canon-images

canon-images is a skill for Claude Code, Codex from Dragoon0x/canon. It costs 75 tokens per session (967 once invoked), scanned A, original, MIT.

A set of web image optimization rules for choosing file formats, serving suitable image sizes, and controlling loading.

In plain words
What is it for?
Use it when choosing AVIF, WebP, PNG, or SVG; adding responsive images with srcset; lazy-loading images; or improving the main image measured by Largest Contentful Paint, a page-speed metric.
Why use it?
It helps reduce image download sizes and prevent images from slowing page loading or appearing with the wrong proportions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when choosing AVIF, WebP, PNG, or SVG; adding responsive images with srcset; lazy-loading images; or improving the main image measured by Largest Contentful Paint, a page-speed metric.

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Install with agentmods
npx agentmods add skills/dragoon0x/canon/canon-images
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 Dragoon0x/canon --skill canon-images
Clone the repo
git clone --depth 1 https://github.com/Dragoon0x/canon

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.

agentmods badge for canon-images

README.md
[![agentmods](https://agentmods.dev/badge/skills/dragoon0x/canon/canon-images/github.svg)](https://agentmods.dev/skills/dragoon0x/canon/canon-images)
Your own site
<a href="https://agentmods.dev/skills/dragoon0x/canon/canon-images"><img src="https://agentmods.dev/badge/skills/dragoon0x/canon/canon-images/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.

agentmods 80×15 button for canon-images

Your own site · 80×15
<a href="https://agentmods.dev/skills/dragoon0x/canon/canon-images"><img src="https://agentmods.dev/badge/skills/dragoon0x/canon/canon-images.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 967 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.
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 5.1 $0.00075 $0.00967
Opus 5 $0.00037 $0.00483
Sonnet 5 $0.00015 $0.00193
Haiku 4.5 $0.00007 $0.00097

Measured 10d ago against content hash 91eb1872ebd2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

canon-images 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 10d 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.

source/skills/canon-images/SKILL.md · 111 lines

How it starts

The opening of the file, as written. The whole thing — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CANON · Images

Images are the largest payload on most pages. Format, size, and loading strategy make or break performance.

Format decision tree

Is it a photo or complex gradient?
  ├─ Yes → AVIF (best compression), WebP fallback, JPEG last resort
  └─ No →
     Is it an icon, logo, or simple shape?
       ├─ Yes → SVG (infinitely scalable, tiny file)
       └─ No →
          Does it need transparency?
            ├─ Yes → WebP or PNG (WebP preferred, smaller)
            └─ No → AVIF/WebP/JPEG

Responsive images — srcset

Serve the right size for the viewport. Don't send a 2400px image to a 375px phone.

<img
  src="hero-800.webp"
  srcset="hero-400.webp 400w, hero-800.webp 800w, hero-1200.webp 1200w, hero-1600.webp 1600w"
  sizes="(max-width: 768px) 100vw, 50vw"
  alt="Product showcase"
  width="1200"
  height="800"
  loading="lazy"
  decoding="async"
>

LCP image — the critical one

The Largest Contentful Paint image needs special treatment:

  • No loading="lazy" — it must load eagerly.
  • fetchpriority="high" — tells the browser to prioritize.
  • Preload<link rel="preload" as="image" href="hero.webp">.
  • Serve at rendered size — don't serve 3000px for a 600px container.
<link rel="preload" as="image" href="hero.webp" fetchpriority="high">
<img src="hero.webp" alt="..." width="1200" height="800" fetchpriority="high">

Always declare width and height

<img src="photo.webp" alt="..." width="800" height="600">

This reserves layout space before the image loads, preventing Cumulative Layout Shift (CLS). The browser calculates aspect ratio from these attributes. CSS can still make the image responsive:

img { max-width: 100%; height: auto; }

Lazy loading

All images below the fold should use loading="lazy". Native browser lazy loading works without JavaScript.

Exception: the LCP image (above the fold) must NOT be lazy loaded.

Image CDNs

Services like Cloudinary, imgix, Cloudflare Images serve optimized formats and sizes automatically:

Read the full file on GitHub · 111 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. 10d ago First seen · 111 lines · 75 tokens per session scan A 91eb1872ebd2

Subscribe to this mod's changes

canon-images is a skill published in the GitHub repository Dragoon0x/canon (5 stars, last pushed 4mo ago), licensed MIT. It adds 75 tokens to every session and 967 once invoked, about $0.0004 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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