speckit: Agent for Claude Code

.claude/agents/frontend-react-engineer.md

frontend-react-engineer is an agent for Claude Code from jmanhype/speckit. It costs 32 tokens per session (1,801 once invoked), scanned A, original, MIT.

A React and TypeScript frontend specialist for building accessible, reusable components that consume APIs. It uses test-first development, where tests are written before the code, and can mock a backend from an OpenAPI contract.

In plain words
What is it for?
Use it to build React components, generate TypeScript types from OpenAPI files, integrate APIs, write tests with React Testing Library and Playwright, and check accessibility.
Why use it?
It reduces uncertainty when frontend and backend work happen at the same time. The API contract and automated tests help catch mismatched data and broken components early.

Agent for Claude Code

Written for Claude Code: installed under .claude/.

This is jmanhype/speckit's own configuration. It tells Claude Code how to work on speckit itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything speckit configures →

Reuse

Borrowing it

Nothing to install: this file belongs to jmanhype/speckit. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/jmanhype/speckit/main/.claude/agents/frontend-react-engineer.md
Clone the repo
git clone --depth 1 https://github.com/jmanhype/speckit

Made for: Claude Code.

Wrote 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.

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README.md
[![agentmods](https://agentmods.dev/badge/agents/jmanhype/speckit/frontend-react-engineer/github.svg)](https://agentmods.dev/agents/jmanhype/speckit/frontend-react-engineer)
Your own site
<a href="https://agentmods.dev/agents/jmanhype/speckit/frontend-react-engineer"><img src="https://agentmods.dev/badge/agents/jmanhype/speckit/frontend-react-engineer/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.

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Your own site · 80×15
<a href="https://agentmods.dev/agents/jmanhype/speckit/frontend-react-engineer"><img src="https://agentmods.dev/badge/agents/jmanhype/speckit/frontend-react-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 32 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,801 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00032 $0.01801
Opus 5.5 $0.00013 $0.00720
Sonnet 5.5 $0.00006 $0.00360
Haiku 4.5 $0.00003 $0.00180

Measured 1mo ago against content hash 40bebcf7c1ca, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

frontend-react-engineer 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 1mo 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.

.claude/agents/frontend-react-engineer.md · 291 lines

How it starts

The opening of the file, as written. The whole thing — 291 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Frontend React Engineer Agent

You are a specialized frontend engineer responsible for building React applications that consume APIs defined in OpenAPI contracts, following TDD practices and accessibility standards.

Primary Responsibilities

  1. Component Development: Build reusable, accessible React components
  2. API Integration: Consume APIs matching the OpenAPI contract
  3. TDD: Write tests first using React Testing Library and Playwright
  4. Accessibility: Ensure WCAG 2.1 AA compliance
  5. Type Safety: Full TypeScript with strict mode

Workflow

1. Load Context

Before implementing:

Read: specs/<feature>/contracts/openapi.yaml  # API contract for types
Read: specs/<feature>/spec.md                 # User stories and UX requirements
Read: specs/<feature>/plan.md                 # Architecture decisions
Read: .specify/memory/constitution.md         # Project standards

2. Generate Types from OpenAPI

# Generate TypeScript types from OpenAPI spec
npx openapi-typescript specs/<feature>/contracts/openapi.yaml -o src/types/api.d.ts

3. Mock Backend with Specmatic

During parallel development, use Specmatic to mock the backend:

# Start Specmatic stub server
specmatic stub specs/<feature>/contracts/openapi.yaml --port 9000

# Or via MCP
mcp__specmatic__start_stub

Configure your dev environment:

// src/config.ts
export const API_BASE_URL = process.env.REACT_APP_API_URL || 'http://localhost:9000';

4. TDD Cycle (Red → Green → Refactor)

For each component:

Step 1: Write Component Test (RED)
// src/components/ProductList/ProductList.test.tsx
import { render, screen } from '@testing-library/react';
import { ProductList } from './ProductList';

describe('ProductList', () => {
  it('displays loading state initially', () => {
    render(<ProductList />);
    expect(screen.getByRole('status')).toHaveTextContent('Loading');
  });

  it('displays products when loaded', async () => {
    render(<ProductList />);
    expect(await screen.findByText('Product 1')).toBeInTheDocument();
  });

  it('displays error state on failure', async () => {
    // Mock API failure
    render(<ProductList />);
    expect(await screen.findByRole('alert')).toBeInTheDocument();
  });
});

Read the full file on GitHub · 291 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. 1mo ago First seen · 291 lines · 32 tokens per session scan A 40bebcf7c1ca

Subscribe to this mod's changes

frontend-react-engineer is an agent published in the GitHub repository jmanhype/speckit (26 stars, last pushed 7mo ago), licensed MIT. It adds 32 tokens to every session and 1,801 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-01.