SnowCat 雪猫底层全源码：NapCat 4.18.28 底座 + SnowLuma 能力移植 + V8 通道适配 9.9.37

26 包 monorepo（TS 全源码）：
- snowcat-core: NT 内核 API 封装 + listener（含 9.9.37 六回调适配）+ Packet 发包
- snowcat-onebot: OneBot v11 全动作 + MCP Streamable HTTP 适配器 + 稳定线
- snowcat-webui-frontend/backend: 雪猫控制台（React+HeroUI）
- snowcat-shell: 单文件 bundle 出口（vite inlineDynamicImports）
- snowcat-native: napi2native / MoeHoo / ffmpeg / pty 运行时
- 56 项 SnowLuma 独门动作移植（qzone 全家桶/群相册/装扮/闪照/收藏）
- 工具件: 解包器/启动器/便携制作器/doctor

GitHub 关联已全量指向 DandanLLab/SnowCatQQ

packages/snowcat-onebot/action/stream/BaseDownloadStream.ts

@@ -0,0 +1,102 @@
+import { OneBotAction, OneBotRequestToolkit } from '@/snowcat-onebot/action/OneBotAction';
+import { StreamPacket, StreamStatus } from './StreamBasic';
+import fs from 'fs';
+import { FileNapCatOneBotUUID } from 'snowcat-common/src/file-uuid';
+import { calculateTimeout } from '@/snowcat-onebot/config/config';
+
+export interface ResolvedFileInfo {
+  downloadPath: string;
+  fileName: string;
+  fileSize: number;
+}
+
+export interface DownloadResult {
+  // 文件信息
+  file_name?: string;
+  file_size?: number;
+  chunk_size?: number;
+
+  // 分片数据
+  index?: number;
+  data?: string;
+  size?: number;
+  progress?: number;
+  base64_size?: number;
+
+  // 完成信息
+  total_chunks?: number;
+  total_bytes?: number;
+  message?: string;
+  data_type?: 'file_info' | 'file_chunk' | 'file_complete';
+
+  // 可选扩展字段
+  width?: number;
+  height?: number;
+  out_format?: string;
+}
+
+export abstract class BaseDownloadStream<PayloadType, ResultType> extends OneBotAction<PayloadType, StreamPacket<ResultType>> {
+  protected async resolveDownload (file?: string): Promise<ResolvedFileInfo> {
+    const target = file || '';
+    let downloadPath = '';
+    let fileName = '';
+    let fileSize = 0;
+
+    const contextMsgFile = FileNapCatOneBotUUID.decode(target);
+    if (contextMsgFile && contextMsgFile.msgId && contextMsgFile.elementId) {
+      const { peer, msgId, elementId } = contextMsgFile;
+      downloadPath = await this.core.apis.FileApi.downloadMedia(msgId, peer.chatType, peer.peerUid, elementId, '', '');
+      const rawMessage = (await this.core.apis.MsgApi.getMsgsByMsgId(peer, [msgId]))?.msgList
+        .find(msg => msg.msgId === msgId);
+      const mixElement = rawMessage?.elements.find(e => e.elementId === elementId);
+      const mixElementInner = mixElement?.videoElement ?? mixElement?.fileElement ?? mixElement?.pttElement ?? mixElement?.picElement;
+      if (!mixElementInner) throw new Error('element not found');
+      fileSize = parseInt(mixElementInner.fileSize?.toString() ?? '0');
+      fileName = mixElementInner.fileName ?? '';
+      return { downloadPath, fileName, fileSize };
+    }
+
+    const contextModelIdFile = FileNapCatOneBotUUID.decodeModelId(target);
+    if (contextModelIdFile && contextModelIdFile.modelId) {
+      const { peer, modelId } = contextModelIdFile;
+      downloadPath = await this.core.apis.FileApi.downloadFileForModelId(peer, modelId, '');
+      return { downloadPath, fileName, fileSize };
+    }
+
+    const searchResult = (await this.core.apis.FileApi.searchForFile([target]));
+    if (searchResult) {
+      const fileSizeNum = parseInt(searchResult.fileSize);
+      const timeoutConfig = this.obContext.configLoader.configData.timeout;
+      const estimatedTime = calculateTimeout(timeoutConfig, fileSizeNum, timeoutConfig.downloadSpeedKBps);
+      downloadPath = await this.core.apis.FileApi.downloadFileById(searchResult.id, fileSizeNum, estimatedTime);
+      fileSize = fileSizeNum;
+      fileName = searchResult.fileName;
+      return { downloadPath, fileName, fileSize };
+    }
+
+    throw new Error('file not found');
+  }
+
+  protected async streamFileChunks (req: OneBotRequestToolkit, streamPath: string, chunkSize: number, chunkDataType: string): Promise<{ totalChunks: number; totalBytes: number }> {
+    const stats = await fs.promises.stat(streamPath);
+    const totalSize = stats.size;
+    const readStream = fs.createReadStream(streamPath, { highWaterMark: chunkSize });
+    let chunkIndex = 0;
+    let bytesRead = 0;
+    for await (const chunk of readStream) {
+      const base64Chunk = (chunk as Buffer).toString('base64');
+      bytesRead += (chunk as Buffer).length;
+      await req.send({
+        type: StreamStatus.Stream,
+        data_type: chunkDataType,
+        index: chunkIndex,
+        data: base64Chunk,
+        size: (chunk as Buffer).length,
+        progress: Math.round((bytesRead / totalSize) * 100),
+        base64_size: base64Chunk.length,
+      } as unknown as StreamPacket<any>);
+      chunkIndex++;
+    }
+    return { totalChunks: chunkIndex, totalBytes: bytesRead };
+  }
+}