# Effect TS

> This skill should be used when implementing, reviewing, or debugging Effect TypeScript code, especially service/layer design, typed error handling, testing strategy, and runtime-boundary integration with frameworks (for example TRPC/HTTP/worker entrypoints).

- Skill: `blogic-cz/effect-ts` (Agent Skill, multi-file: 6 files)
- Install (CLI): `npx skillmds@latest add blogic-cz/effect-ts`
- Raw SKILL.md: https://api.skillmd.com/api/skills/blogic-cz/effect-ts/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: blogic-cz (https://skillmd.com/u/blogic-cz)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/blogic-cz/effect-ts

---


# Effect Expert

Use this skill when working with Effect services, layers, schema errors, config, and runtime integration.

## Load Triggers

Load this skill when:

- User mentions `Effect`, `Layer`, `Context.Tag`, `Schema.TaggedError`, `Effect.gen`, or `Effect.fn`
- You are implementing or reviewing files that define Effect services, layers, or runtime boundaries
- You are debugging Effect runtime behavior, missing spans, layer wiring, or boundary error mapping
- You need test strategy for Effect code (`@effect/vitest`, test layers)
- You need Effect runtime integration (TRPC/server boundaries)

## First Step (Always)

Before substantial implementation, refactor, or formal review, fetch current recommendations:

```bash
effect-solutions list
effect-solutions show tsconfig
effect-solutions show basics
effect-solutions show services-and-layers
effect-solutions show data-modeling
effect-solutions show error-handling
effect-solutions show config
effect-solutions show testing
effect-solutions show cli
```

If `effect-solutions` CLI is unavailable, or if the task is trivial (for example a small wording tweak with no Effect design impact), skip the CLI calls and rely on the relevant reference file(s) in this skill.

Treat recommendations as time-sensitive guidance. Do not rely on stale memory.

## Decision Tree

- **Service design or refactor** -> `references/services-and-layers.md`
- **Typed errors, Option/Either, recovery** -> `references/error-handling.md`
- **TRPC/server runtime boundary** -> `references/framework-integration.md`
- **CLI tooling in `agent-tools/*`** -> `references/agent-tools-patterns.md`
- **Testing and mocks** -> `references/testing-layers.md`

## Project Rules (Do Not Break)

- Prefer service co-location (`Context.Tag` + static `layer` in one file)
- Use `Schema.TaggedError` for domain errors
- Do not access `Option`/`Either` internals via `_tag`; use helpers (`match`, `isNone`, `isLeft`)
- For Effect dependencies, mock with Layers, not `vi.mock()`
- Keep one clear provide boundary at entry points

## Output Expectations

For substantial implementation/review/debug tasks, return:

1. Which `effect-solutions show ...` topics were checked
2. Which reference file(s) were used and why
3. Concrete change proposal following existing project patterns
4. Verification plan (typecheck/tests)

## Reference Index

- `references/services-and-layers.md`
- `references/error-handling.md`
- `references/framework-integration.md`
- `references/agent-tools-patterns.md`
- `references/testing-layers.md`