Effect Patterns

Battle-tested conventions for large Effect-TS codebases. The value is uniformity at scale: every module follows the same skeleton, so any file is navigable the moment you've seen one — dependency wiring stays type-safe, and validation, errors, and IDs flow through a single Schema-based layer.

Effect v4 only. None of this works on v3 — the API surface is different (Schema.TaggedErrorClass vs v3's Schema.TaggedError, Context.Service vs Effect.Service, and so on). When an API question isn't answered here, check in order: the nearest AGENTS.md / project Effect practices doc, the project-pinned effect package source and version in node_modules, and current upstream Effect source — before guessing from training data, which skews v3.

How to use this skill

Read the reference file matching the task. Each is self-contained — load only what the task needs.