Sound Slice Chain

OUSD contract addresses → Contracts page

Required keys.

Add these in your Lovable project under Settings → Secrets before pasting the prompt below.

Paste into a fresh Lovable project. Make sure the secrets above are set first. read the build strategy →

Each chain gets its own complete, self-contained prompt.

Build "Sound Slice Chain" in ONE Lovable message. A single-page app that uses OUSD (Open USD) on mainnet.

CONCEPT
Securely mint and track original sound samples for interactive game soundtracks.
Discipline: Game Design & Interactive Media (game audio sampling). Primitive: OUSD-priced provenance — Buying or licensing a work is an OUSD transfer; the tx hash becomes the provenance record.

USER FLOW
The user licenses a game audio sampling work for an OUSD price. The tx hash, buyer, price and timestamp are saved and rendered as a shareable certificate that links to the explorer.
UI: A certificate card showing buyer, price in OUSD, time and the explorer proof link.

CHAIN — Base MAINNET (real money, no testnet)
- chainId 8453 · RPC https://mainnet.base.org · Explorer https://basescan.org
- OUSD on Base: 0xB2000000000000000000002fEb517dFeC7415344
- Tx link: https://basescan.org/tx/<hash> · Contract page: https://basescan.org/address/0xB2000000000000000000002fEb517dFeC7415344
- Gas: ETH on Base (cheap). Turn on Privy gas sponsorship for Base so users never need ETH.
- viem: `import { base } from 'viem/chains'` — use it as Privy `defaultChain` and in `supportedChains`.
- OUSD is an ERC-20. Transfer with `encodeFunctionData({ abi: erc20Abi, functionName: 'transfer', args: [to, amount] })`, `value: 0n`, sent TO the OUSD address.
- Read `decimals()` from the contract once at boot — never hardcode it.
- Pass `{ sponsor: true }` to Privy `sendTransaction` (needs Base enabled in Privy → Gas Sponsorship).

CODE — paste these files as-is (install: `@privy-io/react-auth viem`)

// src/lib/ousd.ts
import { base as CHAIN } from 'viem/chains';
export { CHAIN };
import { createPublicClient, http, erc20Abi, encodeFunctionData, parseUnits, formatUnits } from 'viem';
export const OUSD = '0xB2000000000000000000002fEb517dFeC7415344' as const;
export const pub = createPublicClient({ chain: CHAIN, transport: http('https://mainnet.base.org') });
let dec: number | undefined;
export async function ousdDecimals() { return dec ??= await pub.readContract({ address: OUSD, abi: erc20Abi, functionName: 'decimals' }); }
export async function ousdBalance(owner: `0x${string}`) {
  const raw = await pub.readContract({ address: OUSD, abi: erc20Abi, functionName: 'balanceOf', args: [owner] });
  return Number(formatUnits(raw, await ousdDecimals()));
}
export async function transferTx(to: `0x${string}`, amount: string) {
  const value = parseUnits(amount, await ousdDecimals());
  return { to: OUSD, value: 0n, chainId: CHAIN.id,
    data: encodeFunctionData({ abi: erc20Abi, functionName: 'transfer', args: [to, value] }) };
}
export const txUrl = (h: string) => 'https://basescan.org/tx/' + h;
export async function waitFor(hash: `0x${string}`) { return pub.waitForTransactionReceipt({ hash, timeout: 90_000 }); }

// src/components/privy-root.tsx  (default export; loaded with React.lazy inside <ClientOnly>)
import { PrivyProvider } from '@privy-io/react-auth';
import { CHAIN } from '@/lib/ousd';
export default function PrivyRoot({ appId, children }: { appId: string; children: React.ReactNode }) {
  return <PrivyProvider appId={appId} config={{ loginMethods: ['google'], defaultChain: CHAIN, supportedChains: [CHAIN],
    embeddedWallets: { ethereum: { createOnLogin: 'users-without-wallets' } } }}>{children}</PrivyProvider>;
}

// Sending (inside a component under PrivyRoot)
// const { sendTransaction } = useSendTransaction();       // from '@privy-io/react-auth'
// const { hash } = await sendTransaction(await transferTx(to, '1.00'), { sponsor: true });
// await waitFor(hash); show txUrl(hash).

