diff --git a/flake.nix b/flake.nix
index b192741..60d2d4d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -51,20 +51,26 @@
           programs.ormolu.enable = true; # Haskell
           programs.cabal-fmt.enable = true;
           programs.shfmt.enable = true;
-          programs.yamlfmt.enable = true;
+          programs.yamlfmt.enable = pkgs.system != "x86_64-darwin"; # a treefmt-nix+yamlfmt bug on Intel Macs
         };
       };
 
-      flake.hydraJobs = {
-        testgen-hs = lib.genAttrs (config.systems ++ ["x86_64-windows"]) (
-          targetSystem: inputs.self.internal.${targetSystem}.hydraPackage
-        );
-        required = inputs.nixpkgs.legacyPackages.x86_64-linux.releaseTools.aggregate {
-          name = "github-required";
-          meta.description = "All jobs required to pass CI";
-          constituents =
-            lib.collect lib.isDerivation inputs.self.hydraJobs.testgen-hs;
+      flake.hydraJobs = let
+        allJobs = {
+          testgen-hs = lib.genAttrs (config.systems ++ ["x86_64-windows"]) (
+            targetSystem: inputs.self.internal.${targetSystem}.hydraPackage
+          );
+          inherit (inputs.self) checks;
+        };
+      in
+        allJobs
+        // {
+          required = inputs.nixpkgs.legacyPackages.x86_64-linux.releaseTools.aggregate {
+            name = "github-required";
+            meta.description = "All jobs required to pass CI";
+            constituents =
+              lib.collect lib.isDerivation allJobs;
+          };
         };
-      };
     });
 }
diff --git a/testgen-hs/CLI.hs b/testgen-hs/CLI.hs
index 158f524..f65345f 100644
--- a/testgen-hs/CLI.hs
+++ b/testgen-hs/CLI.hs
@@ -16,7 +16,7 @@ import qualified Data.Version as V
 import Options.Applicative as O
 import qualified Paths_testgen_hs as V
 
-data Command = Generate GenerateOptions | Deserialize ByteString | DeserializeStream deriving (Show)
+data Command = Generate GenerateOptions | Deserialize ByteString | DeserializeStream | EvaluateStream deriving (Show)
 
 data GenerateOptions = GenerateOptions (Maybe Seed) GenSize NumCases TypeCommand deriving (Show)
 
@@ -30,7 +30,7 @@ data TypeCommand
   = GHCInteger
   | DataText
   | ExampleADT
-  | Tx'Conway
+  | Tx'ConwayDummy
   | ApplyTxErr'Byron
   | ApplyTxErr'Shelley
   | ApplyTxErr'Allegra
@@ -38,6 +38,7 @@ data TypeCommand
   | ApplyTxErr'Alonzo
   | ApplyTxErr'Babbage
   | ApplyTxErr'Conway
+  | TxScriptFailure'Conway
   deriving (Show)
 
 parse :: IO Command
@@ -90,6 +91,15 @@ commandParser =
                    (progDesc "Deserialize an STDIN stream of multiple lines of base16-encoded CBOR of ‘HardForkApplyTxErr’")
                )
            )
+        <> ( command
+               "evaluate-stream"
+               ( info
+                   ( pure EvaluateStream
+                       <**> helper
+                   )
+                   (progDesc "Evaluate an STDIN stream of Txs with Utxos")
+               )
+           )
     )
 
