create-prototype

A guided workflow for creating a working browser-based prototype for a feature, using simulated APIs instead of a live backend. It runs after the feature specification is written and before people review the prototype.

In plain words
What is it for?
Use it to create interactive prototypes for features with user-interface changes. It reads the project's configuration, specification, and feature manifest to determine what to build and where to put it.
Why use it?
It turns a written feature request into something people can click through and evaluate before full implementation. This helps reveal problems in the proposed user interface early.

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/markmhendrickson/neotoma/create-prototype
Any agent
npx skills add markmhendrickson/neotoma --skill create-prototype
Clone the repo
git clone --depth 1 https://github.com/markmhendrickson/neotoma

Made for: Claude Code, Codex.

Per session 6 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 722 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 $0.00006 $0.00722
Opus 5 $0.00003 $0.00361
Sonnet 5 $0.00001 $0.00144
Haiku 4.5 $0.00001 $0.00072

Measured 2d ago against content hash cb3f1f895a93, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

create-prototype 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.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

.claude/skills/create-prototype/SKILL.md · 99 lines

How it starts

The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.


name: create-prototype description: Create prototype per foundation command. triggers:

  • create prototype
  • /create_prototype
  • create-prototype

Create Prototype

Create fully functional client-side prototype for Feature Unit {{input:feature_id}}.

Follow foundation/development/feature_unit_workflow.md Step 1 (Prototype Creation). Configuration is read from foundation-config.yaml.

This happens after Checkpoint 0 (spec creation) and before Checkpoint 1 (prototype review).

Implements prototype creation after Checkpoint 0 (spec) is complete. Creates a fully interactive, client-side prototype with mocked APIs.

Trigger

  • Spec created with UI requirements (Checkpoint 0 complete, UI changes present) OR
  • No UI changes required (skip prototype)

Tasks

  1. Load configuration:

    • Read foundation-config.yaml to get feature unit settings
    • Determine directory structure and prototype paths
  2. Load spec and manifest:

    • {configured_directory}/in_progress/{{input:feature_id}}/{{input:feature_id}}_spec.md (or completed/ if completed)
    • {configured_directory}/in_progress/{{input:feature_id}}/manifest.yaml (or completed/ if completed)
  3. Check if UI changes present:

    • Review spec and manifest for UI components
    • Verify UX Requirements section exists in spec (from Checkpoint 0)
    • If no UI changes → skip to implementation
    • If UI changes present → proceed
  4. Create prototype:

    • Use configured prototype directory structure (or default: frontend/src/prototype/)
    • Create prototype component(s): {prototype_dir}/components/{{input:feature_id}}_*.tsx
    • Create mock API fixtures: {prototype_dir}/fixtures/{{input:feature_id}}_*.ts
    • Integrate into prototype main file
  5. Prototype requirements:

    • Fully interactive (click, type, navigate)
    • All API calls mocked (no real backend)
    • All UI states testable (empty, error, loading, success)
    • Accessible (keyboard nav, ARIA if applicable)
    • Uses existing design system components (if available)
    • Documented mock API responses

Read the full file on GitHub · 99 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. 2d ago First seen · 99 lines · 6 tokens per session scan A cb3f1f895a93

Subscribe to this mod's changes

create-prototype is a skill published in the GitHub repository markmhendrickson/neotoma (29 stars, last pushed 5d ago), licensed MIT. It adds 6 tokens to every session and 722 once invoked, about $0.0000 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 2026-08-30.