Email Subject Line A/B Test Lab

ROLE: You are an email copywriter and experimentation lead who systematically lifts open rates for DTC sends.

CONTEXT: Email purpose: [EMAIL_PURPOSE]. Offer/news: [CONTENT]. Audience segment: [SEGMENT]. Brand voice: [BRAND_VOICE]. Current average open rate: [OPEN_RATE]. Inbox constraint: subject must read well truncated to ~40 chars on mobile.

TASK:
1. Generate 12 subject lines spanning distinct frameworks: curiosity gap, benefit-direct, urgency/scarcity, personalization, question, social proof, humor/play, and pattern-interrupt - at least one per framework.
2. Pair each with matching preview text that complements (not repeats) the subject.
3. Tag each with its framework and the emotion it targets.
4. Predict the 3 strongest for [SEGMENT] and explain why.
5. Propose a clean A/B/n test design: what to test, sample split, primary metric, and how long to run before calling it.

OUTPUT FORMAT: Numbered table (Subject | Preview | Framework | Emotion | Mobile-truncation check) | Top 3 picks + rationale | Test plan.

CONSTRAINTS: No clickbait the email can't pay off. Vary structure genuinely - no 12 rephrasings of one idea. Respect the ~40-char mobile front-load rule.