locker-dapp/
├── package.json
├── next.config.mjs
├── lib/
│   ├── isomorphic-ws-fix.mjs
│   ├── midnight.ts                 # session, patched provider, hex helpers
│   └── locker.ts                   # deploy, lock, release, decode state
├── app/
│   ├── layout.tsx
│   └── locker/
│       └── LockerClient.tsx        # all wallet + contract UI (client component)
├── contract/
│   ├── package.json
│   ├── src/
│   │   ├── locker.compact
│   │   ├── witnesses.ts
│   │   ├── index.ts                # barrel → managed/locker
│   │   └── managed/locker/         # compiler output (gitignored)
│   └── tsconfig.json
└── public/zk/locker/               # synced keys + zkir (gitignored in dev, committed for deploy)

node --version   # 20+ for Next.js; 22+ if adding vitest contract tests
docker --version # optional local stack

Browser: **1AM wallet** extension on `preprod` (or Lace fallback).

---

{
  "name": "locker-dapp",
  "version": "0.1.0",
  "private": true,
  "type": "module",
  "scripts": {
    "dev": "next dev --webpack",
    "build": "npm run sync:assets && next build --webpack",
    "compact": "npm run compact --prefix contract",
    "sync:assets": "node scripts/sync-zk-assets.mjs",
    "postinstall": "npm install --prefix contract"
  },
  "dependencies": {
    "@midnight-ntwrk/compact-runtime": "0.16.0",
    "@midnight-ntwrk/ledger-v8": "8.0.3",
    "@midnight-ntwrk/midnight-js-contracts": "4.0.4",
    "@midnight-ntwrk/midnight-js-fetch-zk-config-provider": "4.0.4",
    "@midnight-ntwrk/midnight-js-indexer-public-data-provider": "4.0.4",
    "@midnight-ntwrk/midnight-js-network-id": "4.0.4",
    "@midnight-ntwrk/midnight-js-types": "4.0.4",
    "@midnight-ntwrk/wallet-sdk-address-format": "3.1.0",
    "next": "^15.0.0",
    "react": "^19.0.0",
    "react-dom": "^19.0.0"
  },
  "devDependencies": {
    "@types/node": "^22.0.0",
    "@types/react": "^19.0.0",
    "@types/react-dom": "^19.0.0",
    "typescript": "^5.7.0"
  }
}

{
  "name": "@locker/contract",
  "version": "0.1.0",
  "private": true,
  "type": "module",
  "scripts": {
    "compact": "compact compile src/locker.compact src/managed/locker"
  },
  "dependencies": {
    "@midnight-ntwrk/compact-runtime": "0.16.0"
  }
}

npm run compact

---

pragma language_version >= 0.23;
import CompactStandardLibrary;

export ledger balance: Uint<128>;
export ledger unlockTime: Uint<64>;
export ledger beneficiary: Bytes<32>;
export ledger lockActive: Boolean;
export ledger totalLocked: Uint<128>;
export ledger totalReleased: Uint<128>;

witness beneficiaryKey(): Bytes<32>;

constructor() {
  balance = 0;
  unlockTime = 0;
  beneficiary = default<Bytes<32>>;
  lockActive = false;
  totalLocked = 0;
  totalReleased = 0;
}

// Deposit unshielded NIGHT and schedule release for beneficiaryPk at releaseTime (Unix seconds).
export circuit lockTokens(
  amount: Uint<128>,
  releaseTime: Uint<64>,
  beneficiaryPk: Bytes<32>
): [] {
  assert(!disclose(lockActive), "Vault already has an active lock");
  assert(disclose(amount) > 0, "Amount must be positive");
  receiveUnshielded(default<Bytes<32>>, disclose(amount));
  beneficiary = disclose(beneficiaryPk);
  unlockTime = disclose(releaseTime);
  balance = disclose(amount);
  lockActive = disclose(true);
  totalLocked = disclose((totalLocked + amount) as Uint<128>);
}

// Beneficiary releases locked tokens after unlockTime to recipient (unshielded UserAddress).
export circuit release(recipient: UserAddress): [] {
  assert(disclose(lockActive), "No active lock");
  assert(blockTimeGte(disclose(unlockTime)), "Lock period not finished");
  assert(deriveKey(beneficiaryKey()) == beneficiary, "Only beneficiary can release");
  const amount = disclose(balance);
  assert(amount > 0, "Nothing to release");
  sendUnshielded(
    default<Bytes<32>>,
    amount,
    right<ContractAddress, UserAddress>(disclose(recipient))
  );
  totalReleased = disclose((totalReleased + amount) as Uint<128>);
  balance = 0;
  lockActive = false;
}

pure circuit deriveKey(sk: Bytes<32>): Bytes<32> {
  return persistentHash<Vector<2, Bytes<32>>>([pad(32, "locker:beneficiary:v1"), sk]);
}

import type { WitnessContext } from '@midnight-ntwrk/compact-runtime';

