fix: pubsub leak and shutdown seq

cmd/root.go

@@ -123,12 +123,12 @@ to assist developers in writing, debugging, and understanding code directly from
 
 		// Cleanup function for when the program exits
 		cleanup := func() {
-			// Shutdown the app
-			app.Shutdown()
-
 			// Cancel subscriptions first
 			cancelSubs()
 
+			// Then shutdown the app
+			app.Shutdown()
+
 			// Then cancel TUI message handler
 			tuiCancel()
 
@@ -188,6 +188,10 @@ func setupSubscriber[T any](
 		defer logging.RecoverPanic(fmt.Sprintf("subscription-%s", name), nil)
 
 		subCh := subscriber(ctx)
+		if subCh == nil {
+			logging.Warn("subscription channel is nil", "name", name)
+			return
+		}
 
 		for {
 			select {

internal/pubsub/broker.go

@@ -64,22 +64,27 @@ func (b *Broker[T]) Subscribe(ctx context.Context) <-chan Event[T] {
 	b.subs[sub] = struct{}{}
 	b.subCount++
 
-	go func() {
-		<-ctx.Done()
-
-		b.mu.Lock()
-		defer b.mu.Unlock()
-
-		select {
-		case <-b.done:
-			return
-		default:
-		}
-
-		delete(b.subs, sub)
-		close(sub)
-		b.subCount--
-	}()
+	// Only start a goroutine if the context can actually be canceled
+	if ctx.Done() != nil {
+		go func() {
+			<-ctx.Done()
+
+			b.mu.Lock()
+			defer b.mu.Unlock()
+
+			select {
+			case <-b.done:
+				return
+			default:
+			}
+
+			if _, exists := b.subs[sub]; exists {
+				delete(b.subs, sub)
+				close(sub)
+				b.subCount--
+			}
+		}()
+	}
 
 	return sub
 }

internal/pubsub/broker_test.go

@@ -0,0 +1,145 @@
+package pubsub
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBrokerSubscribe(t *testing.T) {
+	t.Parallel()
+
+	t.Run("with cancellable context", func(t *testing.T) {
+		t.Parallel()
+		broker := NewBroker[string]()
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		ch := broker.Subscribe(ctx)
+		assert.NotNil(t, ch)
+		assert.Equal(t, 1, broker.GetSubscriberCount())
+
+		// Cancel the context should remove the subscription
+		cancel()
+		time.Sleep(10 * time.Millisecond) // Give time for goroutine to process
+		assert.Equal(t, 0, broker.GetSubscriberCount())
+	})
+
+	t.Run("with background context", func(t *testing.T) {
+		t.Parallel()
+		broker := NewBroker[string]()
+
+		// Using context.Background() should not leak goroutines
+		ch := broker.Subscribe(context.Background())
+		assert.NotNil(t, ch)
+		assert.Equal(t, 1, broker.GetSubscriberCount())
+
+		// Shutdown should clean up all subscriptions
+		broker.Shutdown()
+		assert.Equal(t, 0, broker.GetSubscriberCount())
+	})
+}
+
+func TestBrokerPublish(t *testing.T) {
+	t.Parallel()
+	broker := NewBroker[string]()
+	ctx := t.Context()
+
+	ch := broker.Subscribe(ctx)
+
+	// Publish a message
+	broker.Publish(CreatedEvent, "test message")
+
+	// Verify message is received
+	select {
+	case event := <-ch:
+		assert.Equal(t, CreatedEvent, event.Type)
+		assert.Equal(t, "test message", event.Payload)
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("timeout waiting for message")
+	}
+}
+
+func TestBrokerShutdown(t *testing.T) {
+	t.Parallel()
+	broker := NewBroker[string]()
+
+	// Create multiple subscribers
+	ch1 := broker.Subscribe(context.Background())
+	ch2 := broker.Subscribe(context.Background())
+
+	assert.Equal(t, 2, broker.GetSubscriberCount())
+
+	// Shutdown should close all channels and clean up
+	broker.Shutdown()
+
+	// Verify channels are closed
+	_, ok1 := <-ch1
+	_, ok2 := <-ch2
+	assert.False(t, ok1, "channel 1 should be closed")
+	assert.False(t, ok2, "channel 2 should be closed")
+
+	// Verify subscriber count is reset
+	assert.Equal(t, 0, broker.GetSubscriberCount())
+}
+
+func TestBrokerConcurrency(t *testing.T) {
+	t.Parallel()
+	broker := NewBroker[int]()
+
+	// Create a large number of subscribers
+	const numSubscribers = 100
+	var wg sync.WaitGroup
+	wg.Add(numSubscribers)
+
+	// Create a channel to collect received events
+	receivedEvents := make(chan int, numSubscribers)
+
+	for i := range numSubscribers {
+		go func(id int) {
+			defer wg.Done()
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			ch := broker.Subscribe(ctx)
+
+			// Receive one message then cancel
+			select {
+			case event := <-ch:
+				receivedEvents <- event.Payload
+			case <-time.After(1 * time.Second):
+				t.Errorf("timeout waiting for message %d", id)
+			}
+			cancel()
+		}(i)
+	}
+
+	// Give subscribers time to set up
+	time.Sleep(10 * time.Millisecond)
+
+	// Publish messages to all subscribers
+	for i := range numSubscribers {
+		broker.Publish(CreatedEvent, i)
+	}
+
+	// Wait for all subscribers to finish
+	wg.Wait()
+	close(receivedEvents)
+
+	// Give time for cleanup goroutines to run
+	time.Sleep(10 * time.Millisecond)
+
+	// Verify all subscribers are cleaned up
+	assert.Equal(t, 0, broker.GetSubscriberCount())
+
+	// Verify we received the expected number of events
+	count := 0
+	for range receivedEvents {
+		count++
+	}
+	assert.Equal(t, numSubscribers, count)
+}
+