{
  "id": "09-carbon-coach",
  "title": "Carbon Coach",
  "problem": "Climate-aware consumers want to lower their personal carbon footprint but can't tell which lifestyle changes meaningfully matter and which are theatrical (e.g., reusable straws vs. flying less). Existing carbon calculators give one-shot estimates without sustained behavior change support.",
  "targetUser": "Climate-aware consumers in high-income countries, 25–55, already willing to change habits but unsure where to invest effort.",
  "desiredOutcome": "Sustained, measurable per-user reduction in monthly footprint over a 6-month period, driven by 2–3 high-impact behavior changes per user.",
  "initialHypothesis": "Social comparison via leaderboards (anonymous opt-in) drives behavior change more than absolute numbers — people respond to relative status more than abstract climate goals.",
  "constraints": [
    "Footprint estimates must cite their methodology (no black-box numbers)",
    "Anonymous social features only — no real-name sharing",
    "EU compliance with the upcoming Green Claims Directive"
  ],
  "meta": {
    "isHoldout": true,
    "expectedDifficulty": "medium",
    "testsFor": ["behavioral", "social-mechanics", "regulatory", "sustained-engagement"]
  }
}