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.
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.
git clone --depth 1 https://github.com/open-gsd/gsd-coreWrote 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.
[](https://agentmods.dev/agents/open-gsd/gsd-core/gsd-ui-checker)<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>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.
| Model | Per session | Once 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 |
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.
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>
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.
- yesterday Changed · +16 lines 004c221097ae
- 8d ago First seen · 401 lines · 42 tokens per session scan A 60e3da5abc59
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.
Other agents, from other repositories
gsd-ui-auditor
Retroactive 6-pillar visual audit of implemented frontend code. Produces scored UI-REVIEW.md. Spawned by /gsd:ui-review orchestrator.
gsd-ui-checker
Validates UI-SPEC.md design contracts against 6 quality dimensions. Produces BLOCK/FLAG/PASS verdicts. Spawned by /gsd:ui-phase orchestrator.
gsd-ui-researcher
Produces UI-SPEC.md design contract for frontend phases. Reads upstream artifacts, detects design system state, asks only unanswered questions. Spawned by /gsd:ui-phase orchestrator.
security
OWASP security audit, dependency risks, and secrets detection.
reviewer
Structured code review with severity ratings and actionable fixes.
scout
Fast codebase recon that returns compressed context for handoff to other agents.