fix(whatsapp_native,agent): fixes for resource leak and log noise

- WhatsApp Start(): use deferred cleanup to nil out c.client/c.container
  and disconnect/close resources on any error after struct fields are
  assigned, preventing stale references and double-close in Stop()
- handleReasoning: treat bus.ErrBusClosed as an expected condition
  (DEBUG level) alongside context timeout/cancel, avoiding WARN noise
  during normal shutdown

pkg/channels/whatsapp_native/whatsapp_native.go

@@ -83,6 +83,14 @@ func NewWhatsAppNativeChannel(
 func (c *WhatsAppNativeChannel) Start(ctx context.Context) error {
 	logger.InfoCF("whatsapp", "Starting WhatsApp native channel (whatsmeow)", map[string]any{"store": c.storePath})
 
+	// Reset lifecycle state from any previous Stop() so a restarted channel
+	// behaves correctly.  Use reconnectMu to be consistent with eventHandler
+	// and Stop() which coordinate under the same lock.
+	c.reconnectMu.Lock()
+	c.stopping.Store(false)
+	c.reconnecting = false
+	c.reconnectMu.Unlock()
+
 	if err := os.MkdirAll(c.storePath, 0o700); err != nil {
 		return fmt.Errorf("create session store dir: %w", err)
 	}
@@ -128,22 +136,45 @@ func (c *WhatsAppNativeChannel) Start(ctx context.Context) error {
 	c.client = client
 	c.mu.Unlock()
 
+	// cleanupOnError clears struct references and releases resources when
+	// Start() fails after fields are already assigned.  This prevents
+	// Stop() from operating on stale references (double-close, disconnect
+	// of a partially-initialized client, or stray event handler callbacks).
+	startOK := false
+	defer func() {
+		if startOK {
+			return
+		}
+		c.runCancel()
+		client.Disconnect()
+		c.mu.Lock()
+		c.client = nil
+		c.container = nil
+		c.mu.Unlock()
+		_ = container.Close()
+	}()
+
 	if client.Store.ID == nil {
 		qrChan, err := client.GetQRChannel(c.runCtx)
 		if err != nil {
-			c.runCancel()
-			_ = container.Close()
 			return fmt.Errorf("get QR channel: %w", err)
 		}
 		if err := client.Connect(); err != nil {
-			c.runCancel()
-			_ = container.Close()
 			return fmt.Errorf("connect: %w", err)
 		}
 		// Handle QR events in a background goroutine so Start() returns
 		// promptly.  The goroutine is tracked via c.wg and respects
 		// c.runCtx for cancellation.
+		// Guard wg.Add with reconnectMu + stopping check (same protocol
+		// as eventHandler) so a concurrent Stop() cannot enter wg.Wait()
+		// while we call wg.Add(1).
+		c.reconnectMu.Lock()
+		if c.stopping.Load() {
+			c.reconnectMu.Unlock()
+			return fmt.Errorf("channel stopped during QR setup")
+		}
 		c.wg.Add(1)
+		c.reconnectMu.Unlock()
 		go func() {
 			defer c.wg.Done()
 			for {
@@ -169,12 +200,11 @@ func (c *WhatsAppNativeChannel) Start(ctx context.Context) error {
 		}()
 	} else {
 		if err := client.Connect(); err != nil {
-			c.runCancel()
-			_ = container.Close()
 			return fmt.Errorf("connect: %w", err)
 		}
 	}
 
+	startOK = true
 	c.SetRunning(true)
 	logger.InfoC("whatsapp", "WhatsApp native channel connected")
 	return nil