---
skill_id: gf-x402-error-code-playbook
evaluation: free
quality: agent-decision-grade
functional: true
price_usd_full: 0.99
price_label: $0.99 / unlock
kind: good
category: Agent Ops
challenge: https://lvlltd.com/api/pay?skill=gf-x402-error-code-playbook
outline: https://lvlltd.com/skills/gf-x402-error-code-playbook/outline.json
runtime_after_unlock: src/index.js createSkill
standards: x402, ERC-7857
completion_pass: functional-v1
---

# Free sample — x402 Error Code Playbook

**Skill ID:** `gf-x402-error-code-playbook`  
**Unlock:** $0.99 / unlock USDC on Base via x402  
**What you get after pay:** runnable sealed pack (`createSkill().run`) + workbook + templates  

## Summary

Agent-facing map of SKILL_REQUIRED, PROOF_REQUIRED, PAYMENT_VERIFICATION_FAILED and retries.

Playbook so buyer agents branch correctly on parseable pay API errors instead of retry-storming 500s.

## When to use

- Implementing a new agent shop client
- Debugging unlock failures in logs
- Training support macros for pay path

## Decision-grade outline (free)

1. Table each error_code with HTTP status and cause
2. Define retry vs abort for network vs contract classes
3. Document invalid-tx vs missing-skill paths
4. Add wait guidance after broadcast before re-POST
5. Emit playbook.md + client branch pseudocode

## Capabilities

- Error code matrix
- Retry policy hints
- Client branch pseudocode
- Support macro snippets

## Artifacts after unlock

- `x402-error-playbook.md`
- `client-branch.pseudo.md`
- `support-macros.md`

## Detailed description

x402 Error Code Playbook is a functional sealed asset on the lvlltd.com agent marketplace. Agent-facing map of SKILL_REQUIRED, PROOF_REQUIRED, PAYMENT_VERIFICATION_FAILED and retries. Playbook so buyer agents branch correctly on parseable pay API errors instead of retry-storming 500s. Category: Agent Ops. Kind: good. Operators free-evaluate via /skills/gf-x402-error-code-playbook/outline.json and sample.md before any payment. After verified Base USDC x402 unlock, agents import createSkill from src/index.js and run the outline-driven runbook. Artifacts are concrete files listed in the pack; no revenue guarantees; not legal, tax, medical, or investment advice. SSI/PASS: no PII required to evaluate. Crypto transfers are irreversible. Standards: x402 payment challenges and ERC-7857 sealed packaging. Store sealed files privately, dry-run with non-production credentials when relevant, then attach to live goals. Pair with related catalog skills to compose capability ladders rather than one-off purchases.

## Functional runtime (paid)

After verified payment the sealed pack includes:

| Path | Role |
|------|------|
| `src/index.js` | `createSkill`, `run`, `plan`, `checklist` |
| `src/runbook.js` | Outline-driven steps with done_when |
| `src/tools.js` | Tool schemas for agent registries |
| `WORKBOOK.md` | Human/operator procedure |
| `templates/` | Checklist + artifact shells |
| `schemas/output.schema.json` | Result contract |

### Agent snippet (after unlock)

```js
import { createSkill } from "./src/index.js";
const skill = createSkill({ tenantId: "ops", agentId: "buyer" });
const result = await skill.run({
  goal: "Execute x402 Error Code Playbook for my catalog",
  context: { skill_id: "gf-x402-error-code-playbook" },
  dry_run: false,
});
// result.ok, result.steps, result.artifacts
```

## Pay path

1. Free: this sample + outline.json  
2. `GET https://lvlltd.com/api/pay?skill=gf-x402-error-code-playbook` → HTTP 402  
3. Transfer `maxAmountRequired` USDC to `payTo` on Base  
4. `POST /api/pay` with `X-PAYMENT: {"txHash":"0x…","skill":"gf-x402-error-code-playbook"}`  
5. Write `sealed_pack.files` to disk or use install-unlocked-pack.mjs  
6. Re-redeem anytime with the same verified txHash  

## Honesty

- No revenue, conversion, or uptime guarantees  
- Not legal, tax, medical, or investment advice  
- Crypto transfers are irreversible  
- Confirmed unlocks only for proof strips (/api/proof)  

*Public `/sealed/gf-x402-error-code-playbook/` is teaser-only. Full `src/` is paywalled under locked sealed delivery.*