export type LockerPrivateState = {
  beneficiarySecretKey: Uint8Array;
};

export const witnesses = {
  beneficiaryKey: (context: WitnessContext<LockerPrivateState>) =>
    [context.privateState, context.privateState.beneficiarySecretKey] as const,
};

import { CompiledContract } from '@midnight-ntwrk/compact-runtime';
import { fileURLToPath } from 'node:url';
import path from 'node:path';
import { witnesses } from './witnesses.js';

export {
  Contract,
  ledger,
  pureCircuits,
  type Ledger,
} from './managed/locker/contract/index.js';
import { Contract } from './managed/locker/contract/index.js';

const currentDir = path.dirname(fileURLToPath(import.meta.url));
export const zkConfigPath = path.resolve(currentDir, 'managed', 'locker');

export const CompiledLockerContract = CompiledContract.make('locker', Contract).pipe(
  CompiledContract.withWitnesses(witnesses),
  CompiledContract.withCompiledFileAssets(zkConfigPath),
);

const wallet =
  (window as any).midnight?.['1am'] ??
  Object.values((window as any).midnight ?? {})[0];

import { createUnprovenDeployTx, submitCallTxAsync } from '@midnight-ntwrk/midnight-js-contracts';
import { ContractState, sampleSigningKey } from '@midnight-ntwrk/compact-runtime';
import { CompiledLockerContract, Contract, ledger } from '../contract/src/index.js';
import type { ConnectedSession } from './midnight.js';
import { fromHex, pollForState } from './midnight.js';

const PRIVATE_STATE_ID = 'LockerPrivateState';
const ZK_ASSET_PATH = '/zk/locker';

function makeCompiledContract() {
  return CompiledLockerContract as any;
}

export async function deployLocker(
  session: ConnectedSession,
  beneficiarySecretKey: Uint8Array,
): Promise<string> {
  const initialPrivateState = { beneficiarySecretKey };

  const deployTxData = await (createUnprovenDeployTx as any)(
    {
      zkConfigProvider: session.providers.zkConfigProvider,
      walletProvider: session.providers.walletProvider,
    },
    {
      compiledContract: makeCompiledContract(),
      args: [],
      privateStateId: PRIVATE_STATE_ID,
      initialPrivateState,
      signingKey: sampleSigningKey(),
    },
  );

  const contractAddress = deployTxData.public.contractAddress;
  await (submitTxAsync as any)(session.providers, {
    unprovenTx: deployTxData.private.unprovenTx,
  });

  await session.providers.privateStateProvider.setContractAddress(contractAddress);
  await session.providers.privateStateProvider.set(PRIVATE_STATE_ID, initialPrivateState);
  await session.providers.privateStateProvider.setSigningKey(
    contractAddress,
    deployTxData.private.signingKey,
  );

  return contractAddress;
}

export async function lockTokens(
  session: ConnectedSession,
  contractAddress: string,
  amount: bigint,
  releaseTimeUnix: bigint,
  beneficiaryPkBytes: Uint8Array,
) {
  await (submitCallTxAsync as any)(session.providers, {
    compiledContract: makeCompiledContract(),
    contractAddress,
    circuitId: 'lockTokens',
    args: [amount, releaseTimeUnix, { bytes: beneficiaryPkBytes }],
    privateStateId: PRIVATE_STATE_ID,
  });
}

export async function releaseTokens(
  session: ConnectedSession,
  contractAddress: string,
  recipientBytes: Uint8Array,
) {
  await (submitCallTxAsync as any)(session.providers, {
    compiledContract: makeCompiledContract(),
    contractAddress,
    circuitId: 'release',
    args: [{ bytes: recipientBytes }],
    privateStateId: PRIVATE_STATE_ID,
  });
}

export function decodeLockerState(stateHex: string) {
  const contractState = ContractState.deserialize(fromHex(stateHex));
  const l = ledger(contractState.data);
  return {
    balance: l.balance as unknown as bigint,
    unlockTime: l.unlockTime as unknown as bigint,
    beneficiary: l.beneficiary as unknown as Uint8Array,
    lockActive: l.lockActive as unknown as boolean,
    totalLocked: l.totalLocked as unknown as bigint,
    totalReleased: l.totalReleased as unknown as bigint,
  };
}

export async function fetchLockerState(queryUrl: string, contractAddress: string) {
  const hex = await pollForState(queryUrl, contractAddress);
  return decodeLockerState(hex);
}

