Promotions & Discounts

Discounts are easy to add and hard to control. Model the rules so promotions stack predictably, can't be abused, and never quietly destroy margin — independent of platform.

Before Starting

Gather: promotion types in use, who can stack with what, abuse history (code sharing, repeat redemption), and goal (design the engine, define stacking/exclusivity rules, or audit existing promos for leaks).

How This Skill Works

Mode	Trigger	Output
Design	design	Discount engine model + rule schema
Rules	rules	Stacking, exclusivity, and eligibility matrix
Audit	audit	Margin-leak and abuse-risk review

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Phase 1 — Discount Model

Model every promotion as trigger → condition → effect → constraints:

Part	Examples
Trigger	code entered, automatic, cart threshold
Condition	min subtotal, specific collection, customer segment, first order
Effect	% off, fixed off, free shipping, BOGO, fixed price
Constraints	usage cap (global/per-customer), date window, exclusivity

Rule: Discounts apply to a defined scope (line / shipping / order) and are recomputed server-side at checkout — never client-trusted.

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Phase 2 — Stacking & Exclusivity

The hard part. Define explicitly:

• Stackable vs exclusive: most stores allow one order-level code; auto-discounts may stack with codes. Decide and enforce.
• Application order matters for % vs fixed — define it (typically line discounts → order discounts → shipping).
• Priority when multiple eligible: best-for-customer vs best-for-merchant — pick a policy.
• Caps: max discount per order; floor on post-discount margin.

For the full eligibility matrix and worked stacking examples, model the matrix per the table above.

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Phase 3 — Gift Cards & Abuse Prevention

• Gift cards are stored-value tender, not discounts — track balance, partial redemption, and never let balance go negative or expire silently where regulated.
• Abuse defenses: per-customer usage caps, one-time codes, segment gating, and minimum-order thresholds. Watch for code leaks to coupon sites.

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Output Artifacts

Request	Output
Design	Rule schema + effect/scope model
Rules	Stacking/exclusivity matrix + application order
Audit	Leak/abuse findings: PASS / CONCERNS / FAIL

A promotion engine is COMPLIANT when discounts are server-computed, stacking and application order are explicit, usage caps are enforced, and a margin floor protects every order.

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Related Skills

• cart-checkout: applies discounts at the cart/checkout.
• pricing-strategy: sets the base prices discounts modify.
• commerce-analytics: measures promo ROI and margin impact.
• referral-program: a specialized promotion type.