---
skill_id: sealed-payload-integrity-checker
evaluation: free
price_usd_full: 3.99
challenge: https://lvlltd.com/api/pay?skill=sealed-payload-integrity-checker
outline: https://lvlltd.com/skills/sealed-payload-integrity-checker/outline.json
standards: x402, ERC-7857
---

# Free sample — Sealed Payload Integrity Checker

**Skill ID:** `sealed-payload-integrity-checker`  
**Full unlock:** $3.99 USDC via x402 on Base  
**Challenge:** https://lvlltd.com/api/pay?skill=sealed-payload-integrity-checker  
**Outline JSON:** https://lvlltd.com/skills/sealed-payload-integrity-checker/outline.json

## Summary

Verify data_hash matches delivered sealed content before trusting an unlock.

## When to use

- Agent receives sealed_pack.files and must trust them
- Auditing that teaser paths never leak full payloads
- Dispute where buyer claims files differ from listing

## Decision criteria (buy vs skip)

- You need this when: Agent receives sealed_pack.files and must trust them
- You get capability: Post-unlock hash procedure
- Budget fits: full unlock is $3.99 USDC on Base
- You can automate unlock via HTTP 402 without a browser
- You only need teaser/outline first — sealed src/ops stay locked until payment

## Outline (preview)

1. Record advertised data_hash / pack_meta from listing
2. Canonicalize file list (paths + bytes) after unlock
3. Compute hash tree or concatenated digest per policy
4. Compare; on mismatch quarantine files and open dispute note
5. Emit integrity-report.json for ledger attachment

## Capabilities (preview)

- Post-unlock hash procedure
- Mismatch quarantine steps
- Dispute evidence pack
- Teaser vs sealed path awareness

## What you get after payment

- SKILL.md (teaser public)
- agent-install.json (public meta)
- src/index.js (stub public; full after unlock)
- Full sealed: src/, schemas/, ops/* (when present) after verified X-PAYMENT

## Agent buy path (zero human UI)

```
GET  https://lvlltd.com/skills/sealed-payload-integrity-checker/outline.json
GET  https://lvlltd.com/api/pay?skill=sealed-payload-integrity-checker   → HTTP 402
# transfer maxAmountRequired USDC to payTo on Base
POST https://lvlltd.com/api/pay
  X-PAYMENT: {"txHash":"0x…","skill":"sealed-payload-integrity-checker"}
# response.sealed_pack.files = full pack
```

## Sample excerpt

# Sealed Payload Integrity Checker

ERC-7857-style markets advertise sealed hashes; buyers still need an operational check after unlock. This skill walks canonicalize → hash → compare → quarantine. Reports attach to revenue/dispute ledgers. It does not replace chain verification of payment; it verifies content integrity after payment.

When to use: high-value unlocks, multi-agent installs, marketplace audits.

**Price:** $3.99 USDC on Base via x402 unlock.

**Standards:** x402 payments · ERC-7857 sealed skill model · agent-swarm ready.

Operator notes for Sealed Payload Integrity Checker: treat this as a capability pack you wire into real tools—not a certification or hosted SaaS. Pair it with free evaluation at /skills/sealed-payload-integrity-checker/outline.json before paying. Typical failure modes it reduces include silent misconfiguration, support thrash, and agents inventing process under load. After unlock, store sealed files in your private skill inventory, run a dry-run with non-production credentials, and only then attach the pack to live goals. Cross-sell naturally sits next to related ops, commerce, or networking skills already on lvlltd.com so agents can compose a ladder instead of a one-off purchase.