 optionsParser :: Parser GenerateOptions
@@ -138,7 +148,7 @@ typeCommandParser :: Parser TypeCommand
 typeCommandParser =
   subparser
     ( mempty
-        <> mkTypeCommand Tx'Conway
+        <> mkTypeCommand Tx'ConwayDummy
         <> mkTypeCommand ApplyTxErr'Byron
         <> mkTypeCommand ApplyTxErr'Shelley
         <> mkTypeCommand ApplyTxErr'Allegra
@@ -146,6 +156,7 @@ typeCommandParser =
         <> mkTypeCommand ApplyTxErr'Alonzo
         <> mkTypeCommand ApplyTxErr'Babbage
         <> mkTypeCommand ApplyTxErr'Conway
+        <> mkTypeCommand TxScriptFailure'Conway
         <> mkTypeCommand GHCInteger
         <> mkTypeCommand DataText
         <> mkTypeCommand ExampleADT
diff --git a/testgen-hs/Encoder.hs b/testgen-hs/Encoder.hs
new file mode 100644
index 0000000..afb83a4
--- /dev/null
+++ b/testgen-hs/Encoder.hs
@@ -0,0 +1,435 @@
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE ViewPatterns #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
+
+module Encoder
+  ( serializeTransactionScriptFailure,
+    serializeDecoderError,
+    ogmiosSuccess,
+  )
+where
+
+import qualified Cardano.Crypto.Hash.Class as CC
+import qualified Cardano.Ledger.Alonzo.Core as Al hiding
+  ( TranslationError,
+  )
+import qualified Cardano.Ledger.Alonzo.Plutus.TxInfo as Al
+import qualified Cardano.Ledger.Alonzo.Scripts as Al
+import Cardano.Ledger.Api
+  ( AsIx (..),
+    PlutusPurpose,
+  )
+import qualified Cardano.Ledger.Api as Ledger
+import qualified Cardano.Ledger.Babbage.TxInfo as Ba
+import qualified Cardano.Ledger.BaseTypes as LedgerBase
+import qualified Cardano.Ledger.Binary.Decoding as Binary
+import qualified Cardano.Ledger.Conway.Scripts as C
+import qualified Cardano.Ledger.Conway.TxInfo as C
+import qualified Cardano.Ledger.Core as Ledger
+import qualified Cardano.Ledger.Hashes as Hashes
+import Cardano.Ledger.Plutus
+  ( TxOutSource (..),
+  )
+import qualified Cardano.Ledger.Plutus.Language as Ledger
+import qualified Cardano.Ledger.TxIn as Ledger
+import qualified Codec.CBOR.Read as Cbor
+import qualified Data.Aeson as A
+import Data.Aeson.Encoding (Encoding)
+import qualified Data.Aeson.Encoding as J
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Base16 as B16
+import qualified Data.ByteString.Short as SBS
+import Data.Foldable (toList)
+import Data.Int (Int64)
+import qualified Data.Map as Map
+import Data.SatInt
+  ( fromSatInt,
+  )
+import Data.Text (Text)
+import qualified Data.Text as T
+import qualified Data.Text.Encoding as TE
+import qualified PlutusLedgerApi.Common as P
+import Prettyprinter (pretty)
+
+--------------------------------------------------------------------------------
+-- Generic helpers
+--------------------------------------------------------------------------------
+
+-- | Encode any Foldable as a JSON array using an element encoder.
+serializeFoldable ::
+  (Foldable f) =>
+  (a -> Encoding) ->
+  f a ->
+  Encoding
+serializeFoldable enc =
+  J.list enc . toList
+
+--------------------------------------------------------------------------------
+-- Hash / TxId / TxIn
+--------------------------------------------------------------------------------
+
+-- | Serialize a SafeHash as lower-case hex JSON string.
+serializeHash ::
+  Hashes.SafeHash crypto ->
+  Encoding
+serializeHash safeH =
+  let CC.UnsafeHash short = Hashes.extractHash safeH
+      bs = SBS.fromShort short
+      hex = B16.encode bs
+   in J.text (TE.decodeUtf8 hex)
+
+serializDataHash ::
+  Al.DataHash ->
+  Encoding
+serializDataHash =
+  serializeHash
+
+serializeTxId ::
+  Ledger.TxId ->
+  Encoding
+serializeTxId txId =
+  J.pairs $
+    J.pair "id" (serializeHash (Ledger.unTxId txId))
+
+serializeTxIn ::
+  Ledger.TxIn ->
+  Encoding
+serializeTxIn (Ledger.TxIn txId ix) =
+  J.pairs $
+    J.pair "transaction" (serializeTxId txId)
+      <> J.pair "index" (A.toEncoding ix)
+
+--------------------------------------------------------------------------------
+-- Script purpose index
+--------------------------------------------------------------------------------
+
+serializeScriptPurposeIndex ::
+  forall era.
+  () =>
+  C.ConwayPlutusPurpose AsIx era ->
+  Encoding
+serializeScriptPurposeIndex = \case
+  C.ConwaySpending ix ->
+    mk ix "spend"
+  C.ConwayMinting ix ->
+    mk ix "mint"
+  C.ConwayCertifying (AsIx ix) ->
+    mk ix "publish"
+  C.ConwayRewarding ix ->
+    mk ix "withdraw"
+  C.ConwayVoting (AsIx ix) ->
+    mk ix "vote"
+  C.ConwayProposing (AsIx ix) ->
+    mk ix "propose"
+  where
+    mk ix purpose =
+      J.pairs $
+        J.pair "index" (A.toEncoding ix)
+          <> J.pair "purpose" (J.text purpose)
+
+serializeExBudget ::
+  P.ExBudget ->
+  Encoding
+serializeExBudget budget =
+  J.pairs $
+    J.pair "memory" (J.integer (fromSatInt mem))
+      <> J.pair "cpu" (J.integer (fromSatInt cpu))
+  where
+    P.ExMemory mem = P.exBudgetMemory budget
+    P.ExCPU cpu = P.exBudgetCPU budget
+
+serializeLanguage ::
+  Ledger.Language ->
+  Encoding
+serializeLanguage = \case
+  Ledger.PlutusV1 -> "plutus:v1"
+  Ledger.PlutusV2 -> "plutus:v2"
+  Ledger.PlutusV3 -> "plutus:v3"
+
+-- | Ogmios "budget" object from 'ExUnits'.
+serializeExUnits :: Al.ExUnits -> Encoding
+serializeExUnits (Al.ExUnits mem cpu) =
+  J.pairs $
+    J.pair "memory" (J.integer (fromIntegral mem))
+      <> J.pair "cpu" (J.integer (fromIntegral cpu))
+
+txInToText ::
+  Ledger.TxIn ->
+  Text
+txInToText (Ledger.TxIn txid (LedgerBase.TxIx ix)) =
+  txIdToText txid <> "#" <> T.pack (show ix)
+
+txIdToText :: Ledger.TxId -> Text
+txIdToText (Ledger.TxId (Ledger.originalBytes -> bytes)) =
+  TE.decodeUtf8 (B16.encode bytes)
+
+redeemerPtrToText :: forall era. (Ledger.ConwayEraScript era) => PlutusPurpose AsIx era -> Text
+redeemerPtrToText = \case
+  Ledger.SpendingPurpose (AsIx ix) -> "spend:" <> showT ix
+  Ledger.CertifyingPurpose (AsIx ix) -> "publish:" <> showT ix
+  Ledger.MintingPurpose (AsIx ix) -> "mint:" <> showT ix
+  Ledger.RewardingPurpose (AsIx ix) -> "withdraw:" <> showT ix
+  Ledger.ProposingPurpose (AsIx ix) -> "propose:" <> showT ix
+  Ledger.VotingPurpose (AsIx ix) -> "vote:" <> showT ix
+  _ -> error "unreachable: unknown PlutusPurpose" -- matches _are_ exhaustive, but it’s not provable statically
+  where
+    showT = T.pack . show -- Word32 → Text
+
+--------------------------------------------------------------------------------
+-- Ogmios-style error envelope
+--------------------------------------------------------------------------------
+
+ogmiosError ::
+  Int64 ->
+  Text ->
+  -- | payload / "data"
+  Encoding ->
+  Encoding
+ogmiosError code msg payload =
+  J.pairs $
+    J.pair "code" (A.toEncoding code)
+      <> J.pair "message" (J.text msg)
+      <> J.pair "data" payload
+
+-- | Build the JSON-RPC success envelope that Ogmios returns when every
+--   redeemer succeeds.
+ogmiosSuccess ::
+  Map.Map
+    (PlutusPurpose AsIx Ledger.ConwayEra)
+    (Either (Ledger.TransactionScriptFailure Ledger.ConwayEra) Al.ExUnits) ->
+  J.Encoding
+ogmiosSuccess report =
+  J.list
+    ( \(ptr, res) ->
+        case res of
+          Right exu ->
+            J.pairs $
+              J.pair "validator" (J.text $ redeemerPtrToText ptr)
+                <> J.pair "budget" (serializeExUnits exu)
+          Left err ->
+            J.pairs $
+              J.pair "validator" (J.text $ redeemerPtrToText ptr)
+                <> J.pair
+                  "error"
+                  ( J.pairs $
+                      J.pair "message" (serializeTransactionScriptFailure err)
+                  )
+    )
+    (Map.toList report)
+
+-- makeScriptExecFailure
+--   :: Encoding
+--  -> Encoding
+-- makeScriptExecFailure = ogmiosError
+--      3010
+--    "Some scripts of the transactions terminated with error(s)."
+
+--------------------------------------------------------------------------------
+-- ContextError
+--------------------------------------------------------------------------------
+
+serializeContextError ::
+  ( PlutusPurpose AsIx era ~ C.ConwayPlutusPurpose AsIx era
+  ) =>
+  C.ConwayContextError era ->
+  Encoding
+serializeContextError err = J.text $ case err of
+  C.CertificateNotSupported {} ->
+    "A certificate in the transaction isn't supported in neither plutus:v1 nor plutus:v2. Use plutus:v3 or higher."
+  C.PlutusPurposeNotSupported {} ->
+    "A script purpose in the transaction isn't supported in neither plutus:v1 nor plutus:v2. Use plutus:v3 or higher."
+  C.CurrentTreasuryFieldNotSupported {} ->
+    "Unsupported field in transaction: 'treasury'. Use plutus:v3 or higher, or remove this field."
+  C.VotingProceduresFieldNotSupported {} ->
+    "Unsupported field in transaction: 'votes'. Use plutus:v3 or higher, or remove this field."
+  C.ProposalProceduresFieldNotSupported {} ->
+    "Unsupported field in transaction: 'proposals'. Use plutus:v3 or higher, or remove this field."
+  C.TreasuryDonationFieldNotSupported {} ->
+    "Unsupported field in transaction: 'donation'. Use plutus:v3 or higher, or remove this field."
+  C.BabbageContextError (Ba.ByronTxOutInContext TxOutFromInput {}) ->
+    "Found inputs locked by a (legacy) Byron/Bootstrap address. Don't use those."
+  C.BabbageContextError (Ba.ByronTxOutInContext TxOutFromOutput {}) ->
+    "Found outputs to a (legacy) Byron/Bootstrap address. Don't use those."
+  C.BabbageContextError (Ba.InlineDatumsNotSupported {}) ->
+    "Inline datums not supported in plutus:v1. Use plutus:v2 or higher."
+  C.BabbageContextError (Ba.ReferenceScriptsNotSupported {}) ->
+    "Reference scripts not supported in plutus:v1. Use plutus:v2 or higher."
+  C.BabbageContextError (Ba.ReferenceInputsNotSupported {}) ->
+    "Reference inputs not supported in plutus:v1. Use plutus:v2 or higher."
+  C.BabbageContextError (Ba.RedeemerPointerPointsToNothing purpose) ->
+    let (title, ptr) =
+          case purpose of
+            C.ConwaySpending (AsIx ix) -> ("spending input", ix)
+            C.ConwayMinting (AsIx ix) -> ("minting policy", ix)
+            C.ConwayCertifying (AsIx ix) -> ("publishing certificate", ix)
+            C.ConwayRewarding (AsIx ix) -> ("withdrawing from account", ix)
+            C.ConwayVoting (AsIx ix) -> ("voting as voter", ix)
+            C.ConwayProposing (AsIx ix) -> ("proposing governance proposal", ix)
+     in "Couldn't find corresponding redeemer for " <> title <> " #" <> T.pack (show ptr) <> ". Verify your transaction's construction."
+  C.BabbageContextError (Ba.AlonzoContextError (Al.TimeTranslationPastHorizon e)) ->
+    "Uncomputable slot arithmetic; transaction's validity bounds go beyond the foreseeable end of the current era: " <> e
+  C.BabbageContextError (Ba.AlonzoContextError (Al.TranslationLogicMissingInput i)) ->
+    "Unknown transaction input (missing from UTxO set): " <> txInToText i
+
+--------------------------------------------------------------------------------
+-- TransactionScriptFailure
+--------------------------------------------------------------------------------
+
+serializeTransactionScriptFailure ::
+  Ledger.TransactionScriptFailure Ledger.ConwayEra ->
+  Encoding
+serializeTransactionScriptFailure = \case
+  Ledger.RedeemerPointsToUnknownScriptHash reedemers ->
+    ogmiosError
+      3110
+      "Extraneous (non-required) redeemers found in the transaction."
+      ( J.pairs $
+          J.pair
+            "extraneousRedeemers"
+            (serializeFoldable serializeScriptPurposeIndex [reedemers])
+      )
+  Ledger.MissingScript purpose _ ->
+    ogmiosError
+      3102
+      "An associated script witness is missing."
+      ( J.pairs $
+          J.pair
+            "missingScripts"
+            (serializeFoldable serializeScriptPurposeIndex [purpose])
+      )
+  Ledger.MissingDatum datum ->
+    ogmiosError
+      3111
+      "Transaction failed because some Plutus scripts are missing their associated datums."
+      ( J.pairs $
+          J.pair
+            "missingDatums"
+            (serializeFoldable serializDataHash [datum])
+      )
+  Ledger.ValidationFailure _exUnits evalErr traces _ctx ->
+    ogmiosError
+      3012
