fix(settings): degrade load_features to defaults on PermissionError

load_settings() already catches PermissionError, but load_features() caught only
FileNotFoundError/JSONDecodeError/ValueError. An existing-but-unreadable
data/features.json (e.g. root-owned after a deploy) therefore raised instead of
falling back to DEFAULT_FEATURES, taking down GET /api/auth/features and anything
that reads feature flags. Add PermissionError to the except tuple to match
load_settings().

Adds tests/test_load_features_permission_error.py.

Co-authored-by: Alexandre Teixeira <111787685+alteixeira20@users.noreply.github.com>

src/settings.py

@@ -283,7 +283,7 @@ def load_features() -> dict:
         if not isinstance(saved, dict):
             raise ValueError("features must be an object")
         merged = {**DEFAULT_FEATURES, **saved}
-    except (FileNotFoundError, json.JSONDecodeError, ValueError):
+    except (FileNotFoundError, PermissionError, json.JSONDecodeError, ValueError):
         merged = dict(DEFAULT_FEATURES)
     _features_cache = (now, merged)
     return merged

tests/test_load_features_permission_error.py

@@ -0,0 +1,26 @@
+"""load_features() must degrade to defaults if features.json is unreadable.
+
+load_settings() already catches PermissionError, but load_features() did not, so
+an unreadable data/features.json (e.g. root-owned after a deploy) raised instead
+of falling back to DEFAULT_FEATURES, taking down GET /api/auth/features.
+"""
+import builtins
+
+import src.settings as settings
+
+
+def test_load_features_degrades_on_permission_error(monkeypatch):
+    # Ensure the cache does not short-circuit the read.
+    monkeypatch.setattr(settings, "_features_cache", None, raising=False)
+
+    real_open = builtins.open
+
+    def deny(path, *args, **kwargs):
+        if str(path) == str(settings.FEATURES_FILE):
+            raise PermissionError("denied")
+        return real_open(path, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "open", deny)
+
+    result = settings.load_features()
+    assert result == dict(settings.DEFAULT_FEATURES)