Account abstraction is insufficient. ERC-4337 enables smart accounts on a single chain but fails to synchronize state across rollups. A user's identity on Arbitrum remains isolated from their Optimism profile, fracturing the user experience.
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Why Cross-L2 Account Portability Remains a Distant Dream
The promise of a single smart account across Arbitrum, Optimism, and zkSync is broken by incompatible validation logic, divergent AA implementations, and a lack of shared standards. This is a technical deep dive.
introduction
THE STATE FRAUGHT
Introduction
The seamless movement of user accounts across Ethereum's L2s is blocked by fundamental technical and economic barriers.
Sovereign state is the root cause. Each L2, like Arbitrum or Base, maintains its own independent state machine. Porting an account requires a secure, trust-minimized state sync, a problem more complex than simple asset bridging via Across or Stargate.
Economic incentives are misaligned. Sequencers profit from sequestered liquidity and user lock-in. A truly portable account layer would commoditize execution and erode their revenue, creating a principal-agent problem.
Evidence: No major L2 or interoperability protocol (LayerZero, Hyperlane) offers native account portability. Solutions are limited to read-only social graphs (Lens Protocol) or slow, expensive message-passing, not live state migration.
thesis-statement
THE STANDARDS GAP
The Core Argument: Portability is a Standardization Problem
Cross-L2 account abstraction fails because core primitives lack shared standards, forcing users into fragmented, custodial workarounds.
Account abstraction's promise is fractured by incompatible implementations. Starknet's native AA differs from Arbitrum's ERC-4337, forcing developers to write multiple integration layers for a single user experience.
Key management lacks a portable standard. A smart account's signer logic on Polygon zkEVM is siloed; moving it to Base requires re-deployment and reconfiguration, breaking the concept of a persistent identity.
Bridging assets is easier than bridging state. Protocols like Across and LayerZero optimize for token transfers, not the complex, multi-op execution context of a smart account's session keys or transaction mempool.
The evidence is in adoption metrics. Despite ERC-4337's launch, less than 5% of L2s natively support portable account migration, as seen in the fragmented support for Paymaster and Bundler services across chains.
key-trends
WHY CROSS-L2 PORTABILITY IS STILL A DREAM
The Fractured Landscape of AA Implementation
Account Abstraction (AA) promises a unified user experience, but its implementation is a mess of competing standards and infrastructure silos.
01
The ERC-4337 vs. Native AA Schism
ERC-4337 is a smart contract-based overlay, while chains like zkSync Era and Starknet bake AA directly into the protocol. This creates two incompatible paradigms.
- Overlay Model: Portable but pays overhead gas for a virtual mempool and bundlers.
- Native Model: More efficient but locks users into a single L2's ecosystem and tooling.
~30%
Gas Overhead
2 Models
Competing Standards
02
Bundler and Paymaster Balkanization
ERC-4337's core infrastructure components are not neutral public goods; they are becoming vertically integrated service silos.
- Bundler Lock-in: UserOps are not forwarded between bundlers like Stackup, Alchemy, and Biconomy, fragmenting liquidity.
- Paymaster Walled Gardens: Sponsored transactions rely on paymaster contracts that are chain-specific, preventing cross-chain session keys or gas sponsorship.
0
Cross-Bundler Liquidity
Chain-Specific
Paymaster Logic
03
The Intractability of State Synchronization
An AA smart account's state—its nonce, deployed address, and module permissions—is stored on its native chain. Moving this state is a cryptographic nightmare.
- Nonce Chaos: A single sequential nonce across chains is impossible without a centralized sequencer, breaking atomic composability.
- Address Mismatch: CREATE2 enables deterministic addresses, but verifying signatures and state across different VMs (EVM vs. Cairo VM) requires slow, expensive bridging of proofs.
~2-3s
Proof Relay Time
High Cost
State Bridging
04
The LayerZero Fallacy: Messaging ≠Portability
Cross-chain messaging protocols like LayerZero and Axelar can relay transactions, but they cannot magically synchronize account state or unify execution environments.
- Opaque Execution: A message to a remote chain executes in a different context, with different gas rules and AA support.
- Security Mismatch: You inherit the security of the messaging layer, not the destination chain, adding a new trust vector for simple account actions.
New Trust Layer
Security Model
Context Broken
Execution Environment
05
Economic Incentives Are Misaligned
L2s have no commercial reason to enable easy exit. Portability reduces stickiness and commoditizes their execution environment.
- Captive Users: Value accrues from sequencer fees and locked TVL. A portable account drains both.
- Fragmented Roadmaps: Each L2 team prioritizes features that differentiate their chain (e.g., Starknet's native AA), not interoperability with competitors.
High
Vendor Lock-In
Low Priority
Interop Dev
06
The Only Viable Path: Aggregation Layers
True portability requires a new abstraction layer above the L2s, not integration between them. Think UniswapX for intents, but for entire account sessions.
- Intent-Based Orchestration: Users submit desired outcomes ("swap X for Y on any chain"), and a solver network manages the cross-chain account logistics.
- Unified Front-end: Wallets like Rainbow or Safe become the portable layer, using stealth addresses and proof aggregation to mask underlying fragmentation.
