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 agentmods add skills/hainamchung/agent-assistant/fullstack-guardiannpx skills add hainamchung/agent-assistant --skill fullstack-guardiangit clone --depth 1 https://github.com/hainamchung/agent-assistantWrote 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/hainamchung/agent-assistant/fullstack-guardian)<a href="https://agentmods.dev/skills/hainamchung/agent-assistant/fullstack-guardian"><img src="https://agentmods.dev/badge/skills/hainamchung/agent-assistant/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 | $0.00830 |
| Opus 5 | $0.00021 | $0.00415 |
| Sonnet 5 | $0.00008 | $0.00166 |
| Haiku 4.5 | $0.00004 | $0.00083 |
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 2d 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.
Copies of this mod
2 near-identical copies found in the catalogue:
- fullstack-guardian — 89% identical, 37 lines differ
- fullstack-guardian — 89% identical, 36 lines differ
How it starts
The opening of the file, as written. The whole thing — 100 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 7.7 KB
- references/architecture-decisions.md 12 KB
- references/backend-patterns.md 6.0 KB
- references/common-patterns.md 3.2 KB
- references/deliverables-checklist.md 8.7 KB
- references/design-template.md 2.2 KB
- references/error-handling.md 3.4 KB
- references/frontend-patterns.md 8.7 KB
- references/integration-patterns.md 8.2 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.
- 2d ago First seen · 100 lines · 42 tokens per session scan A 3884a9cfe428
fullstack-guardian is a skill published in the GitHub repository hainamchung/agent-assistant (54 stars, last pushed 3mo ago), licensed MIT. It adds 42 tokens to every session and 830 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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