diff --git a/backend/internal/domain/constants.go b/backend/internal/domain/constants.go
index 9920a76b..36d043b5 100644
--- a/backend/internal/domain/constants.go
+++ b/backend/internal/domain/constants.go
@@ -27,10 +27,10 @@ const (
 
 // Account type constants
 const (
-	AccountTypeOAuth      = "oauth"       // OAuth类型账号（full scope: profile + inference）
-	AccountTypeSetupToken = "setup-token" // Setup Token类型账号（inference only scope）
-	AccountTypeAPIKey     = "apikey"      // API Key类型账号
-	AccountTypeUpstream   = "upstream"    // 上游透传类型账号（通过 Base URL + API Key 连接上游）
+	AccountTypeOAuth         = "oauth"          // OAuth类型账号（full scope: profile + inference）
+	AccountTypeSetupToken    = "setup-token"    // Setup Token类型账号（inference only scope）
+	AccountTypeAPIKey        = "apikey"         // API Key类型账号
+	AccountTypeUpstream      = "upstream"       // 上游透传类型账号（通过 Base URL + API Key 连接上游）
 	AccountTypeBedrock       = "bedrock"        // AWS Bedrock 类型账号（通过 SigV4 签名连接 Bedrock）
 	AccountTypeBedrockAPIKey = "bedrock-apikey" // AWS Bedrock API Key 类型账号（通过 Bearer Token 连接 Bedrock）
 )
diff --git a/backend/internal/service/bedrock_stream.go b/backend/internal/service/bedrock_stream.go
index 30c1011b..98196d27 100644
--- a/backend/internal/service/bedrock_stream.go
+++ b/backend/internal/service/bedrock_stream.go
@@ -282,8 +282,8 @@ func (d *bedrockEventStreamDecoder) Decode() ([]byte, error) {
 		// 验证 message CRC（覆盖 prelude + headers + payload）
 		messageCRC := bedrockReadUint32(data[len(data)-4:])
 		h := crc32.New(crc32IEEETable)
-		h.Write(prelude)
-		h.Write(data[:len(data)-4])
+		_, _ = h.Write(prelude)
+		_, _ = h.Write(data[:len(data)-4])
 		if h.Sum32() != messageCRC {
 			return nil, fmt.Errorf("eventstream message CRC mismatch")
 		}
diff --git a/backend/internal/service/bedrock_stream_test.go b/backend/internal/service/bedrock_stream_test.go
index 500b9292..3d066137 100644
--- a/backend/internal/service/bedrock_stream_test.go
+++ b/backend/internal/service/bedrock_stream_test.go
@@ -76,15 +76,15 @@ func TestExtractEventStreamHeaderValue(t *testing.T) {
 	buildStringHeader := func(name, value string) []byte {
 		var buf bytes.Buffer
 		// name length (1 byte)
-		buf.WriteByte(byte(len(name)))
+		_ = buf.WriteByte(byte(len(name)))
 		// name
-		buf.WriteString(name)
+		_, _ = buf.WriteString(name)
 		// value type (7 = string)
-		buf.WriteByte(7)
+		_ = buf.WriteByte(7)
 		// value length (2 bytes, big-endian)
 		_ = binary.Write(&buf, binary.BigEndian, uint16(len(value)))
 		// value
-		buf.WriteString(value)
+		_, _ = buf.WriteString(value)
 		return buf.Bytes()
 	}
 
@@ -100,9 +100,9 @@ func TestExtractEventStreamHeaderValue(t *testing.T) {
 
 	t.Run("multiple headers", func(t *testing.T) {
 		var buf bytes.Buffer
-		buf.Write(buildStringHeader(":content-type", "application/json"))
-		buf.Write(buildStringHeader(":event-type", "chunk"))
-		buf.Write(buildStringHeader(":message-type", "event"))
+		_, _ = buf.Write(buildStringHeader(":content-type", "application/json"))
+		_, _ = buf.Write(buildStringHeader(":event-type", "chunk"))
+		_, _ = buf.Write(buildStringHeader(":message-type", "event"))
 
 		headers := buf.Bytes()
 		assert.Equal(t, "chunk", extractEventStreamHeaderValue(headers, ":event-type"))
@@ -123,17 +123,17 @@ func TestBedrockEventStreamDecoder(t *testing.T) {
 		// Build headers
 		var headersBuf bytes.Buffer
 		// :event-type header
-		headersBuf.WriteByte(byte(len(":event-type")))
-		headersBuf.WriteString(":event-type")
-		headersBuf.WriteByte(7) // string type
+		_ = headersBuf.WriteByte(byte(len(":event-type")))
+		_, _ = headersBuf.WriteString(":event-type")
+		_ = headersBuf.WriteByte(7) // string type
 		_ = binary.Write(&headersBuf, binary.BigEndian, uint16(len(eventType)))
-		headersBuf.WriteString(eventType)
+		_, _ = headersBuf.WriteString(eventType)
 		// :message-type header
-		headersBuf.WriteByte(byte(len(":message-type")))
-		headersBuf.WriteString(":message-type")
-		headersBuf.WriteByte(7)
+		_ = headersBuf.WriteByte(byte(len(":message-type")))
+		_, _ = headersBuf.WriteString(":message-type")
+		_ = headersBuf.WriteByte(7)
 		_ = binary.Write(&headersBuf, binary.BigEndian, uint16(len("event")))
-		headersBuf.WriteString("event")
+		_, _ = headersBuf.WriteString("event")
 
 		headers := headersBuf.Bytes()
 		headersLen := uint32(len(headers))
@@ -149,10 +149,10 @@ func TestBedrockEventStreamDecoder(t *testing.T) {
 
