guidance-api-design

Component API design guidance for web components, covering properties, HTML attributes, CSS custom properties, slots, events, composition, and package exports. It follows the project's conventions for how components expose behavior and styling.

In plain words
What is it for?
Use it when designing or changing component APIs, theming, custom events, slots, parent-child composition, state handling, or package dependencies.
Why use it?
It helps avoid unclear or contradictory component interfaces and makes decisions such as properties versus attributes more consistent.

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/nvidia/elements/guidance-api-design
Any agent
npx skills add NVIDIA/elements --skill guidance-api-design
Clone the repo
git clone --depth 1 https://github.com/NVIDIA/elements

Made for: Claude Code, Codex.

Per session 103 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 461 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 $0.00103 $0.00461
Opus 5 $0.00051 $0.00230
Sonnet 5 $0.00021 $0.00092
Haiku 4.5 $0.00010 $0.00046

Measured 2d ago against content hash 1620c0574a31, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

guidance-api-design 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.

.agents/skills/guidance-api-design/SKILL.md · 51 lines

What it actually says

Guidance API Design

You MUST review the relevant API design guidelines before designing or modifying component APIs.

When to Use This Skill

  • Designing properties and attributes for new components
  • Creating CSS custom properties for theming
  • Avoiding impossible states in component APIs
  • Choosing between properties, attributes, and slots
  • Designing custom events
  • Planning component composition patterns
  • Setting up package exports and dependencies

Stateless Components

When creating new components or features that may contain user state review the Stateless Components Guidelines.

Properties vs Attributes

When working with JavaScript properties and HTML attributes review the Properties & Attributes Guidelines.

Styles & CSS Custom Properties

When working with CSS, CSS Custom Properties or Design Tokens review the Styles & CSS Custom Properties Guidelines.

Component Composition

When creating a new API or determining API design of parent child relationships between components review the Component Composition Guidelines.

Slots

When working with user provided content or container-like components review the Slots Guidelines.

Custom Events

When creating new events or listening to existing event review the Custom Events Guidelines.

Component Registration

When creating new components or using components as dependencies review the Component Registration Guidelines.

Packaging & Exports

When creating a new component or package review the Packaging & Exports Guidelines.

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 · 51 lines · 103 tokens per session scan A 1620c0574a31

Subscribe to this mod's changes

guidance-api-design is a skill published in the GitHub repository NVIDIA/elements (83 stars, last pushed 2d ago), licensed Apache-2.0. It adds 103 tokens to every session and 461 once invoked, about $0.0005 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.

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