Base Cobalt adds conditional transactions and B20 controls

Base activated its Cobalt upgrade on mainnet on September 30, adding conditional transaction inclusion and new controls for B20 assets. Base’s Cobalt documentation marks the upgrade live and describes validity transactions as signed transactions included only when onchain conditions match.

When does a validity transaction enter a block?

A validity transaction becomes eligible for inclusion only after its submitted conditions match Base’s chain state. Those predicates can check contract storage, a block number or a Flashblock index. In a swap, for example, a trader can set a pool-price threshold and a block deadline; Base holds the transaction until the conditions are true, or leaves it un-included if they are not met in time.

Base says submissions remain private until they land. As Unchained’s report on Cobalt explains, the conditions themselves are not recorded onchain. Matching them makes a transaction eligible, but does not guarantee it will enter a block or execute successfully.

What changes for B20 assets?

Cobalt adds policy composition, scheduled multiplier updates and the seizeWithMemo function to B20, Base’s token standard. Composite Policies let issuers combine existing allowlists and blocklists with AND or OR logic. A transfer rule could, for example, require a recipient to pass a KYC check while also not appearing on a sanctions list. The policies can use live lists, avoiding a separately maintained copy that could become outdated.

Scheduled multiplier updates let issuers set a future change to how an asset’s balance is displayed, such as for a stock split. Base says the update aligns the B20 Asset multiplier with ERC-8056. Existing Beryl integrations will continue to work, while new integrations can adopt the updated standard over time.

The new seizeWithMemo function lets an issuer-authorized administrator reassign a holder’s balance when seizure is enabled for that asset. The transaction records the source, destination, amount and memo onchain. Base describes it as a transfer: it moves the balance to another address, such as a recovery wallet, rather than burning it. Seizure is opt-in per token, and Base says it does not initiate or direct the transfer.

What does the upgrade change for users?

For traders, validity transactions provide a way to submit actions tied to state and timing conditions without repeatedly resubmitting them. For asset issuers, Cobalt adds configurable transfer rules, scheduled display changes and an authorized balance-reassignment path. These features change how transactions qualify for inclusion and how B20 assets are administered; they do not guarantee a trade will execute or determine an issuer’s policies.