diff --git a/order/src/main/java/com/baiyue/order/config/InboundCodeModeProvider.java b/order/src/main/java/com/baiyue/order/config/InboundCodeModeProvider.java
index 581bed483..6cab307f1 100644
--- a/order/src/main/java/com/baiyue/order/config/InboundCodeModeProvider.java
+++ b/order/src/main/java/com/baiyue/order/config/InboundCodeModeProvider.java
@@ -15,7 +15,8 @@ public class InboundCodeModeProvider {
 
     private final Mode mode;
 
-    public InboundCodeModeProvider(@Value("${baiyue.order.inbound-code-mode}") String configuredMode) {
+    public InboundCodeModeProvider(
+        @Value("${baiyue.order.inbound-code-mode:LEGACY_MANUAL}") String configuredMode) {
         if (!StringUtils.hasText(configuredMode)) {
             throw new IllegalStateException("baiyue.order.inbound-code-mode 必须显式配置");
         }
diff --git a/order/src/test/java/com/baiyue/order/config/InboundCodeModeProviderTest.java b/order/src/test/java/com/baiyue/order/config/InboundCodeModeProviderTest.java
index 856ed80c6..00afda61f 100644
--- a/order/src/test/java/com/baiyue/order/config/InboundCodeModeProviderTest.java
+++ b/order/src/test/java/com/baiyue/order/config/InboundCodeModeProviderTest.java
@@ -1,11 +1,25 @@
 package com.baiyue.order.config;
 
 import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Value;
+
+import java.lang.reflect.Constructor;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 class InboundCodeModeProviderTest {
+    @Test
+    void springPlaceholderDefaultsToLegacyManualWhenEnvironmentPropertyIsMissing() {
+        Constructor<?> constructor = InboundCodeModeProvider.class.getDeclaredConstructors()[0];
+        Value value = constructor.getParameters()[0].getAnnotation(Value.class);
+
+        assertThat(value.value())
+            .isEqualTo("${baiyue.order.inbound-code-mode:LEGACY_MANUAL}");
+        assertThat(new InboundCodeModeProvider("LEGACY_MANUAL").mode())
+            .isEqualTo(InboundCodeModeProvider.Mode.LEGACY_MANUAL);
+    }
+
     @Test
     void parsesBothSupportedModesCaseInsensitively() {
         assertThat(new InboundCodeModeProvider("auto").mode())