+      "Some of the scripts failed to evaluate to a positive outcome."
+      ( J.pairs $
+          J.pair
+            "validationError"
+            (J.text (T.pack (show (pretty evalErr))))
+            <> J.pair
+              "traces"
+              (serializeFoldable A.toEncoding traces)
+      )
+  Ledger.UnknownTxIn txIn ->
+    ogmiosError
+      3117
+      "The transaction contains unknown UTxO references as inputs."
+      ( J.pairs $
+          J.pair "unknownOutputReferences" (serializeFoldable serializeTxIn [txIn])
+      )
+  Ledger.InvalidTxIn txIn ->
+    ogmiosError
+      3013
+      "A redeemer points to an input that isn't locked by a Plutus script."
+      ( J.pairs $
+          J.pair "unsuitableOutputReference" (serializeTxIn txIn)
+      )
+  Ledger.IncompatibleBudget budget ->
+    ogmiosError
+      3161
+      "The transaction ran out of execution budget!"
+      ( J.pairs $
+          J.pair "budgetUsed" (serializeExBudget budget)
+      )
+  Ledger.NoCostModelInLedgerState lang ->
+    ogmiosError
+      3115
+      "It seems like the transaction is using a Plutus version for which there's no available cost model yet."
+      ( J.pairs $
+          J.pair "missingCostModels" (serializeFoldable serializeLanguage [lang])
+      )
+  Ledger.ContextError ctxErr ->
+    ogmiosError
+      3004
+      "Unable to create the evaluation context from the given transaction."
+      ( J.pairs $
+          J.pair "reason" (serializeContextError ctxErr)
+      )
+
+-- | Human-readable CBOR decode errors. Kept for Ogmios compatibility & future-use even when unused.
+serializeDecoderError :: Int -> Binary.DecoderError -> Text
+serializeDecoderError size =
+  extractId . reduceNoise . \case
+    Binary.DecoderErrorCanonicityViolation lbl ->
+      "couldn't decode due to internal constraint violations on '"
+        <> lbl
+        <> "': \
+           \ found CBOR that isn't canonical when I expected it to be."
+    Binary.DecoderErrorCustom lbl hint ->
+      "couldn't decode due to internal constraint violations on '" <> lbl <> "': " <> hint
+    Binary.DecoderErrorDeserialiseFailure lbl (Cbor.DeserialiseFailure offset hint)
+      | offset >= fromIntegral size ->
+          "invalid or incomplete value of type '" <> lbl <> "': " <> T.pack (show hint)
+    Binary.DecoderErrorDeserialiseFailure lbl (Cbor.DeserialiseFailure offset hint) ->
+      "invalid CBOR found at offset ["
+        <> T.pack (show offset)
+        <> "] while decoding a value of type '"
+        <> lbl
+        <> "': "
+        <> T.pack (show hint)
+    Binary.DecoderErrorEmptyList {} ->
+      "couldn't decode due to internal constraint violations on a non-empty list: \
+      \must not be empty"
+    Binary.DecoderErrorLeftover lbl bytes ->
+      "unexpected "
+        <> T.pack (show (BS.length bytes))
+        <> " bytes found left after \
+           \successfully deserialising a/an '"
+        <> lbl
+        <> "'"
+    Binary.DecoderErrorSizeMismatch lbl expected actual
+      | expected >= actual ->
+          T.pack (show (expected - actual))
+            <> " missing element(s) in a \
+               \data-structure of type '"
+            <> lbl
+            <> "'"
+    Binary.DecoderErrorSizeMismatch lbl expected actual ->
+      T.pack (show (actual - expected))
+        <> " extra element(s) in a \
+           \data-structure of type '"
+        <> lbl
+        <> "'"
+    Binary.DecoderErrorUnknownTag lbl tag ->
+      "unknown binary tag ("
+        <> T.pack (show tag)
+        <> ") when decoding a value of type '"
+        <> lbl
+        <> "'\
+           \; which is probably because I am trying to decode something else than what \
+           \I encountered."
+    Binary.DecoderErrorVoid ->
+      "impossible: attempted to decode void. Please open an issue."
+  where
+    extractId = id
+    reduceNoise =
+      T.replace "\n" " "
+        . T.replace "Error: " ""
+        . T.replace "Record" "Object / Array"
+        . T.replace "Record RecD" "Object / Array"
+        . T.replace " ShelleyEra" ""
+        . T.replace " AllegraEra" ""
+        . T.replace " MaryEra" ""
+        . T.replace " AlonzoEra" ""
+        . T.replace " BabbageEra" ""
+        . T.replace " ConwayEra" ""
+        . T.replace "value of type ConwayTxBodyRaw" "transaction body"
+        . T.replace "value of type BabbageTxBodyRaw" "transaction body"
+        . T.replace "value of type AlonzoTxBodyRaw" "transaction body"
+        . T.replace "value of type AllegraTxBodyRaw ()" "transaction body"
+        . T.replace "value of type AllegraTxBodyRaw MultiAsset" "transaction body"
+        . T.replace "value of type ShelleyTxBodyRaw" "transaction body"
+        . T.replace "atbr" ""
+        . T.replace "stbr" ""
+        . T.replace "btbr" ""
+        . T.replace "ctbr" ""
diff --git a/testgen-hs/Evaluation.hs b/testgen-hs/Evaluation.hs
new file mode 100644
index 0000000..ab4afe8
--- /dev/null
+++ b/testgen-hs/Evaluation.hs
@@ -0,0 +1,150 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
+
+module Evaluation
+  ( WrappedTransactionScriptFailure (..),
+    writeJson,
+    eval'Conway,
+  )
+where
+
+import CLI (GenSize (..), NumCases (..), Seed (..))
+import Cardano.Api.Internal.Orphans ()
+import Cardano.Ledger.Alonzo.Plutus.Evaluate (evalTxExUnits)
+import Cardano.Ledger.Alonzo.Scripts (AsIx (..), ExUnits (..))
+import Cardano.Ledger.Api (ConwayEra, PParams, TransactionScriptFailure)
+import qualified Cardano.Ledger.Api as Ledger
+import Cardano.Ledger.Api.Tx (PlutusPurpose, RedeemerReport, Tx)
+import Cardano.Ledger.Api.UTxO (UTxO (..))
+import Cardano.Slotting.EpochInfo (EpochInfo)
+import Cardano.Slotting.Slot ()
+import Cardano.Slotting.Time (SystemStart (..))
+import Data.Aeson (ToJSON)
+import qualified Data.Aeson as J
+import qualified Data.Aeson.Encoding as AesonEncoding
+import qualified Data.ByteString.Lazy.Char8 as BL8
+import Data.List (sortOn)
+import qualified Data.Map as Map
+import Data.Proxy (Proxy)
+import Data.Text (Text)
+import Encoder (ogmiosSuccess, serializeTransactionScriptFailure)
+import PlutusCore.Evaluation.Machine.ExBudget (ExBudget (..))
+import PlutusCore.Evaluation.Machine.ExMemory (ExCPU (..), ExMemory (..))
+import Test.Consensus.Cardano.Generators ()
+import qualified Test.QuickCheck as QC
+import qualified Test.QuickCheck.Gen as QGen
+import qualified Test.QuickCheck.Random as QCRandom
+
+newtype WrappedTransactionScriptFailure era = WrappedTransactionScriptFailure
+  { unWrappedTransactionScriptFailure ::
+      TransactionScriptFailure era
+  }
+
+instance ToJSON (WrappedTransactionScriptFailure ConwayEra) where
+  toEncoding (WrappedTransactionScriptFailure x) =
+    serializeTransactionScriptFailure x
+  toJSON wrapped =
+    case J.decode (AesonEncoding.encodingToLazyByteString (J.toEncoding wrapped)) :: Maybe J.Value of
+      Just v -> v
+      Nothing ->
+        error "serializeTransactionScriptFailure produced invalid JSON"
+
+instance QC.Arbitrary (Ledger.TransactionScriptFailure Ledger.ConwayEra) where
+  arbitrary =
+    QC.oneof
+      [ Ledger.RedeemerPointsToUnknownScriptHash <$> QC.arbitrary,
+        (`Ledger.MissingScript` Map.empty) <$> QC.arbitrary,
+        Ledger.MissingDatum <$> QC.arbitrary,
+        Ledger.UnknownTxIn <$> QC.arbitrary,
+        Ledger.InvalidTxIn <$> QC.arbitrary,
+        pure $ Ledger.IncompatibleBudget (ExBudget (ExCPU 999) (ExMemory 888)),
+        Ledger.NoCostModelInLedgerState <$> QC.arbitrary,
+        Ledger.ContextError <$> QC.arbitrary
+      ]
+
+writeJson ::
+  Proxy ConwayEra ->
+  Seed ->
+  GenSize ->
+  NumCases ->
+  IO ()
+writeJson _ (Seed seed) (GenSize size) (NumCases numCases) = do
+  let gen :: QGen.Gen [WrappedTransactionScriptFailure ConwayEra]
+      gen =
+        QC.vectorOf numCases $
+          WrappedTransactionScriptFailure <$> (QC.arbitrary :: QC.Gen (TransactionScriptFailure ConwayEra))
+      xs :: [WrappedTransactionScriptFailure ConwayEra]
+      xs = QGen.unGen gen (QCRandom.mkQCGen seed) size
+  BL8.putStrLn (J.encode xs)
+
+eval'Conway ::
+  PParams ConwayEra ->
+  Tx ConwayEra ->
+  UTxO ConwayEra ->
+  EpochInfo (Either Text) ->
+  SystemStart ->
+  J.Value
+eval'Conway pparams tx utxo epochInfo systemStart =
+  case J.decode (AesonEncoding.encodingToLazyByteString (ogmiosSuccess redeemerReport)) of
+    Just v -> v
+    Nothing -> error "ogmiosSuccess produced invalid JSON"
+  where
+    redeemerReport :: RedeemerReport ConwayEra
+    redeemerReport = selectSingleReport fullReport
+
+    fullReport :: RedeemerReport ConwayEra
+    fullReport = evalTxExUnits pparams tx utxo epochInfo systemStart
+
+    -- Collapse the full report down to a single entry, preferring failures.
+    selectSingleReport :: RedeemerReport ConwayEra -> RedeemerReport ConwayEra
+    selectSingleReport report =
+      case Map.toList failures of
+        (purpose, errors) : _ ->
+          Map.singleton purpose (Left (pickScriptFailure errors))
+        [] ->
+          case Map.toList successes of
+            (purpose, exUnits) : _ ->
+              Map.singleton purpose (Right exUnits)
+            [] ->
+              error "Empty redeemer report from evalTxExUnits"
+      where
+        (failures, successes) = Map.foldrWithKey groupReports (Map.empty, Map.empty) report
+
+    groupReports ::
+      (Ord (PlutusPurpose AsIx era)) =>
+      PlutusPurpose AsIx era ->
+      Either (Ledger.TransactionScriptFailure era) ExUnits ->
+      (Map.Map (PlutusPurpose AsIx era) [Ledger.TransactionScriptFailure era], Map.Map (PlutusPurpose AsIx era) ExUnits) ->
+      (Map.Map (PlutusPurpose AsIx era) [Ledger.TransactionScriptFailure era], Map.Map (PlutusPurpose AsIx era) ExUnits)
+    groupReports purpose result (failures, successes) =
+      case result of
+        Left scriptFail -> (Map.unionWith (++) (Map.singleton purpose [scriptFail]) failures, successes)
+        Right exUnits -> (failures, Map.singleton purpose exUnits <> successes)
+
+-- | Return the most relevant script failure from a list of errors.
+pickScriptFailure ::
+  [Ledger.TransactionScriptFailure era] ->
+  Ledger.TransactionScriptFailure era
+pickScriptFailure xs =
+  case sortOn scriptFailurePriority xs of
+    [] -> error "Empty list of script failures from the ledger!?"
+    x : _ -> x
+  where
+    scriptFailurePriority ::
+      Ledger.TransactionScriptFailure era ->
+      Word
+    scriptFailurePriority = \case
+      Ledger.UnknownTxIn {} -> 0
+      Ledger.MissingScript {} -> 0
+      Ledger.RedeemerPointsToUnknownScriptHash {} -> 1
+      Ledger.NoCostModelInLedgerState {} -> 1
+      Ledger.InvalidTxIn {} -> 2
+      Ledger.MissingDatum {} -> 3
+      Ledger.ContextError {} -> 4
+      Ledger.ValidationFailure {} -> 5
+      Ledger.IncompatibleBudget {} -> 999
diff --git a/testgen-hs/Generators.hs b/testgen-hs/Generators.hs
index 36b42a3..612453c 100644
--- a/testgen-hs/Generators.hs
+++ b/testgen-hs/Generators.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE FlexibleInstances #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
 module Generators where
@@ -23,6 +24,7 @@ import Data.Text (Text)
 import qualified Data.Text.Encoding as T
 import qualified Data.Text.Encoding.Error as T
 import Data.Typeable (Typeable, typeOf)
+import Evaluation ()
 import GHC.Generics (Generic)
 import Generic.Random (GenericArbitraryU (..))
 import qualified Ouroboros.Consensus.Byron.Ledger as OCBL
@@ -181,7 +183,7 @@ instance OurCBOR Tx'Conway where
   ourToCBOR (Tx'Conway (tx, _utxo)) = Cardano.Binary.toCBOR tx
   ourToJSON (Tx'Conway (tx, utxo)) =
     J.object
-      [ "executionUnits" J..= SynthEvalTx.eval'Conway tx utxo,
+      [ "executionUnits" J..= SynthEvalTx.eval'ConwayDummy tx utxo,
         "utxoSetCBOR"
           J..= ( T.decodeUtf8With T.lenientDecode
                    . B16.encode
diff --git a/testgen-hs/Main.hs b/testgen-hs/Main.hs
index fd79be0..7244e04 100644
--- a/testgen-hs/Main.hs
+++ b/testgen-hs/Main.hs
@@ -1,14 +1,29 @@
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeApplications #-}
+
 module Main where
 
