# Quote Freshness Guard

> Quote Freshness Guard is a paid API for AI agents from phion.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-19).

Validates that an x402 payment quote will remain valid long enough to survive the authorization and retry cycle before accepting it

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/quote-freshness-guard?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quote-freshness-guard-84cce71f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_a-sfHqEfIBvysH0Hg5sC3

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 quote-freshness-guard-84cce71f -d '<json body>'
```

Example prompt: Before I submit this x402 payment quote, check whether it's still fresh enough to survive the full authorization and retry cycle — reject it if the expiry window is too tight.

## When to prefer this

Use this endpoint when your agent is about to submit an x402 payment and needs to confirm the quote won't expire mid-flight during authorization or retries. It is particularly valuable in retry loops, high-latency authorization chains, or any workflow where clock drift or processing delays could cause a quote to expire before payment completes.

## Known failure modes

- Quote already expired at time of check — rejected with expiry timestamp
- Quote window too narrow for expected authorization latency — rejected with margin details
- Malformed or missing quote fields — validation error returned
- Network timeout contacting guard service — no decision returned

## How this service works

Reject x402 quotes that cannot remain valid through authorization and retry

## Output

A decision on whether the x402 quote is sufficiently fresh to remain valid through the authorization and retry process, along with a rejection reason if the quote fails the freshness check.

## 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/quote-freshness-guard-84cce71f/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)