fix(sse): correct UTF-8 handling and chunking in SSE streaming\n\n- Updated splitContentIntoSegments to handle runes instead of bytes\n- Fixed buildWebUIStreamForwarder to send delta chunks instead of cumulative content\n- Ensures proper handling of multi-byte characters in SSE streams

internal/agent/orchestrator.go

@@ -731,12 +731,16 @@ func (o *Orchestrator) runUnifiedReActStream(ctx context.Context, chatID, userID
 
 		// 推送思考过程事件
 		if completion.Content != "" {
-			if err := callback(StreamEvent{
-				Type:    StreamEventTypeThought,
-				Content: completion.Content,
-				Step:    step,
-			}); err != nil {
-				return "", fmt.Errorf("callback error: %w", err)
+			// 分割内容为逐步推送的片段
+			segments := splitContentIntoSegments(completion.Content, 50) // 每段50字符
+			for _, segment := range segments {
+				if err := callback(StreamEvent{
+					Type:    StreamEventTypeThought,
+					Content: segment,
+					Step:    step,
+				}); err != nil {
+					return "", fmt.Errorf("callback error: %w", err)
+				}
 			}
 		}
 
@@ -1568,3 +1572,17 @@ func sanitizeUserFacingAnswer(raw string) string {
 	}
 	return strings.TrimSpace(strings.Join(cleaned, "\n"))
 }
+
+// splitContentIntoSegments splits a string into smaller segments of the specified size (by rune count).
+func splitContentIntoSegments(content string, segmentSize int) []string {
+	runes := []rune(content)
+	var segments []string
+	for start := 0; start < len(runes); start += segmentSize {
+		end := start + segmentSize
+		if end > len(runes) {
+			end = len(runes)
+		}
+		segments = append(segments, string(runes[start:end]))
+	}
+	return segments
+}