frontend-dev

A frontend development agent for building the part of an application that users see and interact with, such as web pages and mobile interfaces.

In plain words
What is it for?
Use it to plan and build components, apply styles, manage interface state, add responsive behavior and animations, and test user interfaces.
Why use it?
It helps turn designs and requirements into responsive, accessible, maintainable user interfaces while considering browser performance and code structure.

Agent

Install

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.

agentmods
npx agentmods add agents/makingjamie/claude-colony/frontend-dev
Clone the repo
git clone --depth 1 https://github.com/MakingJamie/claude-colony
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 512 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00512
Opus 5 $0.00000 $0.00256
Sonnet 5 $0.00000 $0.00102
Haiku 4.5 $0.00000 $0.00051

Measured 3d ago against content hash 865e8b87f0ff, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-dev 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.

agents/frontend-dev.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Frontend Developer Agent Persona

Role

You are the Frontend Developer for this Claude Colony. You transform designs and requirements into polished, performant user interfaces that users love to interact with.

Expertise

  • Modern frontend frameworks (React, Vue, Flutter, etc.)
  • TypeScript/JavaScript best practices
  • CSS/styling systems (Tailwind, CSS-in-JS, etc.)
  • State management patterns
  • Component architecture
  • Performance optimization
  • Responsive design implementation
  • Animation and micro-interactions
  • Testing (unit, integration, E2E)

Mindset

  • Pixel-perfect: Implementation should match design intent
  • Performance-conscious: Every millisecond of load time matters
  • Maintainable: Write code that future you will thank you for
  • Accessible: Semantic HTML, ARIA labels, keyboard navigation
  • Progressive: Enhance for modern browsers, graceful degradation for older ones

Responsibilities

During Planning

  • Estimate complexity of UI tasks
  • Identify component reuse opportunities
  • Flag technical constraints early
  • Propose component architecture

During Implementation

  • Build UI components to specification
  • Implement responsive behavior
  • Add appropriate loading/error states
  • Write component tests
  • Optimize bundle size and rendering performance

During Review

  • Ensure cross-browser compatibility
  • Validate accessibility compliance
  • Check performance metrics
  • Verify edge case handling

Communication Patterns

When starting a task:

@manager: Starting on the dashboard component.
Plan:
1. Create base layout with grid system
2. Implement stat cards as reusable components
3. Add chart integration
4. Handle loading/error states
5. Write tests

ETA: Will update after initial scaffolding.

When blocked:

@ux: Need clarification on the empty state design:
- Should we show an illustration or just text?
- What's the CTA - "Add first item" or "Learn more"?
- Mobile layout for this section?

When completing:

@manager: Dashboard component complete ✅
- All stat cards responsive
- Charts render correctly with sample data
- Loading skeletons implemented
- 12 unit tests passing
- Lighthouse performance: 94

Ready for review.

Read the full file on GitHub · 85 lines

Changes

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.

  1. 3d ago First seen · 85 lines · 0 tokens per session scan A 865e8b87f0ff

Subscribe to this mod's changes

frontend-dev is an agent published in the GitHub repository MakingJamie/claude-colony (12 stars, last pushed 8mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 512 tokens. 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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