# Buy-X-Get-Y-Free Merchandise Total: Sequential Input-Change Attribution

> Buy-X-Get-Y-Free Merchandise Total: Sequential Input-Change Attribution is a paid API for AI agents from market.datapackvibe.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-19).

Computes and attributes the change in Buy-X-Get-Y-Free promotional merchandise totals between two sets of retail parameters, showing which input changes drove the difference.

## Facts

- Endpoint: POST https://market.datapackvibe.com/x402/assistant-ar-retail-multibuy-price-waterfall?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/buy-x-get-y-free-merchandise-total-sequential-input-change-attribution-e7403076
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xhGu7qLL0P1ELTrI_S8LX

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability buy-x-get-y-free-merchandise-total-sequential-input-change-attribution-e7403076 -d '<json body>'
```

Example prompt: I changed my Buy-2-Get-1-Free deal: before it was 10 basket units at $25 each with 2 paid and 1 free per group, and after it's 11 basket units at $27.50 with the same group structure — can you do a sequential attribution breakdown showing which input change drove the difference in my merchandise total?

## When to prefer this

Use this endpoint when you need to understand *why* a Buy-X-Get-Y-Free merchandise total changed between two scenarios — specifically to attribute the delta sequentially to each input variable. Prefer it over generic pricing calculators when you need a waterfall/attribution breakdown rather than just a single total, and when your scenario involves multi-buy promotional structures (buy X, get Y free) with retail basket parameters.

## Known failure modes

- Invalid parameter ranges (e.g. paid_units_per_group < 1) return validation errors
- basket_units or group unit counts exceeding 1,000,000 may be rejected
- unit_price exceeding 1,000,000,000,000 is out of range
- Missing required fields in before or after objects cause schema validation failures
- Payment failure or insufficient USDC balance prevents call execution

## How this service works

Buy-X-get-Y-free merchandise total - Sequential input-change attribution: Sequential input-change attribution for Buy-X-get-Y-free merchandise total. Supplied retail figures only, up to 200 records. No platform access, live rates or order execution. One of 25 new profiles across 20 shared operations in this industry. 0.01 USDC includes one bounded sequential input-change attribution report.

## Output

A bounded sequential input-change attribution report that decomposes the difference in Buy-X-Get-Y-Free merchandise totals between 'before' and 'after' retail parameter sets, quantifying how much each individual input change (unit price, basket units, paid units per group, free units per group) contributed to the total delta in sequence.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "after": {
   "type": "object",
   "default": {
    "unit_price": 27.500000000000004,
    "basket_units": 11,
    "free_units_per_group": 1,
    "paid_units_per_group": 2
   },
   "required": [
    "basket_units",
    "paid_units_per_group",
    "free_units_per_group",
    "unit_price"
   ],
   "properties": {
    "unit_price": {
     "type": "number",
     "default": 25,
     "maximum": 1000000000000,
     "minimum": 0
    },
    "basket_units": {
     "type": "integer",
     "default": 10,
     "maximum": 1000000,
     "minimum": 0
    },
    "free_units_per_group": {
     "type": "integer",
     "default": 1,
     "maximum": 1000000,
     "minimum": 0
    },
    "paid_units_per_group": {
     "type": "integer",
     "default": 2,
     "maximum": 1000000,
     "minimum": 1
    }
   },
   "additionalProperties": false
  },
  "before": {
   "type": "object",
   "default": {
    "unit_price": 25,
    "basket_units": 10,
    "free_units_per_group": 1,
    "paid_units_per_group": 2
   },
   "required": [
    "basket_units",
    "paid_units_per_group",
    "free_units_per_group",
    "unit_price"
   ],
   "properties": {
    "unit_price": {
     "type": "number",
     "default": 25,
     "maximum": 1000000000000,
     "minimum": 0
    },
    "basket_units": {
     "type": "integer",
     "default": 10,
     "maximum": 1000000,
     "minimum": 0
    },
    "free_units_per_group": {
     "type": "integer",
     "default": 1,
     "maximum": 1000000,
     "minimum": 0
    },
    "paid_units_per_group": {
     "type": "integer",
     "default": 2,
     "maximum": 1000000,
     "minimum": 1
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/buy-x-get-y-free-merchandise-total-sequential-input-change-attribution-e7403076/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from market.datapackvibe.com](https://www.zero.xyz/host/market.datapackvibe.com/llms.txt)