# HALOWERK Price History Volatility Safe-Drop Checker

> HALOWERK Price History Volatility Safe-Drop Checker 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 determine whether a current price drop is statistically safe (low volatility) or suspicious, using coefficient of variation thresholds.

## Facts

- Endpoint: POST https://handel.halowerk.com/v1/price/articles/history-volatility-safe-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-volatility-safe-drop-checker-385eff6d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lsBnbX_frgCmbgQfaTWIP

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-volatility-safe-drop-checker-385eff6d -d '<json body>'
```

Example prompt: Check whether the 35% price drop on https://shop.example.com/product/123 is statistically safe — here's its price history for the last 30 days (in USD), the previous price was $89.99, and flag it only if the coefficient of variation is under 15%.

## When to prefer this

Choose this endpoint when you need a statistically grounded verdict on whether a price drop is genuine rather than an artifact of high price volatility. It is specifically designed for the 'safe drop' pattern — filtering out discounts that are meaningless because the product's price fluctuates wildly. Prefer this over simple threshold checks when you have a price history array and want a coefficient-of-variation-based filter to avoid false deal alerts.

## Known failure modes

- Fewer than 3 history items provided — minimum minItems:3 not met
- History array exceeds 60 items — maxItems:60 exceeded
- drop_percent or max_cv_percent set to 0 or negative — exclusiveMinimum:0 violated
- Currency code not 3 uppercase letters — pattern mismatch
- Idempotency key too short (min 32 chars) or contains invalid characters
- Payment not included or rejected — x402 payment required
- Malformed URL in url or callback_url fields

## How this service works

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

## Output

Returns a JSON result indicating whether the observed price drop is deemed 'safe' (i.e., the price series has low enough volatility as measured by the coefficient of variation), along with computed statistical measures such as the CV percentage and likely a boolean safe/unsafe verdict. May include supporting statistics from the price history analysis.

## 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
  },
  "max_cv_percent": {
   "type": "number",
   "maximum": 10000,
   "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-volatility-safe-drop-checker-385eff6d/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)