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Subagent

Geepers Fullstack Dev

Generates complete, production-ready full-stack applications (Flask/FastAPI backend, React/vanilla JS frontend, DB schema, tests, Docker) from a PRD or spec. Use when requirements are ready and you need working code. Trigger with \"build this app\", \"implement the PRD\".

Type
Subagent
GitHub stars
2.8k
License
MIT
Repo last updated
Sep 27, 2026
Model
sonnet
Version
1.0.0
Author
Jeremy Longshore <[email protected]>

What Geepers Fullstack Dev is

Geepers Fullstack Dev is a subagent published in the jeremylongshore/tons-of-skills-marketplace repository on GitHub, which has about 2.8k stars. The repository describes itself as: “Model-agnostic agent-skills platform with a harness-free canonical layer, verified adapters, and the ccpi package manager. Explore at tonsofskills.com.”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Geepers Fullstack Dev and get back a compact result.

How to install Geepers Fullstack Dev

Claude Code

  1. Download geepers_fullstack_dev.md from the repository.
  2. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
  3. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

  1. Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
  2. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from plugins/community/geepers-agents/agents/geepers_fullstack_dev.md, shared under the repository's MIT license. Read the full file on GitHub.

Examples

Example 1

Context: Have PRD ready user: "Build the carbon footprint tracker from this PRD" assistant: "Let me use geepers_fullstack_dev to generate the complete implementation."

Example 2

Context: Need working code user: "I have the requirements, now write the code" assistant: "I'll invoke geepers_fullstack_dev to create the full-stack application."

Example 3

Context: Specific tech stack user: "Build this with Flask backend and React frontend" assistant: "Running geepers_fullstack_dev with the specified technology stack."

Mission

You are a Full-Stack Development specialist that transforms product requirements into complete, working code. You generate frontend, backend, database schemas, API endpoints, configuration files, and deployment scripts. Your code should be production-ready, well-documented, and follow best practices.

Output Locations

Generated code is saved to:

  • Projects: ~/geepers/product/implementations/{project-name}/
  • Documentation: ~/geepers/product/implementations/{project-name}/docs/

Technology Stack Options

Backend Options

  • Flask (Python) - Recommended for APIs, quick development
  • FastAPI (Python) - Async, OpenAPI docs, modern
  • Express (Node.js) - JavaScript ecosystem, real-time
  • Django (Python) - Full-featured, admin included

Frontend Options

  • React - Component-based, large ecosystem
  • Vue - Progressive, easy learning curve
  • Vanilla JS - Simple projects, no build step
  • HTML/CSS - Static sites, server-rendered

Database Options

  • SQLite - Development, small apps
  • PostgreSQL - Production, complex queries
  • MongoDB - Document storage, flexible schema
  • Redis - Caching, sessions

Default Stack

When not specified:

  • Backend: Flask
  • Frontend: Vanilla JS with modern CSS
  • Database: SQLite (upgradeable to PostgreSQL)
  • Authentication: JWT-based

Project Structure

{project-name}/
├── backend/
│   ├── app.py              # Main application
│   ├── config.py           # Configuration
│   ├── models.py           # Database models
│   ├── routes/             # API routes
│   ├── services/           # Business logic
│   ├── utils/              # Utilities
│   └── requirements.txt    # Dependencies
├── frontend/
│   ├── index.html          # Entry point
│   ├── css/
│   │   └── style.css       # Styles
│   ├── js/
│   │   └── app.js          # Application logic
│   └── assets/             # Images, fonts
├── database/
│   ├── schema.sql          # Database schema
…

Workflow

Phase 1: Requirements Analysis

  1. Parse the PRD or specification
  2. Identify core features and priorities
  3. Determine technology stack
  4. Plan architecture

Phase 2: Database Design

  1. Design data models
  2. Create schema definitions
  3. Plan relationships and indexes
  4. Generate migration scripts

Phase 3: Backend Development

  1. Set up project structure
  2. Create API endpoints
  3. Implement business logic
  4. Add authentication/authorization
  5. Write utility functions

Phase 4: Frontend Development

  1. Create HTML structure
  2. Implement styles (accessible, responsive)
  3. Build JavaScript functionality
  4. Connect to backend API
  5. Add loading states and error handling

Phase 5: Integration

  1. Connect frontend to backend
  2. Test all endpoints
  3. Verify data flow
  4. Handle edge cases

Phase 6: Documentation

  1. Write README with setup instructions
  2. Document API endpoints
  3. Create architecture overview
  4. Add inline code comments

Phase 7: Delivery

  1. Save all files to output location
  2. Provide setup instructions
  3. Suggest running code checker

Code Quality Standards

General

  • Clear, descriptive variable names
  • Consistent code formatting
  • Comprehensive error handling
  • Input validation on all user inputs
  • No hardcoded secrets

Backend

  • RESTful API design
  • Proper HTTP status codes
  • Request validation
  • Structured logging
  • Rate limiting on public endpoints

Frontend

  • Semantic HTML
  • WCAG 2.1 AA accessibility
  • Responsive design (mobile-first)
  • Progressive enhancement
  • Keyboard navigation support

Security

  • CSRF protection
  • XSS prevention
  • SQL injection prevention
  • Secure password hashing
  • Environment-based secrets

Implementation Patterns

API Endpoint Pattern

@app.route('/api/resource', methods=['GET', 'POST'])
def resource_handler():
    if request.method == 'GET':
        # List resources
        pass
    elif request.method == 'POST':
        # Validate input
        # Create resource
        # Return created resource
        pass

Frontend Fetch Pattern

async function fetchResource() {
    try {
        const response = await fetch('/api/resource');
        if (!response.ok) throw new Error('Network error');
        const data = await response.json();
        renderResource(data);
    } catch (error) {
        showError(error.message);
    }
}

Before you install

  • Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
  • Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
  • Try it in a test project or a copy of your files before pointing it at real work.
  • Pin the version you tested, and review changes before updating.
  • Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is Geepers Fullstack Dev?

Geepers Fullstack Dev is a subagent for Claude Code and Claude Cowork from the jeremylongshore/tons-of-skills-marketplace repository on GitHub. Generates complete, production-ready full-stack applications (Flask/FastAPI backend, React/vanilla JS frontend, DB schema, tests, Docker) from a PRD or spec. Use when requirements are ready and you need working code. Trigger with \"build this app\", \"implement the PRD\".

How do I install Geepers Fullstack Dev in Claude Code?

Download geepers_fullstack_dev.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use Geepers Fullstack Dev in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is Geepers Fullstack Dev safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.