effect-ts

effect-ts is a skill for Claude Code, Codex from pproenca/dot-skills. It costs 206 tokens per session (1,796 once invoked), scanned A, original, MIT.

A set of guidance for using Effect, a TypeScript library for handling errors, services, validation, concurrency, and resources in large applications.

In plain words
What is it for?
Use it when writing or reviewing Effect code, defining validated data with Schema, building services and layers, or moving from Promises, fp-ts, neverthrow, or ZIO.
Why use it?
It helps keep complex TypeScript code predictable by giving common patterns for typed errors, shared services, and safe concurrent work.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when writing or reviewing Effect code, defining validated data with Schema, building services and layers, or moving from Promises, fp-ts, neverthrow, or ZIO.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/pproenca/dot-skills/effect-ts
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.

Any agent
npx skills add pproenca/dot-skills --skill effect-ts
Clone the repo
git clone --depth 1 https://github.com/pproenca/dot-skills

Made for: Claude Code, Codex.

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 effect-ts

README.md
[![agentmods](https://agentmods.dev/badge/skills/pproenca/dot-skills/effect-ts/github.svg)](https://agentmods.dev/skills/pproenca/dot-skills/effect-ts)
Your own site
<a href="https://agentmods.dev/skills/pproenca/dot-skills/effect-ts"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/effect-ts/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for effect-ts

Your own site · 80×15
<a href="https://agentmods.dev/skills/pproenca/dot-skills/effect-ts"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/effect-ts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 206 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,796 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00206 $0.01796
Opus 5 $0.00103 $0.00898
Sonnet 5 $0.00041 $0.00359
Haiku 4.5 $0.00021 $0.00180

Measured 6d ago against content hash cea7a54072da, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

effect-ts scanned grade A with 1 finding 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 6d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

const async = Effect.tryPromise(() => fetch(url))
skills/.experimental/effect-ts/SKILL.md · 209 lines

How it starts

The opening of the file, as written. The whole thing — 209 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Effect TypeScript Best Practices

Effect is a TypeScript library for building complex, type-safe applications with structured error handling, dependency injection via services/layers, fiber-based concurrency, and resource safety.

When to Apply

  • Writing or reviewing TypeScript code that imports from effect, @effect/schema, or @effect/platform
  • Implementing typed error handling with Effect<Success, Error, Requirements>
  • Building services and layers for dependency injection
  • Working with Schema for data validation, decoding, and transformation
  • Using fiber-based concurrency (queues, semaphores, PubSub, deferred)
  • Processing data with Stream and Sink
  • Migrating from Promises, fp-ts, neverthrow, or ZIO to Effect

How to Use

This skill is organized by domain. Read the relevant reference file for the area you're working in.

Read First: The Paradigm

Always read this before diving into API references, especially when refactoring existing code to use Effect or writing new Effect services:

Reference When to Read
Think in Effect: The Paradigm Shift Before any other reference. Mental model shifts, refactoring recipes, anti-patterns, application architecture. Read this to understand HOW to think in Effect — the other files teach WHAT to type.

Core Foundations

Reference When to Read
Getting Started Creating the Effect type, pipelines, generators, running effects
Error Management Typed errors, recovery, retrying, timeouts, sandboxing
Core Concepts Request batching, configuration management, runtime system

Data & Validation

Reference When to Read
Data Types Option, Either, Cause, Chunk, DateTime, Duration, Exit, Data
Schema Basics Schema intro, basic usage, classes, constructors, effect data types
Schema Advanced Transformations, filters, annotations, error formatting, JSON Schema output

Read the full file on GitHub · 209 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. 6d ago First seen · 209 lines · 206 tokens per session scan A cea7a54072da

Subscribe to this mod's changes

effect-ts is a skill published in the GitHub repository pproenca/dot-skills (205 stars, last pushed 24d ago), licensed MIT. It adds 206 tokens to every session and 1,796 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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