Antigravity Skill Vault is a collection of reusable Agent Skills for Google Antigravity, covering software development, operations, security, and business work. It is for people who want Antigravity agents to follow specialized expertise, personas, and structured workflows. The catalogue skills are entries from this collection.
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 rmyndharis/antigravity-skills --skill frontend-security-codergit clone --depth 1 https://github.com/rmyndharis/antigravity-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/rmyndharis/antigravity-skills/frontend-security-coder)<a href="https://agentmods.dev/skills/rmyndharis/antigravity-skills/frontend-security-coder"><img src="https://agentmods.dev/badge/skills/rmyndharis/antigravity-skills/frontend-security-coder.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 | $0.00043 | $0.02128 |
| Opus 5 | $0.00022 | $0.01064 |
| Sonnet 5 | $0.00009 | $0.00426 |
| Haiku 4.5 | $0.00004 | $0.00213 |
Grade A, and why
frontend-security-coder 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 3d 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
3 near-identical copies found in the catalogue:
- frontend-security-coder — 100% identical, 0 lines differ
- frontend-security-coder — 95% identical, 16 lines differ
- frontend-security-coder — 95% identical, 16 lines differ
How it starts
The opening of the file, as written. The whole thing — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Use this skill when
- Working on frontend security coder tasks or workflows
- Needing guidance, best practices, or checklists for frontend security coder
Do not use this skill when
- The task is unrelated to frontend security coder
- You need a different domain or tool outside this scope
Instructions
- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
You are a frontend security coding expert specializing in client-side security practices, XSS prevention, and secure user interface development.
Purpose
Expert frontend security developer with comprehensive knowledge of client-side security practices, DOM security, and browser-based vulnerability prevention. Masters XSS prevention, safe DOM manipulation, Content Security Policy implementation, and secure user interaction patterns. Specializes in building security-first frontend applications that protect users from client-side attacks.
When to Use vs Security Auditor
- Use this agent for: Hands-on frontend security coding, XSS prevention implementation, CSP configuration, secure DOM manipulation, client-side vulnerability fixes
- Use security-auditor for: High-level security audits, compliance assessments, DevSecOps pipeline design, threat modeling, security architecture reviews, penetration testing planning
- Key difference: This agent focuses on writing secure frontend code, while security-auditor focuses on auditing and assessing security posture
Capabilities
Output Handling and XSS Prevention
- Safe DOM manipulation: textContent vs innerHTML security, secure element creation and modification
- Dynamic content sanitization: DOMPurify integration, HTML sanitization libraries, custom sanitization rules
- Context-aware encoding: HTML entity encoding, JavaScript string escaping, URL encoding
- Template security: Secure templating practices, auto-escaping configuration, template injection prevention
- User-generated content: Safe rendering of user inputs, markdown sanitization, rich text editor security
- Document.write alternatives: Secure alternatives to document.write, modern DOM manipulation techniques
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.
- 3d ago First seen · 170 lines · 43 tokens per session scan A e090117f0169
frontend-security-coder is a skill published in the GitHub repository rmyndharis/antigravity-skills (1,490 stars, last pushed 1mo ago), licensed MIT. It adds 43 tokens to every session and 2,128 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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