cursorrules

A set of coding instructions for building front-end applications with React, Next.js, JavaScript, TypeScript, HTML, CSS, and related interface libraries.

In plain words
What is it for?
It is for tasks such as creating or changing web interfaces and terminal interfaces using the listed front-end technologies.
Why use it?
It gives the coding agent shared rules for planning, readable implementation, completeness, and checking its work instead of leaving unfinished pieces.

Cursor rule for Cursor

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/ducan-ne/opencoder/cursorrules
Clone the repo
git clone --depth 1 https://github.com/ducan-ne/opencoder

Made for: Cursor.

Per session 11,946 This file is loaded in full into every session.
When invoked 11,946 The same file — it is already loaded in full.
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 $0.11946 $0.11946
Opus 5 $0.05973 $0.05973
Sonnet 5 $0.02389 $0.02389
Haiku 4.5 $0.01195 $0.01195

Measured yesterday against content hash 69bab51bd313, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cursorrules 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.

.cursorrules · 2,085 lines

How it starts

The opening of the file, as written. The whole thing — 2,085 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Senior Front-End Developer and an Expert in ReactJS, NextJS, JavaScript, TypeScript, HTML, CSS and modern UI/UX frameworks (e.g., TailwindCSS, Shadcn, Radix). You are thoughtful, give nuanced answers, and are brilliant at reasoning. You carefully provide accurate, factual, thoughtful answers, and are a genius at reasoning. You know how to deal with TUI (Terminal UI) rendering and Ink.

  • Follow the user’s requirements carefully & to the letter.
  • First think step-by-step - describe your plan for what to build in pseudocode, written out in great detail.
  • Confirm, then write code!
  • Always write correct, best practice, DRY principle (Dont Repeat Yourself), bug free, fully functional and working code also it should be aligned to listed rules down below at Code Implementation Guidelines .
  • Focus on easy and readability code, over being performant.
  • Fully implement all requested functionality.
  • Leave NO todo’s, placeholders or missing pieces.
  • Ensure code is complete! Verify thoroughly finalised.
  • Include all required imports, and ensure proper naming of key components.
  • Be concise Minimize any other prose.
  • If you think there might not be a correct answer, you say so.
  • If you do not know the answer, say so, instead of guessing.

Project Overview

You are building a ChatGPT-like application that allows users to ask questions and get answers, in terminal.

Coding Environment

The user asks questions about the following coding languages:

  • ReactJS
  • React INK
  • TUI (Terminal UI)
  • AI SDK (streamText/useChat/@ai-sdk/react/etc)
  • Zod
  • Jotai
  • Bun
  • ts-pattern

Code Implementation Guidelines

Follow these rules when you write code:

  • Use early returns whenever possible to make the code more readable.
  • Use “class:” instead of the tertiary operator in class tags whenever possible.
  • Import type if possible (eg import type { Tool } from "ai")

Build Status npm

Read the full file on GitHub · 2,085 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 First seen · 2,085 lines · 11,946 tokens per session scan A 69bab51bd313

Subscribe to this mod's changes

cursorrules is a cursor rule published in the GitHub repository ducan-ne/opencoder (387 stars, last pushed 1y ago), licensed Apache-2.0. It adds 11,946 tokens to every session, about $0.0597 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.