Fix settings boolean parsing robustness

app/backend/app/config/settings.py

@@ -1,6 +1,7 @@
 """Application settings loaded from environment variables."""
 
 import re
+from typing import Any
 
 from pydantic import AliasChoices, Field
 from pydantic import field_validator
@@ -70,6 +71,7 @@ class Settings(BaseSettings):
 
     @field_validator(
         "debug",
+        "serve_frontend",
         "gallica_use_fixtures",
         "bodleian_use_fixtures",
         "europeana_use_fixtures",
@@ -81,32 +83,11 @@ class Settings(BaseSettings):
     def normalize_bool_env_values(cls, value: object, info):
         """Normalize permissive boolean-like environment values for robust deployments."""
 
-        if isinstance(value, bool):
-            return value
-        if isinstance(value, (int, float)):
-            return bool(value)
-        if not isinstance(value, str):
-            return value
-
-        normalized = value.strip().lower()
-        truthy = {"1", "true", "yes", "on"}
-        falsy = {"0", "false", "no", "off", ""}
-
-        if normalized in truthy:
-            return True
-        if normalized in falsy:
-            return False
-
-        first_token = re.split(r"[^a-z0-9]+", normalized, maxsplit=1)[0]
-        if first_token in truthy:
+        default = cls.model_fields[info.field_name].default
+        parsed = _parse_bool_with_fallback(value, default)
+        if isinstance(value, str) and info.field_name.endswith("_use_fixtures") and "fixture" in value.lower():
             return True
-        if first_token in falsy:
-            return False
-
-        if info.field_name.endswith("_use_fixtures") and "fixture" in normalized:
-            return True
-
-        return cls.model_fields[info.field_name].default
+        return parsed
 
     model_config = SettingsConfigDict(env_prefix="CLAFOUTIS_", extra="ignore")
 

app/tests/unit/backend/test_settings.py

@@ -38,3 +38,13 @@ def test_bodleian_use_fixtures_accepts_descriptive_value(monkeypatch) -> None:
     loaded = Settings()
 
     assert loaded.bodleian_use_fixtures is True
+
+
+def test_serve_frontend_accepts_descriptive_value(monkeypatch) -> None:
+    """Frontend serving flag should tolerate descriptive values and keep default-safe behavior."""
+
+    monkeypatch.setenv("CLAFOUTIS_SERVE_FRONTEND", "Serve the built frontend from the backend")
+
+    loaded = Settings()
+
+    assert loaded.serve_frontend is True