diff --git a/ouroboros-network-api/ouroboros-network-api.cabal b/ouroboros-network-api/ouroboros-network-api.cabal
index f02155f54dd..5e0e31830db 100644
--- a/ouroboros-network-api/ouroboros-network-api.cabal
+++ b/ouroboros-network-api/ouroboros-network-api.cabal
@@ -67,6 +67,7 @@ library
                        nothunks,
                        serialise         >=0.2   && <0.3,
                        text              >=1.2 && <2.2,
+                       quiet,
 
                        cardano-slotting,
                        cardano-strict-containers,
diff --git a/ouroboros-network-api/src/Ouroboros/Network/SizeInBytes.hs b/ouroboros-network-api/src/Ouroboros/Network/SizeInBytes.hs
index 8c5309d689b..e92259d8de0 100644
--- a/ouroboros-network-api/src/Ouroboros/Network/SizeInBytes.hs
+++ b/ouroboros-network-api/src/Ouroboros/Network/SizeInBytes.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DeriveGeneric              #-}
 {-# LANGUAGE DerivingStrategies         #-}
 {-# LANGUAGE DerivingVia                #-}
 {-# LANGUAGE GeneralisedNewtypeDeriving #-}
@@ -5,18 +6,25 @@
 module Ouroboros.Network.SizeInBytes (SizeInBytes (..)) where
 
 import Control.DeepSeq (NFData (..))
+import Data.Monoid (Sum (..))
 import Data.Word (Word32)
+import GHC.Generics
 
 import Data.Measure qualified as Measure
 import NoThunks.Class (NoThunks (..))
+import Quiet (Quiet (..))
 
 newtype SizeInBytes = SizeInBytes { getSizeInBytes :: Word32 }
-  deriving (Show, Eq, Ord)
-  deriving Enum     via Word32
-  deriving Num      via Word32
-  deriving Real     via Word32
-  deriving Integral via Word32
-  deriving NoThunks via Word32
+  deriving (Eq, Ord)
+  deriving Show      via Quiet SizeInBytes
+  deriving Enum      via Word32
+  deriving Num       via Word32
+  deriving Real      via Word32
+  deriving Integral  via Word32
+  deriving NoThunks  via Word32
+  deriving Semigroup via Sum Word32
+  deriving Monoid    via Sum Word32
+  deriving Generic
   deriving newtype NFData
   deriving Measure.Measure        via Word32
   deriving Measure.BoundedMeasure via Word32
diff --git a/ouroboros-network-framework/ouroboros-network-framework.cabal b/ouroboros-network-framework/ouroboros-network-framework.cabal
index 4acf4ea0bfa..e21bb0ef662 100644
--- a/ouroboros-network-framework/ouroboros-network-framework.cabal
+++ b/ouroboros-network-framework/ouroboros-network-framework.cabal
@@ -91,6 +91,7 @@ library
                      , si-timers
                      , strict-stm
 
+                     , nothunks       ^>=0.2
                      , psqueues
                      -- ^ only to derive nothunk instances
 
diff --git a/ouroboros-network-protocols/CHANGELOG.md b/ouroboros-network-protocols/CHANGELOG.md
index 678043d23ad..c10cef52158 100644
--- a/ouroboros-network-protocols/CHANGELOG.md
+++ b/ouroboros-network-protocols/CHANGELOG.md
@@ -25,6 +25,8 @@
 * Refactored CBOR mini-protocols codecs to a more modular structure
 * Added `deepseq` dependency and implemented `NFData` for `testlib` types.
 * Added miniprotocols codec benchmarks
+* Use `SizeInBytes` newtype instead of the `TxSizeInBytes` type aliase.
+  `TxSizeInBytes` is now deprecated.
 
 ## 0.8.0.0 -- 2024-02-21
 
diff --git a/ouroboros-network-protocols/ouroboros-network-protocols.cabal b/ouroboros-network-protocols/ouroboros-network-protocols.cabal
index 98117370e93..811009c4e03 100644
--- a/ouroboros-network-protocols/ouroboros-network-protocols.cabal
+++ b/ouroboros-network-protocols/ouroboros-network-protocols.cabal
@@ -98,8 +98,10 @@ library
                        bytestring        >=0.10 && <0.13,
                        cborg             >=0.2.1 && <0.3,
                        deepseq,
+                       quiet,
 
                        io-classes       ^>=1.5.0,
+                       nothunks,
                        si-timers,
 
                        ouroboros-network-api
diff --git a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Client.hs b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Client.hs
index c569d93be42..f7a6a1f2c80 100644
--- a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Client.hs
+++ b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Client.hs
@@ -27,8 +27,6 @@ module Ouroboros.Network.Protocol.TxSubmission2.Client
   , txSubmissionClientPeer
   ) where
 
-import Data.Word (Word16)
-
 import Network.TypedProtocol.Core
 
 import Ouroboros.Network.Protocol.TxSubmission2.Type
@@ -56,8 +54,8 @@ data ClientStIdle txid tx m a = ClientStIdle {
 
     recvMsgRequestTxIds      :: forall blocking.
                                 TokBlockingStyle blocking
-                             -> Word16
-                             -> Word16
+                             -> NumTxIdsToAck
+                             -> NumTxIdsToReq
                              -> m (ClientStTxIds blocking txid tx m a),
 
     recvMsgRequestTxs        :: [txid]
@@ -65,7 +63,7 @@ data ClientStIdle txid tx m a = ClientStIdle {
   }
 
 data ClientStTxIds blocking txid tx m a where
-  SendMsgReplyTxIds :: BlockingReplyList blocking (txid, TxSizeInBytes)
+  SendMsgReplyTxIds :: BlockingReplyList blocking (txid, SizeInBytes)
                     -> ClientStIdle           txid tx m a
                     -> ClientStTxIds blocking txid tx m a
 
