Why Cross-Domain AA is the Final Frontier for Modular UX

Modularity fragments user experience. Rollups, appchains, and L2s create isolated liquidity and identity silos, forcing users to manage multiple wallets and sign transactions across different domains.

Cross-Domain AA is the integration layer. It enables a single smart account, like those built with ERC-4337 or Safe{Core}, to sign and execute actions across chains via intent-based bridges like Across and LayerZero.

This solves the chain abstraction problem. Users express a desired outcome (an intent), and the system's solver network handles the cross-chain routing, similar to how UniswapX and CowSwap operate on a single chain.

Evidence: The success of native AA on Ethereum, with over 4 million smart accounts created, proves the demand; cross-domain execution is the logical next scaling vector for this adoption.

Cross-domain state is the final boss. Account abstraction (AA) solves UX within a single chain, but a user's intent and assets exist across a fragmented multi-chain landscape. The real abstraction layer must manage state across Arbitrum, Base, and Solana, not just within one.

Current bridges are application-specific. Protocols like Across and Stargate move assets, but they don't abstract the user's cross-chain identity or session management. A user must still sign separate transactions on each chain, which defeats the purpose of a unified experience.

The solution is intent-based orchestration. Systems like UniswapX and CoW Swap's solver network demonstrate that users can declare outcomes, not transactions. Extending this to cross-chain actions requires a new intent standard and a network of solvers competing to fulfill it across domains.

Evidence: The failure of native gas sponsorship illustrates the gap. While Biconomy and Pimlico enable gasless txs on a single L2, they collapse when a user's action requires a hop from Ethereum to Polygon. The winning AA stack will own the cross-domain solver network.

The UX problem is fragmentation. A user's smart account on Arbitrum is a different contract on Base, forcing repeated onboarding and fund management. This breaks the single-signer illusion essential for mainstream adoption.

Cross-domain AA requires message passing. The core mechanism is a standardized intent relay where a user signs a single intent, and a relayer network like Biconomy or Gelato executes fragmented actions across chains via bridges like Across or LayerZero.

ERC-4337 is insufficient alone. The standard defines single-chain UX. Cross-chain requires extensions like ERC-7677 for generalized intent signing and ERC-7484 for on-chain registry of smart accounts across domains.

The winning architecture is stateless. Protocols like ZeroDev and Rhinestone champion kernel accounts where the core logic is chain-agnostic. State is managed per domain, but the signing authority and user experience are unified.

Evidence: The Polygon AggLayer's first use-case is cross-chain AA, demonstrating that major L2s view this as the critical path to a cohesive ecosystem, not a niche feature.

The network effect trap is the primary bear case. Existing wallets like MetaMask and Phantom have entrenched user habits and developer SDKs. Migrating dApp liquidity and user bases to a new cross-chain smart account standard requires a killer use case, not just incremental convenience.

Fragmentation will persist because competing standards create friction. The ERC-4337 ecosystem battles native AA implementations from StarkWare and zkSync. This standardization war delays the unified UX that makes cross-domain AA valuable, echoing the early EVM vs. non-EVM bridge chaos.

The gas abstraction fallacy assumes users care about fee payment mechanics. Most users prioritize final cost, not payment token. Solutions like Biconomy's Paymasters or Starknet's fee abstraction must prove economic superiority over simple L2 bridging to win.

Evidence: Despite hype, cross-chain AA transaction volume is negligible versus dominant bridges like LayerZero and Axelar. Real adoption requires dApps like Uniswap or Aave to natively integrate the flow, which is a multi-year integration cycle.

Cross-domain AA is inevitable. Every major L2 and L1 now pursues native AA. The EIP-4337 standard provides a common framework, but its implementation remains siloed. Users will not tolerate managing separate smart accounts on Arbitrum, Optimism, and Base.

The winner solves state synchronization. The core technical challenge is atomic cross-chain intent execution. A user's session key must sign transactions across Arbitrum and Polygon in one action. This requires a new intent relay layer beyond current bridges like Across or LayerZero.

Fragmentation creates a market. This gap is why projects like Kernel and Biconomy are building cross-chain AA SDKs. They compete to become the default session key manager, abstracting the underlying settlement layers from the user.

Evidence: The success of UniswapX proves demand for abstracted, cross-domain execution. Its fill volume migrated from on-chain liquidity because users prioritize outcome over venue. Cross-domain AA applies this logic to identity and session management.