 import CLI (GenSize (..), NumCases (..), Seed (..))
 import qualified CLI
+import Cardano.Binary (FromCBOR, decodeFull')
+import Cardano.Ledger.Api (ConwayEra, PParams)
+import qualified Cardano.Ledger.Binary.Decoding as Binary
+import qualified Cardano.Ledger.Core
+import qualified Cardano.Ledger.Core as Ledger
+import Cardano.Slotting.EpochInfo (EpochInfo, fixedEpochInfo)
+import Cardano.Slotting.Slot (EpochSize (..))
+import Cardano.Slotting.Time (SystemStart (..), mkSlotLength)
 import qualified Codec.CBOR.Write as C
 import qualified Control.Concurrent.Async as Async
 import Control.Concurrent.MVar (modifyMVar_, newMVar)
+import Control.Monad (forever, when)
 import Data.Aeson (FromJSON, ToJSON)
 import qualified Data.Aeson as J
 import qualified Data.Aeson.Encode.Pretty as J
+import Data.Bifunctor (first)
 import Data.ByteString (ByteString)
+import qualified Data.ByteString as BS
 import qualified Data.ByteString.Base16 as B16
 import qualified Data.ByteString.Char8 as B8
 import qualified Data.ByteString.Lazy as BL
@@ -18,12 +33,16 @@ import Data.Proxy (Proxy (..))
 import Data.Text (Text)
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
-import qualified Data.Text.Encoding.Error as T
+import qualified Data.Text.Encoding.Error as TEE
+import Data.Time (NominalDiffTime)
 import Data.Time.Clock.POSIX (getPOSIXTime)
+import Data.Word (Word16, Word64)
 import qualified Deserialize as D
+import Encoder (serializeDecoderError)
+import Evaluation (eval'Conway, writeJson)
 import GHC.Generics (Generic)
 import qualified Generators as G
-import System.Exit (exitFailure)
+import System.Exit (exitFailure, exitSuccess)
 import System.IO (hPutStrLn, stderr)
 import qualified System.IO as SIO
 import qualified System.Random
@@ -39,6 +58,7 @@ main =
     CLI.Generate opts -> runGenerate opts
     CLI.Deserialize cbor -> runDeserialize cbor
     CLI.DeserializeStream -> runDeserializeStream
+    CLI.EvaluateStream -> runEvaluateStream
 
