Use when the user wants to capture a brainstormed idea, feature, or solution into a durable backlog/spec doc under docs/backlog — a human-facing reference that combines context, chosen solution, key decisions (ADR-lite), scope, acceptance criteria, and optional feature/integration/contract/use-case/handoff modules. Drafts the whole doc autonomously from the current conversation and persists docs/backlog/<slug>.md; asks the user only when blocked or a decision genuinely needs their input. NOT a low-level implementation plan (that is superpowers:writing-plans / x-do).