Preconfirmations for Searchers

A preconfirmation is a transaction that the current BAM leader has committed to executing, in a known order, published before the leader shreds the block. Subscribers see what the rest of the slot is building on earlier than any shred-based feed. Early testing with distribution partners measured a p50 advantage of 5–10ms over their existing shred streams.

What you get

Each update carries one committed transaction:

• the leader slot and the serialized transaction;
• the batch it was scheduled in (sequence_id) and its position within that batch (bundle_position);
• whether the batch is all-or-nothing (is_revert_on_error);
• optionally, whether the transaction executed successfully (execution_success), when that is known.

What it is, and what it is not

• A commitment, not a prediction. A transaction appears only after the leader has committed to executing the batch that contains it. Pending work that has not yet been scheduled is never streamed.
• Not finality. The leader can still skip its slot or land on a fork. A preconfirmation says what will execute if the block lands.
• No reordering. Seeing a transaction early tells you what the slot is building on; it does not let anyone reorder or front-run that transaction within its batch.
• BAM leaders only. Non-BAM leaders, and BAM validators that have opted out, produce no preconfirmations. The BAM explorer shows the current share of network stake running BAM.

How to start consuming preconfirmations

Access is through Jito's distribution partners, who handle pricing, billing, onboarding and support. You do not need an account with Jito, and Jito does not sell the stream directly.

• Helius: pre-confirmations documentation
• Triton: customer onboarding

Wire format

The stream is a server-streaming gRPC service. Its protobuf definition is public in preconf/preconf.proto:

service PreconfStream {
  rpc Subscribe(PreconfSubscribeRequest) returns (stream PreconfUpdate);
}

message PreconfSubscribeRequest {
  uint64 slot = 1;
  bytes signature = 2;
}

message PreconfUpdate {
  uint64 slot = 1;
  uint32 sequence_id = 2;
  uint32 bundle_position = 3;
  bool is_revert_on_error = 4;
  bytes transaction = 5;
  optional bool execution_success = 6;
}

Your distribution partner documents how to connect and authenticate to their endpoint.