diff --git a/internal/multiagent/eino_adk_run_loop.go b/internal/multiagent/eino_adk_run_loop.go
index 4f34c904..6f6629a1 100644
--- a/internal/multiagent/eino_adk_run_loop.go
+++ b/internal/multiagent/eino_adk_run_loop.go
@@ -345,7 +345,9 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 	}
 
 	runnerCfg := adk.RunnerConfig{
-		Agent:           da,
+		Agent: da,
+		// 启用 ADK 流式事件：plan_execute 也需要输出 reasoning/response 流，
+		// 与 deep/supervisor/eino_single 的前端体验保持一致。
 		EnableStreaming: true,
 	}
 	var cpStore *fileCheckPointStore
diff --git a/internal/multiagent/eino_orchestration.go b/internal/multiagent/eino_orchestration.go
index 6b2dc3d0..8461225f 100644
--- a/internal/multiagent/eino_orchestration.go
+++ b/internal/multiagent/eino_orchestration.go
@@ -148,14 +148,12 @@ func planExecutePlannerGenInput(
 	}
 	return func(ctx context.Context, userInput []adk.Message) ([]adk.Message, error) {
 		userInput = capPlanExecuteUserInputMessages(userInput, appCfg, mwCfg)
-		msgs := make([]adk.Message, 0, 1+len(userInput))
-		if oi != "" {
-			msgs = append(msgs, schema.SystemMessage(oi))
-		}
+		msgs := make([]adk.Message, 0, len(userInput))
 		msgs = append(msgs, userInput...)
 		if rewritten, rerr := applyBeforeModelRewriteHandlers(ctx, msgs, rewriteHandlers); rerr == nil && len(rewritten) > 0 {
 			msgs = rewritten
 		}
+		msgs = normalizeSingleLeadingSystemMessage(msgs, oi)
 		logPlanExecuteModelInputEstimate(logger, modelName, conversationID, "plan_execute_planner", msgs)
 		return msgs, nil
 	}
@@ -184,9 +182,7 @@ func planExecuteExecutorGenInput(
 		if err != nil {
 			return nil, err
 		}
-		if oi != "" {
-			userMsgs = append([]adk.Message{schema.SystemMessage(oi)}, userMsgs...)
-		}
+		userMsgs = normalizeSingleLeadingSystemMessage(userMsgs, oi)
 		logPlanExecuteModelInputEstimate(logger, modelName, conversationID, "plan_execute_executor_gen_input", userMsgs)
 		return userMsgs, nil
 	}
@@ -233,17 +229,54 @@ func planExecuteReplannerGenInput(
 		if err != nil {
 			return nil, err
 		}
-		if oi != "" {
-			msgs = append([]adk.Message{schema.SystemMessage(oi)}, msgs...)
-		}
 		if rewritten, rerr := applyBeforeModelRewriteHandlers(ctx, msgs, rewriteHandlers); rerr == nil && len(rewritten) > 0 {
 			msgs = rewritten
 		}
+		msgs = normalizeSingleLeadingSystemMessage(msgs, oi)
 		logPlanExecuteModelInputEstimate(logger, modelName, conversationID, "plan_execute_replanner", msgs)
 		return msgs, nil
 	}
 }
 
