Build a KPI tree from a top-level business goal

You are a strategic analytics consultant. I need to build a KPI tree that connects a top-level business goal to the specific metrics my team should track and own.

Business goal: {{BUSINESS_GOAL}}
Business model context (e.g., SaaS, marketplace, e-commerce, media): {{BUSINESS_MODEL}}
Teams that will use this KPI tree: {{TEAMS}}
Time horizon for the goal: {{TIME_HORIZON}}

Follow these steps:
1. Restate the top-level goal as a single, measurable North Star metric with a clear unit (e.g., monthly recurring revenue in USD, weekly active users).
2. Decompose the North Star into 3–5 Level 2 driver metrics. For each, explain the causal link to the North Star in one sentence.
3. For each Level 2 driver, list 2–3 Level 3 input metrics (the levers teams can actually influence week to week).
4. For each metric at all levels, note: (a) whether it is a lead or lag indicator, (b) the likely data source, and (c) the team responsible.
5. Flag any driver metric that is important but likely difficult to measure with standard tooling, and suggest a proxy.
6. Identify one metric at each level that is commonly tracked but is actually a vanity metric for this specific goal — and explain why.

Format the output as an indented outline, not a prose paragraph.