diff --git a/tx_binary.go b/tx_binary.go
index d4a3ba4..46b8dcd 100644
--- a/tx_binary.go
+++ b/tx_binary.go
@@ -1191,7 +1191,7 @@ func (enc *txBinaryEncoder) writeTxBinaryBody(tx *TxBinary, enumTable *txBinaryE
 func (enc *txBinaryEncoder) writePlatformEntries(entries []PlatformBinary, enumTable *txBinaryEnumTable) error {
 	enc.writeUint32(uint32(len(entries)))
 	for i, entry := range entries {
-		enumID, err := enumTable.platforms.id(entry.Platform)
+		enumID, err := enumTable.platforms.idOrFallback(entry.Platform, PlatformNone)
 		if err != nil {
 			return fmt.Errorf("platform[%d]: %w", i, err)
 		}
@@ -1204,7 +1204,7 @@ func (enc *txBinaryEncoder) writePlatformEntries(entries []PlatformBinary, enumT
 func (enc *txBinaryEncoder) writeMevAgentEntries(entries []MevAgentBinary, enumTable *txBinaryEnumTable) error {
 	enc.writeUint32(uint32(len(entries)))
 	for i, entry := range entries {
-		enumID, err := enumTable.mevAgents.id(entry.MevAgent)
+		enumID, err := enumTable.mevAgents.idOrFallback(entry.MevAgent, MevAgentUnknown)
 		if err != nil {
 			return fmt.Errorf("mev_agent[%d]: %w", i, err)
 		}
@@ -1592,7 +1592,7 @@ func txBinaryReadPlatformEntries(dec txBinaryBodyReader, enumTable *txBinaryEnum
 		if err != nil {
 			return nil, err
 		}
-		platform, err := enumTable.platforms.value(enumID)
+		platform, err := enumTable.platforms.valueOrFallback(enumID, PlatformNone)
 		if err != nil {
 			return nil, fmt.Errorf("platform[%d]: %w", i, err)
 		}
@@ -1619,7 +1619,7 @@ func txBinaryReadMevAgentEntries(dec txBinaryBodyReader, enumTable *txBinaryEnum
 		if err != nil {
 			return nil, err
 		}
-		mevAgent, err := enumTable.mevAgents.value(enumID)
+		mevAgent, err := enumTable.mevAgents.valueOrFallback(enumID, MevAgentUnknown)
 		if err != nil {
 			return nil, fmt.Errorf("mev_agent[%d]: %w", i, err)
 		}
@@ -2144,6 +2144,7 @@ var txBinaryEnumTables = map[uint16]*txBinaryEnumTable{
 			MevAgentAllenhark,
 			MevAgentRaiden,
 			MevAgentZan,
+			MevAgentTunneling,
 		},
 	),
 }
@@ -2199,9 +2200,30 @@ func (set txBinaryEnumSet) id(value string) (uint16, error) {
 	return id, nil
 }
 
+func (set txBinaryEnumSet) idOrFallback(value string, fallback string) (uint16, error) {
+	if id, ok := set.ids[value]; ok {
+		return id, nil
+	}
+	id, ok := set.ids[fallback]
+	if !ok {
+		return 0, fmt.Errorf("unsupported %s fallback enum value %q for versioned tx binary", set.name, fallback)
+	}
+	return id, nil
+}
+
 func (set txBinaryEnumSet) value(id uint16) (string, error) {
 	if int(id) >= len(set.values) {
 		return "", fmt.Errorf("unknown %s enum id %d", set.name, id)
 	}
 	return set.values[id], nil
 }
+
+func (set txBinaryEnumSet) valueOrFallback(id uint16, fallback string) (string, error) {
+	if int(id) < len(set.values) {
+		return set.values[id], nil
+	}
+	if _, ok := set.ids[fallback]; !ok {
+		return "", fmt.Errorf("unsupported %s fallback enum value %q for versioned tx binary", set.name, fallback)
+	}
+	return fallback, nil
+}
diff --git a/tx_binary_test.go b/tx_binary_test.go
index c1379fe..2b7ea4b 100644
--- a/tx_binary_test.go
+++ b/tx_binary_test.go
@@ -45,6 +45,10 @@ func TestTxBinaryRoundTrip(t *testing.T) {
 				MevAgent:    MevAgentZan,
 				MevAgentFee: decimal.RequireFromString("0.040000000"),
 			},
+			MevAgentTunneling: {
+				MevAgent:    MevAgentTunneling,
+				MevAgentFee: decimal.RequireFromString("0.050000000"),
+			},
 		},
 		Swaps: []Swap{
 			{
@@ -153,6 +157,9 @@ func TestTxBinaryRoundTrip(t *testing.T) {
 	if !decoded.MevAgent[MevAgentZan].MevAgentFee.Equal(original.MevAgent[MevAgentZan].MevAgentFee) {
