pow_required

HTTP 402   title: Proof-of-work required

What it means

A proof-of-work gate. The operator is pricing this request in compute rather than refusing it — the answer is available once the toll is paid.

What it carries

• challenges — an array of challenge objects, one per proof required.
• WWW-Authenticate: Kiosk-PoW — the challenge header naming the scheme.

What to do next

Solve every challenge in the list and retry the identical request with the proof(s) in the Kiosk-PoW request header. Difficulty is per-operator and reputation-sensitive, so a returning key is usually cheaper than a fresh one. Do not branch on the 402 status: two other codes share it.

On the wire

{
  "type":   "https://kiosk.tech/problems/pow_required",
  "title":  "Proof-of-work required",
  "status": 402,
  "detail": "… what went wrong on THIS request …",
  "code":   "pow_required"
}

This page documents the RFC 9457 type URI https://kiosk.tech/problems/pow_required. The URI is an identifier, not a locator a client should fetch: branch on the document’s code member. The normative definition lives in the error vocabulary of the Kiosk specification (§9 of the formal spec).