+// normalizeSingleLeadingSystemMessage enforces a provider-friendly message shape:
+// exactly one system message at index 0 (when any system context exists).
+// For strict OpenAI-compatible backends (e.g. qwen/vllm templates), this avoids
+// "System message must be at the beginning" caused by multiple/disordered system messages.
+func normalizeSingleLeadingSystemMessage(msgs []adk.Message, extraSystem string) []adk.Message {
+	extraSystem = strings.TrimSpace(extraSystem)
+	if len(msgs) == 0 {
+		if extraSystem == "" {
+			return msgs
+		}
+		return []adk.Message{schema.SystemMessage(extraSystem)}
+	}
+
+	systemParts := make([]string, 0, 2)
+	if extraSystem != "" {
+		systemParts = append(systemParts, extraSystem)
+	}
+	nonSystem := make([]adk.Message, 0, len(msgs))
+	for _, msg := range msgs {
+		if msg == nil {
+			continue
+		}
+		if msg.Role == schema.System {
+			if s := strings.TrimSpace(msg.Content); s != "" {
+				systemParts = append(systemParts, s)
+			}
+			continue
+		}
+		nonSystem = append(nonSystem, msg)
+	}
+	if len(systemParts) == 0 {
+		return nonSystem
+	}
+	out := make([]adk.Message, 0, len(nonSystem)+1)
+	out = append(out, schema.SystemMessage(strings.Join(systemParts, "\n\n")))
+	out = append(out, nonSystem...)
+	return out
+}
+
 func capPlanExecuteUserInputMessages(input []adk.Message, appCfg *config.Config, mwCfg *config.MultiAgentEinoMiddlewareConfig) []adk.Message {
 	if len(input) == 0 {
 		return input
diff --git a/internal/multiagent/eino_orchestration_system_message_test.go b/internal/multiagent/eino_orchestration_system_message_test.go
new file mode 100644
index 00000000..2cb32cfc
--- /dev/null
+++ b/internal/multiagent/eino_orchestration_system_message_test.go
@@ -0,0 +1,45 @@
+package multiagent
+
+import (
+	"testing"
+
+	"github.com/cloudwego/eino/adk"
+	"github.com/cloudwego/eino/schema"
+)
+
+func TestNormalizeSingleLeadingSystemMessage_MergesMultipleSystems(t *testing.T) {
+	in := []adk.Message{
+		schema.SystemMessage("sys-1"),
+		schema.UserMessage("u1"),
+		schema.SystemMessage("sys-2"),
+		schema.AssistantMessage("a1", nil),
+	}
+	out := normalizeSingleLeadingSystemMessage(in, "orch")
+	if len(out) != 3 {
+		t.Fatalf("unexpected output length: got %d want 3", len(out))
+	}
+	if out[0].Role != schema.System {
+		t.Fatalf("first message role must be system, got %s", out[0].Role)
+	}
+	if got := out[0].Content; got != "orch\n\nsys-1\n\nsys-2" {
+		t.Fatalf("unexpected merged system content: %q", got)
+	}
+	if out[1].Role != schema.User || out[2].Role != schema.Assistant {
+		t.Fatalf("non-system message order changed unexpectedly")
+	}
+}
+
+func TestNormalizeSingleLeadingSystemMessage_NoSystemKeepsFlow(t *testing.T) {
+	in := []adk.Message{
+		schema.UserMessage("u1"),
+		schema.AssistantMessage("a1", nil),
+	}
+	out := normalizeSingleLeadingSystemMessage(in, "")
+	if len(out) != 2 {
+		t.Fatalf("unexpected output length: got %d want 2", len(out))
+	}
+	if out[0].Role != schema.User || out[1].Role != schema.Assistant {
+		t.Fatalf("message order changed unexpectedly")
+	}
+}
+
diff --git a/internal/multiagent/eino_transient_retry.go b/internal/multiagent/eino_transient_retry.go
index 895f062b..ca7b214c 100644
--- a/internal/multiagent/eino_transient_retry.go
+++ b/internal/multiagent/eino_transient_retry.go
@@ -3,6 +3,7 @@ package multiagent
 import (
 	"context"
 	"errors"
+	"io"
 	"strings"
 	"time"
 
@@ -23,6 +24,10 @@ func isEinoTransientRunError(err error) bool {
 	if err == nil {
 		return false
 	}
+	// io.EOF 常见于流式正常收尾，不应触发分段重试。
+	if errors.Is(err, io.EOF) {
+		return false
+	}
 	if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
 		return false
 	}
@@ -55,7 +60,6 @@ func isEinoTransientRunError(err error) bool {
 		"no such host",
 		"network is unreachable",
 		"broken pipe",
-		"eof",
 		"read tcp",
 		"write tcp",
 		"dial tcp",
diff --git a/internal/multiagent/eino_transient_retry_test.go b/internal/multiagent/eino_transient_retry_test.go
index 80107501..7ba15afd 100644
--- a/internal/multiagent/eino_transient_retry_test.go
+++ b/internal/multiagent/eino_transient_retry_test.go
@@ -3,6 +3,7 @@ package multiagent
 import (
 	"context"
 	"errors"
+	"io"
 	"testing"
 	"time"
 
@@ -18,9 +19,12 @@ func TestIsEinoTransientRunError(t *testing.T) {
 		want bool
 	}{
 		{"nil", nil, false},
+		{"io eof", io.EOF, false},
+		{"plain eof text", errors.New("EOF"), false},
 		{"429", errors.New("HTTP 429 Too Many Requests"), true},
 		{"rate limit", errors.New(`{"error":"rate limit exceeded"}`), true},
 		{"connection reset", errors.New("read tcp: connection reset by peer"), true},
+		{"unexpected eof", errors.New("unexpected EOF"), true},
 		{"503", errors.New("upstream returned 503"), true},
 		{"iteration limit", errors.New("max iteration reached"), false},
 		{"canceled", context.Canceled, false},