Base activates Cobalt with conditional transactions and issuer controls

Base activated its Cobalt hard fork on mainnet at 18:00 UTC on September 30, adding conditional transaction handling and new controls for assets issued under the network’s B20 token standard. The upgrade matters because it moves functions associated with offchain order logic and regulated-asset administration into Base’s protocol surface, while leaving important guarantees and adoption questions unresolved.

Base’s documentation marked Cobalt live on mainnet after an earlier Sepolia activation. The project’s v1.4.2 release required node operators to upgrade before the mainnet activation time; the release superseded v1.4.1 and added Cobalt support plus the wiring needed for the new transaction interface. The Block independently reported the mainnet launch shortly after activation.

Transactions can wait for onchain conditions

Cobalt’s “validity transactions” let a user submit a signed transaction together with predicates tied to Base state. The supported conditions can inspect balances, storage values, block numbers and Flashblock indexes. Base considers the transaction eligible only when every attached predicate matches.

That creates a native route for actions such as a swap that should become eligible only after an onchain price condition is met, or a withdrawal constrained to a defined block window. A pending transaction can become eligible after another transaction changes the state it watches.

Eligibility is not execution. Base’s specification says an eligible transaction still competes for block space under normal fee rules, so matching the conditions neither reserves capacity nor guarantees inclusion. The criteria are also sent beside the signed transaction and do not appear in the resulting onchain transaction. That reduces public exposure of the conditions after execution, but it is not a license to place secrets in calldata or predicate values; Base expressly warns against doing so.

B20 gains stronger issuer controls

Cobalt also expands B20, Base’s native fungible-token framework. Composite policies allow issuers to combine existing allowlists and blocklists with AND or OR logic instead of copying membership into a separate list. That can express requirements such as satisfying both identity and investor-eligibility checks, with authorization evaluated against the current child policies.

A scheduled multiplier mechanism gives issuers a protocol-level way to change displayed balances for corporate actions such as stock splits while preserving compatibility with the earlier Beryl interface. The mechanism changes the user-interface representation of balances; it should not be confused with minting additional underlying units.

More controversially, an opt-in seize function permits an authorized administrator to move a holder’s balance to another address and record a memo. This is not a power held automatically by Base. The token issuer must configure the relevant policy and role, and the official specification says no account is seizable while that policy slot remains unset. The feature may help issuers implement legal or recovery processes, but it also makes issuer authority a material property users must evaluate asset by asset.

Two infrastructure changes remain qualified

Cobalt moves registration of new trusted-execution-environment signers to onchain verification of AWS Nitro attestations, replacing an external proving flow. Base says enclave key generation, image selection and proof verification otherwise remain unchanged.

The upgrade also introduces a contract-backed schedule that could let nodes apply future fork times without a restart. On mainnet, however, that system is operating only in metrics mode while Base collects data. It should not yet be described as fully controlling production upgrades.

The evidence establishes that Cobalt activated and that these interfaces are available at protocol level. It does not show how many applications will use them, whether conditional orders improve execution outcomes, or how frequently issuers will enable administrative controls. No transaction-volume, fee, adoption or token-price conclusion can be drawn from the launch record alone.