convex-agents-files

name	Convex Agents Files
description	Handles file uploads, image attachments, and media processing in agent conversations. Use this when agents analyze images, process documents, or generate files.

Purpose

Files and images let agents understand and generate visual content. Covers uploading, storing, attaching to messages, and managing file lifecycle.

When to Use This Skill

• Users upload images for agent analysis
• Agents need to process documents or files
• Agents generate images with DALL-E
• Building file-based workflows
• Implementing file cleanup and tracking

Upload and Store a File

import { storeFile } from "@convex-dev/agent";

export const uploadFile = action({
  args: { fileData: v.string(), filename: v.string(), mimeType: v.string() },
  handler: async (ctx, { fileData, filename, mimeType }) => {
    const bytes = Buffer.from(fileData, "base64");

    const { file } = await storeFile(
      ctx,
      components.agent,
      new Blob([bytes], { type: mimeType }),
      { filename, sha256: "hash" }
    );

    return {
      fileId: file.fileId,
      url: file.url,
      storageId: file.storageId,
    };
  },
});

Send File with Message (2-Step)

Upload first, then send message with attachment:

import { saveMessage, getFile } from "@convex-dev/agent";

// Step 1: Save message with file
export const submitFileQuestion = mutation({
  args: { threadId: v.string(), fileId: v.string(), question: v.string() },
  handler: async (ctx, { threadId, fileId, question }) => {
    const { imagePart, filePart } = await getFile(ctx, components.agent, fileId);

    const { messageId } = await saveMessage(ctx, components.agent, {
      threadId,
      message: {
        role: "user",
        content: [
          imagePart ?? filePart,
          { type: "text", text: question },
        ],
      },
      metadata: { fileIds: [fileId] },
    });

    return { messageId };
  },
});

// Step 2: Generate response
export const generateFileResponse = action({
  args: { threadId: v.string(), promptMessageId: v.string() },
  handler: async (ctx, { threadId, promptMessageId }) => {
    const { thread } = await myAgent.continueThread(ctx, { threadId });
    await thread.generateText({ promptMessageId });
  },
});

Inline File Saving (Action Only)

Pass file directly in generation:

export const analyzeImageInline = action({
  args: { threadId: v.string(), imageData: v.string(), question: v.string() },
  handler: async (ctx, { threadId, imageData, question }) => {
    const { thread } = await myAgent.continueThread(ctx, { threadId });

    await thread.generateText({
      message: {
        role: "user",
        content: [
          {
            type: "image",
            image: Buffer.from(imageData, "base64"),
            mimeType: "image/png",
          },
          { type: "text", text: question },
        ],
      },
    });
  },
});

Generate and Save Images

export const generateAndSaveImage = action({
  args: { threadId: v.string(), prompt: v.string() },
  handler: async (ctx, { threadId, prompt }) => {
    const { image } = await generateImage({
      model: openai.image("dall-e-2"),
      prompt,
    });

    const { file } = await storeFile(ctx, components.agent, image, {
      filename: `generated-${Date.now()}.png`,
    });

    return { fileId: file.fileId };
  },
});

Key Principles

• Automatic storage: Files > 64KB stored automatically
• File tracking: Metadata tracks which messages reference files
• URL generation: Signed URLs prevent unauthorized access
• MIME type inference: Auto-detected if not provided
• Cleanup: Files tracked for garbage collection

Next Steps

• See messages for message management
• See streaming for streamed file processing
• See fundamentals for agent setup