Resouce Context 管理

之前的 Drive MCP 设计中提到了 Resource，这里记录一下在实际使用 Resource 过程中遇到的问题：在用户 Attach File 后，我们使用前面说的 MCP Client 获取 Resource，然后把上下文 attach 到 system prompt 中：

private async resolveResourceUris(
  uris: string[],
  _userId: string,
): Promise<string> {
  const parts: string[] = [];

  for (const uri of uris.slice(0, 5)) {
    try {
      const result = await this.mcpClient.readResource(uri);
      const content = result.contents[0]?.text ?? "";

      parts.push(
        `--- Resource (${uri}) ---\n${content}\n--- End of resource ---`,
      );
    } catch (error) {
      const msg = error instanceof Error ? error.message : "Unknown error";
      logger.warn({ uri, error: msg }, "Failed to resolve resource URI");
      parts.push(`--- ${uri}: [Error: ${msg}] ---`);
    }
  }

  return parts.join("\n\n");
}

const resourceUris = request.resourceUris;
if (resourceUris && resourceUris.length > 0) {
  const resolvedContent = await this.resolveResourceUris(resourceUris, userId);
  if (resolvedContent) {
    const resourceMessage: IMessage = {
      role: "system",
      content:
        `[Attached Resources — the user has explicitly shared these for context]\n\n` +
        resolvedContent,
      timestamp: new Date(),
    };
    conversation.messages.push(resourceMessage);
  }
}

然后就结束、测试 Agent 做 Summary，结果它发生了下面的问题：

如果我在一个 Folder 中 Attach 另一个 Folder，那么 Agent 会弄不清楚自己现在在处理哪个 Folder，会在当前的 Folder 查找 Attached Folder 的内容。
backend 日志显示 Attach 内容后日志中会调用 check_index_status 这些实际用不上的工具。

在排查具体问题是发现是上下文 Prompt 的问题，然后进行了如下策略修改：

我们把 System Prompt 加入到消息窗口中，不然 Agent 完全获取不到前面的 Resource 消息：

for (const msg of memoryState.recentMessages) {
  if (msg.role === "user") {
    messages.push({ role: "user", content: msg.content });
  } else if (msg.role === "assistant") {
    messages.push({ role: "assistant", content: msg.content });
  } else if (msg.role === "system") {
    // 注入的 system 消息（比如 Attached resource）
    messages.push({ role: "system", content: msg.content });
  }
}

然后对原先的 Agent，添加上针对 Attached 的上下文并取消原始的 Workspace 上下文注入，防止 Agent 弄不清楚到底该处理哪个 Folder，下面是一个例子：

简单回顾一下：这里的 Workspace Context 是 Agent 在 Drive 特定位置时注入的上下文，比如在某个 Folder 中时这个 Context 就是当前 folderId 和下面的文件。

const workspaceInfo = context.hasExplicitResources
  ? `\n\n## Context Mode: Resource-Focused\nThe user has explicitly attached specific files/folders as reference materials.\nTheir full content/structure is already provided in the conversation as system messages.\n**DO NOT** browse root directory, list folder contents, or explore surrounding folders — the data you need is already in the conversation.\nIf the task requires creating a result file, use folder ID "${context.folderId || "root"}" as the target.`
  : context.workspaceSnapshot
    ? `\n\n## Current Workspace Snapshot\nThe user is currently in this folder:\n\`\`\`json\n${context.workspaceSnapshot}\n\`\`\`\nFolder path: ${context.folderPath || "/"}`
    : "";