diff --git a/internal/multiagent/eino_adk_run_loop.go b/internal/multiagent/eino_adk_run_loop.go
index ff4f752c..f3ad7dd7 100644
--- a/internal/multiagent/eino_adk_run_loop.go
+++ b/internal/multiagent/eino_adk_run_loop.go
@@ -19,6 +19,40 @@ import (
 	"go.uber.org/zap"
 )
 
+// normalizeStreamingDelta 将可能是“累计片段”的 chunk 归一化为“纯增量”。
+// 一些模型/桥接层在流式过程中会重复发送已输出前缀，前端若直接 buffer+=chunk 会出现“结巴”重复。
+func normalizeStreamingDelta(current, incoming string) (next, delta string) {
+	if incoming == "" {
+		return current, ""
+	}
+	if current == "" {
+		return incoming, incoming
+	}
+	if incoming == current {
+		return current, ""
+	}
+	// incoming 是累计全文（包含 current 前缀）
+	if strings.HasPrefix(incoming, current) {
+		return incoming, incoming[len(current):]
+	}
+	// incoming 完全是已输出尾部重发
+	if strings.HasSuffix(current, incoming) {
+		return current, ""
+	}
+
+	// 处理边界重叠：current 后缀与 incoming 前缀重叠，只追加非重叠部分。
+	max := len(current)
+	if len(incoming) < max {
+		max = len(incoming)
+	}
+	for overlap := max; overlap > 0; overlap-- {
+		if current[len(current)-overlap:] == incoming[:overlap] {
+			return current + incoming[overlap:], incoming[overlap:]
+		}
+	}
+	return current + incoming, incoming
+}
+
 func isEinoIterationLimitError(err error) bool {
 	if err == nil {
 		return false
@@ -430,9 +464,10 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 			streamHeaderSent := false
 			var reasoningStreamID string
 			var toolStreamFragments []schema.ToolCall
-			var subAssistantBuf strings.Builder
+			var subAssistantBuf string
 			var subReplyStreamID string
-			var mainAssistantBuf strings.Builder
+			var mainAssistantBuf string
+			var reasoningBuf string
 			var streamRecvErr error
 			for {
 				chunk, rerr := mv.MessageStream.Recv()
@@ -453,59 +488,69 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 					continue
 				}
 				if progress != nil && strings.TrimSpace(chunk.ReasoningContent) != "" {
-					if reasoningStreamID == "" {
-						reasoningStreamID = fmt.Sprintf("eino-reasoning-%s-%d", conversationID, atomic.AddInt64(&reasoningStreamSeq, 1))
-						progress("thinking_stream_start", " ", map[string]interface{}{
-							"streamId":      reasoningStreamID,
-							"source":        "eino",
-							"einoAgent":     ev.AgentName,
-							"einoRole":      einoRoleTag(ev.AgentName),
-							"orchestration": orchMode,
+					var reasoningDelta string
+					reasoningBuf, reasoningDelta = normalizeStreamingDelta(reasoningBuf, chunk.ReasoningContent)
+					if reasoningDelta != "" {
+						if reasoningStreamID == "" {
+							reasoningStreamID = fmt.Sprintf("eino-reasoning-%s-%d", conversationID, atomic.AddInt64(&reasoningStreamSeq, 1))
+							progress("thinking_stream_start", " ", map[string]interface{}{
+								"streamId":      reasoningStreamID,
+								"source":        "eino",
+								"einoAgent":     ev.AgentName,
+								"einoRole":      einoRoleTag(ev.AgentName),
+								"orchestration": orchMode,
+							})
+						}
+						progress("thinking_stream_delta", reasoningDelta, map[string]interface{}{
+							"streamId": reasoningStreamID,
 						})
 					}
-					progress("thinking_stream_delta", chunk.ReasoningContent, map[string]interface{}{
-						"streamId": reasoningStreamID,
-					})
 				}
 				if chunk.Content != "" {
 					if progress != nil && streamsMainAssistant(ev.AgentName) {
-						if !streamHeaderSent {
-							progress("response_start", "", map[string]interface{}{
-								"conversationId":     conversationID,
-								"mcpExecutionIds":    snapshotMCPIDs(),
-								"messageGeneratedBy": "eino:" + ev.AgentName,
-								"einoRole":           "orchestrator",
-								"einoAgent":          ev.AgentName,
-								"orchestration":      orchMode,
+						var contentDelta string
