Rules for writing Effect-TS code, including services, errors, layers, and atoms, using the patterns required by Effect version 4.

Use them when creating or changing Effect-TS programs, services, error handling, layers, or atoms.

They help keep Effect-TS code consistent with the version and conventions used in the codebase.

effect-ts — Cursor rule by millionco

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/millionco/expect/effect-ts

Clone the repo

git clone --depth 1 https://github.com/millionco/expect

Made for: Cursor.

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

When invoked 514 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin unknown 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	$0.00514
Opus 5	$0.00000	$0.00257
Sonnet 5	$0.00000	$0.00103
Haiku 4.5	$0.00000	$0.00051

Measured yesterday against content hash abf6249f0384, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

effect-ts 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.

.cursor/rules/effect-ts.mdc · 73 lines

The source is not reproduced here

No licence file

Read it on GitHub

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 · 73 lines · 0 tokens per session scan A abf6249f0384

Subscribe to this mod's changes

effect-ts is a cursor rule published in the GitHub repository millionco/expect (3,550 stars, last pushed 3mo ago), with no licence file. It costs nothing until one of its globs matches a file; then it loads 514 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.

Browser automation Testing Writing and docs agent expect test

ui-verification

UI layout checks before claiming work is done.

coddy-project/coddy-agent · 0 tokens

nodejs

This guide will walk you through installing Node.js using NVM (Node Version Manager) and setting up pnpm as your package manager.

giselles-ai/giselle · 3 tokens

diagram

Generate or update a mermaid diagram with the .mmd text as source of truth — defaults to a lightweight zero-dependency Node live-preview server that watches the .mmd and hot-reloads a browser tab (pan/zoom), with a self-hosted mermaid.live editor via Docker, system-viewer SVG, VS Code live preview, or a public…

victusfate/scaffold · 133 tokens

effect-ts