spec-author-from-impl

Author a feature spec by working backwards from existing code and tests, capturing what the product actually does today including a user-flow contract for journeys that already exist. Use when the user says "spec this existing feature", "document how this works", "we need a spec for X that's already built", or when backfilling a spec estate on an existing codebase. Pairs with spec-author-greenfield for design-first authoring.