diff --git a/internal/multiagent/eino_adk_run_loop.go b/internal/multiagent/eino_adk_run_loop.go
index 44d15b10..825f3c95 100644
--- a/internal/multiagent/eino_adk_run_loop.go
+++ b/internal/multiagent/eino_adk_run_loop.go
@@ -8,6 +8,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -315,10 +316,12 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 		if len(preview) > 200 {
 			preview = preview[:200] + "..."
 		}
+		backgroundRunning := isErr && isMCPBackgroundWaitResult(content)
+		displayIsErr := isErr && !backgroundRunning
 		data := map[string]interface{}{
 			"toolName":       toolName,
-			"success":        !isErr,
-			"isError":        isErr,
+			"success":        !displayIsErr,
+			"isError":        displayIsErr,
 			"result":         content,
 			"resultPreview":  preview,
 			"agentFacing":    true, // 与 reduction 后送入 ChatModel 的正文一致，供前端展示
@@ -327,6 +330,13 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 			"einoRole":       einoRoleTag(agentName),
 			"source":         "eino",
 		}
+		if backgroundRunning {
+			data["status"] = "background_running"
+			data["modelFacingIsError"] = isErr
+			if execID := mcpExecutionIDFromWaitResult(content); execID != "" {
+				data["executionId"] = execID
+			}
+		}
 		tid := strings.TrimSpace(toolCallID)
 		if tid == "" {
 			if inferred, ok := popNextPendingForAgent(agentName); ok {
@@ -347,8 +357,8 @@ func runEinoADKAgentLoop(ctx context.Context, args *einoADKRunLoopArgs, baseMsgs
 			data["toolCallId"] = tid
 			toolCallID = tid
 		}
-		recordPendingExecuteStdoutDup(toolName, content, isErr)
-		recordEinoADKFilesystemToolMonitor(ctx, args.FilesystemMonitorAgent, args.FilesystemMonitorRecord, args.MCPExecutionBinder, toolName, toolCallID, runAccumulatedMsgs, content, isErr)
+		recordPendingExecuteStdoutDup(toolName, content, displayIsErr)
+		recordEinoADKFilesystemToolMonitor(ctx, args.FilesystemMonitorAgent, args.FilesystemMonitorRecord, args.MCPExecutionBinder, toolName, toolCallID, runAccumulatedMsgs, content, displayIsErr)
 		if args.FilesystemMonitorAgent != nil && args.MCPExecutionBinder != nil {
 			if execID := args.MCPExecutionBinder.ExecutionID(toolCallID); execID != "" {
 				args.FilesystemMonitorAgent.UpdateMCPExecutionDisplayResult(execID, content)
@@ -1242,6 +1252,40 @@ func einoToolResultIsError(toolName, content string) bool {
 	return false
 }
 
