greenfield-project-builder

A planning guide for starting a new frontend application from a product idea. It defines the intended technology, project shape, approval points, and first small working feature before files are created.

In plain words
What is it for?
Use it to plan a new frontend app, choose its technology, define its first vertical slice—a small end-to-end piece of functionality—and prepare onboarding.
Why use it?
It turns a broad idea into an agreed implementation path without unexpectedly scaffolding the project, installing packages, or adding code.

Skill for Claude CodeCodex

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 skills/ytvee-dev/webdev-agent-kit/greenfield-project-builder
Any agent
npx skills add ytvee-dev/webdev-agent-kit --skill greenfield-project-builder
Clone the repo
git clone --depth 1 https://github.com/ytvee-dev/webdev-agent-kit

Made for: Claude Code, Codex.

Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,953 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 $0.00048 $0.01953
Opus 5 $0.00024 $0.00977
Sonnet 5 $0.00010 $0.00391
Haiku 4.5 $0.00005 $0.00195

Measured 2d ago against content hash 7351cff3009c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

greenfield-project-builder 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 2d 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.

skills/greenfield-project-builder/SKILL.md · 226 lines

How it starts

The opening of the file, as written. The whole thing — 226 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Greenfield Project Builder

Purpose

Plan and execute the first safe steps of a new frontend project without turning a vague product idea into uncontrolled scaffolding.

This skill converts a product idea into a minimal frontend project plan, explicit stack assumptions, approval gates, first vertical slice, and onboarding handoff. It must not scaffold, install packages, or create application files unless the user explicitly approves the exact action.

When To Use

Use this skill only for Deep Workflow tasks.

Use this skill when the user asks to:

  • start a new frontend project;
  • plan a new frontend app from a product idea;
  • create a project structure before scaffolding;
  • define the first vertical slice of a new app;
  • choose an intended frontend stack before project creation;
  • prepare onboarding overlays for an empty or new project;
  • turn a broad product concept into a small frontend implementation path.

When Not To Use

Do not use this skill for:

  • existing-project bugfixes;
  • one route or component in an existing project;
  • purely visual redesign of an existing screen;
  • refactoring existing code;
  • UI component library setup;
  • testing workflows;
  • backend, database, ORM, migrations, infrastructure, or production systems;
  • package installation by default;
  • automatic scaffolding without approval.

Do not use this skill when frontend-architecture-planner is enough for an existing project.

Required Context

  1. Read AGENTS.md.
  2. Read common/prompt-intent-routing-rules.md.
  3. Confirm the task is Deep Workflow.
  4. Read common/framework-adaptation-policy.md and common/build-tool-boundary-rules.md.
  5. Read the compact goal contract or project/active-goals.md when present.
  6. Read the compact execution plan or project/active-plan.md when present.
  7. Read existing project overlays only when this is a new app inside a larger existing workspace:
    • project/stack-profile.md;
    • project/architecture-map.md;
    • project/build-profile.md when present;
    • project/workspace-profile.md when present;
    • project/verification-profile.md when present.

Read the full file on GitHub · 226 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 226 lines · 48 tokens per session scan A 7351cff3009c

Subscribe to this mod's changes

greenfield-project-builder is a skill published in the GitHub repository ytvee-dev/webdev-agent-kit (5 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 48 tokens to every session and 1,953 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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