs

@@ -10,6 +10,7 @@ const previewComponentPaths = [
   'DatasetRecordTable.vue',
   'DatasetRecordEditorDialog.vue',
   'DatasetRawPreview.vue',
+  'DatasetSplitNavigator.vue',
 ].map((name) => path.join(previewComponentsDir, name))
 const apiPath = path.join(root, 'src/api/modules/dataset.ts')
 const adapterPath = path.join(root, 'src/mock/adapter.ts')
@@ -50,12 +51,16 @@ function expect(condition, message) {
 }
 
 expect(previewLogicSource.split('\n').length < 520, 'DatasetPreviewView.vue 的逻辑与模板应保持在 520 行以内')
-for (const componentName of ['DatasetVersionBar', 'DatasetRecordTable', 'DatasetRecordEditorDialog', 'DatasetRawPreview']) {
+for (const componentName of ['DatasetVersionBar', 'DatasetRecordTable', 'DatasetRecordEditorDialog', 'DatasetRawPreview', 'DatasetSplitNavigator']) {
   expect(source.includes(`import ${componentName}`), `主页面未导入叶子组件：${componentName}`)
   expect(source.includes(`<${componentName}`), `主页面未挂载叶子组件：${componentName}`)
 }
 expect(source.includes('class="preview-workspace"'), '详情页应提供数据文件工作区')
-expect(!source.includes('class="file-pane"'), '单文件数据集详情不应展示文件选择侧栏')
+expect(previewSurfaceSource.includes('class="split-file-tabs"'), '多切分数据集应提供训练/验证/测试文件切换')
+expect(source.includes('@select="handleFileChange"'), '切换数据切分时应加载对应文件版本')
+expect(previewSurfaceSource.includes('splitCounts.train'), '数据集概览应显示训练集数量')
+expect(previewSurfaceSource.includes('splitCounts.validation'), '数据集概览应显示验证集数量')
+expect(previewSurfaceSource.includes('splitCounts.test'), '数据集概览应显示测试集数量')
 expect(previewSurfaceSource.includes('class="code-line"'), '内容查看器应提供逐行展示')
 expect(previewSurfaceSource.includes('class="line-number"'), '内容查看器应显示行号')
 expect(source.includes('previewLoading'), '切换文件时应提供独立加载状态')