fix fragile hak packing

internal/topdata/topdata_test.go

@@ -15116,6 +15116,60 @@ func writeBytes(t *testing.T, path string, content []byte) {
 	}
 }
 
+func TestSkipTopPackageAsset(t *testing.T) {
+	skipped := []string{
+		"gui/regions/comfyui-generate.sh", // non-NWN extension
+		"gui/regions/_candidates/abyss.opt4.png",
+		"gui/.hidden/banner.png",
+		"gui/.DS_Store",
+		"gui/AGENTS.md",
+		"gui/noextension",
+	}
+	kept := []string{
+		"gui/regions/abyss.png",
+		"2da-src/placeables.2da",
+		"tex/floor01.dds",
+	}
+	for _, rel := range skipped {
+		if !skipTopPackageAsset(rel) {
+			t.Errorf("expected %s to be skipped", rel)
+		}
+	}
+	for _, rel := range kept {
+		if skipTopPackageAsset(rel) {
+			t.Errorf("expected %s to be kept", rel)
+		}
+	}
+}
+
+func TestValidateTopPackageAssetsIgnoresNonNWNFiles(t *testing.T) {
+	dir := t.TempDir()
+	assets := filepath.Join(dir, "assets", "gui", "regions")
+	candidates := filepath.Join(assets, "_candidates")
+	if err := os.MkdirAll(candidates, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	for path, content := range map[string]string{
+		filepath.Join(assets, "comfyui-generate.sh"):  "#!/bin/sh",
+		filepath.Join(assets, "abyss.png"):            "png",
+		filepath.Join(candidates, "abyss.opt4.png"):   "png",
+		filepath.Join(candidates, "notes.txt.backup"): "junk",
+	} {
+		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	dataDir := filepath.Join(dir, "data")
+	if err := os.MkdirAll(dataDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	var report ValidationReport
+	validateTopPackageAssets(dir, dataDir, &report)
+	for _, d := range report.Diagnostics {
+		t.Errorf("unexpected diagnostic: %s: %s", d.Path, d.Message)
+	}
+}
+
 func TestValidateTopPackageAssetsSkipsMarkdown(t *testing.T) {
 	dir := t.TempDir()
 	assets := filepath.Join(dir, "assets", "gui")