# Delx Seeded Multivariate Assignment

> Delx Seeded Multivariate Assignment is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Deterministically assigns a variant from a weighted list using a seed and subject, enabling reproducible A/B or multivariate test bucketing.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/seeded-multivariate-assignment
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-seeded-multivariate-assignment-389a7bab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1vEiI80t7SrxT94i9utmI

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 delx-seeded-multivariate-assignment-389a7bab -d '<json body>'
```

Example prompt: Assign user 'user-42' to one of three variants — 'control', 'copy-a', or 'copy-b' — using seed 'experiment-2024-homepage' and weights [0.5, 0.25, 0.25], and tell me which variant they get.

## When to prefer this

Choose this endpoint when you need a stateless, reproducible, weighted variant assignment that produces the same result for the same seed+subject combination every time, without any server-side state or user data retention. Prefer it over custom hashing logic when you want an auditable evidence trail (input hash, no external calls) and need weighted (non-uniform) probability splits across more than two variants.

## Known failure modes

- Mismatched lengths between variants and weights arrays — may return an error or undefined behavior
- Seed or subject strings exceeding 8192 characters — request rejected
- Weights array exceeding 256 items — request rejected
- Variants array exceeding 256 items — request rejected
- Malformed input types (e.g. non-numeric weights) — validation error
- Payment failure via x402 protocol — 402 response, no computation performed

## How this service works

Seeded Multivariate Assignment: Seeded Multivariate Assignment assigns a stable subject to one weighted variant from bounded caller-supplied values without an external provider. Call Seeded Multivariate Assignment when an agent needs a reproducible decision that another run can independently replay. Returns the deterministic selection plus seed provenance, population bounds, and the operation-specific outcome for Seeded Multivariate Assignment as versioned deterministic JSON. Price: $0.001 USDC…

## Output

Returns a JSON object containing the assigned variant name and its index in the variants array, along with a schema identifier, status, and an evidence block confirming no data was retained, the SHA-256 hash of the input, and zero external calls made.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "seed": {
   "type": "string",
   "maxLength": 8192,
   "description": "Seed supplied to Seeded Multivariate Assignment; used only for this bounded calculation and processed in memory without retention."
  },
  "subject": {
   "type": "string",
   "maxLength": 8192,
   "description": "Subject supplied to Seeded Multivariate Assignment; used only for this bounded calculation and processed in memory without retention."
  },
  "weights": {
   "type": "array",
   "items": {
    "type": "number"
   },
   "maxItems": 256,
   "description": "Weights supplied to Seeded Multivariate Assignment; used only for this bounded calculation and processed in memory without retention."
  },
  "variants": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Variants supplied to Seeded Multivariate Assignment; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "index": 2,
   "variant": "copy-b"
  },
  "schema": "delx/util-seeded-multivariate-assignment/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "d4cc54b28dc2c9127391313e2d1f0fdfeb7409cb441c2107a91ae423c62cc39c",
   "external_calls": 0
  },
  "operation": "seeded_decision:seeded_multivariate_assignment"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-seeded-multivariate-assignment-389a7bab/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)