skill

file-uploads — Claude Code skill: file uploads and cloud storage

Q: How do I install file-uploads in Claude Code?

Run `npx claude-code-templates@latest --skill security/file-uploads`. The skill ends up at `~/.claude/skills/file-uploads/SKILL.md`.

A Claude skill that guides the agent through file uploads and cloud storage: S3, Cloudflare R2, presigned URLs, multipart transfers and image optimization.

Install into Claude Code · claude-code-templates All methods and platforms ↓

npx claude-code-templates@latest --skill security/file-uploads

Open on GitHub

What file-uploads does

The skill puts the agent in the role of a file upload specialist. It treats a client-supplied extension as untrustworthy and routes transfers through presigned URLs rather than a server proxy. Large uploads get their own handling so nothing else stalls.

What you get is a table of sharp edges, each with a severity level and a fix. Magic byte checks instead of trusting the declared type, size caps on incoming uploads, filename sanitizing against path traversal, and control over how presigned URLs are handed out. Two of those rows are marked critical. Skip the magic byte check and a renamed file sails right through.

Install it in Claude with npx claude-code-templates@latest --skill security/file-uploads. The skill file lands at ~/.claude/skills/file-uploads/SKILL.md.

What it helps with

accept a large file without stalling the server
hand a file straight to S3 or R2 with a presigned URL
verify the real file type instead of the extension
cap the size of an incoming upload
block path traversal in a user-supplied filename

Example prompts for the agent

Set up avatar uploads to Cloudflare R2 with a presigned URL
Split a video upload into multipart chunks
Check magic bytes on the uploaded file and reject a spoofed type

How to install file-uploads

1claude-code-templates

npx claude-code-templates@latest --skill security/file-uploads

2Skills CLI (Vercel)

npx skills add davila7/claude-code-templates --skill file-uploads -a claude-code

3Manually: put the files in place

~/.claude/skills/file-uploads/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/file-uploads/

Manually: put the files in place

.agents/skills/file-uploads/SKILL.md

For all projects use ~/.agents/skills/

Manually: put the files in place

.cursor/skills/file-uploads/SKILL.md

Cursor also reads .agents/skills/ and .claude/skills/

1GitHub CLI

gh skill install davila7/claude-code-templates file-uploads

2Manually: put the files in place

.github/skills/file-uploads/SKILL.md

Platform CLI

gemini skills install https://github.com/davila7/claude-code-templates --path cli-tool/components/skills/security/file-uploads

Manually: put the files in place

.devin/skills/file-uploads/SKILL.md

The legacy .windsurf/skills/ path still works

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about file-uploads

How do I install file-uploads in Claude Code?

Run npx claude-code-templates@latest --skill security/file-uploads. The skill ends up at ~/.claude/skills/file-uploads/SKILL.md.

What does file-uploads do?

It tells the agent how to build file uploads and cloud storage: presigned URLs, multipart for big files, image optimization. Security gets its own section — type checks, size limits, filename cleanup.

Which upload mistakes does the skill call critical?

Trusting the file type sent by the client, and letting the user control the filename. The first is fixed with a magic byte check, the second with sanitizing — otherwise path traversal is on the table.

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