A set of rules for building and validating web forms with React Hook Form and Zod, a library for describing and checking data shapes. It defines where schemas, defaults, submissions, and errors should be handled.

It is for constructing forms, defining validation schemas, showing server-side errors, preventing duplicate submissions, and managing watched fields efficiently.

It helps keep form validation and state management consistent and avoids fragile manual event handling, duplicated state, and unclear server-error handling.

forms — Cursor rule by virastack

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 rules/virastack/ai/forms

Clone the repo

git clone --depth 1 https://github.com/virastack/ai

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 396 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.

Model	Per session	Once invoked
Fable 5	$0.00000	$0.00396
Opus 5	$0.00000	$0.00198
Sonnet 5	$0.00000	$0.00079
Haiku 4.5	$0.00000	$0.00040

Measured yesterday against content hash c36a37691239, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

forms 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.

templates/core/.cursor/rules/forms.mdc · 60 lines

What it actually says

Form Management

Constraints

Library: Use react-hook-form + @hookform/resolvers/zod.
Schema: Store schemas in features/[feature]/schemas/.
Defaults: Define defaultValues fully using z.infer from the schema.
Performance: Use useWatch or Controller instead of watch.
Submission: Use handleSubmit. Prevent double clicks with isSubmitting.
Errors: Map server errors using setError.

Bans

Manually managing native form submit events.
Using watch() at the root level.
Synchronizing form state with useEffect.
Defining schemas inside component files.
Managing form inputs with useState.

Mandatory Patterns

1. Server Action Error Handling

ALWAYS handle Server Action validation errors by mapping them to the form using setError.

Correct Implementation

Incorrect Implementation

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.

yesterday First seen · 60 lines · 0 tokens per session scan A c36a37691239

Subscribe to this mod's changes

forms is a cursor rule published in the GitHub repository virastack/ai (23 stars, last pushed 25d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 396 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.

Backend and APIs Frontend agent-skills antigravity claude-code cursor skills virastack

marker-triage

Triage a Marker.io website-feedback backlog at scale. Use when asked to go through, categorize, prioritize, deduplicate, or make sense of many Marker.io issues at once. Splits content fixes from functional bugs, groups by page, rates criticality, flags duplicates and repeat reporters, surfaces quick wins, lists…

marker-io/mcp-skills · 85 tokens

marker-client-report

Turn a project's completed Marker.io work into a client-ready report. Use when asked to write a weekly or monthly recap for a client, summarize what was shipped or fixed this period, or produce a status update for a website project from Marker.io. Read-only: it reads issues and writes a markdown report, it does not…

marker-io/mcp-skills · 67 tokens

marker-insights

Aggregate Marker.io website feedback into recurring patterns. Use when asked to find the most common issues on a site, which pages get the most feedback, recurring content problems, or the content-vs-bug split across many Marker.io reports, and produce a prioritized brief for a website team or agency. Read-only: it…

marker-io/mcp-skills · 73 tokens

marker-bug-to-fix

Take one Marker.io bug report and produce a ready-to-review code fix. Use when asked to fix, investigate, reproduce, or find the root cause of a specific Marker.io issue in the current repository. Pulls the issue's screenshot, console errors, network requests and DOM, locates the cause in code, proposes a minimal…