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 editing service files in packages/services/ or agent-tools/*

• You need test strategy for Effect code (@effect/vitest , test layers)

• You need Effect runtime integration (TRPC/server boundaries)

First Step (Always)

Before implementing or reviewing, 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 cli

Effect guidance evolves. 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

When advising or implementing, 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.md

• references/error-handling.md

• references/framework-integration.md

• references/agent-tools-patterns.md

• references/testing-layers.md