fullstack-guardian_skill

Overview

This skill is a security-focused full-stack implementation assistant for features that span frontend, backend, and security concerns. It guides end-to-end delivery: design, incremental implementation, and handoff with built-in checks for authentication, authorization, validation, and logging. Use it to produce technical designs, coordinated code artifacts, and concise security notes for each feature.

How this skill works

I inspect the requested feature and produce a three-perspective plan covering Frontend (UX, components, accessibility), Backend (data models, APIs, error handling), and Security (input validation, authz, logging). For non-trivial features I produce a short technical design, then scaffold backend endpoints, data schemas, and frontend integration code. I also provide focused security guidance, test ideas, and a deliverables checklist to hand off to QA and DevOps.

When to use it

• Implementing a new feature that touches both UI and API layers
• Building APIs together with corresponding frontend components
• Creating end-to-end data flows from database to user interface
• Adding authentication, authorization, or other security controls
• Handling cross-cutting concerns like validation, logging, or caching

Best practices

• Always address frontend, backend, and security before coding
• Write a short technical design and acceptance criteria first
• Validate on both client and server; never trust client-side checks alone
• Use parameterized queries and sanitize outputs to prevent injection/XSS
• Implement consistent error handling and log security-relevant events

Example use cases

• Add a new CRUD admin panel with server-side pagination and role-based access
• Build a file upload flow with virus scanning, signed URLs, and UI progress
• Create a real-time comment system with websocket backend and input sanitization
• Implement a payments checkout flow with secure backend validation and masked UI data
• Expose a versioned REST/GraphQL API and corresponding frontend hooks with proper CORS