diff --git a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Codec.hs b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Codec.hs
index 605e934ad30..7bfa2f0f806 100644
--- a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Codec.hs
+++ b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Codec.hs
@@ -102,7 +102,10 @@ encodeTxSubmission2 encodeTxId encodeTx = encode
     encode (ClientAgency TokInit)  MsgInit =
         CBOR.encodeListLen 1
      <> CBOR.encodeWord 6
-    encode (ServerAgency TokIdle) (MsgRequestTxIds blocking ackNo reqNo) =
+    encode (ServerAgency TokIdle) (MsgRequestTxIds
+                                     blocking
+                                     (NumTxIdsToAck ackNo)
+                                     (NumTxIdsToReq reqNo)) =
         CBOR.encodeListLen 4
      <> CBOR.encodeWord 0
      <> CBOR.encodeBool (case blocking of
@@ -115,14 +118,15 @@ encodeTxSubmission2 encodeTxId encodeTx = encode
         CBOR.encodeListLen 2
      <> CBOR.encodeWord 1
      <> CBOR.encodeListLenIndef
-     <> foldr (\(txid, sz) r -> CBOR.encodeListLen 2
+     <> foldr (\(txid, SizeInBytes sz) r ->
+                                CBOR.encodeListLen 2
                              <> encodeTxId txid
                              <> CBOR.encodeWord32 sz
                              <> r)
               CBOR.encodeBreak
               txids'
       where
-        txids' :: [(txid, TxSizeInBytes)]
+        txids' :: [(txid, SizeInBytes)]
         txids' = case txids of
                    BlockingReply    xs -> NonEmpty.toList xs
                    NonBlockingReply xs -> xs
@@ -166,11 +170,12 @@ decodeTxSubmission2 decodeTxId decodeTx = decode
           return (SomeMessage MsgInit)
         (ServerAgency TokIdle,       4, 0) -> do
           blocking <- CBOR.decodeBool
-          ackNo    <- CBOR.decodeWord16
-          reqNo    <- CBOR.decodeWord16
-          return $! case blocking of
-            True  -> SomeMessage (MsgRequestTxIds TokBlocking    ackNo reqNo)
-            False -> SomeMessage (MsgRequestTxIds TokNonBlocking ackNo reqNo)
+          ackNo    <- NumTxIdsToAck <$> CBOR.decodeWord16
+          reqNo    <- NumTxIdsToReq <$> CBOR.decodeWord16
+          return $!
+            if blocking
+            then SomeMessage (MsgRequestTxIds TokBlocking    ackNo reqNo)
+            else SomeMessage (MsgRequestTxIds TokNonBlocking ackNo reqNo)
 
         (ClientAgency (TokTxIds b),  2, 1) -> do
           CBOR.decodeListLenIndef
@@ -179,7 +184,7 @@ decodeTxSubmission2 decodeTxId decodeTx = decode
                      (do CBOR.decodeListLenOf 2
                          txid <- decodeTxId
                          sz   <- CBOR.decodeWord32
-                         return (txid, sz))
+                         return (txid, SizeInBytes sz))
           case (b, txids) of
             (TokBlocking, t:ts) ->
               return $
diff --git a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Server.hs b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Server.hs
index bddb6398e2a..c29517ca208 100644
--- a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Server.hs
+++ b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Server.hs
@@ -17,13 +17,13 @@ module Ouroboros.Network.Protocol.TxSubmission2.Server
     TxSubmissionServerPipelined (..)
   , ServerStIdle (..)
   , Collect (..)
-  , TxSizeInBytes
     -- * Execution as a typed protocol
   , txSubmissionServerPeerPipelined
+    -- * deprecated API
+  , TxSizeInBytes
   ) where
 
 import Data.List.NonEmpty (NonEmpty)
-import Data.Word (Word16)
 
 import Network.TypedProtocol.Core
 import Network.TypedProtocol.Pipelined
@@ -44,7 +44,7 @@ data TxSubmissionServerPipelined txid tx m a where
 data Collect txid tx =
        -- | The result of 'SendMsgRequestTxIdsPipelined'. It also carries
        -- the number of txids originally requested.
-       CollectTxIds Word16 [(txid, TxSizeInBytes)]
+       CollectTxIds NumTxIdsToReq [(txid, SizeInBytes)]
 
        -- | The result of 'SendMsgRequestTxsPipelined'. The actual reply only
        -- contains the transactions sent, but this pairs them up with the
@@ -58,18 +58,18 @@ data ServerStIdle (n :: N) txid tx m a where
   -- |
   --
   SendMsgRequestTxIdsBlocking
-    :: Word16                               -- ^ number of txids to acknowledge
-    -> Word16                               -- ^ number of txids to request
+    :: NumTxIdsToAck                        -- ^ number of txids to acknowledge
+    -> NumTxIdsToReq                        -- ^ number of txids to request
     -> m a                                  -- ^ Result if done
-    -> (NonEmpty (txid, TxSizeInBytes)
+    -> (NonEmpty (txid, SizeInBytes)
         -> m (ServerStIdle Z txid tx m a))
     -> ServerStIdle        Z txid tx m a
 
   -- |
   --
   SendMsgRequestTxIdsPipelined
-    :: Word16
-    -> Word16
+    :: NumTxIdsToAck
+    -> NumTxIdsToReq
     -> m (ServerStIdle (S n) txid tx m a)
     -> ServerStIdle       n  txid tx m a
 
diff --git a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Type.hs b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Type.hs
index b09366148ef..220f1f2ab31 100644
--- a/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Type.hs
+++ b/ouroboros-network-protocols/src/Ouroboros/Network/Protocol/TxSubmission2/Type.hs
@@ -1,30 +1,56 @@
-{-# LANGUAGE DataKinds           #-}
-{-# LANGUAGE EmptyCase           #-}
-{-# LANGUAGE FlexibleInstances   #-}
-{-# LANGUAGE GADTs               #-}
-{-# LANGUAGE PolyKinds           #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE StandaloneDeriving  #-}
-{-# LANGUAGE TypeFamilies        #-}
+{-# LANGUAGE DataKinds                  #-}
+{-# LANGUAGE DeriveGeneric              #-}
+{-# LANGUAGE DerivingStrategies         #-}
+{-# LANGUAGE DerivingVia                #-}
+{-# LANGUAGE EmptyCase                  #-}
+{-# LANGUAGE FlexibleInstances          #-}
+{-# LANGUAGE GADTs                      #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE PolyKinds                  #-}
+{-# LANGUAGE ScopedTypeVariables        #-}
+{-# LANGUAGE StandaloneDeriving         #-}
+{-# LANGUAGE TypeFamilies               #-}
 
 -- | The type of the transaction submission protocol.
 --
 -- This is used to relay transactions between nodes.
 --
-module Ouroboros.Network.Protocol.TxSubmission2.Type where
+module Ouroboros.Network.Protocol.TxSubmission2.Type
+  ( TxSubmission2 (..)
+  , Message (..)
+  , ClientHasAgency (..)
+  , ServerHasAgency (..)
+  , NobodyHasAgency (..)
+  , TokBlockingStyle (..)
+  , StBlockingStyle (..)
+  , BlockingReplyList (..)
+  , NumTxIdsToAck (..)
+  , NumTxIdsToReq (..)
+    -- re-exports
+  , SizeInBytes (..)
+    -- deprecated API
+  , TxSizeInBytes
+  ) where
 
