# HALOWERK Price History Median Drop Detector

> HALOWERK Price History Median Drop Detector is a paid API for AI agents from handel.halowerk.com, paid per call via x402, $0.007/call, status unknown (last checked 2026-10-10).

Analyzes a product's price history to compute the median price and detect whether a significant price drop has occurred relative to a previous price or a specified drop threshold.

## Facts

- Endpoint: POST https://handel.halowerk.com/v1/price/articles/history-median-drop?utm_source=zero.xyz
- Price: $0.007/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-price-history-median-drop-detector-8dfaf0d9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_dT-xlRcBF1jOwkRDY5vJC

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 halowerk-price-history-median-drop-detector-8dfaf0d9 -d '<json body>'
```

Example prompt: Look at this product's price history — I have 10 observations over the last 3 months for https://shop.example.com/product/42, the previous price was 89.99 USD, and I want to know if the current price represents a drop of more than 15% from the median. Can you run the median drop analysis?

## When to prefer this

Choose this endpoint when you have a structured price history series (at least 3 observations) for a specific product URL and need to compute the historical median and programmatically detect whether a price drop of a given magnitude has occurred. It is particularly useful in automated deal-detection pipelines, repricing validation workflows, and price-alert systems where you want a statistically grounded drop signal rather than a simple point-to-point comparison. Prefer it over simple delta comparisons when you need median-based robustness against price outliers.

## Known failure modes

- Fewer than 3 history items supplied — minimum minItems:3 validation error
- Currency code not matching 3-letter ISO format — pattern validation failure
- Observed_at timestamps malformed or too long (>40 chars)
- Price values exceeding maximum of 1,000,000,000 or negative — schema validation error
- drop_percent set to 0 or negative — exclusiveMinimum violation
- Idempotency key too short (<32 chars) or contains invalid characters
- Payment not provided or insufficient USDC on Base Mainnet — HTTP 402 response
- callback_url unreachable or malformed — async delivery failure

## How this service works

HALOWERK handelswerk — bezahlte Endpunkte nach x402. Preise in USDC auf Base Mainnet.

## Output

Returns a JSON object containing the computed median price from the supplied history, an indicator of whether a significant price drop was detected relative to the previous price and/or specified drop_percent threshold, the magnitude of the drop, and relevant currency information. If a callback_url was provided, the result may also be delivered asynchronously to that endpoint.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048
  },
  "history": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "url",
     "observed_at",
     "value",
     "currency"
    ],
    "properties": {
     "url": {
      "type": "string",
      "maxLength": 2048
     },
     "value": {
      "type": "number",
      "maximum": 1000000000,
      "minimum": 0
     },
     "currency": {
      "type": "string",
      "pattern": "^[A-Z]{3}$"
     },
     "observed_at": {
      "type": "string",
      "maxLength": 40
     }
    },
    "additionalProperties": false
   },
   "maxItems": 60,
   "minItems": 3
  },
  "previous": {
   "type": "object",
   "required": [
    "value",
    "currency"
   ],
   "properties": {
    "value": {
     "type": "number",
     "maximum": 1000000000,
     "minimum": 0
    },
    "currency": {
     "type": "string",
     "pattern": "^[A-Z]{3}$"
    }
   },
   "additionalProperties": false
  },
  "callback_url": {
   "type": "string",
   "maxLength": 2048
  },
  "drop_percent": {
   "type": "number",
   "maximum": 100,
   "exclusiveMinimum": 0
  },
  "idempotency_key": {
   "type": "string",
   "pattern": "^[A-Za-z0-9_-]+$",
   "maxLength": 128,
   "minLength": 32
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-price-history-median-drop-detector-8dfaf0d9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from handel.halowerk.com](https://www.zero.xyz/host/handel.halowerk.com/llms.txt)