feat: add document support for Claude + image thumbnail generation

1. Coordinator now sends all attachment types to Claude:
   - Images → native image blocks (existing)
   - PDF → native document blocks (Claude PDF support)
   - Text files (txt, csv, json, md) → text blocks with filename
   Extracted common buildAttachmentBlocks() helper.

2. File-service generates thumbnails on image upload:
   - Uses sharp to resize to 400x400 max (inside fit, no upscale)
   - Output as WebP at 80% quality for smaller file size
   - Stored in MinIO under thumbnails/ prefix
   - Generated for both direct upload and presigned URL confirm
   - Non-blocking: thumbnail failure doesn't break upload

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/services/conversation-service/src/infrastructure/agents/coordinator/coordinator-agent.service.ts

@@ -328,6 +328,51 @@ export class CoordinatorAgentService implements OnModuleInit {
   // Message Building
   // ============================================================
 
+  /**
+   * 将附件转换为 Claude API content blocks
+   * - image → { type: 'image', source: { type: 'url', url } }
+   * - PDF   → { type: 'document', source: { type: 'url', url }, title }
+   * - text/csv/json/md → 嵌入为带文件名提示的 text block
+   */
+  private buildAttachmentBlocks(attachments: FileAttachment[]): any[] {
+    const blocks: any[] = [];
+
+    for (const att of attachments) {
+      if (!att.downloadUrl) continue;
+
+      if (att.type === 'image') {
+        blocks.push({
+          type: 'image',
+          source: { type: 'url', url: att.downloadUrl },
+        });
+      } else if (att.mimeType === 'application/pdf') {
+        // Claude 原生支持 PDF 文档
+        blocks.push({
+          type: 'document',
+          source: { type: 'url', url: att.downloadUrl },
+          title: att.originalName,
+        });
+      } else if (this.isTextBasedMime(att.mimeType)) {
+        // 文本类文件：提示模型通过 URL 获取内容
+        blocks.push({
+          type: 'text',
+          text: `[附件: ${att.originalName} (${att.mimeType})] — 文件内容可通过URL获取: ${att.downloadUrl}`,
+        });
+      }
+    }
+
+    return blocks;
+  }
+
+  /** 判断是否为可直接阅读的文本类 MIME */
+  private isTextBasedMime(mimeType: string): boolean {
+    const textMimes = [
+      'text/plain', 'text/csv', 'text/markdown',
+      'application/json',
+    ];
+    return textMimes.includes(mimeType) || mimeType.startsWith('text/');
+  }
+
   private buildMessages(
     context: LegacyConversationContext,
     userContent: string,
@@ -339,21 +384,7 @@ export class CoordinatorAgentService implements OnModuleInit {
     if (context.previousMessages) {
       for (const msg of context.previousMessages) {
         if (msg.attachments?.length) {
-          // Multimodal message with images
-          const contentBlocks: any[] = [];
-
-          for (const att of msg.attachments) {
-            if (att.type === 'image' && att.downloadUrl) {
-              contentBlocks.push({
-                type: 'image',
-                source: {
-                  type: 'url',
-                  url: att.downloadUrl,
-                },
-              });
-            }
-          }
-
+          const contentBlocks = this.buildAttachmentBlocks(msg.attachments);
           contentBlocks.push({ type: 'text', text: msg.content });
           messages.push({ role: msg.role, content: contentBlocks });
         } else {
@@ -364,15 +395,7 @@ export class CoordinatorAgentService implements OnModuleInit {
 
     // Build current user message
     if (attachments?.length) {
-      const contentBlocks: any[] = [];
-      for (const att of attachments) {
-        if (att.type === 'image' && att.downloadUrl) {
-          contentBlocks.push({
-            type: 'image',
-            source: { type: 'url', url: att.downloadUrl },
-          });
-        }
-      }
+      const contentBlocks = this.buildAttachmentBlocks(attachments);
       contentBlocks.push({ type: 'text', text: userContent });
       messages.push({ role: 'user', content: contentBlocks });
     } else {

packages/services/file-service/src/application/services/file.service.ts

@@ -7,6 +7,7 @@ import {
 } from '@nestjs/common';
 import { v4 as uuidv4 } from 'uuid';
 import * as mimeTypes from 'mime-types';
+import sharp from 'sharp';
 import { FileEntity, FileType, FileStatus } from '../../domain/entities/file.entity';
 import { IFileRepository, FILE_REPOSITORY } from '../../domain/repositories/file.repository.interface';
 import { MinioStorageAdapter } from '../../adapters/outbound/storage/minio-storage.adapter';
@@ -38,6 +39,16 @@ const ALLOWED_DOCUMENT_TYPES = [
 
