Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add AppsVortex/arness/plugin install arn-sparkWrote 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.
[](https://agentmods.dev/skills/appsvortex/arness/arn-spark-static-prototype)<a href="https://agentmods.dev/skills/appsvortex/arness/arn-spark-static-prototype"><img src="https://agentmods.dev/badge/skills/appsvortex/arness/arn-spark-static-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.
<a href="https://agentmods.dev/skills/appsvortex/arness/arn-spark-static-prototype"><img src="https://agentmods.dev/badge/skills/appsvortex/arness/arn-spark-static-prototype.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00109 | $0.04821 |
| Opus 5.5 | $0.00044 | $0.01928 |
| Sonnet 5.5 | $0.00022 | $0.00964 |
| Haiku 4.5 | $0.00011 | $0.00482 |
Grade A, and why
arn-spark-static-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 today.
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.
How it starts
The opening of the file, as written. The whole thing — 363 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Arness Static Prototype
Create a static component showcase and validate it through iterative build-review cycles, aided by the arn-spark-prototype-builder agent (in showcase mode) for rendering, the arn-spark-style-capture agent for screenshots, arn-spark-product-strategist and arn-spark-ux-specialist (greenfield agents in this plugin) for expert review, and the arn-spark-ux-judge agent for an independent final verdict. This is a conversational skill that runs in normal conversation (NOT plan mode).
The primary artifacts are versioned showcase pages with component renders, review reports with per-criterion scores, and a final report documenting the complete validation history. All output is versioned so the user can compare evolution across cycles.
This skill covers visual fidelity validation: do the components look correct according to the style brief? It does not cover interactive behavior -- that is /arn-spark-clickable-prototype's job.
Prerequisites
The following artifacts inform the validation. Check in order:
Determine the prototypes output directory:
- Read the project's
CLAUDE.mdand check for a## Arnesssection - If found, extract the configured Prototypes directory path — this is the source of truth
- If no
## Arnesssection exists or Arness Spark fields are missing, inform the user: "Arness Spark is not configured for this project yet. Run/arn-brainstormingto get started — it will set everything up automatically." Do not proceed without it. - If the directory does not exist, create it
All references to
prototypes/in this skill refer to the configured prototypes directory determined above.
Style brief (strongly recommended):
- Read the project's
CLAUDE.mdfor a## Arnesssection. If found, check the configured Vision directory forstyle-brief.md - If no
## Arnesssection found, check.arness/vision/style-brief.mdat the project root
Product concept (recommended):
- Check the configured Vision directory for
product-concept.md - If no
## Arnesssection found, check.arness/vision/product-concept.mdat the project root
What ships with it
3 files 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.
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.
- today First seen · 363 lines · 109 tokens per session scan A 5773f5b1e5ca
arn-spark-static-prototype is a skill published in the GitHub repository AppsVortex/arness (33 stars, last pushed today), licensed MIT. It adds 109 tokens to every session and 4,821 once invoked, about $0.0004 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 2026-10-25.
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