Effect 4.0 ships zero-dependency TypeScript core

Effect 4.0 looks less like a routine framework upgrade and more like an attempt to become TypeScript’s production runtime for reliable applications and AI agents.

• –Core modules now share one ecosystem and version, reducing dependency sprawl and supply-chain exposure
• –Built-in typed errors, structured concurrency, dependency injection, workflows, clustering, and observability target backend systems beyond simple libraries
• –AI, HTTP, SQL, RPC, and CLI capabilities are consolidated under the `effect` namespace, giving coding agents a broader, more coherent API surface
• –The performance gains are compelling, but the v3-to-v4 migration remains a meaningful architectural change
• –At least three years of bug and security support makes v4 a credible option for production teams wary of fast-moving frameworks