WalletBrief

WalletBrief checks any Monad address and returns a live snapshot: MON and WMON balances, transaction count, latest block, and current ERC-20 approvals discovered through HyperSync.

If the connected browser wallet owns an active approval, WalletBrief simulates an exact approve(spender, 0) revoke before requesting its signature. It never asks a server to sign for the user.

Status

The public search-and-revoke app is live. The repository also includes a stricter EIP-7702 batch-executor proof, deployed and source-verified on Monad mainnet. A real WMON approval was detected, revoked through that executor, and reduced to a verified no-op.

Proof	Link
Hosted app	WalletBrief on Railway
Public repository	github.com/gabchess/walletbrief-monad
Verified BatchExecutor	MonadVision · exact-match source record
Harmless WMON approval seed	MonadVision transaction
Successful revoke transaction	MonadVision transaction

Three-minute judge path

1. Open the hosted app and check the timestamp, wallet link, block link, balances, and change since the previous run.
2. Confirm the indexed approval scan resolves to the wallet's current active approvals or a clear no-active-approvals state.
3. Open the approval seed and successful revoke transactions above. The revoke emits Approval(owner, spender, 0).
4. Read the measured deployment, allowance, delegation, no-op, and restart evidence in docs/mainnet-proof.md.
5. Refresh the app. Persistent cursors keep the result fast, and no second transaction is proposed.

How it works

Address search
  -> four parallel read-only Monad calls
  -> live MON + WMON balances, transaction count, latest block
  -> HyperSync indexes Approval events for the owner
  -> Multicall verifies each current on-chain allowance
  -> connected owner selects an active approval
  -> wallet simulates approve(spender, 0)
  -> owner signs and receives explorer evidence

WalletBrief keeps separate cursors for balance activity and approval signals. A wallet without a cursor starts from SCAN_START_BLOCK when configured, or from a bounded 25,000-block lookback. Successful checks persist a new valued snapshot, so the next run reports the change since that check rather than pretending to calculate lifetime profit and loss.

Price reads use CoinGecko first and DefiLlama as a fallback. One wallet failure is isolated from the rest of a multi-wallet run.

Revoke safety model

The public app permits one narrow action: the connected owner can set a discovered ERC-20 allowance to zero. The wallet must match the indexed approval's owner, and the exact write is simulated before signature.

The separate EIP-7702 proof path has two additional boundaries:

• The client sends only a configured wallet address. The server rereads live state and rebuilds the action, digest, implementation address, and calldata.
• BatchExecutor accepts calls only from the delegated wallet itself. Every target must contain code, every payload must be exactly ERC-20 approve(address,uint256), and the amount must be zero. Used digests cannot be replayed.

Hosted execution is disabled. The proof transaction was signed locally from macOS Keychain, so Railway never received a wallet private key. The executor has no payable entry point and no fund-custody logic.

Run locally

Requirements: Node.js 20+, Foundry, and Socket CLI for dependency installation.

socket npm install
cp .env.example .env
npm run dev

Open http://localhost:3000. Keep EXECUTE_ENABLED=false for a read-only local brief.

The production container uses Next.js standalone output and one Node process:

docker build -t walletbrief .
docker run --rm -p 3000:3000 \
  -e BRIEF_WALLETS=0x35160A4238CB5F3166046399c397B6E0c12FD872 \
  walletbrief

GET /api/health returns {"ok":true,"chainId":143} without making an RPC call or exposing configuration.

Configuration

Variable	Default	Purpose
MONAD_RPC_URL	https://rpc.monad.xyz	Read-only Monad mainnet RPC
BRIEF_WALLETS	Dedicated demo wallet	Comma-separated wallets to brief
SCAN_START_BLOCK	Unset	Explicit first block for a wallet with no cursor
SCAN_LOOKBACK_BLOCKS	25000	Bounded first-run lookback when no start block is set
CURSOR_STORE_PATH	.state/cursors.json	Balance-activity scan cursors
ANOMALY_CURSOR_STORE_PATH	.state/anomaly-cursors.json	Approval-signal scan cursors
SNAPSHOT_STORE_PATH	.state/snapshots.json	Last successful valued state
APPROVAL_STATE_STORE_PATH	.state/approvals.json	Tracked approval state
BATCH_EXECUTOR_ADDRESS	Zero address	Verified executor implementation
EXECUTE_ENABLED	false	Explicit hosted execution gate
EXECUTE_RPC_URL	MONAD_RPC_URL	HTTPS RPC used for an approved revoke
DEMO_EXECUTION_WALLET	Dedicated demo wallet	Exact wallet allowed to execute
DEMO_WALLET_PRIVATE_KEY	Unset	Runtime secret for the dedicated demo wallet

For a hosted service, mount persistent storage at /data, point every state path there, and run exactly one replica. WalletBrief serializes state changes within one process; it does not claim distributed locking across replicas.

Verify

npm test
npm run typecheck
npm run web:build

cd contracts
forge fmt --check
forge test
forge build

The default JavaScript suite keeps the Anvil integration test skipped. Run it explicitly with npm run test:integration when Foundry and a Monad RPC are available.

The contract suite covers self-only access, exact revoke validation, replay protection, partial action failure, reentrancy resistance, and zero custody. The application suite covers bounded scans, persisted state, per-wallet failure isolation, server-side action recomputation, disabled-by-default execution, explorer links, and the health endpoint.

Honest limitations

• Approval discovery covers standard ERC-20 Approval events indexed by owner. Nonstandard tokens and permissions outside ERC-20 allowances are out of scope; this is not a full wallet security scanner.
• "Stale" means a live nonzero tracked approval with no observed drawdown in WalletBrief's available history. It is a rule-based signal, not proof of malicious intent.
• USD values depend on external price APIs and are informational.
• Snapshot change is the delta since WalletBrief's previous successful check, not tax accounting or lifetime P&L.
• Stateful file storage requires one process and persistent disk.
• The demo executor is revoke-only. It cannot transfer tokens, set a positive allowance, or run arbitrary calldata.

Built for the Spark Hackathon on Monad.