+import Control.DeepSeq
 import Data.List.NonEmpty (NonEmpty)
-import Data.Word (Word16, Word32)
+import Data.Monoid (Sum (..))
+import Data.Word (Word16)
+import GHC.Generics
+import NoThunks.Class (NoThunks (..))
+
+import Quiet (Quiet (..))
 
 import Network.TypedProtocol.Core
 
-import Control.DeepSeq
+import Ouroboros.Network.SizeInBytes (SizeInBytes (..))
 import Ouroboros.Network.Util.ShowProxy
 
 -- | Transactions are typically not big, but in principle in future we could
 -- have ones over 64k large.
 --
-type TxSizeInBytes = Word32
+type TxSizeInBytes = SizeInBytes
+{-# DEPRECATED TxSizeInBytes "Use 'Ouroboros.Network.SizeInBytes.SizeInBytes' instead" #-}
 
 -- | The kind of the transaction-submission protocol, and the types of the
 -- states in the protocol state machine.
@@ -96,6 +122,21 @@ data StBlockingStyle where
   StNonBlocking :: StBlockingStyle
 
 
+newtype NumTxIdsToAck = NumTxIdsToAck { getNumTxIdsToAck :: Word16 }
+  deriving (Eq, Ord, NFData, Generic)
+  deriving newtype (Num, Enum, Real, Integral, Bounded, NoThunks)
+  deriving Semigroup via (Sum Word16)
+  deriving Monoid via (Sum Word16)
+  deriving Show via (Quiet NumTxIdsToAck)
+
+newtype NumTxIdsToReq = NumTxIdsToReq { getNumTxIdsToReq :: Word16 }
+  deriving (Eq, Ord, NFData, Generic)
+  deriving newtype (Num, Enum, Real, Integral, Bounded, NoThunks)
+  deriving Semigroup via (Sum Word16)
+  deriving Monoid via (Sum Word16)
+  deriving Show via (Quiet NumTxIdsToReq)
+
+
 -- | There are some constraints of the protocol that are not captured in the
 -- types of the messages, but are documented with the messages. Violation
 -- of these constraints is also a protocol error. The constraints are intended
@@ -169,8 +210,8 @@ instance Protocol (TxSubmission2 txid tx) where
     --
     MsgRequestTxIds
       :: TokBlockingStyle blocking
-      -> Word16 -- ^ Acknowledge this number of outstanding txids
-      -> Word16 -- ^ Request up to this number of txids.
+      -> NumTxIdsToAck -- ^ Acknowledge this number of outstanding txids
+      -> NumTxIdsToReq -- ^ Request up to this number of txids.
       -> Message (TxSubmission2 txid tx) StIdle (StTxIds blocking)
 
     -- | Reply with a list of transaction identifiers for available
diff --git a/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Examples.hs b/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Examples.hs
index fb207ff4243..2c9fab3ecc0 100644
--- a/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Examples.hs
+++ b/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Examples.hs
@@ -30,6 +30,7 @@ import Network.TypedProtocol.Pipelined (N, Nat (..))
 
 import Ouroboros.Network.Protocol.TxSubmission2.Client
 import Ouroboros.Network.Protocol.TxSubmission2.Server
+import Ouroboros.Network.Protocol.TxSubmission2.Type
 
 
 --
@@ -37,7 +38,7 @@ import Ouroboros.Network.Protocol.TxSubmission2.Server
 --
 
 data TraceEventClient txid tx =
-     EventRecvMsgRequestTxIds (StrictSeq txid) (Map txid tx) [tx] Word16 Word16
+     EventRecvMsgRequestTxIds (StrictSeq txid) (Map txid tx) [tx] NumTxIdsToAck NumTxIdsToReq
    | EventRecvMsgRequestTxs   (StrictSeq txid) (Map txid tx) [tx] [txid]
   deriving Show
 
@@ -57,7 +58,7 @@ txSubmissionClient
      (Ord txid, Show txid, Monad m)
   => Tracer m (TraceEventClient txid tx)
   -> (tx -> txid)
-  -> (tx -> TxSizeInBytes)
+  -> (tx -> SizeInBytes)
   -> Word16  -- ^ Maximum number of unacknowledged txids allowed
   -> [tx]
   -> TxSubmissionClient txid tx m ()
@@ -81,8 +82,8 @@ txSubmissionClient tracer txId txSize maxUnacked =
 
         recvMsgRequestTxIds :: forall blocking.
                                TokBlockingStyle blocking
-                            -> Word16
-                            -> Word16
+                            -> NumTxIdsToAck
+                            -> NumTxIdsToReq
                             -> m (ClientStTxIds blocking txid tx m ())
         recvMsgRequestTxIds blocking ackNo reqNo = do
           traceWith tracer (EventRecvMsgRequestTxIds unackedSeq unackedMap
@@ -92,8 +93,8 @@ txSubmissionClient tracer txId txSize maxUnacked =
                  ++ "peer acknowledged more txids than possible"
 
           when (  fromIntegral (Seq.length unackedSeq)
-                - ackNo
-                + fromIntegral reqNo
+                - getNumTxIdsToAck ackNo
+                + getNumTxIdsToReq reqNo
                 > maxUnacked) $
             error $ "txSubmissionClientConst.recvMsgRequestTxIds: "
                  ++ "peer requested more txids than permitted"
@@ -157,8 +158,8 @@ txSubmissionClient tracer txId txSize maxUnacked =
 --
 
 data TraceEventServer txid tx =
-     EventRequestTxIdsBlocking  (ServerState txid tx) Word16 Word16
-   | EventRequestTxIdsPipelined (ServerState txid tx) Word16 Word16
+     EventRequestTxIdsBlocking  (ServerState txid tx) NumTxIdsToAck NumTxIdsToReq
+   | EventRequestTxIdsPipelined (ServerState txid tx) NumTxIdsToAck NumTxIdsToReq
    | EventRequestTxsPipelined   (ServerState txid tx) [txid]
 
 deriving instance (Show txid, Show tx) => Show (TraceEventServer txid tx)
@@ -168,7 +169,7 @@ data ServerState txid tx = ServerState {
        -- which have not yet been replied to. We need to track this it keep
        -- our requests within the limit on the number of unacknowledged txids.
        --
-       requestedTxIdsInFlight :: Word16,
+       requestedTxIdsInFlight :: NumTxIdsToReq,
 