 		t.Fatalf("Zan MevAgent fee mismatch")
 	}
+	if !decoded.MevAgent[MevAgentTunneling].MevAgentFee.Equal(original.MevAgent[MevAgentTunneling].MevAgentFee) {
+		t.Fatalf("Tunneling MevAgent fee mismatch")
+	}
 	if len(decoded.Swaps) != 1 {
 		t.Fatalf("Swaps len = %d, want 1", len(decoded.Swaps))
 	}
@@ -232,6 +239,87 @@ func TestTxBinaryRejectsUnknownProgramEnum(t *testing.T) {
 	}
 }
 
+func TestTxBinaryLabelEnumsFallbackToUnknown(t *testing.T) {
+	original := &Tx{
+		Signer: solana.WrappedSol,
+		Platform: map[string]platformInfo{
+			"future-platform": {
+				Platform:    "future-platform",
+				PlatformFee: decimal.RequireFromString("0.010000000"),
+			},
+		},
+		MevAgent: map[string]mevInfo{
+			"future-mev-agent": {
+				MevAgent:    "future-mev-agent",
+				MevAgentFee: decimal.RequireFromString("0.020000000"),
+			},
+		},
+	}
+
+	encoded, err := EncodeTxBinary(original)
+	if err != nil {
+		t.Fatalf("EncodeTxBinary() error = %v", err)
+	}
+	decoded, err := DecodeTxBinary(encoded)
+	if err != nil {
+		t.Fatalf("DecodeTxBinary() error = %v", err)
+	}
+
+	if len(decoded.Platform) != 1 {
+		t.Fatalf("Platform len = %d, want 1", len(decoded.Platform))
+	}
+	if _, exists := decoded.Platform["future-platform"]; exists {
+		t.Fatalf("future platform was preserved, want fallback")
+	}
+	if !decoded.Platform[PlatformNone].PlatformFee.Equal(original.Platform["future-platform"].PlatformFee) {
+		t.Fatalf("PlatformNone fee = %s, want %s", decoded.Platform[PlatformNone].PlatformFee, original.Platform["future-platform"].PlatformFee)
+	}
+
+	if len(decoded.MevAgent) != 1 {
+		t.Fatalf("MevAgent len = %d, want 1", len(decoded.MevAgent))
+	}
+	if _, exists := decoded.MevAgent["future-mev-agent"]; exists {
+		t.Fatalf("future mev agent was preserved, want fallback")
+	}
+	if !decoded.MevAgent[MevAgentUnknown].MevAgentFee.Equal(original.MevAgent["future-mev-agent"].MevAgentFee) {
+		t.Fatalf("MevAgentUnknown fee = %s, want %s", decoded.MevAgent[MevAgentUnknown].MevAgentFee, original.MevAgent["future-mev-agent"].MevAgentFee)
+	}
+}
+
+func TestTxBinaryReadLabelEnumUnknownIDsFallback(t *testing.T) {
+	enumTable := txBinaryEnumTables[txBinaryEnumVersionV1]
+
+	platformFee := uint64(123)
+	platformEnc := txBinaryEncoder{}
+	platformEnc.writeUint32(1)
+	platformEnc.writeUint16(uint16(len(enumTable.platforms.values) + 10))
+	platformEnc.writeUint64(platformFee)
+
+	platformDec := txBinaryDecoder{reader: bytes.NewReader(platformEnc.bytes())}
+	platforms, err := txBinaryReadPlatformEntries(&platformDec, enumTable)
+	if err != nil {
+		t.Fatalf("txBinaryReadPlatformEntries() error = %v", err)
+	}
+	if len(platforms) != 1 || platforms[0].Platform != PlatformNone || platforms[0].PlatformFee != platformFee {
+		t.Fatalf("platform fallback = %+v, want %s/%d", platforms, PlatformNone, platformFee)
+	}
+
+	mevFee := uint64(456)
+	mevEnc := txBinaryEncoder{}
+	mevEnc.writeUint32(1)
+	mevEnc.writeUint16(uint16(len(enumTable.mevAgents.values) + 10))
+	mevEnc.writeUint64(mevFee)
+
+	mevDec := txBinaryDecoder{reader: bytes.NewReader(mevEnc.bytes())}
+	mevAgents, err := txBinaryReadMevAgentEntries(&mevDec, enumTable)
+	if err != nil {
+		t.Fatalf("txBinaryReadMevAgentEntries() error = %v", err)
+	}
+	if len(mevAgents) != 1 || mevAgents[0].MevAgent != MevAgentUnknown || mevAgents[0].MevAgentFee != mevFee {
+		t.Fatalf("mev agent fallback = %+v, want %s/%d", mevAgents, MevAgentUnknown, mevFee)
+	}
+}
+
 func TestTxBinaryAcceptsKnownEventEnums(t *testing.T) {
 	events := []string{
 		TxEventAddLP,