diff --git a/pkg/heartbeat/service.go b/pkg/heartbeat/service.go
index 7c3cd83..33ba313 100644
--- a/pkg/heartbeat/service.go
+++ b/pkg/heartbeat/service.go
@@ -16,28 +16,18 @@ import (
 
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/state"
+	"github.com/sipeed/picoclaw/pkg/tools"
 )
 
 const (
-	minIntervalMinutes    = 5
+	minIntervalMinutes     = 5
 	defaultIntervalMinutes = 30
 	heartbeatOK            = "HEARTBEAT_OK"
 )
 
-// ToolResult represents a structured result from tool execution.
-// This is a minimal local definition to avoid circular dependencies.
-type ToolResult struct {
-	ForLLM  string `json:"for_llm"`
-	ForUser string `json:"for_user,omitempty"`
-	Silent  bool   `json:"silent"`
-	IsError bool   `json:"is_error"`
-	Async   bool   `json:"async"`
-	Err     error  `json:"-"`
-}
-
 // HeartbeatHandler is the function type for handling heartbeat with tool support.
 // It returns a ToolResult that can indicate async operations.
-type HeartbeatHandler func(prompt string) *ToolResult
+type HeartbeatHandler func(prompt string) *tools.ToolResult
 
 // ChannelSender defines the interface for sending messages to channels.
 // This is used to send heartbeat results back to the user.
@@ -213,6 +203,12 @@ func (hs *HeartbeatService) ExecuteHeartbeatWithTools(prompt string) {
 
 // executeHeartbeatWithTools is the internal implementation of tool-supporting heartbeat.
 func (hs *HeartbeatService) executeHeartbeatWithTools(prompt string) {
+	// Check if handler is configured
+	if hs.onHeartbeatWithTools == nil {
+		hs.logError("onHeartbeatWithTools handler not configured")
+		return
+	}
+
 	result := hs.onHeartbeatWithTools(prompt)
 
 	if result == nil {
diff --git a/pkg/heartbeat/service_test.go b/pkg/heartbeat/service_test.go
index 297d2bd..dfd33f0 100644
--- a/pkg/heartbeat/service_test.go
+++ b/pkg/heartbeat/service_test.go
@@ -5,6 +5,8 @@ import (
 	"path/filepath"
 	"testing"
 	"time"
+
+	"github.com/sipeed/picoclaw/pkg/tools"
 )
 
 func TestExecuteHeartbeatWithTools_Async(t *testing.T) {
@@ -23,7 +25,7 @@ func TestExecuteHeartbeatWithTools_Async(t *testing.T) {
 
 	// Track if async handler was called
 	asyncCalled := false
-	asyncResult := &ToolResult{
+	asyncResult := &tools.ToolResult{
 		ForLLM:  "Background task started",
 		ForUser: "Task started in background",
 		Silent:  false,
@@ -31,7 +33,7 @@ func TestExecuteHeartbeatWithTools_Async(t *testing.T) {
 		Async:   true,
 	}
 
-	hs.SetOnHeartbeatWithTools(func(prompt string) *ToolResult {
+	hs.SetOnHeartbeatWithTools(func(prompt string) *tools.ToolResult {
 		asyncCalled = true
 		if prompt == "" {
 			t.Error("Expected non-empty prompt")
@@ -61,7 +63,7 @@ func TestExecuteHeartbeatWithTools_Error(t *testing.T) {
 
 	hs := NewHeartbeatService(tmpDir, nil, 30, true)
 
-	errorResult := &ToolResult{
+	errorResult := &tools.ToolResult{
 		ForLLM:  "Heartbeat failed: connection error",
 		ForUser: "",
 		Silent:  false,
@@ -69,7 +71,7 @@ func TestExecuteHeartbeatWithTools_Error(t *testing.T) {
 		Async:   false,
 	}
 
-	hs.SetOnHeartbeatWithTools(func(prompt string) *ToolResult {
+	hs.SetOnHeartbeatWithTools(func(prompt string) *tools.ToolResult {
 		return errorResult
 	})
 
@@ -101,7 +103,7 @@ func TestExecuteHeartbeatWithTools_Sync(t *testing.T) {
 
 	hs := NewHeartbeatService(tmpDir, nil, 30, true)
 
-	syncResult := &ToolResult{
+	syncResult := &tools.ToolResult{
 		ForLLM:  "Heartbeat completed successfully",
 		ForUser: "",
 		Silent:  true,
@@ -109,7 +111,7 @@ func TestExecuteHeartbeatWithTools_Sync(t *testing.T) {
 		Async:   false,
 	}
 
-	hs.SetOnHeartbeatWithTools(func(prompt string) *ToolResult {
+	hs.SetOnHeartbeatWithTools(func(prompt string) *tools.ToolResult {
 		return syncResult
 	})
 
@@ -185,7 +187,7 @@ func TestExecuteHeartbeatWithTools_NilResult(t *testing.T) {
 
 	hs := NewHeartbeatService(tmpDir, nil, 30, true)
 
