fix: encode ls model credits topic values as base64

backend/internal/pkg/lspool/integration_test.go

@@ -3,6 +3,7 @@ package lspool
 import (
 	"bytes"
 	"context"
+	"encoding/base64"
 	"encoding/binary"
 	"encoding/json"
 	"fmt"
@@ -72,6 +73,65 @@ func decodeProtoBytesField(data []byte, targetField int) []byte {
 	return nil
 }
 
+func decodeProtoBytesFields(data []byte, targetField int) [][]byte {
+	var values [][]byte
+	i := 0
+	for i < len(data) {
+		tag, n := binary.Uvarint(data[i:])
+		if n <= 0 {
+			return values
+		}
+		i += n
+		fieldNum := int(tag >> 3)
+		wireType := tag & 0x7
+		switch wireType {
+		case 0:
+			_, n = binary.Uvarint(data[i:])
+			if n <= 0 {
+				return values
+			}
+			i += n
+		case 2:
+			length, n := binary.Uvarint(data[i:])
+			if n <= 0 {
+				return values
+			}
+			i += n
+			if i+int(length) > len(data) {
+				return values
+			}
+			if fieldNum == targetField {
+				values = append(values, append([]byte(nil), data[i:i+int(length)]...))
+			}
+			i += int(length)
+		case 1:
+			i += 8
+		case 5:
+			i += 4
+		default:
+			return values
+		}
+	}
+	return values
+}
+
+func decodeTopicRows(topic []byte) map[string]string {
+	rows := make(map[string]string)
+	for _, entry := range decodeProtoBytesFields(topic, 1) {
+		key := decodeProtoString(entry, 1)
+		row := decodeProtoBytesField(entry, 2)
+		rows[key] = decodeProtoString(row, 1)
+	}
+	return rows
+}
+
+func requireBase64PrimitiveValue(t *testing.T, got string, want []byte) {
+	t.Helper()
+	decoded, err := base64.StdEncoding.DecodeString(got)
+	require.NoError(t, err)
+	require.Equal(t, want, decoded)
+}
+
 // TestMockExtensionServerTokenInjection verifies the token injection flow:
 // Extension → MockExtensionServer → LS subscribes uss-oauth → gets OAuthTokenInfo
 func TestMockExtensionServerTokenInjection(t *testing.T) {
@@ -232,6 +292,11 @@ func TestUSSTopicWithModelCredits(t *testing.T) {
 	require.Contains(t, string(topic), useAICreditsSentinelKey)
 	require.Contains(t, string(topic), availableCreditsSentinelKey)
 	require.Contains(t, string(topic), minimumCreditAmountForUsageKey)
+
+	rows := decodeTopicRows(topic)
+	requireBase64PrimitiveValue(t, rows[useAICreditsSentinelKey], buildPrimitiveBoolBinary(true))
+	requireBase64PrimitiveValue(t, rows[availableCreditsSentinelKey], buildPrimitiveInt32Binary(available))
+	requireBase64PrimitiveValue(t, rows[minimumCreditAmountForUsageKey], buildPrimitiveInt32Binary(minimum))
 }
 
 func TestMockExtensionServerModelCreditsDynamicUpdate(t *testing.T) {
@@ -269,18 +334,23 @@ func TestMockExtensionServerModelCreditsDynamicUpdate(t *testing.T) {
 		MinimumCreditAmountForUsage: &minimum,
 	})
 
-	keys := make([]string, 0, 3)
+	values := make(map[string]string, 3)
-	for len(keys) < 3 {
+	for len(values) < 3 {
 		frame, readErr := readConnectFrame(resp.Body)
 		require.NoError(t, readErr)
 		applied := decodeProtoBytesField(frame, 2)
 		require.NotEmpty(t, applied)
-		keys = append(keys, decodeProtoString(applied, 1))
+		key := decodeProtoString(applied, 1)
+		row := decodeProtoBytesField(applied, 2)
+		values[key] = decodeProtoString(row, 1)
 	}
 
