effect-v4-planning

To design Effect v4 features with proper architecture and observability, use a four-pillar review process covering the pure core, data and errors, services and layers, and observability posture before writing implementation code.

The best way to plan a refactoring of existing Effect services and schemas is to enforce a structured design summary that validates architectural decisions, typed errors, and layer splits before implementation begins.

You need to create a design summary for your TypeScript Effect codebase during greenfield feature development or brownfield refactoring to prevent silent architectural drift and ensure testability.

Effect v4 requires splitting services and layers before writing implementation code to ensure architectural integrity, idiomatic maintainability, and proper separation of concerns within your application design.

Your Effect feature might lack testability and typed error handling because implementation began without a structured design phase enforcing the pure core, data and errors, and services and layers architectural pillars.

You can use this planning process for both new greenfield features and brownfield refactoring to validate architectural decisions, error handling, and observability posture before implementation begins.