-	hs.SetOnHeartbeatWithTools(func(prompt string) *ToolResult {
+	hs.SetOnHeartbeatWithTools(func(prompt string) *tools.ToolResult {
 		return nil
 	})
 
diff --git a/pkg/tools/cron.go b/pkg/tools/cron.go
index 3f2042e..5669271 100644
--- a/pkg/tools/cron.go
+++ b/pkg/tools/cron.go
@@ -122,10 +122,10 @@ func (t *CronTool) Execute(ctx context.Context, args map[string]interface{}) *To
 }
 
 func (t *CronTool) addJob(args map[string]interface{}) *ToolResult {
-	t.mu.RLock()
+	t.mu.Lock()
 	channel := t.channel
 	chatID := t.chatID
-	t.mu.RUnlock()
+	t.mu.Unlock()
 
 	if channel == "" || chatID == "" {
 		return ErrorResult("no session context (channel/chat_id not set). Use this tool in an active conversation.")
diff --git a/pkg/tools/spawn.go b/pkg/tools/spawn.go
index 54919d3..42dd36a 100644
--- a/pkg/tools/spawn.go
+++ b/pkg/tools/spawn.go
@@ -9,6 +9,7 @@ type SpawnTool struct {
 	manager       *SubagentManager
 	originChannel string
 	originChatID  string
+	callback      AsyncCallback // For async completion notification
 }
 
 func NewSpawnTool(manager *SubagentManager) *SpawnTool {
@@ -19,6 +20,11 @@ func NewSpawnTool(manager *SubagentManager) *SpawnTool {
 	}
 }
 
+// SetCallback implements AsyncTool interface for async completion notification
+func (t *SpawnTool) SetCallback(cb AsyncCallback) {
+	t.callback = cb
+}
+
 func (t *SpawnTool) Name() string {
 	return "spawn"
 }
@@ -61,10 +67,12 @@ func (t *SpawnTool) Execute(ctx context.Context, args map[string]interface{}) *T
 		return ErrorResult("Subagent manager not configured")
 	}
 
-	result, err := t.manager.Spawn(ctx, task, label, t.originChannel, t.originChatID)
+	// Pass callback to manager for async completion notification
+	result, err := t.manager.Spawn(ctx, task, label, t.originChannel, t.originChatID, t.callback)
 	if err != nil {
 		return ErrorResult(fmt.Sprintf("failed to spawn subagent: %v", err))
 	}
 
-	return NewToolResult(result)
+	// Return AsyncResult since the task runs in background
+	return AsyncResult(result)
 }
diff --git a/pkg/tools/subagent.go b/pkg/tools/subagent.go
index 2483409..1e398a1 100644
--- a/pkg/tools/subagent.go
+++ b/pkg/tools/subagent.go
@@ -40,7 +40,7 @@ func NewSubagentManager(provider providers.LLMProvider, workspace string, bus *b
 	}
 }
 
-func (sm *SubagentManager) Spawn(ctx context.Context, task, label, originChannel, originChatID string) (string, error) {
+func (sm *SubagentManager) Spawn(ctx context.Context, task, label, originChannel, originChatID string, callback AsyncCallback) (string, error) {
 	sm.mu.Lock()
 	defer sm.mu.Unlock()
 
@@ -58,7 +58,8 @@ func (sm *SubagentManager) Spawn(ctx context.Context, task, label, originChannel
 	}
 	sm.tasks[taskID] = subagentTask
 
-	go sm.runTask(ctx, subagentTask)
+	// Start task in background with context cancellation support
+	go sm.runTask(ctx, subagentTask, callback)
 
 	if label != "" {
 		return fmt.Sprintf("Spawned subagent '%s' for task: %s", label, task), nil
@@ -66,7 +67,7 @@ func (sm *SubagentManager) Spawn(ctx context.Context, task, label, originChannel
 	return fmt.Sprintf("Spawned subagent for task: %s", task), nil
 }
 
-func (sm *SubagentManager) runTask(ctx context.Context, task *SubagentTask) {
+func (sm *SubagentManager) runTask(ctx context.Context, task *SubagentTask, callback AsyncCallback) {
 	task.Status = "running"
 	task.Created = time.Now().UnixMilli()
 
@@ -81,19 +82,57 @@ func (sm *SubagentManager) runTask(ctx context.Context, task *SubagentTask) {
 		},
 	}
 
+	// Check if context is already cancelled before starting
+	select {
+	case <-ctx.Done():
+		sm.mu.Lock()
+		task.Status = "cancelled"
+		task.Result = "Task cancelled before execution"
+		sm.mu.Unlock()
+		return
+	default:
+	}
+
 	response, err := sm.provider.Chat(ctx, messages, nil, sm.provider.GetDefaultModel(), map[string]interface{}{
 		"max_tokens": 4096,
 	})
 
 	sm.mu.Lock()
-	defer sm.mu.Unlock()
+	var result *ToolResult
+	defer func() {
+		sm.mu.Unlock()
+		// Call callback if provided and result is set
+		if callback != nil && result != nil {
+			callback(ctx, result)
+		}
+	}()
 
 	if err != nil {
 		task.Status = "failed"
 		task.Result = fmt.Sprintf("Error: %v", err)
+		// Check if it was cancelled
+		if ctx.Err() != nil {
+			task.Status = "cancelled"
+			task.Result = "Task cancelled during execution"
+		}
+		result = &ToolResult{
+			ForLLM:  task.Result,
+			ForUser: "",
+			Silent:  false,
+			IsError: true,
+			Async:   false,
+			Err:     err,
+		}
 	} else {
 		task.Status = "completed"
 		task.Result = response.Content
+		result = &ToolResult{
+			ForLLM:  fmt.Sprintf("Subagent '%s' completed: %s", task.Label, response.Content),
+			ForUser: response.Content,
+			Silent:  false,
+			IsError: false,
+			Async:   false,
+		}
 	}
 
 	// Send announce message back to main agent