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.
npx skills add zacklecon/claude-skills --skill fullstack-guardiangit clone --depth 1 https://github.com/zacklecon/claude-skillsWrote 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.
[](https://agentmods.dev/skills/zacklecon/claude-skills/fullstack-guardian)<a href="https://agentmods.dev/skills/zacklecon/claude-skills/fullstack-guardian"><img src="https://agentmods.dev/badge/skills/zacklecon/claude-skills/fullstack-guardian.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.00812 |
| Opus 5 | $0.00021 | $0.00406 |
| Sonnet 5 | $0.00008 | $0.00162 |
| Haiku 4.5 | $0.00004 | $0.00081 |
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 8d 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.
This is a copy
89% identical to fullstack-guardian — 36 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.
How it starts
The opening of the file, as written. The whole thing — 84 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
- Gather requirements - Understand feature scope and acceptance criteria
- Design solution - Consider all three perspectives (Frontend/Backend/Security)
- Write technical design - Document approach in
specs/{feature}_design.md - Implement - Build incrementally, testing as you go
- 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 |
What ships with it
10 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/api-design-standards.md 7.6 KB
- references/architecture-decisions.md 12 KB
- references/backend-patterns.md 5.9 KB
- references/common-patterns.md 3.1 KB
- references/deliverables-checklist.md 8.6 KB
- references/design-template.md 2.1 KB
- references/error-handling.md 3.3 KB
- references/frontend-patterns.md 8.6 KB
- references/integration-patterns.md 8.1 KB
- references/security-checklist.md 2.5 KB
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.
- 8d ago First seen · 84 lines · 42 tokens per session scan A 2ba680142dde
fullstack-guardian is a skill published in the GitHub repository zacklecon/claude-skills (3 stars, last pushed yesterday), licensed MIT. It adds 42 tokens to every session and 812 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 36 lines, and is treated as a copy.
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