web-renderer-test

web-renderer-test is a skill for Claude Code from MoizIbnYousaf/marketing-cli. It costs 13 tokens per session (495 once invoked), scanned A, original, MIT.

A guide for adding visual snapshot tests to a web renderer. It uses Vitest and small React fixtures to check how rendered images look.

In plain words
What is it for?
Use it to create a renderer fixture, add a test, and run that test for a specific video or visual component.
Why use it?
It helps catch visual changes or rendering failures by comparing new output with expected images.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the marketing-cli plugin — 88 skills, 9 commands, 1 hook, 2 MCP servers shipped together

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/moizibnyousaf/marketing-cli/web-renderer-test
Any agent
npx skills add MoizIbnYousaf/marketing-cli --skill web-renderer-test
Clone the repo
git clone --depth 1 https://github.com/MoizIbnYousaf/marketing-cli

Made for: Claude Code.

Or install marketing-cli, the plugin that ships this one along with the rest of its 88 skills, 9 commands, 1 hook, 2 MCP servers.

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 web-renderer-test

README.md
[![agentmods](https://agentmods.dev/badge/skills/moizibnyousaf/marketing-cli/web-renderer-test.svg)](https://agentmods.dev/skills/moizibnyousaf/marketing-cli/web-renderer-test)
Your own site
<a href="https://agentmods.dev/skills/moizibnyousaf/marketing-cli/web-renderer-test"><img src="https://agentmods.dev/badge/skills/moizibnyousaf/marketing-cli/web-renderer-test.svg" alt="Measured on agentmods" height="20"></a>
Per session 13 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 495 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 5.1 $0.00013 $0.00495
Opus 5 $0.00006 $0.00247
Sonnet 5 $0.00003 $0.00099
Haiku 4.5 $0.00001 $0.00049

Measured 2d ago against content hash 92ea781e9786, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

web-renderer-test 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/remotion-best-practices/references/upstream-internal/skills/web-renderer-test/SKILL.md · 80 lines

What it actually says

The web renderer is in packages/web-renderer and the test suite is in packages/web-renderer/src/test.

It uses visual snapshot testing using vitest. A test file can for example be executed using:

bunx vitest src/test/video.test.tsx

Example

Each test is powered by a fixture in packages/web-renderer/src/test/fixtures. A fixture looks like this for example:

import {AbsoluteFill} from 'remotion';

const Component: React.FC = () => {
  return (
    <AbsoluteFill
      style={{
        justifyContent: 'center',
        alignItems: 'center',
      }}
    >
      <div
        style={{
          backgroundColor: 'red',
          width: 100,
          height: 100,
          borderRadius: 20,
        }}
      />
    </AbsoluteFill>
  );
};

export const backgroundColor = {
  component: Component,
  id: 'background-color',
  width: 200,
  height: 200,
  fps: 25,
  durationInFrames: 1,
} as const;

The corresponding test looks like this:

import {test} from 'vitest';
import {renderStillOnWeb} from '../render-still-on-web';
import {backgroundColor} from './fixtures/background-color';
import {testImage} from './utils';

test('should render background-color', async () => {
  const blob = await renderStillOnWeb({
    licenseKey: 'free-license',
    composition: backgroundColor,
    frame: 0,
    inputProps: {},
    imageFormat: 'png',
  });

  await testImage({blob, testId: 'background-color'});
});

Adding a new test

  1. Add a new fixture in packages/web-renderer/src/test/fixtures.
  2. Important: Add the fixture to packages/web-renderer/src/test/Root.tsx to add a way to preview it.
  3. Add a new test in packages/web-renderer/src/test.
  4. Run bunx vitest src/test/video.test.tsx to execute the test.
  5. Important: Update packages/docs/docs/client-side-rendering/limitations.mdx to reflect the newly supported property.
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 · 80 lines · 13 tokens per session scan A 92ea781e9786

Subscribe to this mod's changes

web-renderer-test is a skill published in the GitHub repository MoizIbnYousaf/marketing-cli (31 stars, last pushed 19d ago), licensed MIT. It adds 13 tokens to every session and 495 once invoked, about $0.0001 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 2026-09-03.

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