feat: add generic phased background shutdown to managed services

examples/managedService/main.go

@@ -8,6 +8,7 @@ import (
 	"example.com/managed/internal/handler"
 	"example.com/managed/internal/svc"
 	"flag"
+	"git.yuntuo.hk/k2safe/go-omni/lifecycle"
 	"git.yuntuo.hk/k2safe/go-omni/logx"
 	"log"
 	"os"
@@ -33,7 +34,13 @@ func run(ctx context.Context, path string) (runErr error) {
 	if err != nil {
 		return err
 	}
-	defer func() { runErr = errors.Join(runErr, logger.Close()) }()
+	// Unjoined background work may still log. The owning process exits on this
+	// error; do not close its borrowed logger before that work has finished.
+	defer func() {
+		if !errors.Is(runErr, lifecycle.ErrResourcesRetained) {
+			runErr = errors.Join(runErr, logger.Close())
+		}
+	}()
 	deps, err := svc.New(ctx, logger, cfg)
 	if err != nil {
 		return err