diff --git a/src/main/java/com/yunhai/svchall/service/impl/ServiceItemService.java b/src/main/java/com/yunhai/svchall/service/impl/ServiceItemService.java
index 95e7291..ff62ddd 100644
--- a/src/main/java/com/yunhai/svchall/service/impl/ServiceItemService.java
+++ b/src/main/java/com/yunhai/svchall/service/impl/ServiceItemService.java
@@ -146,7 +146,12 @@ public class ServiceItemService {
 
     public SvcItemEditVo adminGet(BoaUser user, String siteCode, Integer id) {
         SiteInfo site = siteGuard.requireSiteManager(user, siteCode);
-        return SvcItemEditVo.of(requireItem(site, id));
+        ServiceItem item = requireItem(site, id);
+        SvcItemEditVo vo = SvcItemEditVo.of(item);
+        // 封面出参绝对化（与他端列表/详情口径一致），否则管理端编辑页 <img> 拿相对路径 404，看着像"封面没保存上"；
+        // 保存侧 toRelativeIfLocal 会再相对化，往返幂等
+        vo.setCoverImage(FileUtil.absolutizePlain(item.getCoverImage()));
+        return vo;
     }
 
     /** 保存：itemCode 唯一/字典键归属/部门快照/applyUrl 白名单/表单与流程绑定校验；指南附件全量重绑 */
@@ -801,13 +806,13 @@ public class ServiceItemService {
         return StringUtils.hasText(value) ? value : null;
     }
 
-    /** 封面：本应用上传的相对路径原样入库；外部完整 URL 截取 /upload/ 相对段（与附件同口径） */
+    /** 封面：本应用上传的相对路径原样入库；外部完整 URL 截取 /upload/ 相对段（与附件同口径）；折叠历史叠加段自愈 */
     private static String toRelativeIfLocal(String coverImage) {
         if (!StringUtils.hasText(coverImage)) {
             return null;
         }
         int idx = coverImage.indexOf("/upload/");
-        return idx >= 0 ? coverImage.substring(idx) : coverImage;
+        return idx >= 0 ? FileUtil.squashDuplicateUploadSeg(coverImage.substring(idx)) : coverImage;
     }
 
     private static Map<String, Long> countMap(List<Object[]> rows) {
diff --git a/src/main/java/com/yunhai/svchall/utils/FileUtil.java b/src/main/java/com/yunhai/svchall/utils/FileUtil.java
index 0521240..89ce0f8 100644
--- a/src/main/java/com/yunhai/svchall/utils/FileUtil.java
+++ b/src/main/java/com/yunhai/svchall/utils/FileUtil.java
@@ -80,7 +80,23 @@ public final class FileUtil {
         }
         String base = publicBaseUrl.endsWith("/") ? publicBaseUrl : publicBaseUrl + "/";
         String rel = relativeUrl.startsWith("/") ? relativeUrl.substring(1) : relativeUrl;
-        return base + rel;
+        return squashDuplicateUploadSeg(base + rel);
+    }
+
+    /**
+     * 折叠连续 {@code /upload/} 叠加段。存储布局是 {@code /upload/{image|file}/uuid.ext}，
+     * "upload" 不是合法类型名，{@code /upload/upload/} 必为历史损伤：生产 public-base-url 以
+     * /upload/ 结尾而库内相对值以 /upload/ 开头，旧拼接每经一轮"绝对化→存库"多叠一层
+     * （实测部署态封面叠到四层致门户裂图）。出口统一折叠即可对已损伤库值自愈。
+     */
+    public static String squashDuplicateUploadSeg(String url) {
+        if (url == null || url.isEmpty()) {
+            return url;
+        }
+        while (url.contains("/upload/upload/")) {
+            url = url.replace("/upload/upload/", "/upload/");
+        }
+        return url;
     }
 
     /**
@@ -93,10 +109,11 @@ public final class FileUtil {
             return html;
         }
         String base = publicBaseUrl.endsWith("/") ? publicBaseUrl : publicBaseUrl + "/";
-        return html.replace("src=\"/upload/", "src=\"" + base + "upload/")
+        String replaced = html.replace("src=\"/upload/", "src=\"" + base + "upload/")
                 .replace("href=\"/upload/", "href=\"" + base + "upload/")
                 .replace("src='/upload/", "src='" + base + "upload/")
                 .replace("href='/upload/", "href='" + base + "upload/");
+        return squashDuplicateUploadSeg(replaced);
     }
 
