feat(dc/tool-c): Add pivot column ordering and NA handling features

Major features:
1. Pivot transformation enhancements:
   - Add option to keep unselected columns with 3 aggregation methods
   - Maintain original column order after pivot (aligned with source file)
   - Preserve pivot value order (first appearance order)

2. NA handling across 4 core functions:
   - Recode: Support keep/map/drop for NA values
   - Filter: Already supports is_null/not_null operators
   - Binning: Support keep/label/assign for NA values (fix nan display)
   - Conditional: Add is_null/not_null operators

3. UI improvements:
   - Enable column header tooltips with custom header component
   - Add closeable alert for 50-row preview
   - Fix page scrollbar issues

Modified files:
Python: pivot.py, recode.py, binning.py, conditional.py, main.py
Backend: SessionController, QuickActionController, QuickActionService
Frontend: PivotDialog, RecodeDialog, BinningDialog, ConditionalDialog, DataGrid, index

Status: Ready for testing

backend/src/modules/dc/tool-c/controllers/QuickActionController.ts

@@ -113,8 +113,9 @@ export class QuickActionController {
           });
       }
       
-      // 4. 获取完整数据
+      // 4. 获取完整数据和session信息（包含columnMapping）
       let fullData: any[];
+      let session: any;
       try {
         fullData = await sessionService.getFullData(sessionId);
         if (!fullData || fullData.length === 0) {
@@ -124,6 +125,9 @@ export class QuickActionController {
             error: '数据为空，请重新上传文件'
           });
         }
+        
+        // ✨ 获取session信息（用于compute等需要columnMapping的操作）
+        session = await sessionService.getSession(sessionId);
       } catch (error: any) {
         logger.error(`[QuickAction] 获取数据失败: ${error.message}`);
         return reply.code(500).send({
@@ -153,10 +157,32 @@ export class QuickActionController {
             executeResult = await quickActionService.executeDropna(fullData, params);
             break;
           case 'compute':
-            executeResult = await quickActionService.executeCompute(fullData, params);
+            // ✨ 传递columnMapping给compute操作
+            executeResult = await quickActionService.executeCompute(fullData, params, session.columnMapping);
             break;
           case 'pivot':
-            executeResult = await quickActionService.executePivot(fullData, params);
+            // ✨ 传递columnMapping、原始列顺序和透视值顺序给pivot操作
+            const originalColumnOrder = session.columns || [];
+            
+            // ✨ 获取透视列值的原始顺序（按首次出现顺序）
+            const pivotColumn = params.pivotColumn;
+            const seenPivotValues = new Set();
+            const pivotValueOrder: string[] = [];
+            for (const row of fullData) {
+              const pivotValue = row[pivotColumn];
+              if (pivotValue !== null && pivotValue !== undefined && !seenPivotValues.has(pivotValue)) {
+                seenPivotValues.add(pivotValue);
+                pivotValueOrder.push(String(pivotValue));
+              }
+            }
+            
+            executeResult = await quickActionService.executePivot(
+              fullData, 
+              params, 
+              session.columnMapping,
+              originalColumnOrder,
+              pivotValueOrder
+            );
             break;
         }
         

backend/src/modules/dc/tool-c/controllers/SessionController.ts

@@ -392,7 +392,7 @@ export class SessionController {
       // 1. 获取完整数据
       const data = await sessionService.getFullData(id);
 
-      // 2. 提取唯一值（去除空值和首尾空格）
+      // 2. 提取唯一值（保留NA值，但清理字符串）
       const values = data.map((row) => row[column]);
       const cleanedValues = values.map((val) => {
         if (val === null || val === undefined || val === '') return null;
@@ -400,12 +400,22 @@ export class SessionController {
         return typeof val === 'string' ? val.trim() : val;
       });
 
-      // 3. 去重
-      const uniqueValues = Array.from(new Set(cleanedValues))
+      // 3. 去重（✨ 保留null值，但用特殊标记表示）
+      const uniqueSet = Array.from(new Set(cleanedValues));
+      const hasNA = uniqueSet.includes(null);
+      const naCount = cleanedValues.filter(v => v === null).length;  // ✨ 统计NA数量
+      
+      // 过滤掉null和空白，然后排序
+      const nonNAValues = uniqueSet
         .filter((v) => v !== null && v !== '' && v !== '(空白)')
         .sort(); // 排序，方便查看
+      
+      // ✨ 如果有NA，添加到数组末尾（用特殊字符串标记）
+      const uniqueValues = hasNA 
+        ? [...nonNAValues, '<空值/NA>']
+        : nonNAValues;
 
-      logger.info(`[SessionController] 唯一值数量: ${uniqueValues.length}`);
+      logger.info(`[SessionController] 唯一值数量: ${uniqueValues.length} (含NA: ${hasNA}, NA数量: ${naCount})`);
 
