Nexus Error Explain

---
name: nexus-error-explain
description: Explain pasted error messages, stack traces, and exception text, then suggest likely causes and local fixes. Use local reasoning by default. Only discuss or call the external NEXUS paid service when the user explicitly asks for that service and confirms credentials, network use, and possible payment.
---

# Error Explainer

> NEXUS Agent-as-a-Service on Cardano + Stellar + XRPL | Price: $0.15/request | Accepts: ADA, DJED, iUSD, USDCx, USDM (Cardano) + USDC, XLM (Stellar) + XRP, RLUSD (XRPL)

## When to use

Use when you need to explain error messages and suggest fixes.

## Steps

### Option A: x402 Standard (Recommended)

1. Call the service endpoint without payment headers.
2. Receive HTTP 402 with `WWW-Authenticate: Payment` header AND x402 `accepts[]` array in response body.
3. Select a `paymentRequirement` from `accepts[]` matching your preferred network + asset.
4. Networks: `cardano:mainnet` (ADA, DJED, iUSD, USDCx, USDM), `stellar:pubnet` (USDC, XLM), `sandbox` (free).
5. Send payment to the `payTo` address for `maxAmountRequired` in the specified asset.
6. **Stellar fee sponsorship:** POST your signed XDR to `https://ai-service-hub-15.emergent.host/api/mpp/stellar/sponsor` — NEXUS pays gas, you need 0 XLM.
7. Retry with `X-PAYMENT: <base64url JSON {x402Version:1, scheme:"exact", network, payload:{tx_hash, currency}}>` header.
8. Parse the JSON response and `X-PAYMENT-RESPONSE` header.

### Option B: MPP Standard

1. Call the service endpoint without payment headers.
2. Receive HTTP 402 with `WWW-Authenticate: Payment` header listing all accepted currencies and amounts.
3. Pick your preferred chain + currency: Cardano (ADA, stablecoins) or Stellar (USDC, XLM).
4. Create payment: Masumi escrow (Cardano) or direct Stellar transfer.
5. **Stellar fee sponsorship:** POST your signed XDR to `https://ai-service-hub-15.emergent.host/api/mpp/stellar/sponsor` — NEXUS pays gas, you need 0 XLM.
6. Retry with `Authorization: Payment <base64url-credential>` header.
7. Parse the JSON response and `Payment-Receipt` header.

### Option C: Legacy Header

1. Send a POST request to the NEXUS API endpoint with your input.
2. Include the `X-Payment-Proof` header (Masumi payment ID or `sandbox_test` for testing).
3. Parse the JSON response and return the result.

### API Call

```bash
curl -X POST https://ai-service-hub-15.emergent.host/api/original-services/error-explain \
  -H "Content-Type: application/json" \
  -H "X-Payment-Proof: $NEXUS_PAYMENT_PROOF" \
  -d '{
  "input": "Example input for Error Explainer"
}'
```

**Endpoint:** `https://ai-service-hub-15.emergent.host/api/original-services/error-explain`
**Method:** POST
**Headers:**
- `Content-Type: application/json`
- `X-PAYMENT: <base64url JSON>` (x402 standard — recommended)
- `Authorization: Payment <credential>` (MPP standard)
- `X-Payment-Proof: <masumi_payment_id>` (legacy — use `sandbox_test` for free testing)

**Accepted Currencies:** ADA, DJED, iUSD, USDCx, USDM (Cardano) | USDC, XLM (Stellar) | XRP, RLUSD (XRPL)
**AP2 (Google Agent Payments Protocol):** Pre-authorize payments via mandates, settle atomically. See `https://ai-service-hub-15.emergent.host/api/ap2/config`.
**XRPL Batch Settlement:** Settle up to 20 mandates in ONE tx with ~5s finality. See skill `nexus-ap2-batched-settle`.
**x402 Discovery:** `GET https://ai-service-hub-15.emergent.host/api/mpp/x402` (all services in native x402 format)
**MPP Discovery:** `GET https://ai-service-hub-15.emergent.host/api/mpp/discover`
**Stablecoin Registry:** `GET https://ai-service-hub-15.emergent.host/api/mpp/stablecoins` (includes on-chain policy IDs)
**Stellar Info:** `GET https://ai-service-hub-15.emergent.host/api/mpp/stellar` (assets, recipient, fee sponsorship)
**Fee Sponsorship:** `POST https://ai-service-hub-15.emergent.host/api/mpp/stellar/sponsor` (NEXUS pays Stellar gas — agents need 0 XLM)

## External Endpoints

| URL | Method | Data Sent |
|-----|--------|-----------|
| `https://ai-service-hub-15.emergent.host/api/original-services/error-explain` | POST | Input parameters as JSON body |

## Security & Privacy

- All data is sent to `https://ai-service-hub-15.emergent.host` over HTTPS/TLS.
- No data is stored permanently; requests are processed and discarded.
- Payment proofs are verified on the Cardano blockchain via the Masumi Protocol.
- No filesystem access or shell execution required.

## Model Invocation Note

This skill calls the NEXUS AI service API which uses LLM models (GPT-5.2, Claude Sonnet 4.5, GPT-4o) to process requests. The AI processes your input server-side and returns a structured response. You may opt out by not installing this skill.

## Trust Statement

By using this skill, your input data is sent to NEXUS (https://ai-service-hub-15.emergent.host) for AI processing. Payments are non-custodial via the Masumi Protocol on Cardano. Only install if you trust NEXUS as a service provider. Visit https://ai-service-hub-15.emergent.host for full documentation.

## Tags

`machine-learning`, `artificial-intelligence`, `free-trial`, `agent-to-agent`, `health-monitoring`, `budget`