# Gacha RNG Chi-Square Verifier

> Gacha RNG Chi-Square Verifier is a paid API for AI agents from gaming.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).

Runs a Pearson chi-square goodness-of-fit test on gacha draw outcomes to estimate whether the observed frequencies deviate significantly from declared drop probabilities.

## Facts

- Endpoint: POST https://gaming.halowerk.com/v1/gacha-rng-verify
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gacha-rng-chi-square-verifier-c8dc9185
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nlJI6WrxA5X_NtB53M_s2

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 gacha-rng-chi-square-verifier-c8dc9185 -d '<json body>'
```

Example prompt: I pulled 2000 gacha draws from this banner — 1800 common, 150 rare, and 50 legendary. The declared probabilities are 90%, 7.5%, and 2.5% respectively. Can you run a chi-square test at alpha 0.05 to see if the actual drop rates are statistically consistent with what the game advertises?

## When to prefer this

Use this endpoint when you need a quick, structured statistical test of whether observed gacha or loot-box outcome frequencies match developer-declared drop probabilities. It is purpose-built for gaming randomness auditing with a straightforward chi-square + Wilson-Hilferty approximation pipeline. Prefer it over general-purpose statistics APIs when working within the gaming.halowerk.com ecosystem or when you need a lightweight, pay-per-call solution without setting up a full stats library. Not suitable for proving seed fairness, code integrity, or draw independence — only aggregate frequency fit.

## Known failure modes

- Fewer than 10 draws supplied — minimum input size not met
- Expected counts below 5 for one or more outcomes — chi-square approximation unreliable, result flagged
- Probabilities in outcomes array do not sum to 1.0 — normalization error or rejection
- Outcome labels in draws array don't match declared outcome names — key mismatch error
- alpha value outside allowed range (0.000001 to 0.5) — validation rejection
- More than 100000 draws or more than 100 outcome categories — size limit exceeded

## How this service works

Counts supplied outcomes, computes Pearson’s chi-square statistic, and estimates an upper-tail p-value with the Wilson-Hilferty normal approximation. It tests aggregate frequencies only; it cannot prove draw independence, seed fairness, code integrity, or manipulation, especially when expected counts are small.

## Output

Returns the computed Pearson chi-square statistic, degrees of freedom, the Wilson-Hilferty-approximated upper-tail p-value, and a boolean pass/fail verdict comparing the p-value against the supplied alpha threshold. Does not prove independence, seed integrity, or rule out manipulation — only tests aggregate frequency fit.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "alpha": {
   "type": "number",
   "maximum": 0.5,
   "minimum": 0.000001
  },
  "draws": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 128,
    "minLength": 1
   },
   "maxItems": 100000,
   "minItems": 10
  },
  "outcomes": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "outcome",
     "probability"
    ],
    "properties": {
     "outcome": {
      "type": "string",
      "maxLength": 128,
      "minLength": 1
     },
     "probability": {
      "type": "number",
      "maximum": 1,
      "minimum": 1e-9
     }
    },
    "additionalProperties": false
   },
   "maxItems": 100,
   "minItems": 2
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gacha-rng-chi-square-verifier-c8dc9185/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from gaming.halowerk.com](https://www.zero.xyz/host/gaming.halowerk.com/llms.txt)