fix: reorder transaction deserialization and fix mempool UTxO era

utxoFromMempool initialized with UTxOInBabbageEra, causing all
evaluations to hit the Babbage rejection branch even for Conway
transactions. Changed to UTxOInConwayEra.

Reorder deserialiseCBOR to try Conway and Dijkstra before Babbage.
Conway transactions can successfully deserialize as Babbage (the
Babbage decoder accepts Conway-era CBOR), wrapping them as
GenTxBabbage and rejecting them as "unsupported era". Older eras
kept as fallbacks for specific diagnostics.

Use eraProtVerHigh in transaction deserialization to accept
transactions from any protocol version within an era (e.g.
Conway PV9 through PV11).

Co-Authored-By: Claude <noreply@anthropic.com>

Author: johnalotoski

server/src/Ogmios/Data/Json/Query.hs

@@ -2638,19 +2638,19 @@ decodeSerializedTransaction
 decodeSerializedTransaction = Json.withText "Transaction" $ \(encodeUtf8 -> utf8) -> do
     bytes <- decodeBase16 utf8 <|> invalidEncodingError
     -- NOTE (1):
-    -- The order in which we parser matters! Older eras first. formats
-    -- are forward-compatible, and near hard-forks, there's a period where the
-    -- software can understand the next era but, that era isn't available yet.
-    --
-    -- Therefore, we need to favor parsing older eras so that existing code keep
-    -- working. Transactions are only decoded in the new era when they are using
-    -- features not available in older ones.
+    -- The order in which we parse matters! Conway transactions can successfully
+    -- deserialize as Babbage (the Babbage decoder accepts Conway-era CBOR).
+    -- Since Babbage evaluation was dropped (per era rotation policy), this would
+    -- wrap Conway transactions as GenTxBabbage and reject them as "unsupported
+    -- era". We try Conway and Dijkstra first so transactions are evaluated in
+    -- the current era. Older eras are kept as fallbacks to provide specific
+    -- "unsupported era" diagnostics rather than generic deserialization errors.
     --
     -- NOTE (2):
     -- Avoiding 'asum' here because it generates poor errors on failures.
-    pure $  deserialiseCBOR @BabbageEra GenTxBabbage bytes
+    pure $  deserialiseCBOR @ConwayEra  GenTxConway  bytes
         <|> deserialiseCBOR @DijkstraEra GenTxDijkstra bytes
-        <|> deserialiseCBOR @ConwayEra  GenTxConway  bytes
+        <|> deserialiseCBOR @BabbageEra GenTxBabbage bytes
         <|> deserialiseCBOR @AlonzoEra  GenTxAlonzo  bytes
         <|> deserialiseCBOR @MaryEra    GenTxMary    bytes
         <|> deserialiseCBOR @AllegraEra GenTxAllegra bytes
@@ -2683,20 +2683,26 @@ decodeSerializedTransaction = Json.withText "Transaction" $ \(encodeUtf8 -> utf8
         -> ByteString
         -> MultiEraDecoder (GenTx (CardanoBlock crypto))
     deserialiseCBOR mk bytes =
-        mk <$> decodeCborWith @era "Transaction"
-            (\e -> MultiEraDecoderErrors
-                [ ( SomeShelleyEra (shelleyBasedEra @era)
-                  , e
-                  , fromIntegral $ BS.length bytes
-                  )
-                ]
-            )
-            (Binary.fromPlainDecoder fromCBOR)
-            (if  wrapper `BS.isPrefixOf` bytes
-               then fromStrict bytes
-               else wrap bytes
+        mk <$> either reject pure
+            (Binary.decodeFullDecoder version "Transaction"
+                (Binary.fromPlainDecoder fromCBOR)
+                (if  wrapper `BS.isPrefixOf` bytes
+                   then fromStrict bytes
+                   else wrap bytes
+                )
             )
       where
+        -- Use eraProtVerHigh to accept transactions from any protocol
+        -- version within the era (e.g. Conway PV9, PV10, PV11).
+        version = Ledger.eraProtVerHigh @era
+
+        reject e = MultiEraDecoderErrors
+            [ ( SomeShelleyEra (shelleyBasedEra @era)
+              , e
+              , fromIntegral $ BS.length bytes
+              )
+            ]
+
         wrapper = BS.pack [216, 24] -- D818...
 
         -- Cardano tools have a tendency to wrap cbor in cbor (e.g cardano-cli).

server/src/Ogmios/Data/Protocol/TxSubmission.hs

@@ -476,7 +476,7 @@ utxoFromMempool
     => [GenTx block]
     -> MultiEraUTxO block
 utxoFromMempool =
-    go $ UTxOInBabbageEra mempty
+    go $ UTxOInConwayEra mempty
   where
     go :: MultiEraUTxO block -> [GenTx block] -> MultiEraUTxO block
     go utxo = \case