'use client';

import { useCallback, useEffect, useMemo, useState } from 'react';
import {
  deployLocker,
  fetchLockerState,
  lockTokens,
  releaseTokens,
} from '@/lib/locker';

const STARS_PER_NIGHT = 1_000_000n;

export default function LockerClient() {
  const [session, setSession] = useState<ConnectedSession | null>(null);
  const [contractAddress, setContractAddress] = useState<string | null>(null);
  const [ledger, setLedger] = useState<LockerLedgerView | null>(null);
  const [amountNight, setAmountNight] = useState('1');
  const [unlockAt, setUnlockAt] = useState(''); // datetime-local input
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const nowUnix = BigInt(Math.floor(Date.now() / 1000));
  const canRelease = ledger?.lockActive && ledger.unlockTime <= nowUnix;

  const refresh = useCallback(async () => {
    if (!session || !contractAddress) return;
    const state = await fetchLockerState(session.config.indexerUri, contractAddress);
    setLedger(state);
  }, [session, contractAddress]);

  useEffect(() => { void refresh(); }, [refresh]);

  async function onConnect() {
    setError(null);
    const wallet =
      (window as any).midnight?.['1am'] ??
      Object.values((window as any).midnight ?? {})[0];
    if (!wallet) throw new Error('Install a Midnight wallet extension');
    const api = await wallet.connect('preprod');
    const { createConnectedSession } = await import('@/lib/midnight');
    setSession(await createConnectedSession(api, '/zk/locker'));
  }

  async function onDeploy() {
    if (!session) return;
    setBusy(true);
    setError(null);
    try {
      const beneficiarySecretKey = session.coinPublicKeyBytes; // lock to self
      const addr = await deployLocker(session, beneficiarySecretKey);
      setContractAddress(addr);
      await refresh();
    } catch (e) {
      setError(String(e));
    } finally {
      setBusy(false);
    }
  }

  async function onLock() {
    if (!session || !contractAddress) return;
    setBusy(true);
    setError(null);
    try {
      const amount = BigInt(amountNight) * STARS_PER_NIGHT;
      const releaseTime = BigInt(Math.floor(new Date(unlockAt).getTime() / 1000));
      await lockTokens(
        session,
        contractAddress,
        amount,
        releaseTime,
        session.coinPublicKeyBytes,
      );
      await refresh();
    } catch (e) {
      setError(String(e));
    } finally {
      setBusy(false);
    }
  }

  async function onRelease() {
    if (!session || !contractAddress) return;
    setBusy(true);
    setError(null);
    try {
      const recipientBytes = unshieldedAddressToBytes(session.unshieldedAddress);
      await releaseTokens(session, contractAddress, recipientBytes);
      await refresh();
    } catch (e) {
      setError(String(e));
    } finally {
      setBusy(false);
    }
  }

  return (
    <div>
      <h1>Token Locker</h1>
      {!session ? (
        <button type="button" onClick={onConnect} disabled={busy}>Connect Wallet</button>
      ) : (
        <>
          <p>Connected: {session.unshieldedAddress}</p>
          {!contractAddress ? (
            <button type="button" onClick={onDeploy} disabled={busy}>Deploy Locker</button>
          ) : (
            <>
              <p>Contract: {contractAddress}</p>
              {ledger?.lockActive ? (
                <>
                  <p>Locked: {formatStars(ledger.balance)} Stars</p>
                  <p>Unlocks: {new Date(Number(ledger.unlockTime) * 1000).toLocaleString()}</p>
                  <button type="button" onClick={onRelease} disabled={busy || !canRelease}>
                    Release Tokens
                  </button>
                </>
              ) : (
                <>
                  <label>
                    Amount (NIGHT)
                    <input value={amountNight} onChange={(e) => setAmountNight(e.target.value)} />
                  </label>
                  <label>
                    Unlock at
                    <input type="datetime-local" value={unlockAt} onChange={(e) => setUnlockAt(e.target.value)} />
                  </label>
                  <button type="button" onClick={onLock} disabled={busy}>Lock Tokens</button>
                </>
              )}
            </>
          )}
        </>
      )}
      {error ? <p role="alert">{error}</p> : null}
    </div>
  );
}

function formatStars(n: bigint) {
  return n.toString();
}

// Implement: unshieldedAddressToBytes — decode mn_addr_* to 32-byte recipient for circuits
// Never use encodeUserAddress with raw coin pk; use bytes helper from 1am-wallet skill

import { cpSync, mkdirSync, rmSync } from 'node:fs';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';

const root = join(dirname(fileURLToPath(import.meta.url)), '..');
const src = join(root, 'contract/src/managed/locker');
const dest = join(root, 'public/zk/locker');

rmSync(dest, { recursive: true, force: true });
mkdirSync(dest, { recursive: true });
for (const dir of ['keys', 'zkir']) {
  cpSync(join(src, dir), join(dest, dir), { recursive: true });
}

1. npm install && npm run compact && npm run sync:assets
2. npm run dev
3. Connect 1AM wallet (preprod, funded with tNIGHT)
4. Deploy locker contract
5. Lock 1 NIGHT until chosen datetime
6. UI shows locked balance + unlock time (poll indexer every 2s after tx)
7. Wait until unlock (or advance clock on local undeployed only)
8. Beneficiary clicks Release → tokens sent to unshielded address