       // 4. 返回结果
       return reply.send({
@@ -414,6 +424,8 @@ export class SessionController {
           column,
           uniqueValues,
           count: uniqueValues.length,
+          naCount: hasNA ? naCount : 0,  // ✨ 返回NA数量
+          totalCount: data.length,  // ✨ 总行数
         },
       });
     } catch (error: any) {

backend/src/modules/dc/tool-c/services/QuickActionService.ts

@@ -27,6 +27,8 @@ interface RecodeParams {
   mapping: Record<string, any>;
   createNewColumn: boolean;
   newColumnName?: string;
+  naHandling?: 'keep' | 'map' | 'drop';  // ✨ 新增：NA处理方式
+  naValue?: any;  // ✨ 新增：NA映射值
 }
 
 interface BinningParams {
@@ -36,6 +38,9 @@ interface BinningParams {
   bins?: number[];
   labels?: (string | number)[];
   numBins?: number;
+  naHandling?: 'keep' | 'label' | 'assign';  // ✨ 新增：NA处理方式
+  naLabel?: string;  // ✨ 新增：NA标签
+  naAssignTo?: number;  // ✨ 新增：NA分配到的组索引
 }
 
 interface ConditionalParams {
@@ -68,6 +73,8 @@ interface PivotParams {
   pivotColumn: string;
   valueColumns: string[];
   aggfunc: 'first' | 'last' | 'mean' | 'sum' | 'min' | 'max';
+  keepUnusedColumns?: boolean;  // ✨ 新增：是否保留未选择的列
+  unusedAggMethod?: 'first' | 'mode' | 'mean';  // ✨ 新增：未选择列的聚合方式
 }
 
 interface OperationResult {
@@ -128,6 +135,8 @@ export class QuickActionService {
         mapping: params.mapping,
         create_new_column: params.createNewColumn,
         new_column_name: params.newColumnName,
+        na_handling: params.naHandling || 'keep',  // ✨ NA处理方式
+        na_value: params.naValue,  // ✨ NA映射值
       }, {
         timeout: 60000,
       });
@@ -164,6 +173,9 @@ export class QuickActionService {
         bins: params.bins,
         labels: params.labels,
         num_bins: params.numBins,
+        na_handling: params.naHandling || 'keep',  // ✨ NA处理方式
+        na_label: params.naLabel,  // ✨ NA标签
+        na_assign_to: params.naAssignTo,  // ✨ NA分配到的组索引
       }, {
         timeout: 60000,
       });
@@ -254,14 +266,16 @@ export class QuickActionService {
   /**
    * 执行计算列
    */
-  async executeCompute(data: any[], params: ComputeParams): Promise<OperationResult> {
+  async executeCompute(data: any[], params: ComputeParams, columnMapping?: any[]): Promise<OperationResult> {
     try {
       logger.info(`[QuickActionService] 调用计算列API: ${params.newColumnName}, formula=${params.formula}`);
       
+      // ✨ 传递columnMapping给Python（方案B：Python负责替换）
       const response = await axios.post(`${PYTHON_SERVICE_URL}/api/operations/compute`, {
         data,
         new_column_name: params.newColumnName,
         formula: params.formula,
+        column_mapping: columnMapping || [], // ✨ 传递列名映射
       }, {
         timeout: 60000,
       });
@@ -286,16 +300,28 @@ export class QuickActionService {
   /**
    * 执行Pivot（长表→宽表）
    */
-  async executePivot(data: any[], params: PivotParams): Promise<OperationResult> {
+  async executePivot(
+    data: any[], 
+    params: PivotParams, 
+    columnMapping?: any[], 
+    originalColumnOrder?: string[],
+    pivotValueOrder?: string[]
+  ): Promise<OperationResult> {
     try {
       logger.info(`[QuickActionService] 调用Pivot API: ${params.indexColumn} × ${params.pivotColumn}`);
       
+      // ✨ 传递columnMapping、未选择列处理参数和列顺序给Python
       const response = await axios.post(`${PYTHON_SERVICE_URL}/api/operations/pivot`, {
         data,
         index_column: params.indexColumn,
         pivot_column: params.pivotColumn,
         value_columns: params.valueColumns,
         aggfunc: params.aggfunc,
+        column_mapping: columnMapping || [], // ✨ 传递列名映射
+        keep_unused_columns: params.keepUnusedColumns || false,  // ✨ 是否保留未选择的列
+        unused_agg_method: params.unusedAggMethod || 'first',  // ✨ 未选择列的聚合方式
+        original_column_order: originalColumnOrder || [],  // ✨ 原始列顺序
+        pivot_value_order: pivotValueOrder || [],  // ✨ 透视列值的原始顺序
       }, {
         timeout: 60000,
       });