performance-craft

A skill for designing and measuring smooth animation across web, Apple, and game-engine projects, while staying within each platform's rendering limits.

In plain words
What is it for?
Improving CSS, JavaScript, canvas, WebGL, SwiftUI, UIKit, Metal, particle effects, and other motion-heavy interfaces.
Why use it?
It helps identify and avoid dropped frames, slow animation, unnecessary drawing, and excessive battery or hardware use.

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/jangles-byte/atelier/performance-craft
Any agent
npx skills add jangles-byte/atelier --skill performance-craft
Clone the repo
git clone --depth 1 https://github.com/jangles-byte/atelier

Made for: Claude Code, Codex.

Per session 146 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 552 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 $0.00146 $0.00552
Opus 5 $0.00073 $0.00276
Sonnet 5 $0.00029 $0.00110
Haiku 4.5 $0.00015 $0.00055

Measured 2d ago against content hash 7a5adf336f30, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

performance-craft 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/performance-craft/SKILL.md · 41 lines

What it actually says

Performance Craft

A dropped frame is a design defect the user feels before they can name it. This skill treats the frame budget as a design material: know the budget, spend it on what the philosophy values, and degrade in the order that does the least visual damage.

The budget

Frame time = 1000 / refresh rate: 8.3ms at 120Hz, 16.6ms at 60Hz — minus the platform's own compositing overhead. Design for the display the audience has: ProMotion phones and most gaming displays are 120Hz; never hardcode 60. Measure before and after any motion work — profilers, not vibes (DevTools Performance / Instruments' Animation Hitches / engine profilers).

Which reference to load

Situation Load
Web: CSS/JS/canvas/WebGL animation, scroll jank, layout thrash references/web-rendering.md
Apple: SwiftUI/UIKit hitches, Metal, ProMotion, battery/thermals references/apple-silicon.md
Game engines, particles at scale, and the degradation ladder references/budgets-and-degradation.md

Non-negotiables

  • Animate compositor-friendly properties (transform, opacity — and their platform equivalents) unless a measured reason says otherwise.
  • Timing from delta-time or the platform's frame callback, never a hardcoded 1/60 assumption.
  • Always-on ambient animation must be provably cheap: paused off-screen, GPU-only, and off the performance cores / not preventing CPU idle.
  • prefers-reduced-motion (and platform equivalents) is also the low-power path — wire them together.
  • When the budget is blown, cut by the degradation ladder — never ship the stutter, and never fix it by cutting the design's primary feedback motion first.
Files

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.

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 · 41 lines · 0 tokens per session scan A 7a5adf336f30

Subscribe to this mod's changes

performance-craft is a skill published in the GitHub repository jangles-byte/atelier (2 stars, last pushed 1mo ago), licensed MIT. It adds 146 tokens to every session and 552 once invoked, about $0.0007 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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