OpenSpec Progressive Implementation

Structures OpenSpec changes into independently reviewable, testable implementation phases with clear contract boundaries between them. This is a rigid skill — follow it exactly, do not adapt away the discipline.

When This Applies

This skill applies when you are about to create or modify any of these OpenSpec artifacts: proposal.md, tasks.md, or when executing apply.

Phase Design: Structuring proposal.md

When creating a proposal, add an ## Implementation Phases section. Each phase must satisfy: