# Synthex Forge Budget Preflight Check

> Synthex Forge Budget Preflight Check is a paid API for AI agents from x402.synthexforge.com, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-22).

Validates whether an agent action is permitted under a given spending policy before executing a paid operation, returning an approval decision.

## Facts

- Endpoint: POST https://x402.synthexforge.com/v1/budget/preflight?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synthex-forge-budget-preflight-check-a35253d7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_o1wn5V-jRUB3TSMbHtnvh

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 synthex-forge-budget-preflight-check-a35253d7 -d '<json body>'
```

Example prompt: Before my agent 'agent-007' spends $0.25 on the next action, can you run a preflight check against our current budget policy to confirm it's authorized?

## When to prefer this

Use this endpoint when you need to gate an agent's spending action against a declarative policy before committing to a paid operation — especially in multi-agent or automated workflow contexts where budget governance and auditability are required. Prefer this over ad-hoc balance checks when you have a structured policy object and need a signed, attestable compliance decision rather than a simple balance lookup.

## Known failure modes

- Missing or malformed policy object returns a 4xx validation error
- Invalid agent_id format may cause rejection
- action_amount_usd exceeding policy limits returns ok: false rather than an error
- HTTP 402 payment-required if the $0.25 USDC preflight fee is not satisfied
- Network or service unavailability returns 5xx
- Expired or revoked policy may return authorization denial

## How this service works

Synthex Forge x402 Receive: 41 paid verification, attestation and governance endpoints (Ed25519 + SHA-256 signed artifacts) plus free verify/public-key/standard sibling routes. Paid routes answer HTTP 402 with an x402 v2 `payment-required` envelope (atomic USDC on Base mainnet, chain ID 8453). Free routes are declared with `security: []` per the x402scan discovery spec.

## Output

Returns a JSON object with an 'ok' boolean indicating whether the proposed agent action and amount are permitted under the provided spending policy. A true value means the action is authorized; false means it would violate the budget constraints.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "policy": {
   "type": "object"
  },
  "agent_id": {
   "type": "string"
  },
  "action_amount_usd": {
   "type": "number"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synthex-forge-budget-preflight-check-a35253d7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.synthexforge.com](https://www.zero.xyz/host/x402.synthexforge.com/llms.txt)