STACK
- TanStack Start (the Lovable default). One page at the index route.
- Privy for sign-in (Google) and embedded wallets on the chain below. Load Privy with
  `React.lazy(() => import('./privy-root'))` inside `<ClientOnly>` — a static import crashes SSR.
- Secret `PRIVY_APP_ID` (paste in Project Settings → Secrets). Read it in a route loader via a server
  function (`process.env.PRIVY_APP_ID`) and pass it to the provider. NEVER name a secret `VITE_*`.
- Show amounts in OUSD with 2 decimals; convert with the on-chain decimals.
- No smart contract deploy is needed: OUSD is already live. Every action is an OUSD token transfer.

SHARED CODE — paste as-is
// src/lib/privy.functions.ts
import { createServerFn } from '@tanstack/react-start';
export const getPrivyAppId = createServerFn({ method: 'GET' })
  .handler(async () => ({ appId: process.env['PRIVY_APP_ID'] ?? null }));

// src/routes/index.tsx (shape)
// loader: () => getPrivyAppId()
// const { appId } = Route.useLoaderData();
// const PrivyRoot = React.lazy(() => import('@/components/privy-root'));
// if (!appId) render the full UI in demo mode with a banner "Add PRIVY_APP_ID to go live" (no sends).
// else: <ClientOnly fallback={<Skeleton/>}><Suspense><PrivyRoot appId={appId}><App/></PrivyRoot></Suspense></ClientOnly>
// Inside <App/>: const { ready, authenticated, login, logout } = usePrivy(); wait for `ready` before reading wallets.

REAL MONEY RULES (mainnet only)
- Above every Pay button show: "Mainnet · real OUSD". Default demo amounts ≤ 1 OUSD.
- Before sending, check the OUSD balance; if too low, show "Get OUSD" linking to https://joinopenstandard.com/integrate.
- Always confirm the wallet is on the right chain before sending; refuse with a clear "switch network" message otherwise.
- After sending, wait for confirmation, then show the explorer link. Never show success before confirmation.

TROUBLESHOOTING
- "window is not defined" / blank SSR page → Privy was imported statically. Only import it via React.lazy inside <ClientOnly>.
- Wrong network / chain mismatch → defaultChain and supportedChains must be the same chain object; refuse to send otherwise.
- Solana "TokenAccountNotFound" → the idempotent create-ATA instruction must precede the transfer; balance = 0 when no ATA.
- "insufficient funds for gas" → enable Privy gas sponsorship for this chain, or tell the user which gas coin to add.
- Balance too low → disable Pay and show "Get OUSD" linking to https://joinopenstandard.com/integrate.

COMPLIANCE (mandatory — OUSD is issued by Bridge, a Stripe company)
- Show a footer notice: "OUSD is not available in the European Economic Area or sanctioned regions. See https://joinopenstandard.com/legal/geo-restrictions-and-prohibited-use-cases".
- Never build or market for prohibited uses: gambling, games of chance, lotteries, sweepstakes, unlawful
  prediction markets, adult content, cannabis, tobacco, weapons, pharmaceuticals, luxury goods, jewelry,
  watches, precious metals, mixing, multi-level marketing, counterfeit goods or deceptive practices.
- OUSD is acquired through partners (Stripe/Bridge/Privy, Coinbase, Visa, Mastercard) or exchanges
  (Coinbase, Kraken, Uniswap). The app itself never mints or redeems.

DEFINITION OF DONE
1. Google sign-in via Privy creates an embedded wallet on the chain above and shows its OUSD balance.
2. The game audio sampling flow sends a real OUSD transfer, waits for confirmation, and shows a working explorer link.
3. The compliance footer and the real-money notice are visible.
4. The page works with zero secrets (demo mode with a "Add PRIVY_APP_ID to go live" banner).

Credit in the footer: "Built during the Creative AI & Quantum Hackathon organised by StreetKode Fam during Indian Krump Festival 14".

Market sizing.

Indicative figures for hackathon pitches — refine with your own research before raising.