SIP-19 and the Future of Order Flow on Sui
SIP-19 introduces a tipping mechanism for Sui validators, creating the first explicit priority fee market on the network. We look at what this could mean for MEV infrastructure and the emerging order flow landscape.
Sui Improvement Proposal 19 (SIP-19) introduced a mechanism that could prove to be one of the more consequential changes to Sui's execution model: validator tipping. For the first time, transaction submitters can attach an explicit tip to their transactions, creating a direct economic incentive for validators to include and prioritize specific transactions.
This is worth paying attention to because it represents the formalization of something that has existed informally on every programmable blockchain: a priority fee market. And where there is a priority fee market, there tends to be an MEV supply chain.
How SIP-19 works
The mechanism is straightforward. A transaction can include an optional tip, denominated in SUI, that is paid directly to the validator that processes the transaction. Unlike Sui's existing gas fees (which are burned or distributed according to protocol rules), tips go directly to the validator's address.
SIP-19 does not mandate that validators prioritize tipped transactions. It simply makes it possible for them to do so. The actual ordering logic remains at the validator's discretion. But the incentive structure points in a clear direction.
In practice, this creates a nascent priority auction. Participants who need their transactions included quickly (for example, to capture a fleeting arbitrage opportunity) can now express that urgency in economic terms.
Parallels to Ethereum's evolution
Ethereum traversed a similar path, though over a longer timeframe and with different mechanics. Before EIP-1559 and MEV-Boost, Ethereum's priority fee market was implicit: participants bid up gas prices to get their transactions included first. This led to priority gas auctions (PGAs) that congested the network and wasted value in failed transactions.
Over time, the Ethereum ecosystem developed more structured approaches: bundle submission, block building, and relay infrastructure that created competitive auctions for block space. The result is a sophisticated supply chain where value flows through multiple specialized layers.
SIP-19 puts Sui at an early point on a potentially similar arc. The tipping mechanism is a raw, unstructured priority fee market. What comes next will depend on how the ecosystem develops, though Sui's architectural differences will shape the specifics.
What makes Sui different
Sui's object-centric model and parallel execution change the dynamics of a priority fee market in interesting ways. On Ethereum, every transaction competes for position within a single, sequentially executed block. On Sui, transactions touching different objects can execute in parallel, which means ordering only matters for transactions that share object dependencies.
This could lead to a more granular priority fee market than Ethereum's. Rather than a global gas auction, Sui could develop object-specific or pool-specific priority dynamics. This is conceptually similar to how equity market microstructure creates per-symbol order books rather than a single global queue.
Sui validators using the Mysticeti consensus protocol already process transactions with sub-second finality. The value of a tip is therefore likely less about inclusion (transactions are already included quickly) and more about ordering within the set of transactions that share object dependencies.
Early observations
Since SIP-19's activation, early indications suggest that tip adoption is concentrated among a small number of sophisticated participants. This is not surprising since these participants have the clearest economic motivation to pay for priority.
Tip amounts appear modest relative to the value of the transactions they accompany, suggesting the market is still in early price discovery.
What this means going forward
SIP-19 represents the beginning of a more explicit relationship between transaction submitters and validators on Sui. This is the kind of foundation on which more sophisticated infrastructure can potentially be built: formalized block building, relay networks, order flow auctions.
All of these developments would benefit from better visibility into the current state of execution on Sui. Understanding how tips affect ordering, who is using them, and what outcomes they produce will help inform how this infrastructure evolves. That is part of what we are building at Birdai.