        -- | Those transactions (by their identifier) that the client has told
        -- us about, and which we have not yet acknowledged. This is kept in
@@ -182,7 +183,7 @@ data ServerState txid tx = ServerState {
        -- requested. This is not ordered to illustrate the fact that we can
        -- request txs out of order. We also remember the sizes, though this
        -- example does not make use of the size information.
-       availableTxids         :: Map txid TxSizeInBytes,
+       availableTxids         :: Map txid SizeInBytes,
 
        -- | Transactions we have successfully downloaded but have not yet added
        -- to the mempool or acknowledged. This is needed because we request
@@ -195,7 +196,7 @@ data ServerState txid tx = ServerState {
        -- for more transactions. The number here have already been removed from
        -- 'unacknowledgedTxIds'.
        --
-       numTxsToAcknowledge    :: Word16
+       numTxsToAcknowledge    :: NumTxIdsToAck
      }
   deriving Show
 
@@ -238,7 +239,7 @@ txSubmissionServer tracer txId maxUnacked maxTxIdsToRequest maxTxToRequest =
         -- so the only remaining thing to do is to ask for more txids. Since
         -- this is the only thing to do now, we make this a blocking call.
       | otherwise
-      , let numTxIdsToRequest = maxTxIdsToRequest `min` maxUnacked
+      , let numTxIdsToRequest = NumTxIdsToReq $ maxTxIdsToRequest `min` maxUnacked
       = assert (requestedTxIdsInFlight st == 0
              && Seq.null (unacknowledgedTxIds st)
              && Map.null (availableTxids st)
@@ -389,7 +390,8 @@ txSubmissionServer tracer txId maxUnacked maxTxIdsToRequest maxTxToRequest =
         -- This definition is justified by the fact that the
         -- 'numTxsToAcknowledge' are not included in the 'unacknowledgedTxIds'.
         numTxIdsToRequest =
+          NumTxIdsToReq $
                 (maxUnacked
                   - fromIntegral (Seq.length (unacknowledgedTxIds st))
-                  - requestedTxIdsInFlight st)
+                  - getNumTxIdsToReq (requestedTxIdsInFlight st))
           `min` maxTxIdsToRequest
diff --git a/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Test.hs b/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Test.hs
index a5f31a8e2fe..43b7b7c413d 100644
--- a/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Test.hs
+++ b/ouroboros-network-protocols/testlib/Ouroboros/Network/Protocol/TxSubmission2/Test.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DataKinds                  #-}
+{-# LANGUAGE DerivingStrategies         #-}
 {-# LANGUAGE FlexibleContexts           #-}
 {-# LANGUAGE FlexibleInstances          #-}
 {-# LANGUAGE GADTs                      #-}
@@ -7,6 +8,7 @@
 {-# LANGUAGE PolyKinds                  #-}
 {-# LANGUAGE QuantifiedConstraints      #-}
 {-# LANGUAGE RankNTypes                 #-}
+{-# LANGUAGE StandaloneDeriving         #-}
 {-# LANGUAGE TypeFamilies               #-}
 
 {-# OPTIONS_GHC -Wno-orphans #-}
@@ -17,6 +19,7 @@ module Ouroboros.Network.Protocol.TxSubmission2.Test
   , TxId (..)
   ) where
 
+import Data.Bifunctor (second)
 import Data.ByteString.Lazy (ByteString)
 import Data.List (nub)
 import Data.List.NonEmpty qualified as NonEmpty
@@ -240,6 +243,10 @@ prop_pipe_IO params =
     ioProperty (prop_channel createPipeConnectedChannels params)
 
 
+deriving newtype instance Arbitrary NumTxIdsToAck
+deriving newtype instance Arbitrary NumTxIdsToReq
+
+
 instance Arbitrary (AnyMessageAndAgency (TxSubmission2 TxId Tx)) where
   arbitrary = oneof
     [ pure $ AnyMessageAndAgency (ClientAgency TokInit) MsgInit
@@ -255,11 +262,12 @@ instance Arbitrary (AnyMessageAndAgency (TxSubmission2 TxId Tx)) where
 
     , AnyMessageAndAgency (ClientAgency (TokTxIds TokBlocking)) <$>
         MsgReplyTxIds <$> (BlockingReply . NonEmpty.fromList
+                                         . map (second SizeInBytes)
                                          . QC.getNonEmpty
                                        <$> arbitrary)
 
     , AnyMessageAndAgency (ClientAgency (TokTxIds TokNonBlocking)) <$>
-        MsgReplyTxIds <$> (NonBlockingReply <$> arbitrary)
+        MsgReplyTxIds <$> (NonBlockingReply . map (second SizeInBytes) <$> arbitrary)
 
     , AnyMessageAndAgency (ServerAgency TokIdle) <$>
         MsgRequestTxs <$> arbitrary
diff --git a/ouroboros-network/ouroboros-network.cabal b/ouroboros-network/ouroboros-network.cabal
index 7cc92a7e8f5..0c571afb6d5 100644
--- a/ouroboros-network/ouroboros-network.cabal
+++ b/ouroboros-network/ouroboros-network.cabal
@@ -28,6 +28,7 @@ library
   -- At this experiment/prototype stage everything is exposed.
   -- This has to be tidied up once the design becomes clear.
   exposed-modules:
+                       Control.Concurrent.Class.MonadSTM.Strict.TMergeVar
                        Ouroboros.Network.BlockFetch
                        Ouroboros.Network.BlockFetch.Client
                        Ouroboros.Network.BlockFetch.ClientRegistry
diff --git a/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/BlockFetch.hs b/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/BlockFetch.hs
index 7a241ceecf8..e52faaf1068 100644
--- a/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/BlockFetch.hs
+++ b/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/BlockFetch.hs
@@ -6,7 +6,10 @@
 
