diff --git a/src/main/java/com/yunhai/platform/gateway/filter/SanitizeFilter.java b/src/main/java/com/yunhai/platform/gateway/filter/SanitizeFilter.java
index 552da89..13dd121 100644
--- a/src/main/java/com/yunhai/platform/gateway/filter/SanitizeFilter.java
+++ b/src/main/java/com/yunhai/platform/gateway/filter/SanitizeFilter.java
@@ -22,7 +22,8 @@ import java.io.IOException;
  * 含 {@code ..}（含编码形态 {@code %2e%2e}）、路径含双斜杠 {@code //}、
  * 含控制字符（0x00-0x1f，含空字节）。
  * <p>
- * 通过后把<b>原始 URI</b>（逐字节不改写——T0.12 forwardUrl 与 T1.2 canonical 都消费原始形态）
+ * 通过后把<b>业务 URI</b>（ctx 非空时已剥 context-path；ctx 为空时即原始 URI，逐字节不改写——
+ * T0.12 forwardUrl 与 T1.2 canonical 都消费此形态）
  * 与剥掉 target 首段后的路径存 request attribute，后续过滤器与转发器一律取此值。
  */
 @Component
@@ -41,7 +42,7 @@ public class SanitizeFilter implements Filter {
         }
         HttpServletRequest req = (HttpServletRequest) request;
         HttpServletResponse res = (HttpServletResponse) response;
-        String uri = req.getRequestURI();
+        String uri = stripContextPath(req.getRequestURI(), req.getContextPath());
         String decoded = percentDecode(uri);
         if (isRejected(decoded)) {
             EnvelopeWriter.writeBare(res, 400);
@@ -101,4 +102,18 @@ public class SanitizeFilter implements Filter {
         int second = uri.indexOf('/', 1);
         return second < 0 ? uri : uri.substring(second);
     }
+
+    /**
+     * 剥 context-path：Servlet 规范下 getRequestURI() = ctx + servletPath + pathInfo，
+     * 而网关的业务路径空间以 target 为首段——ctx 非空时须先剥离，下游（白名单/target 判定/
+     * 台账/验签路径）看到的才是与 ctx 解耦的业务 URI。ctx 为空的应用 getContextPath() 返回 ""，
+     * 此处零行为变化（向后兼容）。
+     */
+    static String stripContextPath(String uri, String contextPath) {
+        if (uri == null || contextPath == null || contextPath.isEmpty()) {
+            return uri;
+        }
+        String prefix = contextPath + "/";
+        return uri.startsWith(prefix) ? uri.substring(contextPath.length()) : uri;
+    }
 }
diff --git a/src/test/java/com/yunhai/platform/gateway/filter/SanitizeFilterTest.java b/src/test/java/com/yunhai/platform/gateway/filter/SanitizeFilterTest.java
index ae95d96..3d00bfd 100644
--- a/src/test/java/com/yunhai/platform/gateway/filter/SanitizeFilterTest.java
+++ b/src/test/java/com/yunhai/platform/gateway/filter/SanitizeFilterTest.java
@@ -9,8 +9,9 @@ import org.springframework.mock.web.MockHttpServletResponse;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * SanitizeFilter 五用例（T1.1 TDD）：路径穿越（明文/编码）、双斜杠、控制字符均裸 400；
- * 正常路径放行且两个 attribute 契约已设。
+ * SanitizeFilter 九用例（T1.1 TDD）：路径穿越（明文/编码）、双斜杠、控制字符均裸 400；
+ * 正常路径放行且两个 attribute 契约已设。ctx 非空时先剥 context-path 再判定，
+ * 前缀相似不误剥，ctx 为空零行为变化。
  */
 class SanitizeFilterTest {
 
@@ -58,4 +59,51 @@ class SanitizeFilterTest {
         assertThat(req.getAttribute(SanitizeFilter.ATTR_STRIPPED_PATH))
                 .as("stripped.path = 剥 target 首段").isEqualTo("/oapi/x");
     }
+
+    @Test
+    void ctx非空_剥除后存业务URI() throws Exception {
+        MockHttpServletRequest req = new MockHttpServletRequest("GET", "/open-gateway/notice/oapi/x");
+        req.setContextPath("/open-gateway");
+        MockHttpServletResponse res = new MockHttpServletResponse();
+        MockFilterChain chain = new MockFilterChain();
+        new SanitizeFilter().doFilter(req, res, chain);
+        assertThat(res.getStatus()).as("ctx 内正常路径放行").isEqualTo(200);
+        assertThat(req.getAttribute(SanitizeFilter.ATTR_SANITIZED_URI))
+                .as("sanitized.uri = 业务 URI（已去 ctx）").isEqualTo("/notice/oapi/x");
+        assertThat(req.getAttribute(SanitizeFilter.ATTR_STRIPPED_PATH))
+                .as("stripped.path 基于业务 URI 剥 target").isEqualTo("/oapi/x");
+    }
+
+    @Test
+    void ctx非空_前缀相似不误剥() throws Exception {
+        MockHttpServletRequest req = new MockHttpServletRequest("GET", "/open-gateway-other/oapi/x");
+        req.setContextPath("/open-gateway");
+        MockHttpServletResponse res = new MockHttpServletResponse();
+        MockFilterChain chain = new MockFilterChain();
+        new SanitizeFilter().doFilter(req, res, chain);
+        assertThat(req.getAttribute(SanitizeFilter.ATTR_SANITIZED_URI))
+                .as("前缀相似不剥，交由 target 判定 404").isEqualTo("/open-gateway-other/oapi/x");
+    }
+
+    @Test
+    void ctx非空_剥后双斜杠仍拒() throws Exception {
+        MockHttpServletRequest req = new MockHttpServletRequest("GET", "/open-gateway//x");
+        req.setContextPath("/open-gateway");
+        MockHttpServletResponse res = new MockHttpServletResponse();
+        MockFilterChain chain = new MockFilterChain();
+        new SanitizeFilter().doFilter(req, res, chain);
+        assertThat(res.getStatus()).as("剥 ctx 后 // 仍裸 400").isEqualTo(400);
+    }
+
+    @Test
+    void stripContextPath_边界() {
+        assertThat(SanitizeFilter.stripContextPath("/userbase/oapi/x", "")).isEqualTo("/userbase/oapi/x");
+        assertThat(SanitizeFilter.stripContextPath("/userbase/oapi/x", null)).isEqualTo("/userbase/oapi/x");
+        assertThat(SanitizeFilter.stripContextPath(null, "/open-gateway")).isNull();
+        assertThat(SanitizeFilter.stripContextPath("/open-gateway", "/open-gateway"))
+                .as("裸 ctx 不剥（无尾斜杠），原样走 404 语义").isEqualTo("/open-gateway");
+        assertThat(SanitizeFilter.stripContextPath("/open-gateway/x", "/open-gateway")).isEqualTo("/x");
+        assertThat(SanitizeFilter.stripContextPath("/open-gateway-other/x", "/open-gateway"))
+                .isEqualTo("/open-gateway-other/x");
+    }
 }