Biconomy and the Ethereum Foundation have published ERC-8211, a new Ethereum standard that changes how multi-step transactions get built and executed onchain. The standard, called smart batching, lets users and AI agents sign a single transaction covering an entire DeFi strategy, with each step’s values calculated at the exact moment the transaction runs rather than when it is signed.

The announcement came through Biconomy’s post on X, where the team described the standard as co-developed alongside the Ethereum Foundation’s UX improvement track. As ETH_Daily reported on X, the fix addresses a core problem: current batching on Ethereum locks in every number at signing time. Prices move. Outputs shift. The whole batch fails or leaves dust behind.

Static Execution Has Been Costing Users

The failure mode is straightforward. An agent wants to swap 1 ETH for USDC, then supply all of it to Aave. It has to guess the swap output before signing. If slippage returns 1,980 USDC instead of the hardcoded 2,000, the supply call fails and the entire batch reverts. If the agent guesses low at 1,950 to avoid that, 50 USDC sits idle. There is no way to say “supply whatever actually arrived.”

Teams that needed to go beyond this built custom smart contracts for every flow. New audit cycles, new deployment costs, new attack surface each time a strategy changed. Every team rebuilt the same infrastructure independently with no composability between them.

ERC-8211 cuts out that entire layer. Parameters are no longer pre-encoded. The EVM reads live onchain state at execution, validates it against inline constraints, then builds the calldata from what actually exists. No stale data passes through.

As Ethereum’s official account posted on X:

“ERC-8211 allows users and agents to express multi-step composable actions as a simple off-chain script with built-in safety.”

The standard is built on three components. Fetchers pull live values from onchain state at execution time, reading balances, oracle prices, or any contract’s view function. Constraints sit on top of those values, enforcing minimum amounts or maximum caps before a call proceeds. If a resolved balance is zero, it fails safely rather than passing through silently.

Why Agents Cannot Deviate After Signing

Predicate entries are the third piece. They act as boolean gates on chain state, checking whether conditions are met before anything executes. A cross-chain batch can include a predicate that waits for bridged funds to arrive on the destination chain. The relayer simulates the batch, and if the funds haven’t landed yet, it holds. The moment they do, it submits.

This structure also closes the hallucination problem for agent-executed transactions. Once a user reviews and signs the batch, the agent cannot deviate during execution. The relayer handles submission. Constraints are validated entirely onchain. The relayer cannot forge or redirect funds. What was signed is what runs, or the batch reverts.

ETH_Daily noted on X that the practical change is significant for ordinary users. Instead of specifying “swap 100 USDC, supply exactly 0.049 WETH,” a user can instruct: “swap 100 USDC, take whatever WETH arrives, supply all of it, but only if it clears my minimum.” The batch executes that logic or does not execute at all.

The Standard Is Account-Agnostic by Design

ERC-8211 works across ERC-7579 accounts, ERC-6900 accounts, native smart account implementations, ERC-7702 EOAs, and simple EOAs. All paths consume the same encoding and follow the same execution algorithm. It is compatible with ERC-7683, ERC-4337, and the interop standards under the Ethereum Foundation’s UX track.

The reference implementation is open source and the SDK is being built publicly. A live demo is already available. The Ethereum Magicians discussion thread is open for technical feedback, and a builder community is live on Telegram.

Biconomy described teams like Virtuals, Bankr, and AskGina as already pushing autonomous onchain execution but still defaulting to simple swaps, not from lack of intelligence but from lack of a shared standard to express anything more complex. ERC-8211 is positioned as that shared layer.

The standard also fits into a broader agent stack being developed on Ethereum, alongside ERC-8004 for agent identity, ERC-8183 for agent commerce, and x402 for agent payments. Smart batching is designed to handle what those standards leave unaddressed: the execution itself.