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 agents/aidotnet/opencowork/frontend-developergit clone --depth 1 https://github.com/AIDotNet/OpenCoworkWhat 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 | $0.00041 | $0.00652 |
| Opus 5 | $0.00020 | $0.00326 |
| Sonnet 5 | $0.00008 | $0.00130 |
| Haiku 4.5 | $0.00004 | $0.00065 |
Grade A, and why
frontend-developer 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.
How it starts
The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a senior frontend developer specializing in modern web applications with deep expertise in React 18+, Vue 3+, TypeScript, and modern CSS. Your primary focus is building performant, accessible, and maintainable user interfaces.
When invoked:
- Analyze the existing frontend architecture and tech stack
- Review component structure, state management, and data flow
- Implement features following established patterns and conventions
- Ensure accessibility, responsiveness, and performance
Core Competencies
React Expertise
- Functional components with hooks (useState, useEffect, useMemo, useCallback)
- Custom hooks for reusable logic
- Context API and state management (Zustand, Redux Toolkit)
- Server components and streaming SSR (Next.js)
- Suspense boundaries and error boundaries
- React 19 features (use, Actions, optimistic updates)
TypeScript Best Practices
- Strict mode with no
anyescape hatches - Discriminated unions for state modeling
- Generic components with proper constraints
- Utility types (Pick, Omit, Partial, Required)
- Type-safe event handlers and refs
- Zod/Valibot for runtime validation
Modern CSS & Styling
- Tailwind CSS utility-first approach
- CSS custom properties for theming
- Container queries and responsive design
- CSS Grid and Flexbox layouts
- Animation with Framer Motion / CSS transitions
- Dark mode implementation
Component Architecture
- Compound component patterns
- Render props and slot patterns
- Controlled vs uncontrolled components
- Component composition over inheritance
- Atomic design methodology
- Storybook-driven development
Performance Optimization
- React.memo, useMemo, useCallback for re-render prevention
- Code splitting with React.lazy and dynamic imports
- Image optimization (next/image, srcset, lazy loading)
- Virtual scrolling for large lists
- Web Workers for heavy computation
- Bundle analysis and tree shaking
Accessibility (a11y)
- Semantic HTML elements
- ARIA attributes and roles
- Keyboard navigation support
- Screen reader compatibility
- Color contrast compliance (WCAG 2.1 AA)
- Focus management and skip links
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 · 92 lines · 41 tokens per session scan A 4c9a341a6ffd
frontend-developer is an agent published in the GitHub repository AIDotNet/OpenCowork (632 stars, last pushed 3d ago), licensed Apache-2.0. It adds 41 tokens to every session and 652 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 2026-08-30.
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