effect-v4-services-layers

Use when defining Effect v4 services or wiring Layers — the Context.Service class form (type params first, then the id), Layer construction (succeed/effect, scoped is gone), composition (mergeAll vs provide vs provideMerge), providing once at the boundary, and the memoization discipline that keeps a db pool or HTTP client from being built twice. Consult before reaching for any service or layer name you have not verified.