Cardano Leios Prototype Adapts Block Size to Voting Support

Cardano’s consensus team released Ouroboros Leios prototype rc-2026w44 with a feature called adaptive endorsements. It lets producers create smaller endorser blocks when recent blocks draw less voting support. The team designed the feature to preserve some of Leios’ added transaction capacity when larger blocks struggle to get certified and throughput would otherwise fall back to the level supported by Praos, Cardano’s existing consensus protocol.

Why Smaller Blocks Can Help

Leios adds capacity by using endorser blocks to carry transactions alongside the regular blocks that form the chain. Certifying an endorser block requires votes representing a minimum share of stake. In Musashi tests, some larger blocks fell short because voting nodes could not validate transactions they had yet to see before the voting window closed.

The prototype compares the voting weight behind each recent block announcement with the stake that participated across recent rounds. It uses that difference to estimate how much of the margin above the certification threshold the announcement lost. Producers then scale down new endorser blocks, giving voting nodes fewer transactions to check within the same window.

What Changed in the Main Development Branch

Separately from the prototype release, the consensus team added endorser block production to the main development branch. Producers can build these blocks from transactions that do not fit in a regular chain block, known as a ranking block, and store them in a dedicated database called LeiosDB.

When an incoming ranking block carries a Leios certificate, the node checks the certificate and waits for the corresponding endorser block before selecting the ranking block for its chain. The development branch also adds vote relaying. Nodes check each Leios vote once and disconnect from peers that send invalid votes.

[NEWSBREAK]

How Musashi and DijkstraNet Differ

Intersect identified Musashi as the test network for the full Linear Leios implementation. DijkstraNet runs protocol version 12 and supports BLS key registration for stake pool operators. Its current release leaves full Linear Leios out of scope.

Adaptive endorsements are off by default in rc-2026w44. The configuration supplied for Musashi enables the feature. The release keeps the database and network message formats used by rc-2026w43, so nodes on both versions can communicate and operators can upgrade without resynchronizing.