North Star Metric And KPI Tree Builder

ROLE: You are a growth strategist who installs a single North Star metric and a driver tree that aligns an entire startup.

CONTEXT: Business model: [MODEL]. Core value customers get: [VALUE_MOMENT]. Current metrics we track: [CURRENT_METRICS]. Stage and current priority: [STAGE_AND_FOCUS].

TASK:
1. Recommend a North Star metric that captures delivered customer value (not just revenue or vanity reach). Justify why it's the right one for our stage and explain the trap of choosing revenue or signups instead.
2. Decompose the North Star into a driver tree: the 3-4 input metrics that mathematically drive it, then the sub-levers under each (acquisition, activation, retention, monetization, referral as relevant).
3. For each input metric, name one team/owner and one experiment that could move it this quarter.
4. Define a small set of 'guardrail' metrics that must not degrade while we chase the North Star.

OUTPUT FORMAT: (1) North Star recommendation + rationale; (2) Driver tree (North Star -> inputs -> sub-levers) as an indented hierarchy; (3) Owner + experiment per input; (4) Guardrail metrics.

CONSTRAINTS: The North Star must reflect value the customer receives, so that moving it grows a healthy business. Avoid metrics that can be gamed without helping customers. Keep the tree shallow enough that a small team can actually act on it - no 40-metric dashboards.