Coinbase’s layer-2 network Base said its Cobalt upgrade went live on mainnet on Wednesday, giving issuers of tokens built on B20, a token standard native to the chain itself, a new way to remove a holder’s balance: moving it to another wallet, with a note recorded onchain, rather than destroying it.

The new function, seizeWithMemo, supersedes a tool from Base’s previous upgrade, Beryl, which introduced B20 with freeze and blocklist powers. That tool, burnBlocked, could only burn a blocked holder’s tokens; Base has deprecated it but left it callable. Under Cobalt, an administrator the issuer authorizes can send a holder’s balance to another address, such as a recovery wallet, as one transfer, which Base’s developer documentation describes as “A transfer, not a burn.”

“Seize is opt-in per token,” the documentation says. The function does nothing until an issuer names which holders can be seized and grants the seize permission to specific administrators. “The issuer controls whether seizure is enabled and who is authorized to use it; Base does not initiate or direct this transfer,” Base wrote in its announcement. Unchained covered B20’s launch in July.

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Combined Allowlists and Blocklists

Issuers can also combine two to four existing allowlists or blocklists, including lists kept by other parties such as a KYC provider, into one rule using AND or OR logic, for example requiring that a holder be on a KYC allowlist and not on a sanctions blocklist. The token reads those lists live when it checks a transfer, so a change to any one of them applies from the next check. Until now, an issuer relying on several lists had to maintain its own combined copy with offchain software, a copy that Base’s changelog says could fall out of date.

Conditional Transactions for Traders

Cobalt also introduces Validity Transactions. A trader signs a transaction and attaches conditions, such as a minimum account balance, a value stored in a contract or a block-number deadline, and Base waits to include it until every condition is true. Base’s own example is a swap that executes only once a pool’s price clears a threshold. Base says the feature keeps traders’ submissions “private until they land,” and its documentation says the conditions themselves are not recorded onchain. Meeting the conditions does not guarantee a spot in a block: “Predicates are inclusion conditions. They do not guarantee inclusion or successful execution,” the documentation says, using Base’s term for the conditions.

Cobalt is Base’s third network upgrade. Base says its plans for the coming months include Base Transactions, native support for smart-contract wallets whose fees someone else can pay and which can bundle several actions into one, and blocks every 200 milliseconds, down from two seconds.

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