Emerging
Solution Class
User-Centric
Paradigm Shift
CROSS-CHAIN USER OPERATION COMPATIBILITY
AA Implementation Divergence Matrix
Compares core technical divergences in major ERC-4337 Bundler and Paymaster implementations that fracture the user experience and prevent seamless cross-L2 portability.
| Core Feature / Constraint | Stackup (Bundler) | Alchemy (Account Kit) | Pimlico (Paymaster & Bundler) | Ethereum Foundation (Reference) |
|---|---|---|---|---|
Bundler RPC Method | eth_sendUserOperation | rundler_maxiSendUserOperation | pimlico_sendUserOperation | eth_sendUserOperation |
Paymaster Data Format | Custom | Structured | ERC-20 | Minimal spec-compliant |
Gas Fee Abstraction Sponsor | ||||
Non-Atomic Batch Support | ||||
Required EntryPoint Version | 0.7 | 0.6 | 0.6 | 0.6 |
Avg. Bundler Inclusion Latency | < 2 sec | < 5 sec | < 3 sec |
|
Native Cross-L2 UserOp Relay | ||||
Smart Account Deploy Gas Cost | ~250k gas | ~190k gas | ~220k gas | ~300k gas |
deep-dive
THE STATE ROOT PROBLEM
The Technical Quagmire: Why a Simple Bridge Won't Work
Account portability requires a shared, verifiable source of truth that current L2 architectures fundamentally lack.
State is not fungible. A token bridge like Across or Stargate moves assets by locking and minting representations. An account is a complex, mutable state object—its nonce, storage, and code—that cannot be 'locked' on one chain and 'minted' on another without a shared, canonical reference.
L2s are sovereign state machines. Arbitrum, Optimism, and zkSync each maintain independent state roots. A simple messaging bridge like LayerZero cannot prove the validity of an entire account's state; it can only attest to specific, pre-agreed messages, creating a massive trust and data availability gap.
The verifiability gap is insurmountable. For Chain B to accept an account from Chain A, it must verify the entire historical state transition that led to that account. This requires full chain data availability and execution replay, a task that defeats the purpose of a scalable L2 and mirrors the inefficiency of an L1.
Evidence: No major L2 (Arbitrum, Base, Starknet) supports native account portability. Projects attempting it, like ZK-Rollup interoperability, require synchronous communication and shared provers, which centralizes consensus and negates scaling benefits.
counter-argument
THE STANDARDIZATION FALLACY
Steelman: Couldn't a Universal Standard Fix This?
Universal standards fail because they require protocol-level consensus, which is impossible without sacrificing sovereignty or performance.
Standards require consensus. A universal standard like ERC-4337 for account abstraction is a coordination problem. It requires every L2, from Arbitrum to Base, to adopt identical VM modifications and security assumptions, which they reject to preserve technical sovereignty.
Sovereignty kills universality. L2s compete on execution environments; zkEVMs, OP Stack forks, and custom VMs like Starknet's Cairo optimize for different trade-offs. Forcing a single standard creates a lowest-common-denominator that degrades performance for all.
Fragmentation is the feature. The ecosystem's strength is its specialized execution layers. A standard that unifies account portability would homogenize this, negating the reason for multi-chain architectures. The market chose fragmentation over a single, slow standard.
Evidence: Look at EIP-3074 vs ERC-4337. Even within a single ecosystem (Ethereum), competing standards for native vs. smart contract wallet auth stalled for years. Scaling this to dozens of sovereign L2s is intractable.
takeaways
THE STATE-SYNC BARRIER
TL;DR for Protocol Architects
Seamless user identity across L2s is blocked by fundamental architectural trade-offs, not just engineering.
01
The State Sovereignty Problem
Each L2 is a sovereign state with its own execution environment and canonical data. Porting an account requires synchronizing nonce, storage, and code across chains, which is computationally prohibitive and breaks finality assumptions.\n- Impossible to prove state consistency without re-execution.\n- Creates a meta-consensus problem between L1 and L2s.
~10-30s
Finality Lag
O(n²)
Sync Complexity
02
The Gas Token Fragmentation Trap
Every major L2 (Arbitrum, Optimism, zkSync, Starknet) uses a different native gas token. Account portability forces users to hold liquidity on every chain or rely on slow, expensive bridging. This kills UX and locks capital in transit.\n- UniswapX-style intents only solve swaps, not state.\n- LayerZero messages don't transfer execution context.
5-10+
Gas Tokens Needed
$5M+
Bridged Daily
03
The Verifier Complexity Wall
For ZK-Rollups, proving an account's state from another chain requires a verifier for a verifier. A Starknet client must verify a zkSync proof of its own state, which is recursive ZK and not production-ready. EVM equivalence is a myth at the proof level.\n- No shared proof system across major ZK-VMs.\n- Across Protocol and other bridges are asset-focused, not stateful.
1000x
Proof Overhead
~2026+
Realistic ETA
04
The Economic Security Mismatch
An account's security is tied to its underlying chain's economic security (stake, fraud proofs). Porting to a weaker chain reduces security guarantees instantly. No mechanism exists to port security budgets. This makes cross-L2 smart accounts a liability.\n- Optimistic Rollups have a 7-day challenge window.\n- Validiums have no data availability on L1.
$1B vs $100M
Security Delta
7 Days
Vulnerability Window
05
The Wallet Abstraction Illusion
ERC-4337 and smart accounts solve key management, not state portability. A cross-chain smart account is just a set of independent contracts that must be funded and synchronized manually. The "unified" front-end is a facade over fragmented backends.\n- Session keys are chain-specific.\n- Gas sponsorship requires per-chain paymasters.
0
Native Sync
5+
Contracts Per User
06
The Only Viable Path: Aggressive L1 Scaling
True portability requires moving the bottleneck back to L1. EIP-7212 (secp256r1 verification) and Verkle trees for state expiry reduce L1 footprint, making it feasible to keep core identity there. L2s become execution shards, not identity hubs. This aligns with Ethereum's rollup-centric roadmap.\n- Danksharding provides cheap L1 data.\n- L1 as the identity layer is the endgame.
10-100x
L1 Capacity Needed
2025+
Roadmap Horizon
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