 		// Build frame: prelude + prelude_crc + headers + payload
 		var frame bytes.Buffer
-		frame.Write(preludeBytes)
+		_, _ = frame.Write(preludeBytes)
 		_ = binary.Write(&frame, binary.BigEndian, preludeCRC)
-		frame.Write(headers)
-		frame.Write(payload)
+		_, _ = frame.Write(headers)
+		_, _ = frame.Write(payload)
 
 		// Message CRC covers everything before itself
 		messageCRC := crc32.Checksum(frame.Bytes(), crc32IeeeTab)
@@ -173,9 +173,9 @@ func TestBedrockEventStreamDecoder(t *testing.T) {
 	t.Run("skip non-chunk events", func(t *testing.T) {
 		// Write initial-response followed by chunk
 		var buf bytes.Buffer
-		buf.Write(buildFrame("initial-response", []byte(`{}`)))
+		_, _ = buf.Write(buildFrame("initial-response", []byte(`{}`)))
 		chunkPayload := []byte(`{"bytes":"aGVsbG8="}`)
-		buf.Write(buildFrame("chunk", chunkPayload))
+		_, _ = buf.Write(buildFrame("chunk", chunkPayload))
 
 		decoder := newBedrockEventStreamDecoder(&buf)
 		result, err := decoder.Decode()
@@ -214,11 +214,11 @@ func TestBedrockEventStreamDecoder(t *testing.T) {
 		payload := []byte(`{"bytes":"dGVzdA=="}`)
 
 		var headersBuf bytes.Buffer
-		headersBuf.WriteByte(byte(len(":event-type")))
-		headersBuf.WriteString(":event-type")
-		headersBuf.WriteByte(7)
+		_ = headersBuf.WriteByte(byte(len(":event-type")))
+		_, _ = headersBuf.WriteString(":event-type")
+		_ = headersBuf.WriteByte(7)
 		_ = binary.Write(&headersBuf, binary.BigEndian, uint16(len("chunk")))
-		headersBuf.WriteString("chunk")
+		_, _ = headersBuf.WriteString("chunk")
 
 		headers := headersBuf.Bytes()
 		headersLen := uint32(len(headers))
@@ -230,10 +230,10 @@ func TestBedrockEventStreamDecoder(t *testing.T) {
 		preludeBytes := preludeBuf.Bytes()
 
 		var frame bytes.Buffer
-		frame.Write(preludeBytes)
+		_, _ = frame.Write(preludeBytes)
 		_ = binary.Write(&frame, binary.BigEndian, crc32.Checksum(preludeBytes, castagnoliTab))
-		frame.Write(headers)
-		frame.Write(payload)
+		_, _ = frame.Write(headers)
+		_, _ = frame.Write(payload)
 		_ = binary.Write(&frame, binary.BigEndian, crc32.Checksum(frame.Bytes(), castagnoliTab))
 
 		decoder := newBedrockEventStreamDecoder(bytes.NewReader(frame.Bytes()))
diff --git a/backend/internal/service/domain_constants.go b/backend/internal/service/domain_constants.go
index 26905fb9..ad64b467 100644
--- a/backend/internal/service/domain_constants.go
+++ b/backend/internal/service/domain_constants.go
@@ -29,10 +29,10 @@ const (
 
 // Account type constants
 const (
-	AccountTypeOAuth      = domain.AccountTypeOAuth      // OAuth类型账号（full scope: profile + inference）
-	AccountTypeSetupToken = domain.AccountTypeSetupToken // Setup Token类型账号（inference only scope）
-	AccountTypeAPIKey     = domain.AccountTypeAPIKey     // API Key类型账号
-	AccountTypeUpstream   = domain.AccountTypeUpstream   // 上游透传类型账号（通过 Base URL + API Key 连接上游）
+	AccountTypeOAuth         = domain.AccountTypeOAuth         // OAuth类型账号（full scope: profile + inference）
+	AccountTypeSetupToken    = domain.AccountTypeSetupToken    // Setup Token类型账号（inference only scope）
+	AccountTypeAPIKey        = domain.AccountTypeAPIKey        // API Key类型账号
+	AccountTypeUpstream      = domain.AccountTypeUpstream      // 上游透传类型账号（通过 Base URL + API Key 连接上游）
 	AccountTypeBedrock       = domain.AccountTypeBedrock       // AWS Bedrock 类型账号（通过 SigV4 签名连接 Bedrock）
 	AccountTypeBedrockAPIKey = domain.AccountTypeBedrockAPIKey // AWS Bedrock API Key 类型账号（通过 Bearer Token 连接 Bedrock）
 )
diff --git a/backend/internal/service/gateway_service.go b/backend/internal/service/gateway_service.go
index 978ec98f..ce1c746c 100644
--- a/backend/internal/service/gateway_service.go
+++ b/backend/internal/service/gateway_service.go
@@ -5853,25 +5853,6 @@ func containsBetaToken(header, token string) bool {
 	return false
 }
 
-// filterBetaTokensFromHeader removes tokens present in filterSet from a comma-separated header value.
-// Returns the filtered header string, or "" if all tokens were removed.
-func filterBetaTokensFromHeader(header string, filterSet map[string]struct{}) string {
-	if header == "" || len(filterSet) == 0 {
-		return header
-	}
-	var kept []string
-	for _, p := range strings.Split(header, ",") {
-		t := strings.TrimSpace(p)
-		if t == "" {
-			continue
-		}
-		if _, filtered := filterSet[t]; !filtered {
-			kept = append(kept, t)
-		}
-	}
-	return strings.Join(kept, ", ")
-}
-
 func filterBetaTokens(tokens []string, filterSet map[string]struct{}) []string {
 	if len(tokens) == 0 || len(filterSet) == 0 {
 		return tokens