fix(ssa): harden spreadsheet upload recognition and guidance

Fix SSA data-context generation for Excel uploads by parsing xlsx/xls via extension-aware paths instead of UTF-8 fallback.
Add on-demand overview rebuild in Agent flow, align xls friendly prompts on frontend/backend, and surface backend upload errors to users.

Made-with: Cursor

backend/src/modules/ssa/services/DataProfileService.ts

@@ -249,18 +249,26 @@ export class DataProfileService {
       } else if (session.dataOssKey) {
         // 从 OSS 下载文件
         const buffer = await storage.download(session.dataOssKey);
-        const content = buffer.toString('utf-8');
-        
-        // 检测文件格式：JSON 或 CSV
-        const trimmedContent = content.trim();
-        if (trimmedContent.startsWith('[') || trimmedContent.startsWith('{')) {
-          // JSON 格式
-          const data = JSON.parse(content);
-          return await this.generateProfile(sessionId, data);
-        } else {
-          // CSV 格式，直接发给 Python 解析（更高效、更可靠）
+        const ext = this.getFileExtensionFromOssKey(session.dataOssKey);
+
+        // 按文件扩展名处理，避免将 Excel 二进制误当作 UTF-8 文本
+        if (ext === 'csv') {
+          const content = buffer.toString('utf-8');
           return await this.generateProfileFromCSV(sessionId, content);
         }
+
+        if (ext === 'xlsx' || ext === 'xls') {
+          return await this.generateProfileFromExcel(sessionId, buffer);
+        }
+
+        // 兼容历史数据：未知扩展名时再尝试 JSON/CSV 兜底
+        const content = buffer.toString('utf-8');
+        const trimmedContent = content.trim();
+        if (trimmedContent.startsWith('[') || trimmedContent.startsWith('{')) {
+          const data = JSON.parse(content);
+          return await this.generateProfile(sessionId, data);
+        }
+        return await this.generateProfileFromCSV(sessionId, content);
       } else {
         throw new Error('No data available for session');
       }
@@ -278,6 +286,38 @@ export class DataProfileService {
     }
   }
 
+  private getFileExtensionFromOssKey(ossKey: string): string {
+    const match = ossKey.toLowerCase().match(/\.([a-z0-9]+)$/);
+    return match?.[1] || '';
+  }
+
+  /**
+   * 从 Excel 二进制生成画像（xlsx/xls）
+   */
+  private async generateProfileFromExcel(sessionId: string, buffer: Buffer): Promise<DataProfileResult> {
+    try {
+      const xlsx = await import('xlsx');
+      const workbook = xlsx.read(buffer, { type: 'buffer' });
+      const firstSheetName = workbook.SheetNames[0];
+      const firstSheet = workbook.Sheets[firstSheetName];
+      const rows = xlsx.utils.sheet_to_json(firstSheet, {
+        defval: null,
+        raw: false,
+      }) as Record<string, any>[];
+
+      return await this.generateProfile(sessionId, rows);
+    } catch (error: any) {
+      logger.error('[SSA:DataProfile] Excel profile generation failed', {
+        sessionId,
+        error: error.message,
+      });
+      return {
+        success: false,
+        error: error.message || 'Failed to parse Excel file',
+      };
+    }
+  }
+
   /**
    * 保存画像到 Session
    */