Polish: rename _default to default_registry, strengthen unreadable-file test

Agent-Logs-Url: https://github.com/github/spec-kit/sessions/0dca6393-f5a9-40de-bb5c-77ba6af033d2

Co-authored-by: mnriem <15701806+mnriem@users.noreply.github.com>

Author: Copilot

src/specify_cli/workflows/catalog.py

@@ -593,20 +593,20 @@ def __init__(self, project_root: Path) -> None:
 
     def _load(self) -> dict[str, Any]:
         """Load registry from disk or create default."""
-        _default: dict[str, Any] = {"schema_version": self.SCHEMA_VERSION, "steps": {}}
+        default_registry: dict[str, Any] = {"schema_version": self.SCHEMA_VERSION, "steps": {}}
         if self.registry_path.exists():
             try:
                 with open(self.registry_path, encoding="utf-8") as f:
                     data = json.load(f)
                 # Validate shape: must be a dict with a dict "steps" field
                 if not isinstance(data, dict):
-                    return _default
+                    return default_registry
                 if not isinstance(data.get("steps"), dict):
                     data["steps"] = {}
                 return data
             except (json.JSONDecodeError, ValueError, OSError, UnicodeError):
-                return _default
-        return _default
+                return default_registry
+        return default_registry
 
     def save(self) -> None:
         """Persist registry to disk."""

tests/test_workflows.py

@@ -1957,6 +1957,10 @@ def test_registry_unreadable_file_resets(self, project_dir):
         finally:
             registry.registry_path.chmod(0o644)
 
+        # After restoring permissions the registry is fully functional
+        registry2.add("deploy", {"name": "Deploy", "type_key": "deploy"})
+        assert registry2.is_installed("deploy")
+
 
 # ===== Step Catalog Tests =====