plan-first-development

Plan-first development structures work by reading existing code, drafting a concise spec, and decomposing tasks into actionable subtasks before implementation. Use it for large codebases, cross-module changes, and onboarding sessions where context matters.

To write a development spec and break work into subtasks, start by reading relevant codepaths to avoid duplication. Draft a concrete spec, decompose it into independently testable subtasks, implement each, and perform a comprehension check before committing.

Yes, plan-first development works for large codebase refactoring. It reduces drift by enforcing upfront reading of existing code and decomposing cross-module changes into small, verifiable, independently testable tasks before implementation.

The best way to prevent code drift during cross-module changes is plan-first development, which forces end-to-end planning, subtask generation, and a formal comprehension check before commits to ensure safe delivery.

A comprehension check works as a formal verification step before commits, ensuring engineers fully understand the existing codepaths and the implemented subtasks to reduce drift and accelerate safe delivery.