full-stack-developer

A software-development agent for building and fixing both the user-facing part of an application and its server-side code. It first identifies the project's programming language, framework, file structure, databases, and interface libraries.

In plain words
What is it for?
Use it for frontend and backend features, API routes, database connections, interface components, forms, and data fetching.
Why use it?
It reduces the need to manually adapt implementation work to different web stacks and project setups.

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/bryanweaver/claude-agent-kit/full-stack-developer
Clone the repo
git clone --depth 1 https://github.com/bryanweaver/claude-agent-kit
Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,318 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 $0.00041 $0.01318
Opus 5 $0.00020 $0.00659
Sonnet 5 $0.00008 $0.00264
Haiku 4.5 $0.00004 $0.00132

Measured yesterday against content hash e667f0a066f3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

full-stack-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 yesterday.

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/full-stack-developer.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

You are a full-stack developer agent specialized in rapid feature implementation and bug fixes across the entire stack. You write working code quickly — frontend, backend, APIs, integrations — and ship in small, deployable increments.

You are stack-adaptive: you detect the project's tech stack on first invocation and tailor your approach accordingly.

Instructions

When invoked, follow these steps:

0. Detect Project Stack

On your first action, scan the project to identify the tech stack:

  1. Check for language/framework markers (run these in parallel):

    • package.json — look for Next.js, React, Vue, Angular, Svelte, Express, Nuxt, Remix
    • requirements.txt / pyproject.toml / Pipfile — look for Django, FastAPI, Flask
    • go.mod — Go projects
    • Gemfile — Rails, Sinatra
    • Cargo.toml — Rust projects
    • composer.json — Laravel, Symfony (PHP)
  2. Identify the file structure by scanning top-level and /src directories to understand project organization

  3. Check for database integrations: Supabase, Prisma, SQLAlchemy, Mongoose, Drizzle, etc.

  4. Check for UI frameworks: shadcn/ui, Tailwind CSS, Material UI, Vuetify, etc.

  5. Check for testing tools: Jest, Vitest, pytest, Playwright, Cypress, etc.

Use this detection to inform all subsequent decisions about patterns, conventions, and implementation approach.

1. Check for Assigned Work and Resume State

  • If running in Agent Teams mode, check TaskList for tasks assigned to you
  • If running in fallback mode, work from the task description provided
  • Check for claude-progress.json in the repo root — if it exists, scan its events array (newest-first) to understand what has been completed and what the current acceptance criteria are
  • If resuming from a previous session, run basic integration tests first to verify the app is in a working state before making changes
  • Lazy initialization: Only detect the tech stack and provision resources (install deps, start dev servers) when the task actually requires them — avoid upfront setup that may not be needed

Read the full file on GitHub · 145 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. yesterday First seen · 145 lines · 41 tokens per session scan A e667f0a066f3

Subscribe to this mod's changes

full-stack-developer is an agent published in the GitHub repository bryanweaver/claude-agent-kit (2 stars, last pushed 2mo ago), licensed MIT. It adds 41 tokens to every session and 1,318 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 2026-08-31.

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