Why this tool exists

Shopify collapses Neodrift's per-product discount logic into a single Custom Discount line item. Sleek Invoice then flat-distributes that single discount across all products. When an order is modified — cancellation, swap, partial refund — the team can't simply subtract Sleek's line amount, because the cancelled item carried a different share of discount than the flat average.

The Calculator tab replays Shopify Flow as a cart simulator (build a cart → see what the customer would actually pay). The Order modification tab is the original use case (original vs. modified, refund delta).

The discount model

The engine has two branches and a freebie pass:

Branch A — Manual code (NEOCOMSECRET / NEOSAVE / NEOSPECIAL)

If the customer enters one of these codes (and cart ≥ ₹1,000), 7% comes off the whole subtotal and it replaces the cart-level discounts — no tier, no Crazy Deal. The prepaid 5% / ₹250 offer still applies when paying prepaid (it's a payment-page discount, computed on the post-code amount). These codes are stack-type NONE.

Branch B — Auto-stack (default)

1. Crazy Deals — if subtotal ≥ ₹3,000, matching SKUs get fixed % off (Travel Pillow 50%, Tramp 24%, …).
2. Cart tier (AUTOFEST family) — the band is picked on the subtotal of items NOT in a Crazy Deal (₹1k–2.5k: 6%, ₹2.5k–5k: 7%, ₹5k–8.5k: 8%, ≥₹8.5k: 10%), and the % applies to those same items.
3. Prepaid offer — if payment method is UPI / Card / Wallet / Net Banking, 5% of (subtotal − Crazy − tier), capped at ₹250. COD doesn't qualify.

Step 4 — Freebies (both branches)

If a qualifying SKU is in cart (e.g. JungleMax / CrystalMax bike cover), the freebie line item (microfiber) is auto-appended at ₹0. It doesn't count toward subtotal, so it can't push the cart into a higher tier.

Step 5 — COD charge & shipping (mirrors Shopflo + Shopify delivery profiles)

COD fee varies by cart value — ₹50 under ₹2,000, ₹100 from ₹2,000–₹30,000 — and is unavailable above ₹30,000 or for floor-mat / seat-cover SKUs (5DMAT/, 7DMAT/), which ship prepaid-only at ₹499. Shipping mirrors the live Shopify delivery profiles: STANDARD is free up to ₹30,000; EXPRESS (₹75 / ₹150 / ₹300) and PRIORITY (₹149 / ₹250 / ₹500) are optional paid speeds offered only for carts ₹1,000–₹15,000 (post-discount value) and are prepaid-only. When an order is fetched from Shopify, the calculator uses that order's actual shipping charge instead of these rules. Surcharges are never discounted.

Sync check — fetched orders are the source of truth

A fetched Shopify order carries the live discounts and the real paid total. The calculator recomputes the same cart with its rules and compares: a red OUT OF SYNC banner means a rule here has drifted from the store (e.g. a discount condition changed) — the mismatch is auto-logged to the Sync Log tab so it can be reviewed and the rules fixed. Refetching the order after a fix auto-resolves the entry.

Worked example — order #63100

• Sunbrella ₹799 + Car Cover ₹2,687 + Travel Pillow ₹499 = ₹3,985 subtotal
• Subtotal ≥ ₹3,000 → Crazy Deal: Travel Pillow 50% off = -₹249.50
• Subtotal in ₹2.5k-5k tier → 6% on non-crazy items (₹799+₹2,687 = ₹3,486) = -₹209.16
• Prepaid 5% × (₹3,985 - ₹249.50 - ₹209.16) = 5% × ₹3,526.34 = -₹176.32 (under ₹250 cap)
• Grand total: ₹3,985 − ₹634.98 = ₹3,350.02 ✓ matches Shopify

Sunbrella cancellation — the actual problem case

• Remaining: Car Cover ₹2,687 + Travel Pillow ₹499 = ₹3,186 subtotal
• Still ≥ ₹3,000 → Crazy Deal still applies (-₹249.50)
• Still in ₹2.5k-5k tier → 6% on Car Cover (₹2,687) = -₹161.22
• Prepaid 5% × ₹2,775.28 = -₹138.76
• New total: ₹2,636.52
• Correct refund = ₹3,350.02 − ₹2,636.52 = ₹713.50
• Sleek's flat-distributed refund would be only ₹671.68 — customer underpaid by ₹41.82.

How to use this tool

Calculator tab — fresh quote

1. Pick items from the catalog on the left (or "+ Custom" to add a one-off line).
2. Set qty in the live cart; remove with ×.
3. Optionally type a manual code (e.g. NEOCOMSECRET) — it replaces the tier/Crazy-Deal discounts; the prepaid 5%/₹250 offer still applies when paying prepaid.
4. Pick the payment method — COD drops the 5% prepaid offer and adds the ₹100 COD charge.
5. Watch the breakdown panel update live. Copy quote when ready.

Order modification tab — refund calc

1. Open the order in Shopify, copy line items into the Original pane (or use the catalog).
2. Verify the grand total matches Shopify's "Paid by customer".
3. Click ↩ Copy from original, then remove/edit items on the right.
4. Read Refund to issue at the bottom — that's the amount Accounts processes.