diff --git a/apps/desktop-shell/scripts/check-config.mjs b/apps/desktop-shell/scripts/check-config.mjs
index b9551396a..fcd1e31d5 100644
--- a/apps/desktop-shell/scripts/check-config.mjs
+++ b/apps/desktop-shell/scripts/check-config.mjs
@@ -1252,6 +1252,10 @@ const desktopHostBridgePayloadLimits = {
 };
 const desktopMethods = extractRustStringArrayConst(rustHostSource, 'HOST_BRIDGE_METHODS');
 const desktopEvents = extractRustStringArrayConst(rustHostSource, 'HOST_BRIDGE_EVENTS');
+const desktopErrorCodes = extractRustStringArrayConst(
+  rustHostSource,
+  'HOST_BRIDGE_ERROR_CODES',
+);
 const desktopHostBridgeProtocol = extractRustStringConst(
   rustHostSource,
   'HOST_BRIDGE_PROTOCOL',
@@ -1287,6 +1291,25 @@ if (desktopHostBridgeVersion !== sharedHostBridgeVersion) {
   );
 }
 
+assertSameList(
+  desktopErrorCodes,
+  [
+    'invalid_request',
+    'unsupported_method',
+    'unsupported_capability',
+    'timeout',
+    'cancelled',
+    'host_error',
+  ],
+  'desktop shell HostBridge error codes',
+);
+if (
+  !rustHostSource.includes('HOST_BRIDGE_ERROR_CODES.contains(&code)') ||
+  !rustHostSource.includes('desktop host bridge request failed')
+) {
+  throw new Error('desktop shell protocol must normalize non-contract host errors');
+}
+
 if (desktopPublicWebOrigin !== sharedPublicWebOrigin) {
   throw new Error(
     `desktop shell public web origin drifted: expected ${sharedPublicWebOrigin} but got ${desktopPublicWebOrigin}`,
diff --git a/apps/desktop-shell/src-tauri/src/host_bridge/protocol.rs b/apps/desktop-shell/src-tauri/src/host_bridge/protocol.rs
index 2942f4d30..66345aa2c 100644
--- a/apps/desktop-shell/src-tauri/src/host_bridge/protocol.rs
+++ b/apps/desktop-shell/src-tauri/src/host_bridge/protocol.rs
@@ -34,6 +34,14 @@ pub(crate) const HOST_BRIDGE_METHODS: [&str; 25] = [
 ];
 pub(crate) const HOST_BRIDGE_REQUEST_ID_MAX_LENGTH: usize = 120;
 const HOST_BRIDGE_RESPONSE_CACHE_MAX: usize = 128;
+const HOST_BRIDGE_ERROR_CODES: [&str; 6] = [
+    "invalid_request",
+    "unsupported_method",
+    "unsupported_capability",
+    "timeout",
+    "cancelled",
+    "host_error",
+];
 
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
@@ -159,6 +167,12 @@ pub(crate) fn failed(
     code: &'static str,
     message: impl Into<String>,
 ) -> HostBridgeResponse {
+    let (code, message) = if HOST_BRIDGE_ERROR_CODES.contains(&code) {
+        (code, message.into())
+    } else {
+        ("host_error", "desktop host bridge request failed".to_string())
+    };
+
     HostBridgeResponse {
         bridge: HOST_BRIDGE_PROTOCOL,
         version: HOST_BRIDGE_VERSION,
@@ -167,7 +181,7 @@ pub(crate) fn failed(
         result: None,
         error: Some(HostBridgeError {
             code,
-            message: message.into(),
+            message,
         }),
     }
 }
@@ -300,6 +314,20 @@ mod tests {
         assert_eq!(error.message, "invalid host bridge method");
     }
 
