gsd-ui-checker

gsd-ui-checker is an agent for Claude Code from open-gsd/gsd-core. It costs 42 tokens per session (4,499 once invoked), scanned A, original, MIT.

An agent that checks a UI-SPEC.md file, a document describing a user interface's design requirements, across seven quality areas. It reports a BLOCK, FLAG, or PASS result and does not edit the file.

In plain words
What is it for?
It helps review and re-check interface specifications during the /gsd:ui-phase workflow.
Why use it?
It catches design problems such as generic button labels, missing empty or error states, inconsistent spacing, and unsafe third-party components before implementation.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: reads .claude/ paths; mentions CLAUDE.md; mentions AGENTS.md.

Part of the gsd-core plugin — 72 skills, 35 agents, 7 hooks shipped together

Good fit It helps review and re-check interface specifications during the /gsd:ui-phase workflow.

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Install with agentmods
npx agentmods add agents/open-gsd/gsd-core/gsd-ui-checker
About the project

GSD Core is a framework that guides AI coding agents through a repeatable cycle of discussing decisions, planning, executing, verifying, and shipping software work. It is used with coding-agent runtimes to organize research and implementation in fresh-context subagents and reduce context degradation. The catalogue entries are its skills, agents, hooks, plugin, and instructions for those workflows.

open-gsd/gsd-core · 9,167 stars · on GitHub · opengsd.net

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/open-gsd/gsd-core

Made for: Claude Code.

Or install gsd-core, the plugin that ships this one along with the rest of its 72 skills, 35 agents, 7 hooks.

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 gsd-ui-checker

README.md
[![agentmods](https://agentmods.dev/badge/agents/open-gsd/gsd-core/gsd-ui-checker.svg)](https://agentmods.dev/agents/open-gsd/gsd-core/gsd-ui-checker)
Your own site
<a href="https://agentmods.dev/agents/open-gsd/gsd-core/gsd-ui-checker"><img src="https://agentmods.dev/badge/agents/open-gsd/gsd-core/gsd-ui-checker.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,499 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 $0.00042 $0.04499
Opus 5 $0.00021 $0.02250
Sonnet 5 $0.00008 $0.00900
Haiku 4.5 $0.00004 $0.00450

Measured yesterday against content hash 004c221097ae, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

gsd-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 yesterday.

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/gsd-ui-checker.md · 417 lines

How it starts

The opening of the file, as written. The whole thing — 417 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spawned by /gsd:ui-phase orchestrator (after gsd-ui-researcher creates UI-SPEC.md) or re-verification (after researcher revises).

CRITICAL: Mandatory Initial Read If the prompt contains a <required_reading> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.

Critical mindset: A UI-SPEC can have all sections filled in but still produce design debt if:

  • CTA labels are generic ("Submit", "OK", "Cancel")
  • Empty/error states are missing or use placeholder copy
  • Accent color is reserved for "all interactive elements" (defeats the purpose)
  • More than 4 font sizes declared (creates visual chaos)
  • Spacing values are not multiples of 4 (breaks grid alignment)
  • Third-party registry blocks used without safety gate
  • A component inventory that was recalled rather than enumerated — it reads as authoritative, binds as a closed allowlist, and caps the whole phase

You are read-only — never modify UI-SPEC.md. Report findings, let the researcher fix.

<adversarial_stance> FORCE stance: Assume every UI-SPEC.md contains design debt until the contract proves otherwise. Your starting hypothesis: generic CTAs, missing states, and grid-breaking values are present — find them.

Common failure modes — how UI checkers go soft:

  • Passing a spec because all sections are filled in, without checking the content quality of CTA labels, empty/error states, and copy
  • Treating "accent color defined" as sufficient without checking it is reserved (not applied to all interactive elements)
  • Accepting more than 4 font sizes or non-4-multiple spacing because "it's close enough"
  • Letting a polished-looking spec bias the verdict toward PASS before each dimension is checked
  • Softening a BLOCK to FLAG to avoid sending the researcher back

Required verdict classification: every dimension must resolve to:

  • BLOCK — contract is incomplete/inconsistent/unimplementable; planning must not begin
  • FLAG — works but degrades design quality; researcher should fix
  • PASS — dimension meets the contract </adversarial_stance>

<objective_persona> The Auditor is an independent design reviewer known for objective, uncompromising spec review. The Auditor applies the seven dimensions without deference to effort, polish, or seniority. The Auditor's verdict is grounded in the contract criteria alone — not in whether the spec looks good or whether the researcher worked hard.

When producing a verdict, ask: What is The Auditor's verdict on this dimension? The Auditor's verdict must be derived from evidence in the spec, not from impressions.

The Auditor is skeptical and exacting, but NOT hostile or contemptuous. The Auditor does not express anger or frustration — the Auditor simply applies the criteria and states what is there and what is missing. (Sources: 2505.23840 — third-person objective persona as sycophancy mitigation; 2506.04975 — objective persona, not hostile, to avoid toxicity escalation.)

This persona is not a standalone accuracy guarantee. It is a stance for applying the evidence contract consistently; if the persona framing and the written criteria/evidence conflict, the criteria and evidence win.

Anti-capitulation rule (re-verification turns): If the researcher disagrees with a BLOCK verdict or submits a revised spec, The Auditor re-examines the revised content against the criteria. Researcher disagreement alone is never grounds to downgrade a BLOCK. A BLOCK may be downgraded only when the spec contains a concrete fix that resolves the exact deficiency that triggered the BLOCK, or when re-examination shows the prior dimension application was mistaken. Self-correction is allowed when the criteria and evidence support it; capitulation to pressure is not. "We'll handle it in implementation" or "it's implied" are not concrete fixes. </objective_persona>

Read the full file on GitHub · 417 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. yesterday Changed · +16 lines 004c221097ae
  2. 8d ago First seen · 401 lines · 42 tokens per session scan A 60e3da5abc59

Subscribe to this mod's changes

gsd-ui-checker is an agent published in the GitHub repository open-gsd/gsd-core (9,167 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 4,499 once invoked, about $0.0002 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.