Fix fan chart gaps and task durations

audit/internal/webui/tasks_test.go

@@ -55,6 +55,9 @@ func TestTaskQueuePersistsAndRecoversPendingTasks(t *testing.T) {
 	if got.Status != TaskPending {
 		t.Fatalf("status=%q want %q", got.Status, TaskPending)
 	}
+	if got.StartedAt != nil {
+		t.Fatalf("started_at=%v want nil for recovered pending task", got.StartedAt)
+	}
 	if got.params.Duration != 300 || got.params.BurnProfile != "smoke" {
 		t.Fatalf("params=%+v", got.params)
 	}
@@ -236,6 +239,26 @@ func TestRunTaskBuildsSupportBundleWithoutApp(t *testing.T) {
 	}
 }
 
+func TestTaskElapsedSecClampsInvalidStartedAt(t *testing.T) {
+	now := time.Date(2026, 4, 1, 19, 10, 0, 0, time.UTC)
+	created := time.Date(2026, 4, 1, 19, 4, 5, 0, time.UTC)
+	started := time.Time{}
+	task := &Task{
+		Status:    TaskRunning,
+		CreatedAt: created,
+		StartedAt: &started,
+	}
+	if got := taskElapsedSec(task, now); got != 0 {
+		t.Fatalf("taskElapsedSec(zero start)=%d want 0", got)
+	}
+
+	stale := created.Add(-24 * time.Hour)
+	task.StartedAt = &stale
+	if got := taskElapsedSec(task, now); got != int(now.Sub(created).Seconds()) {
+		t.Fatalf("taskElapsedSec(stale start)=%d want %d", got, int(now.Sub(created).Seconds()))
+	}
+}
+
 func TestRunTaskInstallUsesSharedCommandStreaming(t *testing.T) {
 	q := &taskQueue{
 		opts: &HandlerOptions{},