+						mainAssistantBuf, contentDelta = normalizeStreamingDelta(mainAssistantBuf, chunk.Content)
+						if contentDelta != "" {
+							if !streamHeaderSent {
+								progress("response_start", "", map[string]interface{}{
+									"conversationId":     conversationID,
+									"mcpExecutionIds":    snapshotMCPIDs(),
+									"messageGeneratedBy": "eino:" + ev.AgentName,
+									"einoRole":           "orchestrator",
+									"einoAgent":          ev.AgentName,
+									"orchestration":      orchMode,
+								})
+								streamHeaderSent = true
+							}
+							progress("response_delta", contentDelta, map[string]interface{}{
+								"conversationId":  conversationID,
+								"mcpExecutionIds": snapshotMCPIDs(),
+								"einoRole":        "orchestrator",
+								"einoAgent":       ev.AgentName,
+								"orchestration":   orchMode,
 							})
-							streamHeaderSent = true
 						}
-						progress("response_delta", chunk.Content, map[string]interface{}{
-							"conversationId":  conversationID,
-							"mcpExecutionIds": snapshotMCPIDs(),
-							"einoRole":        "orchestrator",
-							"einoAgent":       ev.AgentName,
-							"orchestration":   orchMode,
-						})
-						mainAssistantBuf.WriteString(chunk.Content)
 					} else if !streamsMainAssistant(ev.AgentName) {
-						if progress != nil {
-							if subReplyStreamID == "" {
-								subReplyStreamID = fmt.Sprintf("eino-sub-reply-%s-%d", conversationID, atomic.AddInt64(&einoSubReplyStreamSeq, 1))
-								progress("eino_agent_reply_stream_start", "", map[string]interface{}{
+						var subDelta string
+						subAssistantBuf, subDelta = normalizeStreamingDelta(subAssistantBuf, chunk.Content)
+						if subDelta != "" {
+							if progress != nil {
+								if subReplyStreamID == "" {
+									subReplyStreamID = fmt.Sprintf("eino-sub-reply-%s-%d", conversationID, atomic.AddInt64(&einoSubReplyStreamSeq, 1))
+									progress("eino_agent_reply_stream_start", "", map[string]interface{}{
+										"streamId":       subReplyStreamID,
+										"einoAgent":      ev.AgentName,
+										"einoRole":       "sub",
+										"conversationId": conversationID,
+										"source":         "eino",
+									})
+								}
+								progress("eino_agent_reply_stream_delta", subDelta, map[string]interface{}{
 									"streamId":       subReplyStreamID,
-									"einoAgent":      ev.AgentName,
-									"einoRole":       "sub",
 									"conversationId": conversationID,
-									"source":         "eino",
 								})
 							}
-							progress("eino_agent_reply_stream_delta", chunk.Content, map[string]interface{}{
-								"streamId":       subReplyStreamID,
-								"conversationId": conversationID,
-							})
 						}
-						subAssistantBuf.WriteString(chunk.Content)
 					}
 				}
 				if len(chunk.ToolCalls) > 0 {
@@ -513,7 +558,7 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 				}
 			}
 			if streamsMainAssistant(ev.AgentName) {
-				if s := strings.TrimSpace(mainAssistantBuf.String()); s != "" {
+				if s := strings.TrimSpace(mainAssistantBuf); s != "" {
 					lastAssistant = s
 					runAccumulatedMsgs = append(runAccumulatedMsgs, schema.AssistantMessage(s, nil))
 					if orchMode == "plan_execute" && strings.EqualFold(strings.TrimSpace(ev.AgentName), "executor") {
@@ -521,8 +566,8 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 					}
 				}
 			}
-			if subAssistantBuf.Len() > 0 && progress != nil {
-				if s := strings.TrimSpace(subAssistantBuf.String()); s != "" {
+			if strings.TrimSpace(subAssistantBuf) != "" && progress != nil {
+				if s := strings.TrimSpace(subAssistantBuf); s != "" {
 					if subReplyStreamID != "" {
 						progress("eino_agent_reply_stream_end", s, map[string]interface{}{
 							"streamId":       subReplyStreamID,