-	require.Contains(t, keys, useAICreditsSentinelKey)
+	require.Contains(t, values, useAICreditsSentinelKey)
-	require.Contains(t, keys, availableCreditsSentinelKey)
+	require.Contains(t, values, availableCreditsSentinelKey)
-	require.Contains(t, keys, minimumCreditAmountForUsageKey)
+	require.Contains(t, values, minimumCreditAmountForUsageKey)
+	requireBase64PrimitiveValue(t, values[useAICreditsSentinelKey], buildPrimitiveBoolBinary(true))
+	requireBase64PrimitiveValue(t, values[availableCreditsSentinelKey], buildPrimitiveInt32Binary(available))
+	requireBase64PrimitiveValue(t, values[minimumCreditAmountForUsageKey], buildPrimitiveInt32Binary(minimum))
 }
 
 // TestBuildInitialStateUpdate verifies the USS update wrapper

backend/internal/pkg/lspool/mock_extension_server.go

@@ -248,6 +248,18 @@ func buildPrimitiveInt32Binary(val int32) []byte {
 	return encodeProtoVarint(3, uint64(uint32(val)))
 }
 
+func encodeUSSBinaryValue(value []byte) string {
+	return base64.StdEncoding.EncodeToString(value)
+}
+
+func encodeUSSPrimitiveBoolValue(val bool) string {
+	return encodeUSSBinaryValue(buildPrimitiveBoolBinary(val))
+}
+
+func encodeUSSPrimitiveInt32Value(val int32) string {
+	return encodeUSSBinaryValue(buildPrimitiveInt32Binary(val))
+}
+
 func buildUSSTopicRow(key string, value string) []byte {
 	row := buildUSSRowBinary(value)
 
@@ -277,7 +289,7 @@ func buildUSSTopicWithModelCredits(info *ModelCreditsInfo) []byte {
 	entries := make([][]byte, 0, 3)
 	entries = append(entries, buildUSSTopicRow(
 		useAICreditsSentinelKey,
-		string(buildPrimitiveBoolBinary(info.UseAICredits)),
+		encodeUSSPrimitiveBoolValue(info.UseAICredits),
 	))
 	// JS protocol: useAICreditsSentinelKey carries the toggle state.
 	// availableCreditsSentinelKey is only present when credits are enabled.
@@ -286,9 +298,9 @@ func buildUSSTopicWithModelCredits(info *ModelCreditsInfo) []byte {
 		if info.AvailableCredits != nil {
 			credits = *info.AvailableCredits
 		}
-		entries = append(entries, buildUSSTopicRow(availableCreditsSentinelKey, string(buildPrimitiveInt32Binary(credits))))
+		entries = append(entries, buildUSSTopicRow(availableCreditsSentinelKey, encodeUSSPrimitiveInt32Value(credits)))
 	}
-	entries = append(entries, buildUSSTopicRow(minimumCreditAmountForUsageKey, string(buildPrimitiveInt32Binary(minimum))))
+	entries = append(entries, buildUSSTopicRow(minimumCreditAmountForUsageKey, encodeUSSPrimitiveInt32Value(minimum)))
 
 	var topic []byte
 	for _, entry := range entries {
@@ -577,7 +589,7 @@ func buildModelCreditsAppliedUpdates(info *ModelCreditsInfo) [][]byte {
 	updates := make([][]byte, 0, 3)
 	updates = append(updates, buildAppliedUpdate(
 		useAICreditsSentinelKey,
-		buildUSSRowBinary(string(buildPrimitiveBoolBinary(info.UseAICredits))),
+		buildUSSRowBinary(encodeUSSPrimitiveBoolValue(info.UseAICredits)),
 	))
 
 	if info.UseAICredits {
@@ -587,14 +599,14 @@ func buildModelCreditsAppliedUpdates(info *ModelCreditsInfo) [][]byte {
 		}
 		updates = append(updates, buildAppliedUpdate(
 			availableCreditsSentinelKey,
-			buildUSSRowBinary(string(buildPrimitiveInt32Binary(credits))),
+			buildUSSRowBinary(encodeUSSPrimitiveInt32Value(credits)),
 		))
 	} else {
 		updates = append(updates, buildAppliedUpdate(availableCreditsSentinelKey, nil))
 	}
 	updates = append(updates, buildAppliedUpdate(
 		minimumCreditAmountForUsageKey,
-		buildUSSRowBinary(string(buildPrimitiveInt32Binary(minimum))),
+		buildUSSRowBinary(encodeUSSPrimitiveInt32Value(minimum)),
 	))
 
 	return updates