If Ethereum L1 is the World Ledger, then base assets should never leave it. Classically, rollups both execute your transactions and hold your balances until you bridge them back. That works for scaling, but it fragments liquidity and makes direct Mainnet interoperability harder. A different design would keep all assets locked in a Mainnet vault, with rollups used only for high-speed execution. Instead of holding your funds, the rollup periodically posts a single proof plus a root of per-account balance changes. When you want, you "pull" your update back to Mainnet with a small claim. That means 100 trades on a rollup → 1 net update on Mainnet (e.g. +500 USDC, –0.2 ETH). Your vault always lives on Mainnet, secured by Ethereum itself, while rollups are simply fast workspaces that batch and compress activity. Why this works: • The rollup commits only a proof and a compact root, not every transaction. • Users prove their own balance change with a short inclusion proof when they claim. • This keeps costs low: one global proof per rollup epoch, and only users who claim pay gas for their own update. The benefits: • Single source of truth: balances are always Mainnet-native, never siloed. • Seamless composability: instantly usable with any Mainnet contract. • Lower user cost: you only pay to update when you actually want to. • Better UX: one vault on Ethereum, with fast front ends attached, instead of juggling balances across multiple rollup front ends. That feels far more consistent with Vitalik’s vision of L1 as the World Ledger: a single, secure balance sheet for everyone, with front ends providing speed while Mainnet keeps the authoritative record.