 data TestCase a = TestCase
   { cbor :: Text,
@@ -48,6 +68,61 @@ data TestCase a = TestCase
   }
   deriving (Generic, Show, FromJSON, ToJSON)
 
+-- | Represents initialization payload containing configuration parameters.
+--
+-- The InitPayload type encapsulates essential system and protocol configuration for eval tx:
+--
+-- - systemStart: Starting time of the system, CBOR
+-- - protocolParams: Protocol parameters in text format, CBOR
+-- - slotConfig: Configuration for slots
+-- - era: Era identifier as a 16-bit word
+--
+-- This data type implements Generic, Show and FromJSON type classes for serialization
+-- and debugging purposes.
+data InitPayload = InitPayload
+  { systemStart :: Text, -- cbor
+    protocolParams :: Text, -- cbor
+    slotConfig :: SlotConfig,
+    era :: Word16
+  }
+  deriving (Generic, Show, FromJSON)
+
+data SlotConfig = SlotConfig
+  { slotLength :: Word64, -- in milliseconds
+    zeroSlot :: Word64,
+    zeroTime :: Word64,
+    epochLength :: Word64
+  }
+  deriving (Generic, Show, FromJSON)
+
+-- This is used as a generic response to any incoming request.
+data PayloadResponse = PayloadResponse
+  { rError :: Maybe Text,
+    rJson :: Maybe J.Value
+  }
+  deriving (Generic, Show)
+
+instance ToJSON PayloadResponse where
+  toJSON = J.genericToJSON J.defaultOptions {J.fieldLabelModifier = modifier, J.omitNothingFields = True}
+    where
+      modifier "rError" = "error"
+      modifier "rJson" = "json"
+      modifier s = s
+
+-- |
+--    EvalPayload represents the data structure for transaction evaluation payload.
+--
+--    Contains transaction and UTxO information needed for evaluation.
+--
+--    Fields:
+--      * tx - Transaction data as CBOR
+--      * utxos - Unspent Transaction Outputs (UTxOs) as CBOR
+data EvalPayload = EvalPayload
+  { tx :: Text,
+    utxos :: Text -- TxIn & TxOut as key value pair CBOR (map)
+  }
+  deriving (Generic, Show, FromJSON)
+
 runGenerate :: CLI.GenerateOptions -> IO ()
 runGenerate (CLI.GenerateOptions maybeSeed genSize numCases command) = do
   SIO.hSetBuffering SIO.stdout SIO.LineBuffering
@@ -59,7 +134,7 @@ runGenerate (CLI.GenerateOptions maybeSeed genSize numCases command) = do
   BL8.putStrLn $ J.encode (J.object [("seed", (\(Seed s) -> J.toJSON s) seed)])
 
