StackGuard lets you run overlapping promotions — percentage, fixed, BOGO, buy-A-get-B, mix-and-match bundles, and volume tiers — while a hard guardrail caps the total discount on every cart and item, so a stack can never cut below your margin floor. Every discount is explainable: a clear trace shows exactly which rules applied and why. Set cart-wide or per-item caps, use Exclusive mode to block outside discounts, and preview any cart before going live — the same engine runs at checkout.

• Hard cap on total and per-item discount so stacks never break your margin
• 7 discount types: percentage, fixed, BOGO, buy-A-get-B, bundles, volume tiers
• Clear trace shows exactly which rules applied to every cart and why
• Clear trace shows exactly which rules applied to every cart and why
• Exclusive mode stops outside discounts; auto-skip items already on sale