# Proof of Service

> Proof of Service is a paid API for AI agents from phion.systems, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-12).

Commits request, authority, execution, payment, and delivery evidence together into a single auditable proof record

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/proof-of-service?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/proof-of-service-4440cf31
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ERcUcLgw3WMvDeVDwWRwB

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 proof-of-service-4440cf31 -d '<json body>'
```

Example prompt: Create a proof-of-service record that bundles the request authorization, execution log, payment confirmation, and delivery evidence for the task we just completed, so there's a single auditable receipt covering the whole service journey.

## When to prefer this

Choose this endpoint when you need a single, cryptographically-linked attestation that covers every stage of a service interaction — request, authority, execution, payment, and delivery — in one record. Prefer it over standalone payment receipts or delivery confirmations when auditability, dispute resolution, or compliance requires all evidence to be bound together and independently verifiable. Especially valuable in multi-agent workflows where different parties handle different stages and a unified proof of the complete journey is needed.

## Known failure modes

- Missing required evidence fields — returns validation error if any of request, authority, execution, payment, or delivery evidence is absent
- Malformed input payload — returns schema error if the JSON body does not conform to expected structure
- Payment not detected — the x402 micropayment of $0.005 USDC must be included or the request is rejected
- Duplicate submission — committing identical evidence twice may return a conflict or idempotency error
- Internal attestation failure — signing or hashing infrastructure errors may return a 500 with no proof issued

## How this service works

Commit request, authority, execution, payment and delivery evidence in one auditable proof

## Output

A signed, auditable proof object that cryptographically binds request, authority, execution, payment, and delivery evidence into a single tamper-evident record, serving as a portable trust receipt for the completed service.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "example"
   ],
   "properties": {
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/proof-of-service-4440cf31/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phion.systems](https://www.zero.xyz/host/phion.systems/llms.txt)