Fix topdata lock file generation

internal/topdata/topdata_test.go

@@ -6362,6 +6362,55 @@ func TestBuildGenerated2DAAssetsAppendsCachedModelsFromHeadVisualeffects(t *test
 	}
 }
 
+func TestBuildGenerated2DAAssetsWritesLockfilesForSelectedDatasets(t *testing.T) {
+	root := testProjectRoot(t)
+	mkdirAll(t, filepath.Join(root, "assets"))
+	mkdirAll(t, filepath.Join(root, "topdata", "data", "cachedmodels", "modules"))
+	writeFile(t, filepath.Join(root, "topdata", "data", "cachedmodels", "base.json"), `{
+  "columns": ["Model"],
+  "rows": [
+    {"id": 0, "key": "cachedmodels:base_model", "Model": "base_model"}
+  ]
+}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "cachedmodels", "modules", "add_chatbubble.json"), `{
+  "entries": {
+    "cachedmodels:vdr_chatbubble": {
+      "Model": "vdr_chatbubble"
+    }
+  }
+}`+"\n")
+
+	p := testProject(root)
+	p.Config.Paths.Assets = "assets"
+	p.Config.Generated.TopData2DA = []project.GeneratedTopData2DAConfig{
+		{
+			ID:              "cachedmodels",
+			Source:          "topdata",
+			Output:          ".cache/generated-assets/cachedmodels-2da",
+			IncludeDatasets: []string{"cachedmodels"},
+			PackageRoot:     "vfxs",
+		},
+	}
+
+	if _, err := BuildGenerated2DAAssets(p, nil); err != nil {
+		t.Fatalf("BuildGenerated2DAAssets failed: %v", err)
+	}
+
+	lockBytes, err := os.ReadFile(filepath.Join(root, "topdata", "data", "cachedmodels", "lock.json"))
+	if err != nil {
+		t.Fatalf("read generated cachedmodels lockfile: %v", err)
+	}
+	lockText := string(lockBytes)
+	for _, want := range []string{
+		`"cachedmodels:base_model": 0`,
+		`"cachedmodels:vdr_chatbubble": 1`,
+	} {
+		if !strings.Contains(lockText, want) {
+			t.Fatalf("expected generated asset lockfile to contain %q, got:\n%s", want, lockText)
+		}
+	}
+}
+
 func TestNormalizeProjectImportsLegacyLoadscreens(t *testing.T) {
 	root := testProjectRoot(t)
 	mkdirAll(t, filepath.Join(root, "topdata", "data"))