Living spec

Living spec is ystack's lightweight documentation layer. Keep the repository's current product behavior understandable without requiring a full specification framework for every task.

This skill is intentionally small. It distinguishes:

• current truth — what the product now promises;
• change context — what one in-progress change is trying to alter;
• decision rationale — why one durable technical choice won;
• execution evidence — how the work was performed and verified.

Do not combine those into one ever-growing document.

Portability (required)