 {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 
-module Test.Ouroboros.Network.BlockFetch (tests) where
+module Test.Ouroboros.Network.BlockFetch
+  ( PeerGSVT (..)
+  , tests
+  ) where
 
 import Test.ChainGenerators (TestChainFork (..))
 import Test.QuickCheck
@@ -798,6 +801,8 @@ prop_terminate (TestChainFork _commonChain forkChain _forkChain) (Positive (Smal
 
     fork'  = chainToAnchoredFragment forkChain
 
+-- TODO: moved to some shared place (cannot be moved to
+-- `ouroboros-network-testing` which doesn't depend on `ouroboros-network`)
 newtype PeerGSVT = PeerGSVT {
       unPeerGSVT :: PeerGSV
     } deriving Show
diff --git a/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/TxSubmission.hs b/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/TxSubmission.hs
index fc1a2ce782f..83d1c76ff09 100644
--- a/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/TxSubmission.hs
+++ b/ouroboros-network/sim-tests-lib/Test/Ouroboros/Network/TxSubmission.hs
@@ -73,7 +73,7 @@ tests = testGroup "TxSubmission"
 
 data Tx txid = Tx {
     getTxId    :: txid,
-    getTxSize  :: TxSizeInBytes,
+    getTxSize  :: SizeInBytes,
     -- | If false this means that when this tx will be submitted to a remote
     -- mempool it will not be valid.  The outbound mempool might contain
     -- invalid tx's in this sense.
@@ -88,11 +88,21 @@ instance ShowProxy txid => ShowProxy (Tx txid) where
 instance Arbitrary txid => Arbitrary (Tx txid) where
     arbitrary =
       Tx <$> arbitrary
-         <*> arbitrary
+         <*> chooseEnum (0, maxTxSize)
+             -- note:
+             -- generating small tx sizes avoids overflow error when semigroup
+             -- instance of `SizeInBytes` is used (summing up all inflight tx
+             -- sizes).
          <*> frequency [ (3, pure True)
                        , (1, pure False)
                        ]
 
+
+-- maximal tx size
+maxTxSize :: SizeInBytes
+maxTxSize = 65536
+
+
 newtype Mempool m txid = Mempool (TVar m (Seq (Tx txid)))
 
 
@@ -109,7 +119,7 @@ newMempool = fmap Mempool
            . Seq.fromList
 
 readMempool :: MonadSTM m => Mempool m txid -> m [Tx txid]
-readMempool (Mempool mempool) = toList <$> atomically (readTVar mempool)
+readMempool (Mempool mempool) = toList <$> readTVarIO mempool
 
 
 getMempoolReader :: forall txid m.
@@ -136,7 +146,7 @@ getMempoolReader (Mempool mempool) =
           mempoolHasTx      = \txid -> isJust $ find (\tx -> getTxId tx == txid) seq
        }
 
-    f :: Int -> Tx txid -> (txid, Int, TxSizeInBytes)
+    f :: Int -> Tx txid -> (txid, Int, SizeInBytes)
     f idx Tx {getTxId, getTxSize} = (getTxId, idx, getTxSize)
 
 
@@ -177,13 +187,13 @@ txSubmissionCodec2 =
     encodeTx Tx {getTxId, getTxSize, getTxValid} =
          CBOR.encodeListLen 3
       <> CBOR.encodeInt getTxId
-      <> CBOR.encodeWord32 getTxSize
+      <> CBOR.encodeWord32 (getSizeInBytes getTxSize)
       <> CBOR.encodeBool getTxValid
 
     decodeTx = do
       _ <- CBOR.decodeListLen
       Tx <$> CBOR.decodeInt
-         <*> CBOR.decodeWord32
+         <*> (SizeInBytes <$> CBOR.decodeWord32)
          <*> CBOR.decodeBool
 
 
@@ -207,7 +217,7 @@ txSubmissionSimulation
 
      , txid ~ Int
      )
-  => Word16
+  => NumTxIdsToAck
   -> [Tx txid]
   -> ControlMessageSTM m
   -> Maybe DiffTime
@@ -226,7 +236,7 @@ txSubmissionSimulation maxUnacked outboundTxs
                 txSubmissionCodec2
                 (byteLimitsTxSubmission2 (fromIntegral . BSL.length))
                 timeLimitsTxSubmission2
-                (fromMaybe id (delayChannel <$> outboundDelay) outboundChannel)
+                (maybe id delayChannel outboundDelay outboundChannel)
                 (txSubmissionClientPeer (outboundPeer outboundMempool))
 
     inboundAsync <-
@@ -235,7 +245,7 @@ txSubmissionSimulation maxUnacked outboundTxs
                 txSubmissionCodec2
                 (byteLimitsTxSubmission2 (fromIntegral . BSL.length))
                 timeLimitsTxSubmission2
-                (fromMaybe id (delayChannel <$> inboundDelay) inboundChannel)
+                (maybe id delayChannel inboundDelay inboundChannel)
                 (txSubmissionServerPeerPipelined (inboundPeer inboundMempool))
 
     _ <- waitAnyCancel [ outboundAsync, inboundAsync ]
@@ -289,7 +299,7 @@ prop_txSubmission (Positive maxUnacked) (NonEmpty outboundTxs) delay =
                     * realToFrac (length outboundTxs `div` 4))
                 atomically (writeTVar controlMessageVar Terminate)
             txSubmissionSimulation
-              maxUnacked outboundTxs
+              (NumTxIdsToAck maxUnacked) outboundTxs
               (readTVar controlMessageVar)
               mbDelayTime mbDelayTime
             ) in
diff --git a/ouroboros-network/src/Control/Concurrent/Class/MonadSTM/Strict/TMergeVar.hs b/ouroboros-network/src/Control/Concurrent/Class/MonadSTM/Strict/TMergeVar.hs
new file mode 100644
index 00000000000..73af34070e0
--- /dev/null
+++ b/ouroboros-network/src/Control/Concurrent/Class/MonadSTM/Strict/TMergeVar.hs
@@ -0,0 +1,44 @@
+{-# LANGUAGE BangPatterns #-}
+
+-- | STM TMergeVar mini-abstraction
+--
+module Control.Concurrent.Class.MonadSTM.Strict.TMergeVar
+  ( TMergeVar
+  , newTMergeVar
+  , writeTMergeVar
+  , takeTMergeVar
+  , tryReadTMergeVar
+  ) where
+
+import Control.Concurrent.Class.MonadSTM.Strict
+
+-- | The 'TMergeVar' is like a 'TMVar' in that we take it, leaving it empty.
+-- Unlike an ordinary 'TMVar' with a blocking \'put\' operation, it has a
+-- non-blocking combining write operation: if a value is already present then
+-- the values are combined using the 'Semigroup' operator.
+--
+-- This is used much like a 'TMVar' as a one-place queue between threads but
+-- with the property that we can \"improve\" the current value (if any).
+--
+newtype TMergeVar m a = TMergeVar (StrictTMVar m a)
+
+newTMergeVar :: MonadSTM m => STM m (TMergeVar m a)
+newTMergeVar = TMergeVar <$> newEmptyTMVar
+
+-- | Merge the current value with the given one and store it, return the updated
+-- value.
+--
+writeTMergeVar :: (MonadSTM m, Semigroup a) => TMergeVar m a -> a -> STM m a
+writeTMergeVar (TMergeVar v) x = do
+    mx0 <- tryTakeTMVar v
+    case mx0 of
+      Nothing -> x  <$ putTMVar v x
+      Just x0 -> x' <$ putTMVar v x' where !x' = x0 <> x
+
+takeTMergeVar :: MonadSTM m => TMergeVar m a -> STM m a
+takeTMergeVar (TMergeVar v) = takeTMVar v
+
+tryReadTMergeVar :: MonadSTM m
+                 => TMergeVar m a
+                 -> STM m (Maybe a)
+tryReadTMergeVar (TMergeVar v) = tryReadTMVar v
diff --git a/ouroboros-network/src/Ouroboros/Network/BlockFetch/ClientState.hs b/ouroboros-network/src/Ouroboros/Network/BlockFetch/ClientState.hs
index 2ff01c54618..40b8661c61d 100644
--- a/ouroboros-network/src/Ouroboros/Network/BlockFetch/ClientState.hs
+++ b/ouroboros-network/src/Ouroboros/Network/BlockFetch/ClientState.hs
@@ -41,6 +41,7 @@ import Data.Set (Set)
 import Data.Set qualified as Set
 