+    #[test]
+    fn invalid_error_code_is_normalized_before_response() {
+        let response = failed(
+            "request-1".to_string(),
+            "native_clipboard_failure",
+            "native clipboard failed",
+        );
+
+        assert!(!response.ok);
+        let error = response.error.expect("error");
+        assert_eq!(error.code, "host_error");
+        assert_eq!(error.message, "desktop host bridge request failed");
+    }
+
     #[test]
     fn host_bridge_replay_state_reuses_first_response_for_duplicate_id() {
         let replay_state = HostBridgeReplayState::default();
diff --git a/docs/project-memory/shared-memory/decision-log.md b/docs/project-memory/shared-memory/decision-log.md
index 10f36ccf4..28438ab1b 100644
--- a/docs/project-memory/shared-memory/decision-log.md
+++ b/docs/project-memory/shared-memory/decision-log.md
@@ -93,7 +93,7 @@
 - 2026-06-18 桌面壳 Tauri 命令白名单：桌面壳源码、Tauri build manifest、主窗口 capability 和本地自动生成权限目录都只能暴露 `host_bridge_request` 一个受控 command；所有桌面能力继续在 Rust 内部按 HostBridge method 白名单分发，不新增可被 H5 直接 `invoke` 的 Tauri command，也不授予插件 JS guest API。检查脚本会拒绝自动生成权限目录缺失、权限文件集合漂移、多余 command、权限列表顺序漂移和残留的自动生成权限文件。
 - 2026-06-18 桌面壳 capability 最小化：Tauri 主窗口 capability 只授予 `allow-host-bridge-request`，不得授予 `core:default`、`core:*:default`、任意 core 子权限或 dialog / fs / notification / opener / clipboard / deep-link / window-state 等插件权限。窗口、菜单、托盘、剪贴板、文件、通知和外链能力只能由 Rust 壳内部调用，再经 `host_bridge_request` 分发。
 - 2026-06-18 HostBridge request id replay：Expo 和 Tauri 壳都必须按 request id 回放首次完成结果；同 id 进行中的请求共享同一执行结果，已完成请求直接回放缓存响应，避免系统分享、外链、剪贴板、文件选择 / 保存、本地通知、窗口导航等宿主副作用被重复触发。两端配置检查和测试会锁住 replay 结构。
-- 2026-06-18 HostBridge request envelope 校验：共享契约提供 `isHostBridgeMethod` 与 `normalizeHostBridgeRequestId`，Expo 壳直接复用，Tauri 壳镜像同一白名单和 id 规则；空 id、控制字符 id、超长 id 和未知 method 都必须在 replay / 能力分发前返回 `invalid_request`，已知但当前壳未实现的登录 / 支付等 method 才返回 `unsupported_method`。Expo 壳捕获原生异常时只透传共享 `HostBridgeError.code` 白名单内且 `message` 为字符串的协议错误；未知原生错误对象统一归一为 `host_error` 和固定失败文案，不把 native 私有字段、任意错误码或非字符串 message 回传给 H5。
+- 2026-06-18 HostBridge request envelope 校验：共享契约提供 `isHostBridgeMethod` 与 `normalizeHostBridgeRequestId`，Expo 壳直接复用，Tauri 壳镜像同一白名单和 id 规则；空 id、控制字符 id、超长 id 和未知 method 都必须在 replay / 能力分发前返回 `invalid_request`，已知但当前壳未实现的登录 / 支付等 method 才返回 `unsupported_method`。Expo 壳捕获原生异常时只透传共享 `HostBridgeError.code` 白名单内且 `message` 为字符串的协议错误，Tauri 壳的 `failed(...)` 出口也必须先校验同一错误码白名单；未知原生错误对象或非法错误码统一归一为 `host_error` 和固定失败文案，不把 native 私有字段、任意错误码或非字符串 message 回传给 H5。
 - 2026-06-18 HostBridge method 白名单跨壳门禁：`packages/shared/src/contracts/hostBridge.ts` 的 `HOST_BRIDGE_METHODS` 是唯一协议来源；Expo 壳 HostBridge 分发不得处理共享契约外 method，Tauri 壳 Rust `HOST_BRIDGE_METHODS` 必须与共享契约逐项一致。新增宿主 method 必须先更新共享契约，再落两端壳实现或明确 unsupported。
 - 2026-06-18 HostBridge capability / handler 关系门禁：两端壳声明 request method capability 时必须有对应 HostBridge handler；壳 handler 处理的 method 必须已被该壳声明，登录 / 支付等 SDK-backed method 只能保留明确 `unsupported_method` 路径。事件类 capability 不要求 request handler。
 - 2026-06-18 桌面壳 CSP 分层：Tauri release `csp` 不得包含 `http://127.0.0.1:*`、`ws://127.0.0.1:*` 或其它本机调试源，本机 Vite、HMR WebSocket 和开发 frame 只允许出现在 `devCsp`。桌面壳配置检查会同时拒绝 release CSP 混入本机调试源、dev CSP 缺失本机开发源，以及 release / dev CSP 加入 `unsafe-eval`、`tauri:` 或 `file:`。