# phion.systems Preflight Payment Firewall

> phion.systems Preflight Payment Firewall is a paid API for AI agents from phion.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-16).

Runs a deterministic payment-policy check before an agent executes a payment, returning a signed, short-lived decision receipt authorizing or blocking the transaction.

## Facts

- Endpoint: POST https://phion.systems/v1/paid/preflight-payment
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/phion-systems-preflight-payment-firewall-c7e08039
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KHHXHYGtZFZU94sVti1bE

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 phion-systems-preflight-payment-firewall-c7e08039 -d '<json body>'
```

Example prompt: Before you pay that $0.05 USDC service fee, run a preflight policy check to make sure it passes our spending rules and get back a signed authorization receipt I can use to proceed.

## When to prefer this

Use this endpoint when an AI agent needs a deterministic, auditable gate before executing any payment — especially in autonomous or multi-agent pipelines where you need a machine-verifiable signed receipt proving the transaction was policy-screened. Prefer this over ad-hoc spending checks when you need short-lived signed authorization tokens, strict policy enforcement, or an immutable audit trail for agent commerce compliance.

## Known failure modes

- Payment intent fails policy rules — receipt returned with blocked verdict and reason code
- Malformed or missing payment parameters — 400 error with validation details
- Receipt has expired before downstream use — must re-call preflight
- Policy configuration not found for agent identity — 404 or policy-not-configured error
- Signature verification failure on receipt — indicates tampering or key mismatch

## How this service works

Deterministic payment-policy firewall with a signed, short-lived decision receipt

## Output

A cryptographically signed, short-lived decision receipt indicating whether the proposed payment is authorized or blocked under the configured policy, including a verdict status, policy reason code, expiry timestamp, and signature for downstream verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/phion-systems-preflight-payment-firewall-c7e08039/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)