 import Control.Concurrent.Class.MonadSTM.Strict
+import Control.Concurrent.Class.MonadSTM.Strict.TMergeVar
 import Control.Exception (assert)
 import Control.Monad (when)
 import Control.Monad.Class.MonadTime.SI
@@ -750,38 +751,3 @@ takeTFetchRequestVar :: MonadSTM m
                                PeerFetchInFlightLimits)
 takeTFetchRequestVar v = (\(r,g,l) -> (r, getLast g, getLast l))
                      <$> takeTMergeVar v
-
---
--- STM TMergeVar mini-abstraction
---
-
--- | The 'TMergeVar' is like a 'TMVar' in that we take it, leaving it empty.
--- Unlike an ordinary 'TMVar' with a blocking \'put\' operation, it has a
--- non-blocking combining write operation: if a value is already present then
--- the values are combined using the 'Semigroup' operator.
---
--- This is used much like a 'TMVar' as a one-place queue between threads but
--- with the property that we can \"improve\" the current value (if any).
---
-newtype TMergeVar m a = TMergeVar (StrictTMVar m a)
-
-newTMergeVar :: MonadSTM m => STM m (TMergeVar m a)
-newTMergeVar = TMergeVar <$> newEmptyTMVar
-
--- | Merge the current value with the given one and store it, return the updated
--- value.
---
-writeTMergeVar :: (MonadSTM m, Semigroup a) => TMergeVar m a -> a -> STM m a
-writeTMergeVar (TMergeVar v) x = do
-    mx0 <- tryTakeTMVar v
-    case mx0 of
-      Nothing -> x  <$ putTMVar v x
-      Just x0 -> x' <$ putTMVar v x' where !x' = x0 <> x
-
-takeTMergeVar :: MonadSTM m => TMergeVar m a -> STM m a
-takeTMergeVar (TMergeVar v) = takeTMVar v
-
-tryReadTMergeVar :: MonadSTM m
-                 => TMergeVar m a
-                 -> STM m (Maybe a)
-tryReadTMergeVar (TMergeVar v) = tryReadTMVar v
diff --git a/ouroboros-network/src/Ouroboros/Network/TxSubmission/Inbound.hs b/ouroboros-network/src/Ouroboros/Network/TxSubmission/Inbound.hs
index 4f2aabddf66..cf216548a02 100644
--- a/ouroboros-network/src/Ouroboros/Network/TxSubmission/Inbound.hs
+++ b/ouroboros-network/src/Ouroboros/Network/TxSubmission/Inbound.hs
@@ -40,6 +40,7 @@ import Network.TypedProtocol.Pipelined (N, Nat (..), natToInt)
 
 import Ouroboros.Network.NodeToNode.Version (NodeToNodeVersion)
 import Ouroboros.Network.Protocol.TxSubmission2.Server
+import Ouroboros.Network.Protocol.TxSubmission2.Type
 import Ouroboros.Network.TxSubmission.Mempool.Reader (MempoolSnapshot (..),
            TxSubmissionMempoolReader (..))
 
@@ -118,7 +119,7 @@ data ServerState txid tx = ServerState {
        -- are a subset of the 'unacknowledgedTxIds' that we have not yet
        -- requested. This is not ordered to illustrate the fact that we can
        -- request txs out of order. We also remember the size.
-       availableTxids         :: !(Map txid TxSizeInBytes),
+       availableTxids         :: !(Map txid SizeInBytes),
 
        -- | Transactions we have successfully downloaded but have not yet added
        -- to the mempool or acknowledged. This needed because we can request
@@ -177,17 +178,17 @@ txSubmissionInbound
      , MonadThrow m
      )
   => Tracer m (TraceTxSubmissionInbound txid tx)
-  -> Word16         -- ^ Maximum number of unacknowledged txids allowed
+  -> NumTxIdsToAck  -- ^ Maximum number of unacknowledged txids allowed
   -> TxSubmissionMempoolReader txid tx idx m
   -> TxSubmissionMempoolWriter txid tx idx m
   -> NodeToNodeVersion
   -> TxSubmissionServerPipelined txid tx m ()
-txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
+txSubmissionInbound tracer (NumTxIdsToAck maxUnacked) mpReader mpWriter _version =
     TxSubmissionServerPipelined $
       continueWithStateM (serverIdle Zero) initialServerState
   where
     -- TODO #1656: replace these fixed limits by policies based on
-    -- TxSizeInBytes and delta-Q and the bandwidth/delay product.
+    -- SizeInBytes and delta-Q and the bandwidth/delay product.
     -- These numbers are for demo purposes only, the throughput will be low.
     maxTxIdsToRequest = 3 :: Word16
     maxTxToRequest    = 2 :: Word16
@@ -224,15 +225,15 @@ txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
                   && Map.null (bufferedTxs st)) $
               pure $
               SendMsgRequestTxIdsBlocking
-                (numTxsToAcknowledge st)
-                numTxIdsToRequest
+                (NumTxIdsToAck (numTxsToAcknowledge st))
+                (NumTxIdsToReq numTxIdsToRequest)
                 -- Our result if the client terminates the protocol
                 (traceWith tracer TraceTxInboundTerminated)
                 ( collectAndContinueWithState (handleReply Zero) st {
                     numTxsToAcknowledge    = 0,
                     requestedTxIdsInFlight = numTxIdsToRequest
                   }
-                . CollectTxIds numTxIdsToRequest
+                . CollectTxIds (NumTxIdsToReq numTxIdsToRequest)
                 . NonEmpty.toList)
 
