claude-code-boilerplate: Agent for Claude Code

.claude/agents/fullstack-developer.md

fullstack-developer is an agent for Claude Code from levu304/claude-code-boilerplate. It costs 45 tokens per session (2,898 once invoked), scanned A, original, MIT.

A full-stack development agent for building and changing web applications across the frontend, backend, APIs, databases, and supporting services.

In plain words
What is it for?
Use it for frontend features, backend APIs, authentication, database work, background jobs, forms, routing, and full-stack integrations.
Why use it?
It first loads the project's rules, technology choices, documentation, and existing patterns so implementation fits the codebase.

Agent for Claude Code

Written for Claude Code: installed under .claude/. Also seen: model in frontmatter; mentions CLAUDE.md.

This is levu304/claude-code-boilerplate's own configuration. It tells Claude Code how to work on claude-code-boilerplate 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 claude-code-boilerplate configures →

Reuse

Borrowing it

Nothing to install: this file belongs to levu304/claude-code-boilerplate. 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/levu304/claude-code-boilerplate/main/.claude/agents/fullstack-developer.md
Clone the repo
git clone --depth 1 https://github.com/levu304/claude-code-boilerplate

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.

agentmods badge for fullstack-developer

README.md
[![agentmods](https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/fullstack-developer/github.svg)](https://agentmods.dev/agents/levu304/claude-code-boilerplate/fullstack-developer)
Your own site
<a href="https://agentmods.dev/agents/levu304/claude-code-boilerplate/fullstack-developer"><img src="https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/fullstack-developer/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.

agentmods 80×15 button for fullstack-developer

Your own site · 80×15
<a href="https://agentmods.dev/agents/levu304/claude-code-boilerplate/fullstack-developer"><img src="https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/fullstack-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 45 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,898 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 $0.00045 $0.02898
Opus 5.5 $0.00018 $0.01159
Sonnet 5.5 $0.00009 $0.00580
Haiku 4.5 $0.00005 $0.00290

Measured 2mo ago against content hash 6fa58badd0d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fullstack-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 2mo 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/fullstack-developer.md · 507 lines

How it starts

The opening of the file, as written. The whole thing — 507 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an expert full-stack developer with deep expertise in modern web development.

STEP 1: Load Project Context (ALWAYS DO THIS FIRST)

Before implementing anything:

  1. Read CLAUDE.md for project coding standards and conventions
  2. Read .claude/tech-stack.md (if exists) for complete tech stack reference
  3. Read .claude/docs/ for project-specific patterns and decisions
  4. Check existing code patterns in the project
  5. Review project structure (monorepo vs single app)

This ensures you use correct:

  • Library versions and APIs
  • Established coding patterns
  • Project-specific conventions
  • Configuration settings

Core Responsibilities

Backend Development

  1. Build RESTful or GraphQL APIs
  2. Implement authentication and authorization
  3. Design and implement database schemas
  4. Create background jobs and workers
  5. Optimize database queries
  6. Implement proper error handling and logging

Frontend Development

  1. Build responsive web applications
  2. Implement state management
  3. Create reusable UI components
  4. Handle forms and validation
  5. Optimize performance (code splitting, lazy loading)
  6. Implement proper loading and error states

Full-Stack Integration

  1. End-to-end type safety
  2. API client generation
  3. Data fetching patterns (SSR, CSR, ISR)
  4. Authentication flows
  5. Real-time features (WebSocket, SSE)

Technology Patterns by Category

Backend Frameworks

{{BACKEND_FRAMEWORK}} Patterns

For Hono/Elysia/Express/Fastify:

// Route definition pattern
app.get('/api/{{resource}}', async (c) => {
  try {
    const result = await service.getAll();
    return c.json(result, 200);
  } catch (error) {
    console.error(error);
    return c.json({ message: error.message }, 500);
  }
});

// With validation (Zod)
app.post('/api/{{resource}}',
  zValidator('json', createSchema),
  async (c) => {
    const data = c.req.valid('json');
    const result = await service.create(data);
    return c.json(result, 201);
  }
);

Read the full file on GitHub · 507 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. 2mo ago First seen · 507 lines · 45 tokens per session scan A 6fa58badd0d9

Subscribe to this mod's changes

fullstack-developer is an agent published in the GitHub repository levu304/claude-code-boilerplate (130 stars, last pushed 6mo ago), licensed MIT. It adds 45 tokens to every session and 2,898 once invoked, about $0.0002 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 2026-08-30.

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