Base activates Cobalt with conditional transactions and B20 changes

Base activated its third mainnet upgrade, Cobalt, on Sept. 30, adding conditional transactions and three functions for B20 assets, according to Base’s announcement. The changes let users set conditions for transaction inclusion and give asset issuers added policy and balance-management tools.

How do Cobalt’s conditional transactions work?

Validity Transactions remain ineligible for inclusion until user-set conditions are met, Base said. Users submit a signed transaction with criteria through the base_sendRawTransactionValidity API; Base’s example uses a pool price of at least 4,000 USDC and a deadline before block 1,157,000.

Base evaluates the conditions as each block is built, and the transaction is not included if the deadline arrives first, the company said. The Block reported that submissions remain private until they land, and that meeting the conditions makes a transaction eligible for inclusion rather than guaranteeing it will be included.

What changed for B20 assets?

Cobalt adds Composite Policies, Schedule Multiplier Updates and seizeWithMemo to Base’s B20 standard, according to The Block’s report and Base. Composite Policies let issuers combine existing allowlists and blocklists using AND or OR logic, which Base said can support checks such as KYC and sanctions screening without copying lists.

Schedule Multiplier Updates let issuers schedule changes to an asset’s displayed balance for corporate actions such as splits. Base said the change affects the UI-denominated view while raw balances and transfer behavior remain unchanged; existing Beryl integrations will continue to work.

Who can use seizeWithMemo?

Only authorized administrators can use the function, and seizure must be enabled for the token, Base said. It reassigns a holder’s balance as a transfer and records the source, destination, amount and memo onchain.

Base’s example describes moving shares from a frozen account to a recovery wallet. The issuer controls whether seizure is enabled and who is authorized; Base said it does not initiate or direct the transfer.

Sources

• Base’s announcement — blog.base.dev
• The Block’s report — theblock.co