         Succ n' -> if canRequestMoreTxs st
@@ -270,7 +271,7 @@ txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
                    Nat n
                 -> StatefulCollect (ServerState txid tx) n txid tx m
     handleReply n = StatefulCollect $ \st collect -> case collect of
-      CollectTxIds reqNo txids -> do
+      CollectTxIds (NumTxIdsToReq reqNo) txids -> do
         -- Check they didn't send more than we asked for. We don't need to
         -- check for a minimum: the blocking case checks for non-zero
         -- elsewhere, and for the non-blocking case it is quite normal for
@@ -342,12 +343,13 @@ txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
             bufferedTxs2 = Foldable.foldl' (flip Map.delete)
                                    bufferedTxs1 acknowledgedTxIds
 
-            -- If we are acknowleding transactions that are still in unacknowledgedTxIds'
-            -- we need to re-add them so that we also can acknowledge them again later.
-            -- This will happen incase of duplicate txids within the same window.
+            -- If we are acknowledging transactions that are still in
+            -- unacknowledgedTxIds' we need to re-add them so that we also can
+            -- acknowledge them again later. This will happen in case of
+            -- duplicate txids within the same window.
             live = filter (`elem` unacknowledgedTxIds') $ toList acknowledgedTxIds
             bufferedTxs3 = forceElemsToWHNF $ bufferedTxs2 <>
-                               (Map.fromList (zip live (repeat Nothing)))
+                               Map.fromList (zip live (repeat Nothing))
 
         let !collected = length txs
         traceWith tracer $
@@ -378,7 +380,7 @@ txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
     --
     acknowledgeTxIds :: ServerState txid tx
                      -> StrictSeq txid
-                     -> Map txid TxSizeInBytes
+                     -> Map txid SizeInBytes
                      -> MempoolSnapshot txid tx idx
                      -> ServerState txid tx
     acknowledgeTxIds st txidsSeq _ _ | Seq.null txidsSeq  = st
@@ -446,7 +448,7 @@ txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
         -- We will also uses the size of txs in bytes as our limit for
         -- upper and lower watermarks for pipelining. We'll also use the
         -- amount in flight and delta-Q to estimate when we're in danger of
-        -- becomming idle, and need to request stalled txs.
+        -- becoming idle, and need to request stalled txs.
         --
         let (txsToRequest, availableTxids') =
               Map.splitAt (fromIntegral maxTxToRequest) (availableTxids st)
@@ -472,8 +474,8 @@ txSubmissionInbound tracer maxUnacked mpReader mpWriter _version =
 
       if numTxIdsToRequest > 0
         then pure $ SendMsgRequestTxIdsPipelined
-          (numTxsToAcknowledge st)
-          numTxIdsToRequest
+          (NumTxIdsToAck (numTxsToAcknowledge st))
+          (NumTxIdsToReq numTxIdsToRequest)
           (continueWithStateM (serverIdle (Succ n)) st {
                 requestedTxIdsInFlight = requestedTxIdsInFlight st
                                        + numTxIdsToRequest,
diff --git a/ouroboros-network/src/Ouroboros/Network/TxSubmission/Mempool/Reader.hs b/ouroboros-network/src/Ouroboros/Network/TxSubmission/Mempool/Reader.hs
index 079cf2a68ef..771bbbfe6b1 100644
--- a/ouroboros-network/src/Ouroboros/Network/TxSubmission/Mempool/Reader.hs
+++ b/ouroboros-network/src/Ouroboros/Network/TxSubmission/Mempool/Reader.hs
@@ -6,8 +6,7 @@ module Ouroboros.Network.TxSubmission.Mempool.Reader
   ) where
 
 import Control.Monad.Class.MonadSTM (MonadSTM, STM)
-
-import Ouroboros.Network.Protocol.TxSubmission2.Client (TxSizeInBytes)
+import Ouroboros.Network.SizeInBytes (SizeInBytes)
 
 -- | The consensus layer functionality that the inbound and outbound side of
 -- the tx submission logic requires.
@@ -53,7 +52,7 @@ mapTxSubmissionMempoolReader f rdr =
 --
 data MempoolSnapshot txid tx idx =
      MempoolSnapshot {
-       mempoolTxIdsAfter :: idx -> [(txid, idx, TxSizeInBytes)],
+       mempoolTxIdsAfter :: idx -> [(txid, idx, SizeInBytes)],
        mempoolLookupTx   :: idx -> Maybe tx,
        mempoolHasTx      :: txid -> Bool
      }
diff --git a/ouroboros-network/src/Ouroboros/Network/TxSubmission/Outbound.hs b/ouroboros-network/src/Ouroboros/Network/TxSubmission/Outbound.hs
index 41e96e6da3a..d5cac825788 100644
--- a/ouroboros-network/src/Ouroboros/Network/TxSubmission/Outbound.hs
+++ b/ouroboros-network/src/Ouroboros/Network/TxSubmission/Outbound.hs
@@ -12,10 +12,9 @@ module Ouroboros.Network.TxSubmission.Outbound
 
 import Data.Foldable (find)
 import Data.List.NonEmpty qualified as NonEmpty
-import Data.Maybe (catMaybes, isNothing)
+import Data.Maybe (catMaybes, isNothing, mapMaybe)
 import Data.Sequence.Strict (StrictSeq)
 import Data.Sequence.Strict qualified as Seq
-import Data.Word (Word16)
 
 import Control.Exception (assert)
 import Control.Monad (unless, when)
@@ -27,6 +26,7 @@ import Ouroboros.Network.ControlMessage (ControlMessage, ControlMessageSTM,
            timeoutWithControlMessage)
 import Ouroboros.Network.NodeToNode.Version (NodeToNodeVersion)
 import Ouroboros.Network.Protocol.TxSubmission2.Client
+import Ouroboros.Network.Protocol.TxSubmission2.Type
 import Ouroboros.Network.TxSubmission.Mempool.Reader (MempoolSnapshot (..),
            TxSubmissionMempoolReader (..))
 
