What is spectre-prototype?

A workflow for creating one self-contained HTML prototype to clarify an idea, test user flows, or preview an interface before planning or production coding.

Use it to create mockups from UX or scope documents, explore rough layouts, validate flows, and render documented screens and interactions.

It makes unclear screens and interactions easier to inspect early, when changes are cheaper and before a multi-file application is built.

spectre-prototype — Skill for Claude Code and Codex by joenandez

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.

Any agent

npx skills add joenandez/spectre --skill spectre-prototype

Clone the repo

git clone --depth 1 https://github.com/joenandez/spectre

Made for: Claude Code, Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/joenandez/spectre/spectre-prototype/github.svg)](https://agentmods.dev/skills/joenandez/spectre/spectre-prototype)

Your own site

<a href="https://agentmods.dev/skills/joenandez/spectre/spectre-prototype"><img src="https://agentmods.dev/badge/skills/joenandez/spectre/spectre-prototype/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/joenandez/spectre/spectre-prototype"><img src="https://agentmods.dev/badge/skills/joenandez/spectre/spectre-prototype.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,198 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. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00054	$0.01198
Opus 5.5	$0.00022	$0.00479
Sonnet 5.5	$0.00011	$0.00240
Haiku 4.5	$0.00005	$0.00120

Measured 1mo ago against content hash 584212179ca7, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

spectre-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 1mo 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.

plugins/spectre-codex/skills/spectre-prototype/SKILL.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

prototype

Purpose

Produce one HTML prototype at {FEATURE_ROOT}/prototypes/{slug}_{MMDDYY}.html. The primary owns it; agents provide evidence only.

Inputs

$ARGUMENTS: feature root/name or descendant, description, optional --explore; marker FROM_UX=true.
Read existing concepts/scope.md, specs/prd.md, ux.md, then legacy specs/ux.md fully before questions.
Silently read repo-root product.md when present, plus design.md or fallback design/design.md; apply them; do not mention missing files.

Mode	Signal	Fidelity	Contract
`post-ux`	complete `ux.md`: Screens, Layouts, Components, Interactions, States, Content	high	render faithfully; exact documented copy; no invented screens
`flows-only ux`	`FROM_UX=true` or flows without complete Stage 2	mid	preserve approved flows; choose UI details
`explore`	`--explore`	low, grayscale/layout-only	visualize an unvalidated concept
`post-scope`	scope, no UX	mid	validate scope
`standalone`	no artifact	mid	establish what to prototype

Working Set

Reuse a managed FEATURE_ROOT only when explicit/current-thread evidence ties it to this work (physical directory wins; never branch/recency/lifecycle/scans); distinct work ignores ambient roots. Otherwise, including on collision, standalone MUST first load and follow Skill(spectre-feature-root) through DONE; orchestrated calls escalate. Keep writes beneath it and pass it unchanged.
Repair stale feature/root metadata in artifacts this workflow touches.

Outputs + DONE

The single HTML file contains:

<!DOCTYPE html>, viewport metadata, inline CSS, and inline end-of-body JavaScript.
A top-of-head comment beginning Feature: and Feature Root:, followed by Fidelity, Generated, Flow covered, Screens/states, Visual anchor, Source spec, Key assumptions, post-UX Filled assumptions, NOT included, and Next step.
A design-token comment for Primary, Accent, Surface, Text, Font, Border-radius, Spacing, mirrored as :root custom properties.
If multi-screen, vanilla-JS display:block/none navigation; one ordered <section> per screen, each with happy path plus an empty, error, or loading state.

Read the full file on GitHub · 72 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.

agents/openai.yaml 43 B

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.

1mo ago Changed 584212179ca7
1mo ago Changed 8bdee7495a2e
1mo ago Changed · +4 lines bab307000d7c
2mo ago Changed b6b07c1c1fe8
2mo ago First seen · 68 lines · 54 tokens per session scan A 0ce7c932ada7

Subscribe to this mod's changes

spectre-prototype is a skill published in the GitHub repository joenandez/spectre (164 stars, last pushed 1mo ago), licensed MIT. It adds 54 tokens to every session and 1,198 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.

CSS and styling Design and UX Frontend

spectre-prototype next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
spectre-prototypejoenandez/spectre	Skill	164	1mo ago	MIT	A	54	Claude Code, Codex
anti-slop-designsickn33/agentic-awesome-skills	Skill	49k	yesterday	MIT	A	34	Claude Code
chakra-ui-builderchakra-ui/chakra-ui	Skill	41k	yesterday	MIT	A	214	Claude Code, Codex
visual-ralphYeachan-Heo/oh-my-codex	Skill	34k	3d ago	MIT	A	52	Codex
open-design-setupcompozy/compozy	Skill	2.8k	yesterday	MIT	A	67	Claude Code, Codex
frontend-visual-qadaymade/claude-code-skills	Skill	1.5k	yesterday	MIT	A	125	Claude Code, Codex
prototype-webnexu-io/html-anything	Skill	9.4k	25d ago	Apache-2.0	A	24	Claude Code, Codex