diff --git a/backend-java/src/main/java/com/nanri/aiimage/modules/softwareversion/service/support/PublicVersionLookup.java b/backend-java/src/main/java/com/nanri/aiimage/modules/softwareversion/service/support/PublicVersionLookup.java
index 83da6cd6..5c0b20ec 100644
--- a/backend-java/src/main/java/com/nanri/aiimage/modules/softwareversion/service/support/PublicVersionLookup.java
+++ b/backend-java/src/main/java/com/nanri/aiimage/modules/softwareversion/service/support/PublicVersionLookup.java
@@ -12,6 +12,11 @@ import java.util.Map;
  */
 public final class PublicVersionLookup {
 
+    /** 公开客户端版本路径(与旧 Flask/客户端地址完全一致)。 */
+    public static final String PUBLIC_VERSION_PATH = "/api/version";
+    public static final String PUBLIC_VERSION_LATEST_PATH = "/api/version/latest";
+    public static final String ADMIN_UPLOAD_PATH = "/api/admin/version";
+
     /** web_config 版本记录投影(id 用于同时间稳定排序)。 */
     public record WebVersion(Long id, String version, String fileUrl, LocalDateTime createdAt) {
     }
@@ -19,6 +24,11 @@ public final class PublicVersionLookup {
     private PublicVersionLookup() {
     }
 
+    /** 是否属于公开版本接口路径(与后台上传路径解耦)。 */
+    public static boolean isPublicVersionPath(String path) {
+        return PUBLIC_VERSION_PATH.equals(path) || PUBLIC_VERSION_LATEST_PATH.equals(path);
+    }
+
     /** 取最新版本记录：created_at DESC，同一时间按 id 倒序稳定；空/无有效回 null。 */
     public static WebVersion selectLatest(List<WebVersion> rows) {
         if (rows == null || rows.isEmpty()) {
diff --git a/backend-java/src/test/java/com/nanri/aiimage/modules/softwareversion/service/support/Task162Test.java b/backend-java/src/test/java/com/nanri/aiimage/modules/softwareversion/service/support/Task162Test.java
new file mode 100644
index 00000000..d8738c2c
--- /dev/null
+++ b/backend-java/src/test/java/com/nanri/aiimage/modules/softwareversion/service/support/Task162Test.java
@@ -0,0 +1,77 @@
+package com.nanri.aiimage.modules.softwareversion.service.support;
+
+import com.nanri.aiimage.modules.softwareversion.service.support.PublicVersionLookup.WebVersion;
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/** task-162: module 09 公开版本契约测试(latest 契约)。 */
+class Task162Test {
+
+    private WebVersion v(Long id, String version, String fileUrl, LocalDateTime at) {
+        return new WebVersion(id, version, fileUrl, at);
+    }
+
+    @Test
+    void test_task_162_normal_primary_path() {
+        WebVersion latest = PublicVersionLookup.selectLatest(List.of(
+                v(1L, "1.0.1", "https://a/1.zip", LocalDateTime.of(2026, 1, 1, 0, 0)),
+                v(2L, "1.0.2", "https://a/2.zip", LocalDateTime.of(2026, 1, 2, 0, 0))));
+        assertNotNull(latest);
+        assertEquals("1.0.2", latest.version());
+        assertEquals("https://a/2.zip", latest.fileUrl());
+    }
+
+    @Test
+    void test_task_162_normal_variant_input() {
+        WebVersion latest = PublicVersionLookup.selectLatest(List.of(
+                v(5L, "1.0.5", "u5", LocalDateTime.of(2026, 2, 2, 0, 0)),
+                v(4L, "1.0.4", "u4", LocalDateTime.of(2026, 2, 1, 0, 0))));
+        assertEquals("1.0.5", latest.version());
+    }
+
+    @Test
+    void test_task_162_normal_repeated_is_idempotent() {
+        List<WebVersion> rows = List.of(v(1L, "1.0.0", "u", LocalDateTime.of(2026, 1, 1, 0, 0)));
+        assertTrue(PublicVersionLookup.selectLatest(rows).equals(PublicVersionLookup.selectLatest(rows)));
+    }
+
+    @Test
+    void test_task_162_boundary_empty_input() {
+        assertNull(PublicVersionLookup.selectLatest(null));
+        assertNull(PublicVersionLookup.selectLatest(List.of()));
+    }
+
+    @Test
+    void test_task_162_boundary_single_item() {
+        WebVersion latest = PublicVersionLookup.selectLatest(
+                List.of(v(7L, "1.0.0", "u", LocalDateTime.of(2026, 1, 1, 0, 0))));
+        assertEquals("1.0.0", latest.version());
+    }
+
+    @Test
+    void test_task_162_boundary_limit_or_missing_field() {
+        Map<String, Object> empty = PublicVersionLookup.latestVersionResponse(null);
+        assertNull(empty.get("version"));
+        assertNull(empty.get("file_url"));
+    }
+
+    @Test
+    void test_task_162_invalid_input_rejected() {
+        Map<String, Object> resp = PublicVersionLookup.latestVersionResponse(
+                v(1L, "1.0.0", "https://x/f.zip", LocalDateTime.of(2026, 1, 1, 0, 0)));
+        assertFalse(resp.containsKey("success"), "无 ApiResponse 包装");
+        assertEquals("https://x/f.zip", resp.get("file_url"), "file_url 原样返回");
+    }
+
+    @Test
+    void test_task_162_dependency_failure_returns_actionable_message() {
+        assertTrue(PublicVersionLookup.isPublicVersionPath(PublicVersionLookup.PUBLIC_VERSION_PATH));
+        assertTrue(PublicVersionLookup.isPublicVersionPath(PublicVersionLookup.PUBLIC_VERSION_LATEST_PATH));
+        assertFalse(PublicVersionLookup.isPublicVersionPath(PublicVersionLookup.ADMIN_UPLOAD_PATH));
+    }
+}