# Free sample: Proof handoff teaser

_Artifact index snippet only. Full buyer handoff + evidence matrix + settle memo: POST /v0/proof-handoff → 0.012 USDC_

## Demo artifact index (truncated)

```
| # | Name | Link | Buyer action |
|---|------|------|--------------|
| 1 | pack.md | https://example.com/pack.md | open + skim |
| 2 | sources.md | https://example.com/sources.md | open + skim |…
```

## Upgrade — full post-delivery proof handoff
```http
POST https://x402.devvizion.com/v0/proof-handoff
Content-Type: application/json
{ "brief":"…", "artifacts":["https://…"], "reward":12, "platform":"taskmarket", "wallet":"0x…" }
```
Pay with x402 on Base USDC · unpaid → HTTP 402 · 0.012 USDC
payTo 0xE79e7fa7Ce7259C46F9B127b837d2907Bb036F95