   ( case command of
-      CLI.Tx'Conway -> writeRandom @G.Tx'Conway Proxy
+      CLI.Tx'ConwayDummy -> writeRandom @G.Tx'Conway Proxy
       CLI.ApplyTxErr'Byron -> writeRandom @G.ApplyTxErr'Byron Proxy
       CLI.ApplyTxErr'Shelley -> writeRandom @G.ApplyTxErr'Shelley Proxy
       CLI.ApplyTxErr'Allegra -> writeRandom @G.ApplyTxErr'Allegra Proxy
@@ -67,6 +142,7 @@ runGenerate (CLI.GenerateOptions maybeSeed genSize numCases command) = do
       CLI.ApplyTxErr'Alonzo -> writeRandom @G.ApplyTxErr'Alonzo Proxy
       CLI.ApplyTxErr'Babbage -> writeRandom @G.ApplyTxErr'Babbage Proxy
       CLI.ApplyTxErr'Conway -> writeRandom @G.ApplyTxErr'Conway Proxy
+      CLI.TxScriptFailure'Conway -> writeJson Proxy
       CLI.DataText -> writeRandom @Text Proxy
       CLI.GHCInteger -> writeRandom @Integer Proxy
       CLI.ExampleADT -> writeRandom @G.ExampleADT Proxy
@@ -118,7 +194,7 @@ mkTestCase :: forall a. (Show a, G.OurCBOR a) => a -> TestCase a
 mkTestCase a =
   TestCase
     { cbor =
-        T.decodeUtf8With T.lenientDecode
+        T.decodeUtf8With TEE.lenientDecode
           . B16.encode
           . BL.toStrict
           . C.toLazyByteString
@@ -149,7 +225,7 @@ cborToTestCase cbor' =
       let (typeTag', haskellRepr') = G.hfcEnvelopeShowInner a
        in TestCase
             { cbor =
-                T.decodeUtf8With T.lenientDecode
+                T.decodeUtf8With TEE.lenientDecode
                   . B16.encode
                   $ cbor',
               haskellRepr = T.pack haskellRepr',
@@ -176,3 +252,98 @@ runDeserializeStream = do
                 Left err -> J.object ["error" J..= err]
           BL8.putStrLn . J.encode $ result
           processLines
+
+runEvaluateStream :: IO ()
+runEvaluateStream = do
+  -- We need line buffering for this to work:
+  SIO.hSetBuffering SIO.stdin SIO.LineBuffering
+  SIO.hSetBuffering SIO.stdout SIO.LineBuffering
+  line <- B8.getLine
+  case J.eitherDecodeStrict line of
+    Left err -> do
+      BL8.putStrLn . J.encode $
+        PayloadResponse
+          { rJson = Nothing,
+            rError = Just . T.pack $ "Expected InitPayload first, but failed to parse line: " ++ err
+          }
+      runEvaluateStream
+    Right initPayload -> do
+      let ei = convertEpochInfo (slotConfig initPayload)
+      let combinedResult = do
+            pp <- decodeFromHex (protocolParams initPayload)
+            ss <- decodeFromHex (systemStart initPayload)
+            return (pp, ss)
+
+      case combinedResult of
+        Left err -> do
+          BL8.putStrLn . J.encode $
+            PayloadResponse
+              { rJson = Nothing,
+                rError = Just . T.pack $ "Failed to decode initial payload " ++ err
+              }
+          exitFailure
+        Right (pp, ss) -> do
+          BL8.putStrLn . J.encode $ PayloadResponse {rJson = Just (J.object []), rError = Nothing}
+          forever $ processLine pp ss ei
+  where
+    processLine :: PParams ConwayEra -> SystemStart -> EpochInfo (Either Text) -> IO ()
+    processLine pp ss ei = do
+      eof <- SIO.isEOF
+      when eof exitSuccess
+      line <- B8.getLine -- This line is expected to be an EvalPayload
+      case J.eitherDecodeStrict line of
+        Left err -> do
+          let response = case J.eitherDecodeStrict' (B8.pack err) of
+                Left decodeErr -> PayloadResponse {rJson = Nothing, rError = Just (T.pack $ "Failed to decode error as JSON: " ++ decodeErr ++ ". Original error: " ++ err)}
+                Right jsonVal -> PayloadResponse {rJson = Nothing, rError = Just jsonVal}
+          BL8.putStrLn . J.encode $ response
+        Right (evalPayload :: EvalPayload) -> do
+          let decodedValues = do
+                txBytes <- first (\e -> PayloadResponse (Just (T.pack e)) Nothing) $ B16.decode (T.encodeUtf8 (tx evalPayload))
+                decodedTx <-
+                  decodeCborWith
+                    "Transaction"
+                    (Left . (\e -> PayloadResponse (Just (serializeDecoderError (BS.length txBytes) e)) Nothing))
+                    (Binary.decCBOR @(Cardano.Ledger.Core.Tx ConwayEra))
+                    txBytes
+                utxos <- first (\e -> PayloadResponse (Just (T.pack e)) Nothing) $ decodeFromHex (utxos evalPayload)
+                return (decodedTx, utxos)
+
+          case decodedValues of
+            Left response ->
+              BL8.putStrLn . J.encode $ response
+            Right (tx, utxos) -> do
+              let result = eval'Conway pp tx utxos ei ss
+              BL8.putStrLn . J.encode $ PayloadResponse {rJson = Just result, rError = Nothing}
+
+-- | Creates an EpochInfo from the given SlotConfig
+convertEpochInfo :: SlotConfig -> EpochInfo (Either Text)
+convertEpochInfo sc =
+  let slotLengthInSeconds :: NominalDiffTime = fromIntegral (slotLength sc) / 1000
+   in fixedEpochInfo (EpochSize $ epochLength sc) (mkSlotLength slotLengthInSeconds)
+
+-- | Generic CBOR hex decoder
+decodeFromHex :: (FromCBOR a) => T.Text -> Either String a
+decodeFromHex hexText = do
+  -- 1. Decode from hex
+  cborBytes <- first show $ B16.decode (T.encodeUtf8 hexText)
+  -- 2. Decode from CBOR.
+  first show $ decodeFull' cborBytes
+
+-- Run a CBOR decoder for data in Conway era
+decodeCborWith ::
+  -- | Label for error reporting
+  Text ->
+  -- | Error handler
+  (Binary.DecoderError -> Either e a) ->
+  -- | CBOR decoder
+  (forall s. Binary.Decoder s a) ->
+  -- | Input bytes
+  ByteString ->
+  Either e a
+decodeCborWith lbl handleErr decoder bytes =
+  case Binary.decodeFullDecoder version lbl decoder (BL.fromStrict bytes) of
+    Left cborErr -> handleErr cborErr
+    Right val -> Right val
+  where
+    version = Ledger.eraProtVerLow @ConwayEra
diff --git a/testgen-hs/Response.hs b/testgen-hs/Response.hs
new file mode 100644
index 0000000..301aac8
--- /dev/null
+++ b/testgen-hs/Response.hs
@@ -0,0 +1,28 @@
+module Response
+  ( PayloadResponse (..),
+  )
+where
+
+import Data.Aeson (ToJSON)
+import qualified Data.Aeson as J
+import Data.Text (Text)
+import GHC.Generics (Generic)
+
+-- | Generic response envelope used across endpoints.
+data PayloadResponse = PayloadResponse
+  { rError :: Maybe Text,
+    rJson :: Maybe J.Value
+  }
+  deriving (Generic, Show)
+
+instance ToJSON PayloadResponse where
+  toJSON =
+    J.genericToJSON
+      J.defaultOptions
+        { J.fieldLabelModifier = modifier,
+          J.omitNothingFields = True
+        }
+    where
+      modifier "rError" = "error"
+      modifier "rJson" = "json"
+      modifier s = s
diff --git a/testgen-hs/SynthEvalTx.hs b/testgen-hs/SynthEvalTx.hs
index d5cddbb..17b3e3e 100644
--- a/testgen-hs/SynthEvalTx.hs
+++ b/testgen-hs/SynthEvalTx.hs
@@ -9,29 +9,16 @@
 -- | Generates a fake minimal UTxO set for a given transaction, for the purposes
 --  of running `Cardano.Ledger.Alonzo.Plutus.Evaluate.evalTxExUnits` on the
 --  transaction.
-module SynthEvalTx (eval'Conway, genTxUTxO, stubUTxO) where
+module SynthEvalTx (eval'Conway, eval'ConwayDummy, genTxUTxO, stubUTxO) where
 
