Preconfirmation
A fast, economically backed promise from a sequencer or proposer that a submitted transaction will be included exactly as sent, offered well before actual on-chain finality.
A preconfirmation is a fast promise, issued by a sequencer or an upcoming block proposer, that a submitted transaction will be included in an upcoming block exactly as the user sent it, offered within a fraction of a second — well before the transaction actually achieves on-chain finality (see Kaavon's "Finality" glossary definition). This lets applications offer users and other on-chain actors near-instant confidence about a transaction's eventual inclusion, without needing to wait for the base chain's full confirmation and finality timeline.
The practical value of a preconfirmation depends entirely on it being credibly backed by some real economic consequence for breaking the promise — for example, a proposer's stake being slashed if they fail to honor a preconfirmation they issued — since a preconfirmation with no such backing would just be an unenforceable claim rather than a meaningful guarantee. Preconfirmations have become particularly relevant to based rollups (see Kaavon's "Based Rollup" glossary definition), which rely directly on the base chain's own proposers for sequencing and can use preconfirmations to offer users fast feedback despite the base chain's own block time.
Examples
- A based rollup might rely on economically backed preconfirmations to give users near-instant feedback that their transaction will be included, despite the underlying base chain's slower actual block time.
- A preconfirmation only provides a meaningful guarantee if breaking it carries a real economic consequence for the issuer, such as a slashing penalty on their staked collateral.