fix(channels): make email Stop() wait for checkLoop (lifecycle compliance)

- Add loopWg sync.WaitGroup: Start() calls Add(1) before starting
  checkLoop; checkLoop defers Done(); Stop() calls Wait() after
  cancel so the goroutine fully exits before returning.
- Harden TestEmailChannel_lifecycleCheck to assert Stop() takes at
  least 1s when CheckNewEmails is mocked to sleep 1s,
  [Refactor]: Channel System Refactoring / [Refactor]: Channel系统重构 #621

pkg/channels/email.go

@@ -51,6 +51,9 @@ type EmailChannel struct {
 	cancel      context.CancelFunc
 	checkTicker *time.Ticker
 
+	// loopWg waits for checkLoop goroutine to exit in Stop().
+	loopWg sync.WaitGroup
+
 	// reconnect control
 	reconnectClientVersion int
 	reconnectMutex         sync.Mutex
@@ -88,6 +91,7 @@ func (c *EmailChannel) Start(ctx context.Context) error {
 	c.setRunning(true)
 	logger.InfoC("email", "Email channel started")
 
+	c.loopWg.Add(1)
 	go c.checkLoop(runCtx)
 
 	return nil
@@ -111,6 +115,8 @@ func (c *EmailChannel) Stop(ctx context.Context) error {
 	}
 	c.mu.Unlock()
 
+	c.loopWg.Wait() // wait for checkLoop goroutine to exit
+
 	c.setRunning(false)
 	logger.InfoC("email", "Email channel stopped")
 	return nil
@@ -412,6 +418,7 @@ func (c *EmailChannel) reconnectWithBackoff(ctx context.Context) error {
 }
 
 func (c *EmailChannel) checkLoop(ctx context.Context) {
+	defer c.loopWg.Done()
 	interval := time.Duration(c.config.CheckInterval) * time.Second
 	if interval <= 0 {
 		interval = 30 * time.Second

pkg/channels/email_test.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -360,3 +361,57 @@ func TestEmailChannel_runIdleLoop(t *testing.T) {
 	})
 
 }
+
+func TestEmailChannel_lifecycleCheck(t *testing.T) {
+	// check if the current runtime is go1.25.xx
+	if !strings.HasPrefix(runtime.Version(), "go1.25") {
+		//  github.com/bytedance/mockey v1.4.4 is supported in go1.25.xx
+		t.Skip("skipping test in non-go1.25.xx environment")
+		return
+	}
+
+	mockey.PatchConvey("lifecycle test", t, func() {
+		// --------------- mock start ---------------
+		c := &EmailChannel{
+			BaseChannel: &BaseChannel{
+				bus: bus.NewMessageBus(),
+			},
+			config: config.EmailConfig{
+				Enabled:       true,
+				CheckInterval: 1,
+				ForcedPolling: true,
+				IMAPServer:    "imap.example.com",
+				Username:      "testuser",
+				Password:      "testpassword",
+			},
+		}
+		// mock login and select to return mockClient
+		mockey.Mock(mockey.GetMethod(c, "connect")).To(func(*EmailChannel) error {
+			return nil
+		}).Build()
+		mockey.Mock(mockey.GetMethod(c, "CheckNewEmails")).To(func(*EmailChannel, context.Context) {
+			time.Sleep(1 * time.Second)
+		}).Build()
+		// --------------- mock end ---------------
+		ctx := context.Background()
+		err := c.Start(ctx)
+		assert.NoError(t, err)
+		wg := sync.WaitGroup{}
+		wg.Add(1)
+		var stopDone time.Time
+		stopStart := time.Now()
+		go func() {
+			defer wg.Done()
+			c.Stop(ctx)
+			stopDone = time.Now()
+		}()
+		// wait for checkNewEmails to finish
+		assert.True(t, c.IsRunning())
+		wg.Wait()
+		elapsed := stopDone.Sub(stopStart)
+		// stop exit normally
+		assert.False(t, c.IsRunning())
+		// If Stop() did not wait for checkLoop, it would return in milliseconds.
+		assert.GreaterOrEqual(t, elapsed, 1*time.Second, "Stop() must wait for checkLoop (lifecycle compliance)")
+	})
+}