Cache get_comfy_package_versions()

Mirrors the PACKAGE_VERSIONS cache in utils/install_util.py. Installed
package versions don't change over the lifetime of the process, so a
one-shot module-level cache makes /system_stats polling effectively free
instead of doing N importlib.metadata.version() lookups per call.

app/frontend_management.py

@@ -42,9 +42,12 @@ def get_required_frontend_version():
     return get_required_packages_versions().get("comfyui-frontend-package", None)
 
 
+COMFY_PACKAGE_VERSIONS = []
 def get_comfy_package_versions():
     """List installed/required versions for every comfy* package in requirements.txt."""
-    out = []
+    if COMFY_PACKAGE_VERSIONS:
+        return COMFY_PACKAGE_VERSIONS.copy()
+    out = COMFY_PACKAGE_VERSIONS
     for name, required in (get_required_packages_versions() or {}).items():
         if not name.startswith("comfy"):
             continue
@@ -53,7 +56,7 @@ def get_comfy_package_versions():
         except Exception:
             installed = None
         out.append({"name": name, "installed": installed, "required": required})
-    return out
+    return out.copy()
 
 
 def check_comfy_packages_versions():

tests-unit/app_test/frontend_manager_test.py

@@ -52,7 +52,10 @@ def mock_provider(mock_releases):
 @pytest.fixture(autouse=True)
 def clear_cache():
     import utils.install_util
+    import app.frontend_management
+
     utils.install_util.PACKAGE_VERSIONS = {}
+    app.frontend_management.COMFY_PACKAGE_VERSIONS = []
 
 
 def test_get_release(mock_provider, mock_releases):
@@ -277,7 +280,9 @@ def test_get_installed_templates_version():
 
 def test_get_installed_templates_version_not_installed():
     # Act
-    with patch("app.frontend_management.version", side_effect=Exception("Package not found")):
+    with patch(
+        "app.frontend_management.version", side_effect=Exception("Package not found")
+    ):
         version = FrontendManager.get_installed_templates_version()
 
     # Assert