The Cost of Interoperability in a Multi-Chain ERC-4337 World

ERC-4337's paymaster model abstracts gas, but cross-chain execution creates a hidden tax. Each chain requires a separate paymaster deposit, fragmenting liquidity and creating $10M+ in idle capital across ecosystems. This is a direct cost of sovereignty.

• Capital Inefficiency: Locked funds per chain for gas sponsorship.
• Operational Overhead: Managing multiple paymaster keys and top-ups.
• Slippage Risk: Paymasters often rely on bridges or DEXs for cross-chain value transfer, adding cost.

A user's smart account state (nonce, session keys, modules) is chain-specific. Moving assets via a bridge doesn't migrate this state, forcing a re-initialization on the destination chain. This breaks the seamless UX intent-based protocols like UniswapX or Across promise.

• Broken Sessions: Cross-chain moves invalidate existing permissions.
• Replay Attack Vectors: Managing nonces across parallel chains.
• UX Friction: Users must 'redeploy' their account logic on new chains.

A sovereign smart account uses custom validation logic (e.g., multisig, 2FA). For a bridge or cross-chain messaging protocol like LayerZero or Axelar to trust a message from this account, it must verify this custom logic on both chains. This either requires universal verifier standards (costly) or forces accounts into a lowest-common-denominator security model.

• Verifier Fragmentation: No standard for cross-chain custom logic proof.
• Security Dilution: Forced adoption of simpler, bridge-compatible schemes.
• Audit Surface: Each new module expands the cross-chain attack surface.

Bundlers are chain-specific. A user operation spanning Arbitrum and Base requires coordination between two separate, untrusted bundler networks. This creates a meta-coordination problem, introducing latency and failure points that don't exist in single-chain EIP-4337.

• Atomicity Risk: Partial execution if one chain's bundle fails.
• Latency Stacking: Waiting for finality on the source chain before bundling on destination.
• MEV Leakage: Cross-chain intent reveals more of the user's strategy.

Solutions like UniswapX and CowSwap abstract the complexity by having a solver network fulfill the user's intent across chains. However, this transfers sovereignty from the user's smart account to the solver's reputation and economic security. It's an interoperability cost paid in trust.

• Sovereignty Trade-off: User cedes control for cross-chain simplicity.
• Solver Monopolies: Risk of centralization in the solver network.
• Economic Security: Relies on solver bonds, not cryptographic guarantees.

The only clean solution is a new standard for natively portable accounts. Think ERC-4337 but with state proofs that can be verified by any chain's EN, and a single global paymaster contract. This is the ZK-rollup model applied to the account layer, but requires massive L1/L2 client coordination.

• True Portability: Account state moves with the user via proofs.
• Capital Efficiency: One liquidity pool for global gas.
• Long-Term Play: Requires protocol-level upgrades, not dApp patches.

Bundlers are the execution layer for user operations, but cross-chain execution fragments them. The winning infrastructure will abstract this.\n- Key Benefit: Single point of entry for users across all supported chains (Ethereum, Polygon, Arbitrum).\n- Key Benefit: Aggregates gas sponsorship and fee logic, enabling ~30-50% gas optimization via MEV capture.

Sponsored transactions require the paymaster to hold native gas tokens on every chain. This creates massive capital inefficiency and fragmentation risk.\n- Key Benefit: Solutions like Circle's CCTP or LayerZero enable canonical USDC bridging to fund paymasters, reducing required capital by >80%.\n- Key Benefit: Unlocks stablecoin-denominated gas across chains, the true killer app for mass adoption.

The high cost of atomic cross-chain UserOps will push activity to solvers. Users express what they want, not how to do it.\n- Key Benefit: Protocols like UniswapX, CowSwap, and Across act as natural intent solvers, batching and routing cross-chain actions off-chain.\n- Key Benefit: Drives cost down by aggregating liquidity and settling in the most efficient venue, not the most atomic one.

Interoperability for smart accounts isn't about moving assets; it's about verifying actions and state. Light clients and ZK proofs are the endgame.\n- Key Benefit: Ethereum's enshrined ZK-EVM and projects like Succinct enable trust-minimized verification of chain B's state on chain A for <$0.01.\n- Key Benefit: Removes dependency on external bridge security models, the single largest point of failure in multi-chain designs.

No single chain will dominate ERC-4337 activity. Infrastructure that aggregates liquidity, bundlers, and paymasters across chains will capture the premium.\n- Key Benefit: Think LayerZero for messaging meets EigenLayer for shared security, creating a unified settlement layer for cross-chain UserOps.\n- Key Benefit: Enables "gasless on any chain" as a service, the ultimate developer acquisition tool.

The entry point for all cross-chain activity shifts from the DApp to the smart account wallet interface (e.g., Safe, Rabby). They control the routing.\n- Key Benefit: Wallets that integrate the best bundler networks, paymaster deals, and intent solvers will achieve >60% user retention.\n- Key Benefit: Massive opportunity for wallet-specific fee markets and order flow auctions, capturing value previously lost to L1 sequencers.