File Uploads Agent Skill
Presigned URL uploads, multipart for large files, S3/R2/Supabase Storage.
The Skill
Full content, every format. Copy it, download it, or install with one command.
---
description: Presigned URL uploads, multipart for large files, S3/R2/Supabase Storage.
homepage: https://yepapi.com/skills/file-uploads
metadata:
tags: [uploads, files, s3, presigned-urls]
---
# File Uploads
## Rules
- Presigned URLs for direct-to-storage uploads — don't proxy through your server
- Multipart upload for files > 5MB — chunk into parts, upload in parallel
- Client-side validation: file type, file size limits — server validates again
- Image optimization: resize on upload (max 2048px), convert to WebP, strip EXIF
- Progress tracking: `XMLHttpRequest` or `fetch` with `ReadableStream` for upload progress
- Storage: S3, R2 (Cloudflare), or Supabase Storage — presigned URL pattern is the same
- File type validation server-side: check magic bytes, not just file extension
- Virus scanning for user uploads in high-security contextsInstall
Why Use the File Uploads Skill?
Without this skill, your AI guesses at file uploads patterns. It might hallucinate deprecated APIs, use outdated conventions, or miss best practices entirely. With it, your AI follows a proven ruleset — every suggestion aligns with current standards.
Drop this skill into your project and your AI instantly knows the rules. Better code suggestions, fewer errors, faster shipping.
Try These Prompts
These prompts work better with the File Uploads skill installed. Your AI knows the context and writes code that fits.
"Build a file upload system with presigned URLs, progress tracking, and S3 storage"
"Create a multi-file uploader with drag-and-drop, image preview, and size validation"
"Set up secure file uploads with virus scanning, type validation, and CDN delivery"
Works Great With
File Uploads skill — FAQ
It covers presigned URL uploads, multipart handling for large files, and S3/R2/Supabase Storage integration. Your AI builds secure, scalable file upload systems with proper validation.
Run `npx skills add YepAPI/skills --skill file-uploads` in your project root. This copies the skill file into your repo where your AI coding tool can read it automatically.
Use presigned URLs for direct-to-S3 uploads. This avoids server memory issues with large files and reduces latency. The skill includes patterns for generating presigned URLs and verifying uploads.