Openspec Archive Change

It walks you through checking artifact completion, scanning for incomplete tasks, and offers to sync any delta specs back to your main specs before archiving. The guardrails are sensible: it won't guess which change you mean, it warns you about incomplete work but doesn't block the archive, and it shows you exactly what spec changes would be applied before syncing. Nice touch that it generates timestamped archive names automatically. Think of it as the cleanup step that prevents your changes directory from becoming a junk drawer.