# Delx Seeded Window Pick

> Delx Seeded Window Pick is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Deterministically selects a contiguous window of items from a list using a seed string, returning the sub-array and its start index.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/seeded-window-pick
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-seeded-window-pick-7ed842b3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_y39uxdn0LoLNqZGr5RY-y

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-window-pick-7ed842b3 -d '<json body>'
```

Example prompt: Pick a deterministic window of 3 items from the list [1, 2, 3, 4, 5, 6, 7] using the seed 'user-42-session' — give me the selected items and the start index.

## When to prefer this

Choose this endpoint when you need a reproducible, seed-driven contiguous window selection from a list of integers — for example, for deterministic feature flag assignment, fair slot rotation, or stable quiz question sampling. It is processed entirely in memory with no retention and no external calls, making it safe for privacy-sensitive use cases. Prefer it over random sampling when the same seed must always yield the same window.

## Known failure modes

- Window size larger than the items array length — likely returns an error or empty result
- Empty items array with a positive window size — may return an empty result or error
- Invalid or missing seed string — may cause a 400 bad request
- Items array exceeds the 256-element maximum — request rejected
- Non-integer values in items array — schema validation failure

## How this service works

Seeded Window Pick: Seeded Window Pick selects a reproducible contiguous window from caller items from bounded caller-supplied values without an external provider. Call Seeded Window Pick 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 Window Pick as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, statel…

## Output

Returns a JSON object with the selected sub-array of items, the start index of the window within the original list, a schema identifier ('delx/util-seeded-window-pick/v1'), a 'pass' status, and an evidence block confirming no data retention, no external calls, and the SHA-256 of the input.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "seed": {
   "type": "string",
   "maxLength": 8192,
   "description": "Seed supplied to Seeded Window Pick; used only for this bounded calculation and processed in memory without retention."
  },
  "items": {
   "type": "array",
   "items": {
    "type": "integer"
   },
   "maxItems": 256,
   "description": "Items supplied to Seeded Window Pick; used only for this bounded calculation and processed in memory without retention."
  },
  "window_size": {
   "type": "integer",
   "description": "Window Size supplied to Seeded Window Pick; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "items": [
    2,
    3,
    4
   ],
   "start_index": 1
  },
  "schema": "delx/util-seeded-window-pick/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "1046227e8b1c61c8658038d68757f80f7254aa306a9fdab930936da0103b9e24",
   "external_calls": 0
  },
  "operation": "seeded_decision:seeded_window_pick"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-seeded-window-pick-7ed842b3/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)