@@ -44,7 +44,7 @@ data TraceTxSubmissionOutbound txid tx
 data TxSubmissionProtocolError =
        ProtocolErrorAckedTooManyTxids
      | ProtocolErrorRequestedNothing
-     | ProtocolErrorRequestedTooManyTxids Word16 Word16
+     | ProtocolErrorRequestedTooManyTxids NumTxIdsToReq NumTxIdsToAck
      | ProtocolErrorRequestBlocking
      | ProtocolErrorRequestNonBlocking
      | ProtocolErrorRequestedUnavailableTx
@@ -78,7 +78,7 @@ txSubmissionOutbound
   :: forall txid tx idx m.
      (Ord txid, Ord idx, MonadSTM m, MonadThrow m)
   => Tracer m (TraceTxSubmissionOutbound txid tx)
-  -> Word16         -- ^ Maximum number of unacknowledged txids allowed
+  -> NumTxIdsToAck  -- ^ Maximum number of unacknowledged txids allowed
   -> TxSubmissionMempoolReader txid tx idx m
   -> NodeToNodeVersion
   -> ControlMessageSTM m
@@ -92,18 +92,18 @@ txSubmissionOutbound tracer maxUnacked TxSubmissionMempoolReader{..} _version co
       where
         recvMsgRequestTxIds :: forall blocking.
                                TokBlockingStyle blocking
-                            -> Word16
-                            -> Word16
+                            -> NumTxIdsToAck
+                            -> NumTxIdsToReq
                             -> m (ClientStTxIds blocking txid tx m ())
         recvMsgRequestTxIds blocking ackNo reqNo = do
 
-          when (ackNo > fromIntegral (Seq.length unackedSeq)) $
+          when (getNumTxIdsToAck ackNo > fromIntegral (Seq.length unackedSeq)) $
             throwIO ProtocolErrorAckedTooManyTxids
 
           when (  fromIntegral (Seq.length unackedSeq)
-                - ackNo
-                + reqNo
-                > maxUnacked) $
+                - getNumTxIdsToAck ackNo
+                + getNumTxIdsToReq reqNo
+                > getNumTxIdsToAck maxUnacked) $
             throwIO (ProtocolErrorRequestedTooManyTxids reqNo maxUnacked)
 
           -- Update our tracking state to remove the number of txids that the
@@ -119,7 +119,7 @@ txSubmissionOutbound tracer maxUnacked TxSubmissionMempoolReader{..} _version co
                       !lastIdx'
                         | null txs  = lastIdx
                         | otherwise = idx where (_, idx, _) = last txs
-                      txs'         :: [(txid, TxSizeInBytes)]
+                      txs'         :: [(txid, SizeInBytes)]
                       txs'          = [ (txid, size) | (txid, _, size) <- txs ]
                       client'       = client unackedSeq'' lastIdx'
                   in  (txs', client')
@@ -183,7 +183,7 @@ txSubmissionOutbound tracer maxUnacked TxSubmissionMempoolReader{..} _version co
           -- The 'mempoolLookupTx' will return nothing if the transaction is no
           -- longer in the mempool. This is good. Neither the sending nor
           -- receiving side wants to forward txs that are no longer of interest.
-          let txs          = catMaybes (map mempoolLookupTx txidxs')
+          let txs          = mapMaybe mempoolLookupTx txidxs'
               client'      = client unackedSeq lastIdx
 
           -- Trace the transactions to be sent in the response.
diff --git a/scripts/ci/check-stylish.sh b/scripts/ci/check-stylish.sh
index 4710e56b0b9..4375c32df8f 100755
--- a/scripts/ci/check-stylish.sh
+++ b/scripts/ci/check-stylish.sh
@@ -2,13 +2,70 @@
 
 set -euo pipefail
 
+function usage {
+  echo "Usage $(basename "$0") [-ch]"
+  echo "Check files with 'stylish-haskell'; by default check all files."
+  echo
+  echo "        -u                        only check files uncommitted"
+  echo "        -c                        only check files committed in HEAD"
+  echo "        -h                        this help message"
+  exit
+}
+
 export LC_ALL=C.UTF-8
+
+STYLISH_HASKELL_ARGS="-c .stylish-haskell-network.yaml -i"
+
+optstring=":uch"
+while getopts ${optstring} arg; do
+  case ${arg} in
+    h)
+      usage;
+      exit 0
+      ;;
+    c)
+      PATHS=$(git show --pretty='' --name-only HEAD)
+      for path in $PATHS; do
+        if [ "${path##*.}" == "hs" ]; then
+          if grep -qE '^#' $path; then
+            echo "$path contains CPP.  Skipping."
+          else
+            echo $path
+            stylish-haskell $STYLISH_HASKELL_ARGS $path
+          fi
+        fi
+      done
+      exit 0
+      ;;
+    u)
+      PATHS=$(git diff --name-only HEAD)
+      for path in $PATHS; do
+        if [ "${path##*.}" == "hs" ]; then
+          if grep -qE '^#' $path; then
+            echo "$path contains CPP.  Skipping."
+          else
+            echo $path
+            stylish-haskell $STYLISH_HASKELL_ARGS $path
+          fi
+        fi
+      done
+      exit 0
+      ;;
+    ?)
+      echo "Invalid argument ${arg}"
+      exit 1
+      ;;
+  esac
+done
+
 # TODO CPP pragmas in export lists are not supported by stylish-haskell
-fd . './quickcheck-monoids' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './network-mux' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './ouroboros-network-api' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './ouroboros-network-framework' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './ouroboros-network-mock' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './ouroboros-network-protocols' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './ouroboros-network' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
-fd . './cardano-client' -e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell -c .stylish-haskell-network.yaml -i
+FD_OPTS="-e hs --ignore-file ./scripts/ci/check-stylish-ignore -X stylish-haskell $STYLISH_HASKELL_ARGS"
+
+fd . './quickcheck-monoids'          $FD_OPTS
+fd . './network-mux'                 $FD_OPTS
+fd . './ouroboros-network-api'       $FD_OPTS
+fd . './ouroboros-network-framework' $FD_OPTS
+fd . './ouroboros-network-mock'      $FD_OPTS
+fd . './ouroboros-network-protocols' $FD_OPTS
+fd . './ouroboros-network'           $FD_OPTS
+fd . './cardano-client'              $FD_OPTS