Redo coordinator's Substrate scanner

processor/bin/src/coordinator.rs

@@ -5,9 +5,8 @@ use tokio::sync::mpsc;
 
 use scale::Encode;
 use serai_client::{
-  primitives::Signature,
-  validator_sets::primitives::Session,
-  in_instructions::primitives::{Batch, SignedBatch},
+  primitives::Signature, validator_sets::primitives::Session,
+  in_instructions::primitives::SignedBatch,
 };
 
 use serai_db::{Get, DbTxn, Db, create_db, db_channel};

processor/bin/src/lib.rs

@@ -272,20 +272,17 @@ pub async fn main_loop<
         }
         messages::substrate::CoordinatorMessage::Block {
           serai_block_number: _,
-          batches,
+          batch,
           mut burns,
         } => {
           let scanner = scanner.as_mut().unwrap();
 
-          // Substrate sets this limit to prevent DoSs from malicious validator sets
-          // That bound lets us consume this txn in the following loop body, as an optimization
-          assert!(batches.len() <= 1);
-          for messages::substrate::ExecutedBatch {
+          if let Some(messages::substrate::ExecutedBatch {
             id,
             publisher,
             in_instructions_hash,
             in_instruction_results,
-          } in batches
+          }) = batch
           {
             let key_to_activate =
               KeyToActivate::<KeyFor<S>>::try_recv(txn.as_mut().unwrap()).map(|key| key.0);

processor/messages/src/lib.rs

@@ -145,7 +145,7 @@ pub mod sign {
 pub mod coordinator {
   use super::*;
 
-  // TODO: Why does this not simply take the block hash?
+  // TODO: Remove this for the one defined in serai-cosign
   pub fn cosign_block_msg(block_number: u64, block: [u8; 32]) -> Vec<u8> {
     const DST: &[u8] = b"Cosign";
     let mut res = vec![u8::try_from(DST.len()).unwrap()];
@@ -203,7 +203,7 @@ pub mod substrate {
     /// A block from Serai with relevance to this processor.
     Block {
       serai_block_number: u64,
-      batches: Vec<ExecutedBatch>,
+      batch: Option<ExecutedBatch>,
       burns: Vec<OutInstructionWithBalance>,
     },
   }

processor/signers/src/lib.rs

@@ -12,7 +12,7 @@ use frost::dkg::{ThresholdCore, ThresholdKeys};
 
 use serai_primitives::Signature;
 use serai_validator_sets_primitives::{Session, Slash};
-use serai_in_instructions_primitives::{Batch, SignedBatch};
+use serai_in_instructions_primitives::SignedBatch;
 
 use serai_db::{DbTxn, Db};