fix: address review - add missing whitespace patterns and narrow error matching

Author: alfadb

backend/internal/service/gateway_request.go

@@ -32,6 +32,8 @@ var (
 	// Fast-path patterns for empty text blocks: {"type":"text","text":""}
 	patternEmptyText       = []byte(`"text":""`)
 	patternEmptyTextSpaced = []byte(`"text": ""`)
+	patternEmptyTextSp1    = []byte(`"text" : ""`)
+	patternEmptyTextSp2    = []byte(`"text" :""`)
 )
 
 // SessionContext 粘性会话上下文，用于区分不同来源的请求。
@@ -247,7 +249,9 @@ func FilterThinkingBlocksForRetry(body []byte) []byte {
 	// Check for empty text blocks: {"type":"text","text":""}
 	// These cause upstream 400: "text content blocks must be non-empty"
 	hasEmptyTextBlock := bytes.Contains(body, patternEmptyText) ||
-		bytes.Contains(body, patternEmptyTextSpaced)
+		bytes.Contains(body, patternEmptyTextSpaced) ||
+		bytes.Contains(body, patternEmptyTextSp1) ||
+		bytes.Contains(body, patternEmptyTextSp2)
 
 	// Fast path: nothing to process
 	if !hasThinkingContent && !hasEmptyContent && !hasEmptyTextBlock {

backend/internal/service/gateway_service.go

@@ -6071,7 +6071,7 @@ func (s *GatewayService) isThinkingBlockSignatureError(respBody []byte) bool {
 	// 例如: "all messages must have non-empty content"
 	//       "messages: text content blocks must be non-empty"
 	if strings.Contains(msg, "non-empty content") || strings.Contains(msg, "empty content") ||
-		strings.Contains(msg, "must be non-empty") {
+		strings.Contains(msg, "content blocks must be non-empty") {
 		logger.LegacyPrintf("service.gateway", "[SignatureCheck] Detected empty content error")
 		return true
 	}