# Oblique Markets Ghost Bid Audit

> Oblique Markets Ghost Bid Audit is a paid API for AI agents from api.oblique.markets, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Audits a selected agent offer against rejected cheaper alternatives, computing counterfactual savings, regret scores, and producing a tamper-evident receipt.

## Facts

- Endpoint: POST https://api.oblique.markets/api/v1/paid/ghost-bid-audit
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/oblique-markets-ghost-bid-audit-9b85b1ce
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Feo6bjgcDOzFOP2QxF-hE

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 oblique-markets-ghost-bid-audit-9b85b1ce -d '<json body>'
```

Example prompt: Audit my agent's selected offer — it chose an offer at 5000 atomic units when there were cheaper alternatives at 3200 and 4100 — give me the counterfactual savings, regret score, and a tamper-evident receipt using my signature secret.

## When to prefer this

Choose this endpoint when an AI agent needs to produce a verifiable, tamper-evident audit trail of a marketplace offer selection — particularly when accountability, counterfactual analysis, or proof of due diligence is required. It is the right choice when you need to quantify regret or savings relative to rejected bids, or when a downstream party needs a signed receipt proving alternatives were considered. Prefer this over simple price comparison when cryptographic integrity of the audit record matters.

## Known failure modes

- Missing or malformed selected_offer object returns 400 validation error
- Empty alternatives array yields trivial audit with zero counterfactual savings
- Signature secret mismatch or absence prevents tamper-evident receipt generation
- max_price_atomic out of range or negative returns input validation failure
- selected_offer_declared flag inconsistency with signed_selected_offer causes rejection
- Payment not attached (x402 protocol) results in 402 Payment Required

## How this service works

Use when an agent needs ghost bid audit. Returns Audit a selected agent offer against rejected affordable alternatives with counterfactual savings, regret, and a tamper-evident receipt. $0.01.

## Output

Returns a structured audit report including: counterfactual savings (how much cheaper the best rejected alternative was), a regret score quantifying the suboptimality of the selection, a comparison of the selected offer versus all provided alternatives, and a tamper-evident cryptographic receipt tied to the signature secret, confirming the declared offer and audit inputs.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "alternatives": {
   "type": "array"
  },
  "selected_offer": {
   "type": "object"
  },
  "max_price_atomic": {
   "type": "integer"
  },
  "signature_secret": {
   "type": "string"
  },
  "signed_selected_offer": {
   "type": "object"
  },
  "selected_offer_declared": {
   "type": "boolean"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "generated_at": "2026-08-24T12:00:00.000Z",
  "regret_score": 0.25,
  "audit_receipt": "sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
  "audit_version": "ghost-bid-audit.v1",
  "budget_atomic": 12000,
  "savings_atomic": 3000,
  "selected_offer": {
   "id": "offer-selected",
   "provider": "seller-a",
   "price_atomic": 12000
  },
  "price_delta_atomic": 3000,
  "alternatives_considered": 2,
  "selected_offer_verification": "explicit",
  "best_rejected_affordable_option": {
   "id": "offer-rejected",
   "provider": "seller-b",
   "price_atomic": 9000
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/oblique-markets-ghost-bid-audit-9b85b1ce/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.oblique.markets](https://www.zero.xyz/host/api.oblique.markets/llms.txt)