+func isMCPBackgroundWaitResult(content string) bool {
+	text := strings.ToLower(strings.TrimSpace(content))
+	if text == "" {
+		return false
+	}
+	hasExecutionID := strings.Contains(text, "execution_id:") || strings.Contains(text, `"execution_id"`)
+	hasRunningStatus := strings.Contains(text, "status: running") || strings.Contains(text, "status: queued") ||
+		strings.Contains(text, `"status": "running"`) || strings.Contains(text, `"status":"running"`) ||
+		strings.Contains(text, `"status": "queued"`) || strings.Contains(text, `"status":"queued"`)
+	hasSoftWaitSignal := strings.Contains(text, "工具已提交到后台执行") ||
+		strings.Contains(text, "本次等待已到达") ||
+		strings.Contains(text, "wait_timeout:") ||
+		strings.Contains(text, "background execution") ||
+		strings.Contains(text, "still running") ||
+		strings.Contains(text, "仍未完成")
+	return hasExecutionID && hasRunningStatus && hasSoftWaitSignal
+}
+
+func mcpExecutionIDFromWaitResult(content string) string {
+	re := regexp.MustCompile(`(?i)"?execution_id"?\s*[:=]\s*"?([0-9a-f]{8}-[0-9a-f-]{12,})"?`)
+	if m := re.FindStringSubmatch(content); len(m) > 1 {
+		return strings.TrimSpace(m[1])
+	}
+	for _, line := range strings.Split(content, "\n") {
+		line = strings.TrimSpace(line)
+		lower := strings.ToLower(line)
+		if !strings.HasPrefix(lower, "execution_id:") {
+			continue
+		}
+		return strings.Trim(strings.TrimSpace(line[len("execution_id:"):]), `"'`)
+	}
+	return ""
+}
+
 // einoToolResultBody 去掉工具错误前缀，返回展示/持久化正文。
 func einoToolResultBody(content string) string {
 	if strings.HasPrefix(content, einomcp.ToolErrorPrefix) {
diff --git a/internal/multiagent/eino_execute_failure_format_test.go b/internal/multiagent/eino_execute_failure_format_test.go
index c83e2853..5b831d81 100644
--- a/internal/multiagent/eino_execute_failure_format_test.go
+++ b/internal/multiagent/eino_execute_failure_format_test.go
@@ -112,3 +112,41 @@ func TestFriendlyEinoExecuteInvokeTail(t *testing.T) {
 		t.Fatal("unexpected error should get tail")
 	}
 }
+
+func TestMCPBackgroundWaitResultIsDisplayRunning(t *testing.T) {
+	body := `工具已提交到后台执行，但本次等待已到达上限。
+
+execution_id: 3eaaa391-050b-4be1-a870-48a855923cb7
+tool: exec
+status: running
+wait_timeout: 10s
+elapsed: 10s
+
+你可以继续推理、改用其他工具，或调用 wait_tool_execution 继续等待该 execution_id；也可以调用 cancel_tool_execution 取消。`
+	modelFacing := einomcp.ToolErrorPrefix + body
+	if !einoToolResultIsError("exec", modelFacing) {
+		t.Fatal("soft wait timeout must remain model-facing tool error")
+	}
+	if !isMCPBackgroundWaitResult(einoToolResultBody(modelFacing)) {
+		t.Fatal("soft wait timeout should display as background running")
+	}
+	if got := mcpExecutionIDFromWaitResult(einoToolResultBody(modelFacing)); got != "3eaaa391-050b-4be1-a870-48a855923cb7" {
+		t.Fatalf("execution id = %q", got)
+	}
+	if isMCPBackgroundWaitResult("execution_id: abc\nstatus: failed\nerror: boom") {
+		t.Fatal("real failures must not display as background running")
+	}
+	jsonBody := `{
+  "execution_id": "e98baefc-72eb-4a7e-9091-9be179a75d71",
+  "tool": "exec",
+  "status": "running"
+}
+
+本次等待已到达 timeout_seconds，上述 execution 仍未完成。可继续等待、取消，或采用其他步骤。`
+	if !isMCPBackgroundWaitResult(jsonBody) {
+		t.Fatal("json wait_tool_execution timeout should display as background running")
+	}
+	if got := mcpExecutionIDFromWaitResult(jsonBody); got != "e98baefc-72eb-4a7e-9091-9be179a75d71" {
+		t.Fatalf("json execution id = %q", got)
+	}
+}
diff --git a/internal/multiagent/runner.go b/internal/multiagent/runner.go
index 7020ac78..5e328d08 100644
--- a/internal/multiagent/runner.go
+++ b/internal/multiagent/runner.go
@@ -715,7 +715,7 @@ func historyToMessages(history []agent.ChatMessage, appCfg *config.Config, mwCfg
 				opts = append(opts, schema.WithToolName(tn))
 			}
 			content := h.Content
-			if !h.ModelFacingTrace {
+			if !h.ModelFacingTrace || (toolContentMax > 0 && len(content) > toolContentMax) {
 				content = normalizeRestoredToolContent(content, toolContentMax)
 			}
 			raw = append(raw, schema.ToolMessage(content, h.ToolCallID, opts...))
diff --git a/internal/multiagent/runner_reasoning_history_test.go b/internal/multiagent/runner_reasoning_history_test.go
index 792582ef..6dc3f0ca 100644
--- a/internal/multiagent/runner_reasoning_history_test.go
+++ b/internal/multiagent/runner_reasoning_history_test.go
@@ -44,7 +44,7 @@ func TestHistoryToMessagesNormalizesLegacyRawToolOutput(t *testing.T) {
 
 func TestHistoryToMessagesRestoresModelFacingTraceByteForByte(t *testing.T) {
 	mw := &config.MultiAgentEinoMiddlewareConfig{
-		ReductionMaxLengthForTrunc: 128,
+		ReductionMaxLengthForTrunc: 4096,
 		LatestUserMessageMaxRunes:  64,
 	}
 	userContent := strings.Repeat("model-facing-user-", 100)
@@ -66,6 +66,24 @@ func TestHistoryToMessagesRestoresModelFacingTraceByteForByte(t *testing.T) {
 	}
 }
 
+func TestHistoryToMessagesCapsOversizedModelFacingToolTrace(t *testing.T) {
+	mw := &config.MultiAgentEinoMiddlewareConfig{ReductionMaxLengthForTrunc: 128}
+	h := []agent.ChatMessage{
+		{Role: "assistant", ModelFacingTrace: true, ToolCalls: []agent.ToolCall{{ID: "t1", Type: "function", Function: agent.FunctionCall{Name: "exec"}}}},
+		{Role: "tool", ToolCallID: "t1", ToolName: "exec", Content: strings.Repeat("model-facing-tool-", 1000), ModelFacingTrace: true},
+	}
+	msgs := historyToMessages(h, nil, mw)
+	if len(msgs) != 2 {
+		t.Fatalf("len=%d", len(msgs))
+	}
+	if len(msgs[1].Content) > 128 {
+		t.Fatalf("restored model-facing tool bytes=%d, want <=128", len(msgs[1].Content))
+	}
+	if !strings.Contains(msgs[1].Content, "legacy tool output discarded") {
+		t.Fatalf("missing cap marker: %q", msgs[1].Content)
+	}
+}
+
 func TestHistoryToMessagesNeverReinjectsRawOversizedUserFallback(t *testing.T) {
 	appCfg := &config.Config{OpenAI: config.OpenAIConfig{MaxTotalTokens: 10000}}
 	mw := &config.MultiAgentEinoMiddlewareConfig{LatestUserMessageMaxRunes: 8000}