feat: allow production provider bootstrap

backend/internal/settings/service_test.go

@@ -100,6 +100,23 @@ func TestServiceGetUsesInjectedEnvironmentWithoutMutatingProcess(t *testing.T) {
 	assertSecretProjection(t, value, "SEEDANCE_API_KEY", true)
 }
 
+func TestLoadEnvironmentAllowsBootstrapRuntimeFlagButIgnoresUnknownKeys(t *testing.T) {
+	path := filepath.Join(t.TempDir(), ".env.local")
+	if err := os.WriteFile(path, []byte("ZHINIAN_ALLOW_UNCONFIGURED_PROVIDERS=true\nUNKNOWN_RUNTIME_FLAG=true\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	values, err := LoadEnvironment(path, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if values["ZHINIAN_ALLOW_UNCONFIGURED_PROVIDERS"] != "true" {
+		t.Fatalf("bootstrap flag = %q", values["ZHINIAN_ALLOW_UNCONFIGURED_PROVIDERS"])
+	}
+	if _, exists := values["UNKNOWN_RUNTIME_FLAG"]; exists {
+		t.Fatal("unknown runtime flag was loaded")
+	}
+}
+
 func TestServiceSynchronizesBillingAccountWithoutRequiringRestart(t *testing.T) {
 	writer := &billingWriterStub{}
 	service := New(filepath.Join(t.TempDir(), ".env.local"), nil, nil).WithBillingAccountWriter(writer)