diff --git a/backend-java/src/test/java/com/nanri/aiimage/config/ModuleTypeAlignmentTest.java b/backend-java/src/test/java/com/nanri/aiimage/config/ModuleTypeAlignmentTest.java
new file mode 100644
index 00000000..3806428f
--- /dev/null
+++ b/backend-java/src/test/java/com/nanri/aiimage/config/ModuleTypeAlignmentTest.java
@@ -0,0 +1,83 @@
+package com.nanri.aiimage.config;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * module_type 对齐守卫（task 外防回归）。
+ *
+ * 服务端 module_type 规范为大写下划线（SIMILAR_ASIN / COLLECT_DATA / …），写入 DB 的
+ * 值必须与各 Service 的 MODULE_TYPE 常量一致；小写写法（如 similarasin）会导致按模块
+ * 查找/心跳/handler 不命中。本测试扫描 src/main：① MODULE_TYPE 等常量取值必须大写；
+ * ② setModuleType("小写") 不允许（仅允许显式 legacy 兼容值 "collectdata"）。
+ */
+class ModuleTypeAlignmentTest {
+
+    private static final Set<String> ALLOWED_LEGACY = Set.of("collectdata");
+
+    private static final Pattern CONST_DECL = Pattern.compile(
+            "(?:MODULE_TYPE|LEGACY_MODULE_TYPE|_MODULE)\\s*=\\s*\"([A-Za-z0-9_]+)\"");
+    private static final Pattern WRITE_LITERAL = Pattern.compile(
+            "setModuleType\\s*\\(\\s*\"([A-Za-z0-9_]+)\"");
+    private static final Pattern UPPER = Pattern.compile("^[A-Z][A-Z0-9_]*$");
+
+    private static List<Path> javaFiles() throws IOException {
+        Path root = Path.of(System.getProperty("user.dir"), "src/main/java/com/nanri/aiimage");
+        try (Stream<Path> s = Files.walk(root)) {
+            return s.filter(p -> p.toString().endsWith(".java")).toList();
+        }
+    }
+
+    @Test
+    void moduleTypeConstantsAreUppercase() throws IOException {
+        List<String> violations = new ArrayList<>();
+        for (Path f : javaFiles()) {
+            List<String> lines = Files.readAllLines(f);
+            for (int i = 0; i < lines.size(); i++) {
+                Matcher m = CONST_DECL.matcher(lines.get(i));
+                while (m.find()) {
+                    String value = m.group(1);
+                    if (!ALLOWED_LEGACY.contains(value) && !UPPER.matcher(value).matches()) {
+                        violations.add(f + ":" + (i + 1) + " 小写/不规范模块常量: " + value);
+                    }
+                }
+            }
+        }
+        assertTrue(violations.isEmpty(), "module_type 常量必须规范大写：\n  " + String.join("\n  ", violations));
+    }
+
+    @Test
+    void noLowercaseModuleTypeWrites() throws IOException {
+        List<String> violations = new ArrayList<>();
+        for (Path f : javaFiles()) {
+            List<String> lines = Files.readAllLines(f);
+            for (int i = 0; i < lines.size(); i++) {
+                Matcher m = WRITE_LITERAL.matcher(lines.get(i));
+                while (m.find()) {
+                    String value = m.group(1);
+                    if (!ALLOWED_LEGACY.contains(value) && !UPPER.matcher(value).matches()) {
+                        violations.add(f + ":" + (i + 1) + " setModuleType(\"" + value + "\") 应用常量而非小写字面量");
+                    }
+                }
+            }
+        }
+        assertTrue(violations.isEmpty(), "写入 module_type 应用规范大写常量：\n  " + String.join("\n  ", violations));
+    }
+
+    @Test
+    void similarasinCanonicalValueLocksUpperSnake() {
+        // 锚定本次发现的隐患点：similarasin 的规范值为大写 SIMILAR_ASIN
+        assertTrue(UPPER.matcher("SIMILAR_ASIN").matches());
+    }
+}
diff --git a/backend-java/src/test/java/com/nanri/aiimage/config/PythonContractFixtureTest.java b/backend-java/src/test/java/com/nanri/aiimage/config/PythonContractFixtureTest.java
index 53d724cc..18e025b8 100644
--- a/backend-java/src/test/java/com/nanri/aiimage/config/PythonContractFixtureTest.java
+++ b/backend-java/src/test/java/com/nanri/aiimage/config/PythonContractFixtureTest.java
@@ -60,6 +60,8 @@ class PythonContractFixtureTest {
         JsonNode resp = json("heartbeat.response.json");
         assertTrue(req.has("moduleType") && req.has("phase"));
         assertTrue(resp.has("alive") && resp.has("status"));
+        assertEquals("SIMILAR_ASIN", req.path("moduleType").asText(),
+                "夹具 moduleType 须用规范大写（与服务 MODULE_TYPE 常量一致，防小写漂移 bug）");
     }
 
     @Test
diff --git a/backend-java/src/test/resources/python-contract/heartbeat.request.json b/backend-java/src/test/resources/python-contract/heartbeat.request.json
index 0ca768a4..3b1535ba 100644
--- a/backend-java/src/test/resources/python-contract/heartbeat.request.json
+++ b/backend-java/src/test/resources/python-contract/heartbeat.request.json
@@ -1,5 +1,5 @@
 {
-  "moduleType": "similarasin",
+  "moduleType": "SIMILAR_ASIN",
   "phase": "search",
   "current": 3,
   "total": 10,