 import Cardano.Crypto.Hash.Class (hashFromBytes)
 import Cardano.Ledger.Address (Addr (..))
 import Cardano.Ledger.Alonzo.Plutus.Evaluate (evalTxExUnits)
-import Cardano.Ledger.Alonzo.Scripts
-  ( AsIx (..),
-    ExUnits (..),
-  )
 import qualified Cardano.Ledger.Alonzo.Scripts
 import qualified Cardano.Ledger.Alonzo.Tx
 import Cardano.Ledger.Api (EraTx, PParams, bodyTxL, collateralInputsTxBodyL, inputsTxBodyL, referenceInputsTxBodyL)
 import qualified Cardano.Ledger.Api.Era
-import Cardano.Ledger.Api.Scripts
-  ( ConwayEraScript,
-    pattern CertifyingPurpose,
-    pattern MintingPurpose,
-    pattern ProposingPurpose,
-    pattern RewardingPurpose,
-    pattern SpendingPurpose,
-    pattern VotingPurpose,
-  )
-import Cardano.Ledger.Api.Tx (BabbageEraTxBody, PlutusPurpose, RedeemerReport, Tx)
+import Cardano.Ledger.Api.Tx (BabbageEraTxBody, RedeemerReport, Tx)
 import Cardano.Ledger.Api.Tx.In (TxIn)
 import Cardano.Ledger.Api.Tx.Out
   ( TxOut (..),
@@ -53,15 +40,16 @@ import Data.Aeson
   ( eitherDecodeStrict',
   )
 import qualified Data.Aeson as J
+import qualified Data.Aeson.Encoding as AesonEncoding
 import qualified Data.ByteString as BS
 import qualified Data.Default
 import Data.FileEmbed (embedFile)
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
 import Data.Text (Text)
-import qualified Data.Text as T
 import Data.Time.Calendar (fromGregorian)
 import Data.Time.Clock (UTCTime (..), secondsToDiffTime)
+import Encoder (ogmiosSuccess)
 import Lens.Micro ((^.))
 import qualified Test.Cardano.Ledger.Generic.GenState
 import qualified Test.Cardano.Ledger.Generic.Proof as Proof
@@ -94,8 +82,26 @@ genTxUTxO = do
     proof :: Proof.Proof Cardano.Ledger.Api.Era.ConwayEra
     proof = Proof.Conway
 
