diff --git a/docs/plans/2026-08-17-edge151-origin-portless-fence.md b/docs/plans/2026-08-17-edge151-origin-portless-fence.md
new file mode 100644
index 0000000..1c10a97
--- /dev/null
+++ b/docs/plans/2026-08-17-edge151-origin-portless-fence.md
@@ -0,0 +1,50 @@
+# Edge 151 无端口 Origin 导致的侧边栏 403 forbidden 修复
+
+日期：2026-08-17
+
+## 现象
+
+Windows + Edge 151（151.0.4129.86）下，`dsh web` 主应用一切正常，但 better-sidebar 的文件管理（Explorer / 文件树）显示 `forbidden`。抓包确认：`POST /sidebar/api/fs.tree` 返回 `403`，响应体为 `{"ok":false,"error":{"code":"forbidden","message":"forbidden"}}`——命中插件自身信任栅栏的拒绝分支，而不是业务错误。
+
+## 根因
+
+`src/trust-fence.ts` 是 DSH `/api` 网关信任栅栏（`@deepseek-ai/dsh-client-connection` 的 `api-request-trust.ts`）的行为镜像。Origin 校验一段，镜像版仍按 `host`（含端口）比较：
+
+```ts
+return new URL(origin).host === hostUrl.host
+```
+
+DSH 官方栅栏后来修复为按 `hostname` 比较，理由是：**部分 Chromium 构建（Edge 151）会把非默认端口 loopback 页面的 Origin 序列化为不带端口的形式**（`http://127.0.0.1:3080` 的页面，fetch 携带 `Origin: http://127.0.0.1`）。
+
+于是 Edge 151 下：
+
+- 页面 `http://127.0.0.1:3080` 发出的请求，`Origin: http://127.0.0.1`，`Host: 127.0.0.1:3080`；
+- 镜像栅栏比较 `new URL('http://127.0.0.1').host`（= `127.0.0.1`）与 Host `127.0.0.1:3080` → 不等 → 403；
+- DSH 自己的 `/api` 栅栏比较 hostname → 相等 → 放行，所以主应用正常，只有 `/sidebar/*` 全部 403。
+
+镜像与官方行为漂移，正好打破镜像文件头声明的「behaviorally identical」契约。
+
+## 证据
+
+- 本机 Edge 版本 151.0.4129.86（DSH 注释点名的构建）。
+- curl 实测（对运行中的 `dsh web`，`/sidebar/api/fs.list` 用错方法名以区分 403 与方法分发）：
+  - `Origin: http://127.0.0.1:3080`（带端口）→ 200 `unknown sidebar API method`（过了栅栏）；
+  - `Origin: http://127.0.0.1`（Edge 151 形式）→ 403 `forbidden`。
+- DSH 修复参考：`packages/client/connection/src/api-request-trust.ts`（注释点名 Edge 151）及测试 `tests/api-request-trust.host.spec.ts` 的「accepts an Origin that names the Host hostname without its port (Edge 151 serialization)」。
+
+## 方案
+
+1. `src/trust-fence.ts` 的 Origin 校验改为 `new URL(origin).hostname === hostUrl.hostname`，注释写明与 DSH 官方栅栏保持一致的语义与理由（Host 栅栏已绑定 authority，端口不再重决信任）。
+2. `tests/trusted-hosts.spec.ts` 增加回归用例：loopback Host + 不带端口的 Origin → 200；同时保留带端口与跨域拒绝用例。
+
+行为语义变化（有意为之，与 DSH 一致）：Origin 与 Host 的 hostname 相同即认为同源，端口差异不再拒绝。安全前提不变：Host 栅栏仍要求 Host 为 loopback 或 `webRuntime.trustedHosts` 授权项，`sec-fetch-site: cross-site` 仍一律拒绝。
+
+## 验证
+
+1. `pnpm test`（vitest）新增用例通过，既有 trusted-hosts 用例不回归。
+2. `pnpm typecheck`。
+3. 本地挂载：`pnpm build` 后覆盖 web profile 的 node_modules 产物，重启 `dsh web`，curl 以 `Origin: http://127.0.0.1`（无端口）请求 `/sidebar/api/*` 应进入方法分发（404 unknown method）而非 403；浏览器硬刷新后文件管理恢复。
+
+## 发布
+
+按仓库 §0 流程：`fix/*` 分支 → PR → review 合并 → bump 版本打 tag 走 release workflow。即时修复可先本地覆盖 profile 产物验证，正式生效待 0.13.1 发布后 `dsh plugin add dsh-better-sidebar@latest`。
diff --git a/src/trust-fence.ts b/src/trust-fence.ts
index c1abda5..431d6f5 100644
--- a/src/trust-fence.ts
+++ b/src/trust-fence.ts
@@ -67,10 +67,17 @@ export function isTrustedApiRequest(request: ApiTrustRequest, trustedHosts: read
   if (hostUrl === undefined) return false
   if (!isLoopbackHostname(hostUrl.hostname) && !isTrustedAuthority(hostUrl, trustedHosts)) return false
