# Delx Seeded A/B Assignment

> Delx Seeded A/B 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 subject to an A/B variant (A or B) using a seed and configurable weight, returning a stable bucket value and variant label.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/seeded-ab-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-a-b-assignment-0788e009
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_y7Nxeq8tNhx4X13lwAyx8

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-a-b-assignment-0788e009 -d '<json body>'
```

Example prompt: Assign user ID 'user_8821' to an A/B variant using experiment seed 'checkout-flow-v3' with a 70% weight for variant A.

## When to prefer this

Use this endpoint when you need deterministic, reproducible A/B variant assignment — i.e., the same seed+subject pair must always return the same variant. Prefer it over random assignment when you need consistency across sessions or services without storing assignment state, and when you want configurable weighting between variants.

## Known failure modes

- Missing required 'seed' or 'subject' fields returns a validation error
- weight_a outside 0–1 range may produce unexpected bucketing behavior
- Very long seed or subject strings (approaching 8192 char limit) may cause payload rejection
- Network timeouts on the $0.001 USDC x402 payment flow before computation begins

## How this service works

Seeded Ab Assignment: Seeded Ab Assignment assigns a stable subject to A or B using caller weights from bounded caller-supplied values without an external provider. Call Seeded Ab 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 Ab Assignment as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, s…

## Output

Returns a JSON object with a floating-point bucket value (0–1), a variant label ('A' or 'B'), operation name, status ('pass'), and evidence block confirming no data retention and zero external calls made during computation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "seed": {
   "type": "string",
   "maxLength": 8192,
   "description": "Seed supplied to Seeded Ab Assignment; used only for this bounded calculation and processed in memory without retention."
  },
  "subject": {
   "type": "string",
   "maxLength": 8192,
   "description": "Subject supplied to Seeded Ab Assignment; used only for this bounded calculation and processed in memory without retention."
  },
  "weight_a": {
   "type": "number",
   "description": "Weight A supplied to Seeded Ab Assignment; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "bucket": 0.207537504388443,
   "variant": "A"
  },
  "schema": "delx/util-seeded-ab-assignment/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "96739ac478c933dfd4385515e11012fab06dfd8342764dd368da174bbe750bfa",
   "external_calls": 0
  },
  "operation": "seeded_decision:seeded_ab_assignment"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-seeded-a-b-assignment-0788e009/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)