 const MAX_FILE_SIZE = 50 * 1024 * 1024; // 50MB
 
+// 缩略图配置
+const THUMBNAIL_MAX_WIDTH = 400;
+const THUMBNAIL_MAX_HEIGHT = 400;
+const THUMBNAIL_QUALITY = 80;
+
+/** sharp 支持生成缩略图的 MIME 类型 (svg 不支持 resize) */
+const THUMBNAIL_SUPPORTED_MIMES = [
+  'image/jpeg', 'image/png', 'image/webp', 'image/gif',
+];
+
 @Injectable()
 export class FileService {
   private readonly logger = new Logger(FileService.name);
@@ -126,6 +137,20 @@ export class FileService {
 
     // 更新文件状态
     file.confirmUpload(fileSize);
+
+    // 生成缩略图（大文件上传路径）
+    if (file.type === FileType.IMAGE && THUMBNAIL_SUPPORTED_MIMES.includes(file.mimeType) && !file.thumbnailPath) {
+      try {
+        const buffer = await this.storageAdapter.downloadFile(file.storagePath);
+        const thumbnailPath = await this.generateThumbnail(buffer, file.storagePath, file.mimeType);
+        if (thumbnailPath) {
+          file.thumbnailPath = thumbnailPath;
+        }
+      } catch (err) {
+        this.logger.warn(`Thumbnail generation failed on confirm for ${fileId}: ${err}`);
+      }
+    }
+
     await this.fileRepo.update(file);
 
     return this.toResponseDto(file);
@@ -167,6 +192,16 @@ export class FileService {
       'x-amz-meta-user-id': userId,
     });
 
+    // 生成缩略图 (仅图片，fire-and-forget 不阻塞主流程)
+    let thumbnailPath: string | null = null;
+    if (fileType === FileType.IMAGE && THUMBNAIL_SUPPORTED_MIMES.includes(mimetype)) {
+      try {
+        thumbnailPath = await this.generateThumbnail(buffer, objectName, mimetype);
+      } catch (err) {
+        this.logger.warn(`Thumbnail generation failed for ${fileId}: ${err}`);
+      }
+    }
+
     // 创建文件记录
     const fileEntity = FileEntity.create({
       id: fileId,
@@ -180,9 +215,13 @@ export class FileService {
       status: FileStatus.READY,
     });
 
+    if (thumbnailPath) {
+      fileEntity.thumbnailPath = thumbnailPath;
+    }
+
     await this.fileRepo.save(fileEntity);
 
-    this.logger.log(`File uploaded: ${fileId} by user ${userId}`);
+    this.logger.log(`File uploaded: ${fileId} by user ${userId}${thumbnailPath ? ' (with thumbnail)' : ''}`);
 
     return this.toResponseDto(fileEntity);
   }
@@ -253,6 +292,41 @@ export class FileService {
     this.logger.log(`File deleted: ${fileId} by user ${userId}`);
   }
 
+  /**
+   * 生成缩略图并上传到 MinIO
+   * @returns thumbnailPath 或 null
+   */
+  private async generateThumbnail(
+    imageBuffer: Buffer,
+    originalPath: string,
+    mimeType: string,
+  ): Promise<string | null> {
+    // 将原始路径 uploads/images/.../xxx.png → thumbnails/images/.../xxx.webp
+    const thumbnailPath = originalPath
+      .replace(/^uploads\//, 'thumbnails/')
+      .replace(/\.[^.]+$/, '.webp');
+
+    const thumbnailBuffer = await sharp(imageBuffer)
+      .resize(THUMBNAIL_MAX_WIDTH, THUMBNAIL_MAX_HEIGHT, {
+        fit: 'inside',
+        withoutEnlargement: true,
+      })
+      .webp({ quality: THUMBNAIL_QUALITY })
+      .toBuffer();
+
+    await this.storageAdapter.uploadFile(
+      thumbnailPath,
+      thumbnailBuffer,
+      'image/webp',
+    );
+
+    this.logger.debug(
+      `Thumbnail generated: ${thumbnailPath} (${thumbnailBuffer.length} bytes)`,
+    );
+
+    return thumbnailPath;
+  }
+
   /**
    * 确定文件类型
    */