Fix server file workspace null handling

platform_web/pages/ServerDetailPage.tsx

@@ -596,7 +596,7 @@ function ServerFilesSection({ instance, session, operations }: ServerFilesSectio
   const [editor, setEditor] = useState<ServerFileEditorState>({ entry: null, key: "", draft: "", loading: false, saving: false });
 
   const activeDirectory = workspace.status === "ready" ? workspace.data.directories.find((item) => item.key === directoryKey) : undefined;
-  const canUpload = workspace.status === "ready" && activeDirectory?.scope !== "logs" && !uploadBusy;
+  const canUpload = workspace.status === "ready" && Boolean(activeDirectory) && activeDirectory?.scope !== "logs" && !uploadBusy;
   const entries = list.status === "ready" ? list.data.entries : [];
 
   const loadWorkspace = useCallback(async () => {
@@ -604,7 +604,11 @@ function ServerFilesSection({ instance, session, operations }: ServerFilesSectio
     try {
       const response = await platformApiClient.getServerFileWorkspace(instance.id);
       setWorkspace({ status: "ready", data: response });
-      setDirectoryKey((current) => current || response.defaultDirectoryKey || response.directories[0]?.key || "");
+      const nextDirectoryKey = response.defaultDirectoryKey || response.directories[0]?.key || "";
+      setDirectoryKey((current) => current || nextDirectoryKey);
+      if (!nextDirectoryKey) {
+        setList({ status: "ready", data: { serverInstanceId: response.serverInstanceId, pluginId: response.pluginId, directoryKey: "", state: "declared", entries: [], reason: "插件尚未声明文件工作区；需要在插件 manifest 中添加 fileWorkspace。" } });
+      }
     } catch (error) {
       setWorkspace({ status: "error", reason: error instanceof Error ? error.message : "文件工作区加载失败" });
       setList({ status: "error", reason: "文件工作区不可用" });
@@ -773,6 +777,7 @@ function ServerFilesSection({ instance, session, operations }: ServerFilesSectio
       </div>
       <div className="server-file-toolbar">
         <div className="server-file-directory-tabs" role="tablist" aria-label="文件目录">
+          {workspace.data.directories.length === 0 && <span className="provider-id">插件尚未声明可浏览目录</span>}
           {workspace.data.directories.map((directory) => (
             <button key={directory.key} type="button" className={cx("segmented-button", directory.key === directoryKey && "segmented-button-active")} onClick={() => { setDirectoryKey(directory.key); setRelativePath(""); }}>
               {directory.label}