Enable Agents to Generate Downloadable Files

[jezweb]

Summary

Allow agents to create and output downloadable files (CSV, JSON, PDF, TXT, MD) in chat messages, similar to how the image generation tool currently works.

Current State

• The image generation tool can upload files to storage and return download URLs
• The FileMessagePart UI component fully supports displaying and downloading files
• Vercel Blob and S3 storage backends are configured and working
• However, agents cannot currently access file storage or return file attachments

Desired Behavior

When an agent tool needs to output a file:

1. Tool creates file content (buffer/blob)
2. Uploads via existing serverFileStorage.upload() API
3. Returns file reference (URL, filename, MIME type)
4. Agent message displays file as downloadable attachment (using existing FileMessagePart component)

Use Cases

• CSV exports: Analysis results, data tables
• Generated documents: Markdown reports, formatted text
• JSON data: API responses, configuration files
• Code files: .js, .py, .ts, .tsx generated code
• Plain text: Reports, summaries, formatted output

Technical Details

The infrastructure already exists:

• ✅ File storage: serverFileStorage.upload() in /src/lib/file-storage/
• ✅ File UI: FileMessagePart component in /src/components/message-parts.tsx
• ✅ Download functionality: Working download buttons
• ✅ Proof of concept: Image generation tool already does this

The gap: Agents need:

1. Access to serverFileStorage.upload() from within tools
2. A file attachment result type (similar to ImageToolResult)
3. Tool results to flow through as FileUIPart in message rendering

Acceptance Criteria

• Agent tools can create files programmatically
• Files appear in chat as downloadable attachments
• Works with common MIME types: CSV, JSON, PDF, TXT, MD, code files
• Download links remain functional (public URLs from storage)
• Files respect existing storage cleanup/expiration rules

Example Implementation Pattern

Based on existing image tool pattern:

// In agent tool
const fileContent = "name,value\nFoo,123\nBar,456"; // Generated CSV
const uploadedFile = await serverFileStorage.upload(
  Buffer.from(fileContent, 'utf-8'),
  {
    contentType: 'text/csv',
    filename: 'export.csv'
  }
);

return {
  type: 'file',
  url: uploadedFile.sourceUrl,
  filename: 'export.csv',
  mimeType: 'text/csv'
};

Related Files

• /src/lib/file-storage/file-storage.interface.ts - Storage interface
• /src/lib/ai/tools/image/index.ts - Working example (image tool)
• /src/components/message-parts.tsx - File rendering UI
• /src/lib/ai/file-support.ts - Supported MIME types

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[jezweb]

maybe just a download option for md files will be enough i realise now that the csv download is part of the tables tool!