feat(app): add TaskPoller, wire DI, and add task integration tests

internal/app/task_poller_test.go

@@ -0,0 +1,70 @@
+package app
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+type mockTaskPollable struct {
+	refreshFunc func(ctx context.Context) error
+	callCount   int
+	mu          sync.Mutex
+}
+
+func (m *mockTaskPollable) RefreshStaleTasks(ctx context.Context) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.callCount++
+	if m.refreshFunc != nil {
+		return m.refreshFunc(ctx)
+	}
+	return nil
+}
+
+func (m *mockTaskPollable) getCallCount() int {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.callCount
+}
+
+func TestTaskPoller_StartStop(t *testing.T) {
+	mock := &mockTaskPollable{}
+	logger := zap.NewNop()
+	poller := NewTaskPoller(mock, 1*time.Second, logger)
+
+	poller.Start(context.Background())
+	time.Sleep(100 * time.Millisecond)
+	poller.Stop()
+
+	// No goroutine leak — Stop() returned means wg.Wait() completed.
+}
+
+func TestTaskPoller_RefreshesStaleTasks(t *testing.T) {
+	mock := &mockTaskPollable{}
+	logger := zap.NewNop()
+	poller := NewTaskPoller(mock, 50*time.Millisecond, logger)
+
+	poller.Start(context.Background())
+	defer poller.Stop()
+
+	time.Sleep(300 * time.Millisecond)
+
+	if count := mock.getCallCount(); count < 1 {
+		t.Errorf("expected RefreshStaleTasks to be called at least once, got %d", count)
+	}
+}
+
+func TestTaskPoller_StopsCleanly(t *testing.T) {
+	mock := &mockTaskPollable{}
+	logger := zap.NewNop()
+	poller := NewTaskPoller(mock, 1*time.Second, logger)
+
+	poller.Start(context.Background())
+	poller.Stop()
+
+	// No panic and WaitGroup is done — Stop returned successfully.
+}