   if (header(request.headers, 'sec-fetch-site') === 'cross-site') return false
+  // Origin fence: when a browser attaches an Origin it must name this
+  // hostname (the Host fence above already bound the authority, so the port
+  // must not re-decide trust). Comparing hostname, not host: some Chromium
+  // builds (Edge 151) serialize the Origin of a non-default-port loopback page
+  // without the port, and refusing those bricks every /sidebar route. Absent
+  // Origin is fine — the Host fence above already bound the request. The
+  // literal "null" (sandboxed iframes, file: pages) is an opaque origin, refused.
   const origin = header(request.headers, 'origin')
   if (origin === undefined) return true
   try {
-    return new URL(origin).host === hostUrl.host
+    return new URL(origin).hostname === hostUrl.hostname
   } catch {
     return false
   }
diff --git a/tests/trusted-hosts.spec.ts b/tests/trusted-hosts.spec.ts
index 3bc7432..0c5ae83 100644
--- a/tests/trusted-hosts.spec.ts
+++ b/tests/trusted-hosts.spec.ts
@@ -147,6 +147,55 @@ describe('remote-access trust (webRuntime.trustedHosts)', () => {
     }
   })
 
+  it('accepts an Origin that names the Host hostname without its port (Edge 151 serialization)', async () => {
+    // Some Chromium builds serialize the Origin of a non-default-port loopback
+    // page without the port; refusing those bricks every /sidebar route.
+    const { api, cleanup } = mount([])
+    try {
+      const res = fakeRes()
+      await api(req('POST', '/sidebar/api/session.cwd', {
+        host: '127.0.0.1:3080',
+        'sec-fetch-site': 'same-origin',
+        origin: 'http://127.0.0.1',
+      }, '{"sessionId":"test-session"}'), res as unknown as ServerResponse)
+      expect(res.status).toBe(200)
+    } finally {
+      cleanup()
+    }
+  })
+
+  it('rejects an Origin whose hostname differs from the Host even on loopback', async () => {
+    // hostname, not port, re-decides trust: a same-127/8 address that is not
+    // the page's own hostname is still a different authority.
+    const { api, cleanup } = mount([])
+    try {
+      const res = fakeRes()
+      await api(req('POST', '/sidebar/api/session.cwd', {
+        host: '127.0.0.1:3080',
+        'sec-fetch-site': 'same-origin',
+        origin: 'http://127.0.0.2',
+      }, '{"sessionId":"test-session"}'), res as unknown as ServerResponse)
+      expect(res.status).toBe(403)
+    } finally {
+      cleanup()
+    }
+  })
+
+  it('rejects the opaque "null" origin', async () => {
+    const { api, cleanup } = mount([])
+    try {
+      const res = fakeRes()
+      await api(req('POST', '/sidebar/api/session.cwd', {
+        host: '127.0.0.1:3080',
+        'sec-fetch-site': 'same-origin',
+        origin: 'null',
+      }, '{"sessionId":"test-session"}'), res as unknown as ServerResponse)
+      expect(res.status).toBe(403)
+    } finally {
+      cleanup()
+    }
+  })
+
   it('rejects cross-site browser markers even for a trusted host', async () => {
     const { api, cleanup } = mount(['example.com'])
     try {