vertical-fitness

# Fitness & wellness — spec it like a studio bills and books Boutique studios, gyms, coaches, on-demand brands. Members on recurring plans, classes with finite capacity, retention won or lost on attendance. A builder who models this as "events + tickets" ships something no studio owner will run their business on — because the hard parts are *billing* and *waitlists*, not the calendar. This skill is the domain briefing so the spec is right before code starts. ## 1. Domain vocabulary (know these or look naive) - **Class pack vs unlimited membership vs drop-in** — three distinct products. A **pack** is N prepaid classes that decrement (10-class pack); an **unlimited membership** is a recurring plan (often monthly auto-renew) with no per-class deduction; a **drop-in** is a single paid visit. The schema must hold all three, not collapse them into "credits". - **Recurring billing / auto-renew** — memberships rebill on a cycle (monthly is the norm) until cancelled. This is the revenue engine and the hardest thing to get right (see §2). - **Waitlist** — a full class has an ordered queue; when a spot opens (someone late-cancels), the system **auto-promotes** the next person and notifies them. Core, not optional. - **Late-cancel / no-show fee** — cancelling inside the policy window (e.g. <12h) or not showing forfeits the class (pack decrements) or charges a fee. The policy *is* the booking discipline. - **Class capacity** — every class has a hard cap (bikes, mats...