---
skill_id: gf-proof-strip-for-listings
evaluation: free
quality: agent-decision-grade
functional: true
price_usd_full: 1.49
price_label: $1.49 / unlock
kind: good
category: Growth
challenge: https://lvlltd.com/api/pay?skill=gf-proof-strip-for-listings
outline: https://lvlltd.com/skills/gf-proof-strip-for-listings/outline.json
runtime_after_unlock: src/index.js createSkill
standards: x402, ERC-7857
completion_pass: functional-v1
---

# Free sample — Proof Strip for Listings

**Skill ID:** `gf-proof-strip-for-listings`  
**Unlock:** $1.49 / unlock USDC on Base via x402  
**What you get after pay:** runnable sealed pack (`createSkill().run`) + workbook + templates  

## Summary

Add honest proof strips (explorer links, unlock counts) without fake social proof.

Template for marketplace cards that cite /api/proof and Basescan only when real.

## When to use

- Landing page needs a trust strip
- Skill page should show last real unlock if any
- Avoiding fabricated testimonials

## Decision-grade outline (free)

1. Fetch /api/proof and read activity.unlock_count
2. If zero, render empty-state copy not fake stars
3. If nonzero, format last_successful_agent_purchase with explorer link
4. Never invent volume; label confirmed-only
5. Emit proof-strip.md + embed snippet

## Capabilities

- Empty-state honest copy
- Confirmed unlock formatting
- Explorer link builder
- Embed snippet for hub pages

## Artifacts after unlock

- `proof-strip.md`
- `proof-strip-embed.html`
- `empty-state-copy.md`

## Detailed description

Proof Strip for Listings is a functional sealed asset on the lvlltd.com agent marketplace. Add honest proof strips (explorer links, unlock counts) without fake social proof. Template for marketplace cards that cite /api/proof and Basescan only when real. Category: Growth. Kind: good. Operators free-evaluate via /skills/gf-proof-strip-for-listings/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 Proof Strip for Listings for my catalog",
  context: { skill_id: "gf-proof-strip-for-listings" },
  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-proof-strip-for-listings` → HTTP 402  
3. Transfer `maxAmountRequired` USDC to `payTo` on Base  
4. `POST /api/pay` with `X-PAYMENT: {"txHash":"0x…","skill":"gf-proof-strip-for-listings"}`  
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-proof-strip-for-listings/` is teaser-only. Full `src/` is paywalled under locked sealed delivery.*