figma-plugin-core

figma-plugin-core is a cursor rule for Cursor from hoshikitsunoda/figma-plugins-vibe-coding-template. It costs 3,038 tokens per session, scanned A, original, MIT.

A set of rules for building Figma plugins with attention to both design details and engineering choices. It explains the two separate parts of a plugin and how they communicate.

In plain words
What is it for?
Use it when designing or implementing plugin features, deciding how the interface should behave, handling Figma API work, and explaining technical decisions to designers.
Why use it?
It helps prevent confusing behavior and rough edges when a plugin's interface and internal code need to work together.

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/hoshikitsunoda/figma-plugins-vibe-coding-template/figma-plugin-core
Clone the repo
git clone --depth 1 https://github.com/hoshikitsunoda/figma-plugins-vibe-coding-template

Made for: Cursor.

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 figma-plugin-core

README.md
[![agentmods](https://agentmods.dev/badge/rules/hoshikitsunoda/figma-plugins-vibe-coding-template/figma-plugin-core.svg)](https://agentmods.dev/rules/hoshikitsunoda/figma-plugins-vibe-coding-template/figma-plugin-core)
Your own site
<a href="https://agentmods.dev/rules/hoshikitsunoda/figma-plugins-vibe-coding-template/figma-plugin-core"><img src="https://agentmods.dev/badge/rules/hoshikitsunoda/figma-plugins-vibe-coding-template/figma-plugin-core.svg" alt="Measured on agentmods" height="20"></a>
Per session 3,038 This file is loaded in full into every session.
When invoked 3,038 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 $0.03038 $0.03038
Opus 5 $0.01519 $0.01519
Sonnet 5 $0.00608 $0.00608
Haiku 4.5 $0.00304 $0.00304

Measured 5d ago against content hash 5fb6bf4936aa, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

figma-plugin-core 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 5d 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.

.cursor/rules/figma-plugin-core.mdc · 323 lines

How it starts

The opening of the file, as written. The whole thing — 323 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Design Technologist Mindset

Think and act as an experienced design technologist — someone who bridges design and engineering with care, curiosity, and clarity.

Attention to Detail

  • Care about edge cases and polish, not just "does it work?"
  • Consider how things feel from the designer's perspective
  • Think about the workflow: what happens before and after this action?

Curiosity for New Technology

  • Explore what Figma's API can do — suggest creative solutions
  • Stay current with plugin capabilities and best practices
  • When unsure, check the official docs rather than guessing

Clear Communication of Intent

  • Explain the reasoning behind decisions, not just the implementation
  • Connect technical choices to user goals
  • Make the invisible visible — why this approach over alternatives?

Figma Plugin Architecture

This is a Figma plugin built with React + Vite + TypeScript. Understanding the two-context architecture is critical.

The Sandbox Model

Figma plugins run in two separate JavaScript contexts that cannot directly share memory:

┌─────────────────────────┐     postMessage      ┌─────────────────────────┐
│     MAIN THREAD         │ ◄──────────────────► │      UI THREAD          │
│   (Plugin Sandbox)      │                      │      (iframe)           │
├─────────────────────────┤                      ├─────────────────────────┤
│ ✓ figma.* API           │                      │ ✓ DOM / React           │
│ ✓ SceneNode access      │                      │ ✓ fetch() / XHR         │
│ ✓ Document manipulation │                      │ ✓ window / localStorage │
│ ✗ NO DOM                │                      │ ✗ NO figma.* API        │
│ ✗ NO fetch              │                      │ ✗ NO direct node access │
│ ✗ NO window             │                      │                         │
└─────────────────────────┘                      └─────────────────────────┘

Project Structure

manifest.json       # Plugin config - update name and id for your plugin
src/
  plugin/           # Main thread code (runs in Figma sandbox)
    main.ts         # Entry point, message router
    handlers/       # Message handlers
    utils/          # Figma API utilities
  ui/               # UI thread code (React app in iframe)
    App.tsx
    components/
    hooks/
  shared/           # Shared types (message definitions)
    messages.ts     # PluginMessage & UIMessage types

Read the full file on GitHub · 323 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. 5d ago First seen · 323 lines · 3,038 tokens per session scan A 5fb6bf4936aa

Subscribe to this mod's changes

figma-plugin-core is a cursor rule published in the GitHub repository hoshikitsunoda/figma-plugins-vibe-coding-template (21 stars, last pushed 8mo ago), licensed MIT. It adds 3,038 tokens to every session, about $0.0152 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.