Bugfix

internal/composeedit/composeedit_test.go

@@ -29,3 +29,31 @@ func TestArrayPatch(t *testing.T) {
 		t.Fatal(out)
 	}
 }
+
+func TestAddTopLevelNamedVolumePreservesServiceMounts(t *testing.T) {
+	src := "services:\n  app:\n    volumes:\n      - db_data:/var/lib/db\n      - /srv/app:/data:ro\n    x-future: keep\n"
+	out, err := Apply(src, Patch{Path: []string{"volumes", "db_data"}, Value: map[string]any{}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{"db_data:/var/lib/db", "/srv/app:/data:ro", "x-future: keep", "volumes:", "db_data:"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("expected %q to be preserved/added:\n%s", want, out)
+		}
+	}
+	parsed, err := Parse(out)
+	if err != nil {
+		t.Fatal(err)
+	}
+	root, ok := parsed.Value.(map[string]any)
+	if !ok {
+		t.Fatalf("unexpected parse result %#v", parsed.Value)
+	}
+	vols, ok := root["volumes"].(map[string]any)
+	if !ok {
+		t.Fatalf("top-level volumes missing: %#v", root["volumes"])
+	}
+	if _, ok := vols["db_data"]; !ok {
+		t.Fatalf("db_data declaration missing: %#v", vols)
+	}
+}