Effect-TS (v4)

Patterns from effect-solutions and the Effect source. This covers the latest v4 APIs.

Source-First Rule

When working in any repo that uses Effect (effect or @effect/* in package/dependency files), reference the official Effect source before writing, reviewing, or refactoring Effect code. Do not rely on stale memory, blog posts, or high-level docs alone.

• If the effect_source tool is available, use it for status, hydrate, and search instead of hand-rolled shell commands.
• First check for a repo-local shallow source mirror at .agent-sources/effect/.
• If it is missing, create it before doing Effect work: mkdir -p .agent-sources && git clone --depth 1 --filter=blob:none https://github.com/effect-ts/effect.git .agent-sources/effect
• Keep the mirror out of product commits. If needed, add .agent-sources/ to .git/info/exclude, not the project .gitignore, unless Joel explicitly wants it committed.
• Search the mirror for current patterns and APIs, especially under packages/effect/src/ and package tests/examples, before calling something an Effect best practice.

Local Source References