forms-validation

forms-validation is a skill for Claude Code, Codex from sukirman1901/frontend-expert. It costs 47 tokens per session (620 once invoked), scanned A, original, MIT.

A guide for building accessible web forms, including their labels, validation messages, keyboard behavior, and submission states. It also covers multi-step forms and showing advanced fields only when needed.

In plain words
What is it for?
Use it for login, settings, checkout, filters, create and edit dialogs, and wizard-style flows. It helps add field errors, pending submit states, focus handling, and mobile-friendly controls.
Why use it?
It reduces confusing errors, lost input, and forms that are difficult to use with a keyboard or on a phone. It makes failed submissions easier to recover from.

Skill for Claude CodeCodex

Part of the frontend-expert plugin — 25 skills, 5 commands, 3 agents, 2 hooks 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/sukirman1901/frontend-expert/forms-validation
Any agent
npx skills add sukirman1901/frontend-expert --skill forms-validation
Clone the repo
git clone --depth 1 https://github.com/sukirman1901/frontend-expert

Made for: Claude Code, Codex.

Or install frontend-expert, the plugin that ships this one along with the rest of its 25 skills, 5 commands, 3 agents, 2 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 forms-validation

README.md
[![agentmods](https://agentmods.dev/badge/skills/sukirman1901/frontend-expert/forms-validation.svg)](https://agentmods.dev/skills/sukirman1901/frontend-expert/forms-validation)
Your own site
<a href="https://agentmods.dev/skills/sukirman1901/frontend-expert/forms-validation"><img src="https://agentmods.dev/badge/skills/sukirman1901/frontend-expert/forms-validation.svg" alt="Measured on agentmods" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 620 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 $0.00047 $0.00620
Opus 5 $0.00023 $0.00310
Sonnet 5 $0.00009 $0.00124
Haiku 4.5 $0.00005 $0.00062

Measured 4d ago against content hash d5c8f7b4a3c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

forms-validation 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 4d 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/forms-validation/SKILL.md · 65 lines

How it starts

The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Forms & Validation

Overview

Forms must be keyboard-accessible, show clear errors, and never lose user input on soft failures.

When to use

  • Any form, wizard, filter bar with submit
  • Auth, settings, checkout, create/edit dialogs

When to skip

  • Read-only detail with no inputs
  • Pure button that is not a form submit

MUST (ship)

Rule Detail
Labels Every control has a visible label or aria-label; htmlFor/id associated
Errors Text + association (aria-describedby / equivalent) — not border-only
Submit Pending/disabled while in flight; values kept on 4xx/5xx
Focus On submit failure, move focus to first invalid field
Mobile Primary submit width: 100% below 768; inputs font-size ≥ 16px
No Lorem Real hint/error copy
Selects Product filters / status pickers: prefer custom select (see ui-components) — not bare native OS chrome

Workflow

  1. Labels — visible label (or aria-label); associate with htmlFor / id
  2. Validation — prefer inline field errors after submit or on blur; don’t block typing with aggressive live errors
  3. Submit — disable or show pending on the primary button; keep values on error
  4. Errors — field-level + optional form-level summary with links to fields
  5. Progressive disclosure — hide advanced fields until needed
  6. Mobile — full-width primary submit; adequate tap targets (responsive-ui)
  7. Async submit — pair with data-fetching for retry/toast; never wipe the form on soft fail

Agent boundaries

  • May decide: validation timing (submit vs blur), wizard step count, inline vs summary errors
  • Must not: invent purple/error hex off-token; skip labels for “clean UI”; use alert() for validation

Checklist

  • Labels + focus order correct
  • Error text linked to fields (aria-describedby / equivalent)
  • Pending + error + success submit states
  • First invalid field focused after failed submit
  • No Lorem placeholder as the only copy
  • Full-width primary + ≥16px inputs at 320px
  • Works at 320px width (no horizontal overflow)

Read the full file on GitHub · 65 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. 4d ago First seen · 65 lines · 47 tokens per session scan A d5c8f7b4a3c0

Subscribe to this mod's changes

forms-validation is a skill published in the GitHub repository sukirman1901/frontend-expert (10 stars, last pushed yesterday), licensed MIT. It adds 47 tokens to every session and 620 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 2026-08-31.

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