Agent-skills-standard nestjs-file-uploads

Validate and stream file uploads securely with Validation and S3 streaming in NestJS. Use when implementing secure file uploads, validation, or S3 streaming in NestJS. (triggers: **/*.controller.ts, FileInterceptor, Multer, S3, UploadedFile)

install

source · Clone the upstream repo

git clone https://github.com/HoangNguyen0403/agent-skills-standard

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/HoangNguyen0403/agent-skills-standard "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/nestjs/nestjs-file-uploads" ~/.claude/skills/hoangnguyen0403-agent-skills-standard-nestjs-file-uploads && rm -rf "$T"

manifest: skills/nestjs/nestjs-file-uploads/SKILL.md

source content

File Upload Patterns

Priority: P0 (FOUNDATIONAL)

Magic Bytes: NEVER trust
```
content-type
```
header or file extension.
Tool: Use
```
file-type
```
or
```
mmmagic
```
to verify actual buffer signature.
Limits: Set strict
```
limits: { fileSize: 5000000 }
```
(5MB) in Multer config to prevent DoS.

Streaming (Scalability)

Memory Warning: Default Multer
```
MemoryStorage
```
crashes servers with large files.
Pattern: Use Streaming for any file > 10MB.
Library:
```
multer-s3
```
(direct upload to bucket) or
```
busboy
```
(raw stream processing).
Architecture:

Client requests Signed URL from API.
Client uploads directly to S3/GCS (Bypassing API server completely).
Pro Tip: Only approach to scale file uploads infinitely.

Processing

Async: Don't process images/videos in HTTP Request.
Flow:

Upload file.
Push
```
FileUploadedEvent
```
to Queue (BullMQ).
Worker downloads, resizes/converts, and re-uploads.

Anti-Patterns

No content-type trust: Always verify file magic bytes; MIME header can spoofed.
No MemoryStorage for large files: Use streaming or signed URL pattern for files > 10MB.
No synchronous file processing: Offload image/video work to BullMQ workers via FileUploadedEvent.