diff --git a/backend/app/config.py b/backend/app/config.py
index 4deafe4..4bba2f9 100644
--- a/backend/app/config.py
+++ b/backend/app/config.py
@@ -71,7 +71,7 @@ class Settings(BaseSettings):
     # ---------- CORS ----------
     CORS_ORIGINS: str = "http://localhost:5173,http://10.10.10.7:5173,http://10.10.10.7"
 
-    model_config = {"env_file": ".env", "env_file_encoding": "utf-8"}
+    model_config = {"env_file": ".env", "env_file_encoding": "utf-8", "extra": "ignore"}
 
     @property
     def CASDOOR_ENDPOINT(self) -> str:
diff --git a/backend/tests/test_settings_validation.py b/backend/tests/test_settings_validation.py
index 48386d8..6ca5065 100644
--- a/backend/tests/test_settings_validation.py
+++ b/backend/tests/test_settings_validation.py
@@ -66,3 +66,13 @@ def test_enabled_wecom_delivery_requires_all_credentials():
 
     with pytest.raises(ValueError, match="WECOM"):
         validate_runtime_settings(settings)
+
+
+def test_ignores_compose_only_environment_fields():
+    settings = Settings(
+        environment="test",
+        postgres_password="compose-only",
+        pingwatch_backend_bind="127.0.0.1:18065",
+    )
+
+    assert settings.environment == "test"