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 vignesh2027/AI-AGENT-SKILLS --skill frontend-engineeringgit clone --depth 1 https://github.com/vignesh2027/AI-AGENT-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/vignesh2027/ai-agent-skills/frontend-engineering)<a href="https://agentmods.dev/skills/vignesh2027/ai-agent-skills/frontend-engineering"><img src="https://agentmods.dev/badge/skills/vignesh2027/ai-agent-skills/frontend-engineering/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/vignesh2027/ai-agent-skills/frontend-engineering"><img src="https://agentmods.dev/badge/skills/vignesh2027/ai-agent-skills/frontend-engineering.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00018 | $0.00506 |
| Opus 5 | $0.00009 | $0.00253 |
| Sonnet 5 | $0.00004 | $0.00101 |
| Haiku 4.5 | $0.00002 | $0.00051 |
Grade A, and why
frontend-engineering 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Overview
Frontend engineering is full-stack engineering from the network edge to the pixel. Performance, accessibility, maintainability, and security are all first-class concerns — not features to add later.
When to Use
- Before implementing a new UI feature
- Before a frontend component is marked complete
- As part of the
/reviewworkflow for frontend PRs
Process
Step 1: Define the UI states
Every component has states: loading, empty, error, populated, and edge cases. Define and implement all of them before calling it done.
Step 2: Accessibility first
See accessibility-engineering skill. Apply before visual polish.
Step 3: Performance budget
Define before building:
- Largest Contentful Paint (LCP) target: < 2.5s
- Cumulative Layout Shift (CLS) target: < 0.1
- First Input Delay (FID) / INP target: < 200ms
- Bundle size budget for new routes
Measure with Lighthouse on a representative device.
Step 4: Component design
- Components are pure functions of their props/state
- No side effects in render
- Extract business logic from UI components
- Co-locate styles with components
Step 5: State management
Prefer: local state → lifted state → context → global store (in that order). Only reach for global state when local state genuinely doesn't work.
Step 6: Error boundaries
Wrap sections of the UI in error boundaries. A crash in one section should not take down the whole page.
Step 7: Testing
- Unit test business logic extracted from components
- Component tests for component behavior (not implementation)
- E2E tests for critical user journeys
Step 8: Security
- Sanitize all user-generated HTML rendered to the DOM
- No dangerouslySetInnerHTML or equivalent without sanitization
- Content Security Policy headers configured
Verification Requirements
- All UI states implemented (loading, empty, error, populated)
- Accessibility requirements met (see accessibility-engineering)
- Lighthouse performance score ≥ 90
- Error boundaries in place
- Critical journeys covered by E2E tests
- No XSS vulnerabilities in dynamic HTML rendering
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.
- 9d ago First seen · 65 lines · 18 tokens per session scan A 865c2b48064d
frontend-engineering is a skill published in the GitHub repository vignesh2027/AI-AGENT-SKILLS (2 stars, last pushed 11d ago), licensed MIT. It adds 18 tokens to every session and 506 once invoked, about $0.0001 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 2026-08-31.
Other skills, from other repositories
visual-regression-tester
Use when the user asks to detect, review, prevent, or update visual regressions in a web, desktop, or mobile interface. Capture comparable rendered states, control viewport and data variance, inspect image differences, and distinguish intended design changes from rendering defects.
create-pi-web-extension
Como criar/extender extensões web no pi com arquitetura determinística, segurança mínima e testes automatizados (smoke + e2e via pi-test-harness).
react-web
React web development with hooks, React Query, Zustand.
app-user-story-qa
End-to-end app feature inventory and user-story testing workflow with a canonical tracker. Use when the user asks to audit every feature, derive expected behavior from code, test user journeys, or explicitly fix and retest documented UX or logistical defects.
ui-aqa-flow
Workflow for automated QA: integration and end-to-end UI test automation, page objects, etc.
ring:checking-frontend-quality
Checking frontend quality against changed UI via ring:qa-frontend in accessibility, visual, e2e, or performance mode and aggregating pass/fail verdicts. Use when a frontend change needs standalone a11y, visual-snapshot, Playwright e2e, or Lighthouse/Core-Web-Vitals validation outside the dev cycle. Skip for…