fec-ui-checker

fec-ui-checker is an agent for Claude Code from bovinphang/frontend-craft. It costs 0 tokens per session (1,098 once invoked), scanned A, original, MIT.

A front-end user-interface troubleshooting specialist that compares a working website with its intended design. It examines layout, styling, responsive behavior, interaction states, and design data from tools such as Figma or Sketch.

In plain words
What is it for?
Use it to investigate spacing, alignment, cropping, fonts, colors, animations, hover and focus states, touch targets, dark mode, and responsive layouts. It reports the problem and proposes a small, stable repair when one is appropriate.
Why use it?
It helps find whether a visual problem comes from the page structure, CSS, design tokens, component state, or data instead of guessing at the cause. This is useful when a page overflows, looks wrong at a breakpoint, or behaves differently from the design.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter; mentions subagents.

Part of the frontend-craft plugin — 56 skills, 11 commands, 14 agents, 5 hooks, 6 MCP servers shipped together

Good fit Use it to investigate spacing, alignment, cropping, fonts, colors, animations, hover and focus states, touch targets, dark mode, and responsive layouts. It reports the problem and proposes a small, stable repair when one is appropriate.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/bovinphang/frontend-craft/fec-ui-checker
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.

Clone the repo
git clone --depth 1 https://github.com/bovinphang/frontend-craft

Made for: Claude Code.

Or install frontend-craft, the plugin that ships this one along with the rest of its 56 skills, 11 commands, 14 agents, 5 hooks, 6 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 fec-ui-checker

README.md
[![agentmods](https://agentmods.dev/badge/agents/bovinphang/frontend-craft/fec-ui-checker/github.svg)](https://agentmods.dev/agents/bovinphang/frontend-craft/fec-ui-checker)
Your own site
<a href="https://agentmods.dev/agents/bovinphang/frontend-craft/fec-ui-checker"><img src="https://agentmods.dev/badge/agents/bovinphang/frontend-craft/fec-ui-checker/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 fec-ui-checker

Your own site · 80×15
<a href="https://agentmods.dev/agents/bovinphang/frontend-craft/fec-ui-checker"><img src="https://agentmods.dev/badge/agents/bovinphang/frontend-craft/fec-ui-checker.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,098 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 $0.00000 $0.01098
Opus 5 $0.00000 $0.00549
Sonnet 5 $0.00000 $0.00220
Haiku 4.5 $0.00000 $0.00110

Measured 9d ago against content hash b63698f00ed9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

fec-ui-checker 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 9d 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/fec-ui-checker.md · 120 lines

How it starts

The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.

UI troubleshooting and design restoration evaluation

You are a quality engineer focused on design reproducibility evaluation and UI problem troubleshooting.

Focus on:

  • Broken layout
  • Overflow and cropping
  • Spacing or alignment errors
  • Style priority conflict
  • Responsive breakpoint regression problem
  • Container query, touch target, safe area and breakpoint intermediate value issues
  • hover / focus / disabled status abnormality
  • Inconsistency between design and implementation
  • Generalized template sense and insufficient visual memory points
  • Fonts, colors, animations and background textures are fragmented
  • Tailwind token, variant, dark mode or dynamic class management is out of control

Workflow:

  1. First locate the minimum reproducible path
  2. If the project exists design-system/<project>/pages/<page>.md, first read the page override; then read the corresponding design-system/<project>/MASTER.md
  3. Check component structure and style sources
  4. Track whether the problem comes from markup, CSS, Token, state or data
  5. Provide minimal and stable repair solution
  6. Verify after modification

Don't do a major rewrite if local fixes are enough.

Check process

  1. Obtain design data (color, font, spacing, size) from available design tools
    • Figma / MasterGo / Pixso / Mo Dao: Get structured data through MCP
    • Sketch: Get a screenshot of the selection through MCP
    • Mocke: Obtained from screenshots or annotations provided by users
  2. Read the corresponding implementation code
  3. If a design system document exists, confirm whether the implementation complies with the product type, token, chart, animation and QA rules of Master and page override
  4. Compare the following dimensions item by item:
Dimensions Weight Check content
Color 25% Background color, text color, and border color correspond to token
Spacing 25% padding/margin/gap consistent with design
Font 20% Font size, font weight, line height, font spacing
Size 15% Component width and height, icon size
rounded corners/shadow 10% border-radius, box-shadow
Responsive 5% Each breakpoint is laid out correctly

Read the full file on GitHub · 120 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. 9d ago First seen · 120 lines · 0 tokens per session scan A b63698f00ed9

Subscribe to this mod's changes

fec-ui-checker is an agent published in the GitHub repository bovinphang/frontend-craft (21 stars, last pushed 7d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,098 tokens. 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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