     /** 裸相对封面值 → 完整 URL（空值原样；绝对地址原样） */
diff --git a/src/test/java/com/yunhai/svchall/utils/FileUtilTest.java b/src/test/java/com/yunhai/svchall/utils/FileUtilTest.java
new file mode 100644
index 0000000..e5e384e
--- /dev/null
+++ b/src/test/java/com/yunhai/svchall/utils/FileUtilTest.java
@@ -0,0 +1,102 @@
+package com.yunhai.svchall.utils;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * 文件 URL 拼接契约单测（2026-09-20 封面裂图修复）：
+ * 生产 public-base-url 以 /upload/ 结尾（https://base.yunhaixingtong.com/svc-hall/upload/），
+ * 而库内相对值以 /upload/ 开头——拼接必须不产生 /upload/upload/ 叠加，
+ * 且对历史已叠加损伤值（/upload/upload/…，实测库里叠了三层导致门户裂图）具备折叠自愈能力。
+ * 不变式：存储布局 /upload/{image|file}/uuid.ext，upload 不是合法类型名，/upload/upload/ 永远非法。
+ */
+@DisplayName("FileUtil - 文件 URL 拼接与 /upload/ 段折叠")
+class FileUtilTest {
+
+    /** 生产形态：带 ctx 且以 /upload/ 结尾 */
+    private static final String PROD_BASE = "http://base.yunhaixingtong.com/svc-hall/upload/";
+    /** 本地形态：裸 host 以 /upload/ 结尾 */
+    private static final String LOCAL_BASE = "http://localhost:8086/upload/";
+
+    @AfterEach
+    void reset() {
+        FileUtil.init("target/test-fileutil-root", "http://localhost:8086/upload/");
+    }
+
+    @Test
+    @DisplayName("buildUrl：生产 base+/upload/ 结尾，干净相对值不叠加")
+    void buildUrlProdBaseNoDouble() {
+        FileUtil.init("target/test-fileutil-root", PROD_BASE);
+        assertThat(FileUtil.buildUrl("/upload/image/e7df.png"))
+                .isEqualTo("http://base.yunhaixingtong.com/svc-hall/upload/image/e7df.png");
+    }
+
+    @Test
+    @DisplayName("buildUrl：本地 base+/upload/ 结尾，干净相对值不叠加")
+    void buildUrlLocalBaseNoDouble() {
+        FileUtil.init("target/test-fileutil-root", LOCAL_BASE);
+        assertThat(FileUtil.buildUrl("/upload/file/abc.pdf"))
+                .isEqualTo("http://localhost:8086/upload/file/abc.pdf");
+    }
+
+    @Test
+    @DisplayName("buildUrl：base 不带 /upload/ 尾时行为不变")
+    void buildUrlBaseWithoutUploadTail() {
+        FileUtil.init("target/test-fileutil-root", "http://localhost:8086");
+        assertThat(FileUtil.buildUrl("/upload/image/a.png"))
+                .isEqualTo("http://localhost:8086/upload/image/a.png");
+    }
+
+    @Test
+    @DisplayName("buildUrl：历史损伤相对值（叠三层）出口折叠自愈——部署态门户裂图修复点")
+    void buildUrlSquashesCorruptedRelative() {
+        FileUtil.init("target/test-fileutil-root", PROD_BASE);
+        assertThat(FileUtil.buildUrl("/upload/upload/upload/image/e7df.png"))
+                .isEqualTo("http://base.yunhaixingtong.com/svc-hall/upload/image/e7df.png");
+    }
+
+    @Test
+    @DisplayName("absolutizePlain：绝对地址原样返回（含历史损伤值，不篡改外链）")
+    void absolutizePlainPassthrough() {
+        FileUtil.init("target/test-fileutil-root", PROD_BASE);
+        String external = "https://cdn.example.com/pic.png";
+        assertThat(FileUtil.absolutizePlain(external)).isEqualTo(external);
+    }
+
+    @Test
+    @DisplayName("absolutize：富文本内链绝对化不叠加 /upload/")
+    void absolutizeHtmlNoDouble() {
+        FileUtil.init("target/test-fileutil-root", PROD_BASE);
+        String html = "<p><img src=\"/upload/image/a.png\">§<a href=\"/upload/file/b.pdf\">附件</a></p>";
+        String out = FileUtil.absolutize(html);
+        assertThat(out).contains("src=\"http://base.yunhaixingtong.com/svc-hall/upload/image/a.png\"");
+        assertThat(out).contains("href=\"http://base.yunhaixingtong.com/svc-hall/upload/file/b.pdf\"");
+        assertThat(out).doesNotContain("/upload/upload/");
+    }
+
+    @Test
+    @DisplayName("squashDuplicateUploadSeg：任意层数叠加收敛为一层")
+    void squashCollapsesAnyDepth() {
+        assertThat(FileUtil.squashDuplicateUploadSeg("/upload/upload/upload/upload/image/x.png"))
+                .isEqualTo("/upload/image/x.png");
+        assertThat(FileUtil.squashDuplicateUploadSeg("/upload/image/ok.png"))
+                .isEqualTo("/upload/image/ok.png");
+        assertThat(FileUtil.squashDuplicateUploadSeg(null)).isNull();
+    }
+
+    @Test
+    @DisplayName("往返幂等：绝对化 → 存库相对化 → 再绝对化，值稳定不增长")
+    void roundTripIdempotent() {
+        FileUtil.init("target/test-fileutil-root", PROD_BASE);
+        String stored = "/upload/image/e7df.png";
+        String out1 = FileUtil.absolutizePlain(stored);
+        // 模拟保存侧：取第一个 /upload/ 起的相对段（ServiceItemService.toRelativeIfLocal 同款逻辑）
+        String back = out1.substring(out1.indexOf("/upload/"));
+        String out2 = FileUtil.absolutizePlain(back);
+        assertThat(out2).isEqualTo(out1);
+        assertThat(out2).doesNotContain("/upload/upload/");
+    }
+}