Guest posted by Harmonic
Preconfirmations aren't new to Solana. Leader-side preconf feeds already exist, streaming a transaction's execution result the moment the leader processes it, ahead of that block being shredded and broadcast. What Harmonic and Triton are bringing isn't another version of that. It's a different source for the signal entirely, one that sits a full stage earlier in the pipeline. Harmonic is the source of the data well and Triton is the portal for how that data is access, consumed, and distributed.
On Harmonic, block construction splits into two roles. An external builder selects and simulates the transactions that will go into a block, then forwards that selection to whichever validator is currently serving as leader, which executes, shreds, and broadcasts it. A Harmonic preconf is emitted at the first of those steps: the moment the builder makes that selection, before the transaction has even reached the leader.
That's the distinction worth sitting with. A leader-side preconf tells you what happened, reported immediately after execution. A Harmonic preconf provides data on what might happen, reported at selection, before execution has started. Different question, different point of origin, and structurally impossible for anything downstream of the leader, preconf or shred, to answer earlier.
Where a shred fits, and where it doesn't
A shred is the leader's receipt: a signed, MTU-sized fragment of a block the leader has already executed, capped at 1228 bytes and erasure-coded into FEC sets so the network can reconstruct a full block even with some packet loss. Every shred-derived product, raw shreds, decoded shred streams, Triton's own Deshred endpoint, is reading data that only exists once the leader has finished executing and packaging the block. Deshred gets impressively close to that moment, tapping in right after shred verification and before the receiving node's own replay, at roughly 6ms median and 20ms p90 from shred arrival. But it's still downstream of execution. There's no version of a shred-based product that can read earlier than the leader's own machine allows, because the artifact it's reading doesn't exist before that.
A Harmonic preconf isn't downstream of any of that. It doesn't wait on the leader at all. It's a read of Harmonic's own builder, publishing a decision the instant that decision is made, before the transaction is even in the leader's hands.
What a preconf is, and isn't
A few things worth being precise about:
Not a mempool. A mempool is an open, contestable waiting room, anyone can see it and act on it before selection happens. A preconf is the opposite: a committed decision Harmonic's builder has already made and simulated for the current block, published after the fact of that decision, not before it.
Not resubmittable, and not a bundle input. A preconf can't be resubmitted as its own transaction and can't become part of a bundle. It's a read-only view into a selection that's already been made.
Not final. The transaction still has to be executed by the leader, shredded, distributed, and voted on. A preconf is one of the earliest steps toward a transaction becoming official, not a substitute for any of the steps after it.
The full picture
Each layer is answering a different question, not competing to answer the same one faster.
Who this opens up to
This is for the apps and infra teams that need visibility earlier than a shred can offer it: monitoring tools, analytics platforms, indexers, and application backends currently waiting on data that's already several steps old by the time it reaches them. Harmonic validators stand to benefit too, if this data generates value, Harmonic shares it with the validators running its infrastructure, but the reach of this partnership goes beyond any single group. It's a new vantage point into Solana's block-building pipeline, from a stage nothing else currently touches.
Getting started
Preconf data is available through Triton's streaming infrastructure alongside the shred and account streams teams are already integrated with. Reach out to the Harmonic or Triton team to get access, or check the docs for integration details.