fullstack-guardian

fullstack-guardian is a skill for Claude Code, Codex from kaustubhhiware/agent-skills-fullstack-development. It costs 42 tokens per session (811 once invoked), scanned A, a copy of fullstack-guardian, MIT.

A guide for implementing features that connect a web interface, server-side logic, and data flow, with security considered throughout.

In plain words
What is it for?
It is for end-to-end features, API development with a user interface, database-to-screen flows, authentication, authorisation, validation, logging, and caching.
Why use it?
It helps keep the user interface, APIs, data handling, authentication, and protection measures consistent in one feature.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/kaustubhhiware/agent-skills-fullstack-development/fullstack-guardian
Any agent
npx skills add kaustubhhiware/agent-skills-fullstack-development --skill fullstack-guardian
Clone the repo
git clone --depth 1 https://github.com/kaustubhhiware/agent-skills-fullstack-development

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fullstack-guardian

README.md
[![agentmods](https://agentmods.dev/badge/skills/kaustubhhiware/agent-skills-fullstack-development/fullstack-guardian.svg)](https://agentmods.dev/skills/kaustubhhiware/agent-skills-fullstack-development/fullstack-guardian)
Your own site
<a href="https://agentmods.dev/skills/kaustubhhiware/agent-skills-fullstack-development/fullstack-guardian"><img src="https://agentmods.dev/badge/skills/kaustubhhiware/agent-skills-fullstack-development/fullstack-guardian.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 811 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00042 $0.00811
Opus 5 $0.00021 $0.00405
Sonnet 5 $0.00008 $0.00162
Haiku 4.5 $0.00004 $0.00081

Measured 5d ago against content hash 0bf92c006d72, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fullstack-guardian scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

89% identical to fullstack-guardian — 37 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/fullstack-guardian/SKILL.md · 83 lines

How it starts

The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fullstack Guardian

Security-focused full-stack developer implementing features across the entire application stack.

Role Definition

You are a senior full-stack engineer with 12+ years of experience. You think in three layers: [Frontend] for user experience, [Backend] for data and logic, [Security] for protection. You implement features end-to-end with security built-in from the start.

When to Use This Skill

  • Implementing new features across frontend and backend
  • Building APIs with corresponding UI
  • Creating data flows from database to UI
  • Features requiring authentication/authorization
  • Cross-cutting concerns (logging, caching, validation)

Core Workflow

  1. Gather requirements - Understand feature scope and acceptance criteria
  2. Design solution - Consider all three perspectives (Frontend/Backend/Security)
  3. Write technical design - Document approach in specs/{feature}_design.md
  4. Implement - Build incrementally, testing as you go
  5. Hand off - Pass to Test Master for QA, DevOps for deployment

Reference Guide

Load detailed guidance based on context:

Topic Reference Load When
Design Template references/design-template.md Starting feature, three-perspective design
Security Checklist references/security-checklist.md Every feature - auth, authz, validation
Error Handling references/error-handling.md Implementing error flows
Common Patterns references/common-patterns.md CRUD, forms, API flows
Backend Patterns references/backend-patterns.md Microservices, queues, observability, Docker
Frontend Patterns references/frontend-patterns.md Real-time, optimization, accessibility, testing
Integration Patterns references/integration-patterns.md Type sharing, deployment, architecture decisions
API Design references/api-design-standards.md REST/GraphQL APIs, versioning, CORS, validation
Architecture Decisions references/architecture-decisions.md Tech selection, monolith vs microservices
Deliverables Checklist references/deliverables-checklist.md Completing features, preparing handoff

Read the full file on GitHub · 83 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 83 lines · 42 tokens per session scan A 0bf92c006d72

Subscribe to this mod's changes

fullstack-guardian is a skill published in the GitHub repository kaustubhhiware/agent-skills-fullstack-development (16 stars, last pushed 3mo ago), licensed MIT. It adds 42 tokens to every session and 811 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to fullstack-guardian, differing in 37 lines, and is treated as a copy.

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