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, orEffect.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:
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 cliIf 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+ staticlayerin one file) - Use
Schema.TaggedErrorfor domain errors - Do not access
Option/Eitherinternals 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:
- Which
effect-solutions show...topics were checked - Which reference file(s) were used and why
- Concrete change proposal following existing project patterns
- Verification plan (typecheck/tests)
Reference Index
references/services-and-layers.mdreferences/error-handling.mdreferences/framework-integration.mdreferences/agent-tools-patterns.mdreferences/testing-layers.md