diff --git a/cmd/summer/runtime.go b/cmd/summer/runtime.go
index b3ab945..25f19b9 100644
--- a/cmd/summer/runtime.go
+++ b/cmd/summer/runtime.go
@@ -13,14 +13,23 @@ import (
 	"git.golem15.com/golem15/summercms/modules/bonfire"
 )
 
+// appRunner runs the app binary with argv; tests replace it.
+var appRunner = runAppBinary
+
 func delegateCommand(name, description string) bonfire.Command {
 	return bonfire.Command{
 		Name:        name,
 		Description: description,
+		Passthrough: true,
 		Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
-			argv := []string{name}
-			argv = append(argv, in.Args()...)
-			return runAppBinary(ctx, argv, out)
+			args := in.Args()
+			// One leading "--" is dropped so the older
+			// `summer serve -- --addr :8123` form keeps working.
+			if len(args) > 0 && args[0] == "--" {
+				args = args[1:]
+			}
+			argv := append([]string{name}, args...)
+			return appRunner(ctx, argv, out)
 		},
 	}
 }
diff --git a/cmd/summer/runtime_test.go b/cmd/summer/runtime_test.go
new file mode 100644
index 0000000..7757df8
--- /dev/null
+++ b/cmd/summer/runtime_test.go
@@ -0,0 +1,44 @@
+package main
+
+import (
+	"context"
+	"slices"
+	"testing"
+
+	"git.golem15.com/golem15/summercms/modules/bonfire"
+)
+
+// captureAppRunner replaces appRunner for the test and returns a pointer to
+// the argv of the last call.
+func captureAppRunner(t *testing.T) *[]string {
+	t.Helper()
+	got := new([]string)
+	prev := appRunner
+	appRunner = func(ctx context.Context, argv []string, out bonfire.Output) error {
+		*got = append([]string(nil), argv...)
+		return nil
+	}
+	t.Cleanup(func() { appRunner = prev })
+	return got
+}
+
+func TestDelegatedServePassesFlags(t *testing.T) {
+	for _, tc := range []struct {
+		args []string
+		want []string
+	}{
+		{[]string{"serve", "--addr", ":8123"}, []string{"serve", "--addr", ":8123"}},
+		{[]string{"serve", "--help"}, []string{"serve", "--help"}},
+		{[]string{"serve", "-h"}, []string{"serve", "-h"}},
+		{[]string{"serve", "--addr=:8123"}, []string{"serve", "--addr=:8123"}},
+		{[]string{"serve", "--", "--addr", ":8123"}, []string{"serve", "--addr", ":8123"}},
+	} {
+		got := captureAppRunner(t)
+		if out, err := runSummer(t, tc.args...); err != nil {
+			t.Fatalf("%q: %v\n%s", tc.args, err, out)
+		}
+		if !slices.Equal(*got, tc.want) {
+			t.Fatalf("%q: argv = %q, want %q", tc.args, *got, tc.want)
+		}
+	}
+}