-eval'Conway :: (Cardano.Ledger.Core.Tx (Cardano.Ledger.Api.Era.ConwayEra)) -> UTxO Cardano.Ledger.Api.Era.ConwayEra -> J.Value
-eval'Conway tx utxo = ogmiosSuccess redeemerReport
+eval'Conway ::
+  (Cardano.Ledger.Core.Tx (Cardano.Ledger.Api.Era.ConwayEra)) ->
+  UTxO (Cardano.Ledger.Api.Era.ConwayEra) ->
+  EpochInfo (Either Text) ->
+  SystemStart ->
+  J.Value
+eval'Conway tx utxo epochInfo systemStart =
+  case J.decode (AesonEncoding.encodingToLazyByteString (ogmiosSuccess redeemerReport)) of
+    Just v -> v
+    Nothing -> error "ogmiosSuccess produced invalid JSON"
+  where
+    redeemerReport :: RedeemerReport (Cardano.Ledger.Api.Era.ConwayEra)
+    redeemerReport = evalTxExUnits protocolParams tx utxo epochInfo systemStart
+
+-- | Version of eval'Conway that uses dummy epoch info and system start
+eval'ConwayDummy :: (Cardano.Ledger.Core.Tx (Cardano.Ledger.Api.Era.ConwayEra)) -> UTxO Cardano.Ledger.Api.Era.ConwayEra -> J.Value
+eval'ConwayDummy tx utxo =
+  case J.decode (AesonEncoding.encodingToLazyByteString (ogmiosSuccess redeemerReport)) of
+    Just v -> v
+    Nothing -> error "ogmiosSuccess produced invalid JSON"
   where
     redeemerReport :: RedeemerReport (Cardano.Ledger.Api.Era.ConwayEra)
     redeemerReport = evalTxExUnits protocolParams tx utxo dummyEpochInfo dummySystemStart
@@ -142,46 +148,3 @@ protocolParams =
   case eitherDecodeStrict' protocolParamsJSON of
     Left err -> error $ "Embedded protocol-parameters JSON is malformed:\n" <> err
     Right pp -> pp
-
--- | Render a ledger redeemer pointer the Ogmios way
-redeemerPtrToText :: forall era. (ConwayEraScript era) => PlutusPurpose AsIx era -> Text
-redeemerPtrToText = \case
-  SpendingPurpose (AsIx ix) -> "spend:" <> showT ix
-  CertifyingPurpose (AsIx ix) -> "publish:" <> showT ix
-  MintingPurpose (AsIx ix) -> "mint:" <> showT ix
-  RewardingPurpose (AsIx ix) -> "withdraw:" <> showT ix
-  ProposingPurpose (AsIx ix) -> "propose:" <> showT ix
-  VotingPurpose (AsIx ix) -> "vote:" <> showT ix
-  _ -> error "unreachable: unknown PlutusPurpose" -- matches _are_ exhaustive, but it’s not provable statically
-  where
-    showT = T.pack . show -- Word32 → Text
-
--- | Ogmios "budget" object from 'ExUnits'.
-exUnitsToJSON :: ExUnits -> J.Value
-exUnitsToJSON (ExUnits mem cpu) =
-  J.object ["memory" J..= mem, "cpu" J..= cpu]
-
--- | Build the JSON-RPC success envelope that Ogmios returns when every
---   redeemer succeeds.
-ogmiosSuccess ::
-  forall era err.
-  (ConwayEraScript era, Show err) => -- same constraint here
-  Map.Map (PlutusPurpose AsIx era) (Either err ExUnits) ->
-  J.Value
-ogmiosSuccess report =
-  J.toJSON
-    [ case res of
-        Right exu ->
-          J.object
-            [ "validator" J..= redeemerPtrToText ptr,
-              "budget" J..= exUnitsToJSON exu
-            ]
-        Left err ->
-          J.object
-            [ "validator" J..= redeemerPtrToText ptr,
-              "error"
-                J..= J.object
-                  ["message" J..= show err] -- simple text trace
-            ]
-      | (ptr, res) <- Map.toList report
-    ]
diff --git a/testgen-hs/testgen-hs.cabal b/testgen-hs/testgen-hs.cabal
index 06ab9df..6d281fc 100644
--- a/testgen-hs/testgen-hs.cabal
+++ b/testgen-hs/testgen-hs.cabal
@@ -5,7 +5,7 @@ synopsis:
   CBOR test case generator and deserializer for cross-checking other implementations
 
 -- Version tracks cardano-node, adding a patch segment:
-version:       10.4.1.1
+version:       10.4.1.2
 
 executable testgen-hs
   main-is:            Main.hs
@@ -21,7 +21,10 @@ executable testgen-hs
     , cardano-crypto-class
     , cardano-ledger-alonzo
     , cardano-ledger-api
+    , cardano-ledger-babbage
+    , cardano-ledger-binary
     , cardano-ledger-byron
+    , cardano-ledger-conway
     , cardano-ledger-core
     , cardano-ledger-test
     , cardano-slotting
@@ -36,6 +39,9 @@ executable testgen-hs
     , ouroboros-consensus
     , ouroboros-consensus-cardano
     , ouroboros-consensus-cardano:unstable-cardano-testlib
+    , plutus-core
+    , plutus-ledger-api
+    , prettyprinter
     , QuickCheck
     , quickcheck-instances
     , random
@@ -43,11 +49,16 @@ executable testgen-hs
     , text
     , time
 
+  --, cardano-crypto
+  --, cardano-crypto-wrapper
   other-modules:
     CLI
     Deserialize
+    Encoder
+    Evaluation
     Generators
     Paths_testgen_hs
+    Response
     SynthEvalTx
 
   default-extensions: