fix: continue cleanup after shutdown deadline

main.go

@@ -47,7 +47,20 @@ func shutdownAll(ctx context.Context, cancelRoot context.CancelFunc, steps ...sh
 	defer cancelRoot()
 	var shutdownErr error
 	for _, step := range steps {
-		if err := step.run(ctx); err != nil {
+		done := make(chan error, 1)
+		started := make(chan struct{})
+		go func() {
+			close(started)
+			done <- step.run(ctx)
+		}()
+		<-started
+		var err error
+		select {
+		case err = <-done:
+		case <-ctx.Done():
+			err = ctx.Err()
+		}
+		if err != nil {
 			log.Printf("[main] %s shutdown: %v", step.name, err)
 			shutdownErr = errors.Join(shutdownErr, fmt.Errorf("%s shutdown: %w", step.name, err))
 		}

main_test.go

@@ -70,6 +70,48 @@ func TestShutdownAllContinuesAfterTimeoutWithSharedDeadline(t *testing.T) {
 	}
 }
 
+func TestShutdownAllContinuesWhenStepIgnoresDeadline(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Millisecond)
+	defer cancel()
+
+	blocked := make(chan struct{})
+	defer close(blocked)
+	cleanupStarted := make(chan struct{})
+	rootCtx, rootCancel := context.WithCancel(context.Background())
+	result := make(chan error, 1)
+	go func() {
+		result <- shutdownAll(ctx, rootCancel,
+			shutdownStep{name: "blocked", run: func(context.Context) error {
+				<-blocked
+				return nil
+			}},
+			shutdownStep{name: "cleanup", run: func(context.Context) error {
+				close(cleanupStarted)
+				return nil
+			}},
+		)
+	}()
+
+	select {
+	case err := <-result:
+		if !errors.Is(err, context.DeadlineExceeded) {
+			t.Fatalf("shutdownAll() error = %v, want deadline exceeded", err)
+		}
+	case <-time.After(250 * time.Millisecond):
+		t.Fatal("shutdownAll did not enforce the shared deadline")
+	}
+	select {
+	case <-cleanupStarted:
+	default:
+		t.Fatal("cleanup after blocked step was not started")
+	}
+	select {
+	case <-rootCtx.Done():
+	default:
+		t.Fatal("root context was not canceled")
+	}
+}
+
 func recordShutdown(order *[]string, contexts *[]context.Context, name string, err error) func(context.Context) error {
 	return func(ctx context.Context) error {
 		*order = append(*order, name)