fix(platform): keep route permissions intact across router rebuilds

Opening a board and clicking 编辑 landed on /404 while the board list
itself stayed reachable — the two routes disagreed about the same
`board` permission.

The route filter wrote its result back into the shared `privateRouter`
(`cur.children = filterMenuItem(cur.children)`), and those children had
already had their `permission` key destructured away. The router is
rebuilt whenever `user` changes, so from the second build on nested routes
carried no permission to check and survived unconditionally, while
top-level routes — the board editor among them — were still filtered. A
user without `board` therefore kept the list page and lost its editor.

The filter now builds a fresh tree and never touches the shared table, so
both routes make the same decision. The regression test fails on the old
code with exactly the reported asymmetry: `dashboard` retained,
`dashboard/:id` dropped.

src/frontend/platform/src/routes/index.tsx

@@ -205,28 +205,29 @@ export const getPrivateRouter = (
   permissions: string[],
   opts?: { menuApprovalMode?: boolean },
 ) => {
-  const filterMenuItem = (_privateRouter) => {
-    const result = _privateRouter.reduce((res, cur) => {
-      // 递归
-      if (cur.children?.length) {
-        cur.children = filterMenuItem(cur.children)
-      }
+  // Builds a fresh route tree; `privateRouter` itself is never touched. It used
+  // to write the filtered children back into the shared table, and those copies
+  // had already lost their `permission` key — so from the second build on (the
+  // router is rebuilt whenever `user` changes) nested routes were no longer
+  // filtered at all, while top-level ones still were. That asymmetry let a user
+  // reach a list page they should not see and then hit /404 on its top-level
+  // editor route.
+  const filterMenuItem = (routes) =>
+    routes.reduce((res, cur) => {
+      const { permission, children, ...other } = cur
+      const next = children?.length ? { ...other, children: filterMenuItem(children) } : { ...other }
 
-      const { permission, ...other } = cur
       if (permission && !hasRoutePermission(permissions, permission)) {
         if (opts?.menuApprovalMode) {
-          res.push({ ...other, element: <MenuPermissionPlaceholder /> })
+          res.push({ ...next, element: <MenuPermissionPlaceholder /> })
         }
         return res
       }
 
-      res.push(other)
+      res.push(next)
       return res
     }, [])
 
-    return result
-  }
-
   return createBrowserRouter(permissions ? filterMenuItem(privateRouter) : [],
     baseConfig)
 }

src/frontend/platform/src/test/routeFilterPurity.test.ts

@@ -0,0 +1,38 @@
+/**
+ * The route filter must not touch the shared route table.
+ *
+ * It used to write filtered children back into `privateRouter`, and those copies
+ * had already lost their `permission` key — so every build after the first left
+ * nested routes unfiltered while top-level ones were still filtered. A user then
+ * reached a list page they should not see and hit /404 on its editor route.
+ */
+import { describe, expect, it } from "vitest"
+
+import { getPrivateRouter } from "@/routes"
+
+type RouteNode = { path?: string; children?: RouteNode[] }
+
+const pathsOf = (routes: RouteNode[]): string[] =>
+  routes.flatMap((route) => [route.path, ...(route.children ? pathsOf(route.children) : [])]).filter(Boolean)
+
+describe("getPrivateRouter", () => {
+  it("filters the same way however many times it is called", () => {
+    const withBoard = pathsOf(getPrivateRouter(["board"]).routes as RouteNode[])
+    expect(withBoard).toContain("dashboard")
+    expect(withBoard).toContain("dashboard/:id")
+
+    const withoutBoard = pathsOf(getPrivateRouter([]).routes as RouteNode[])
+    expect(withoutBoard).not.toContain("dashboard")
+    expect(withoutBoard).not.toContain("dashboard/:id")
+
+    const withBoardAgain = pathsOf(getPrivateRouter(["board"]).routes as RouteNode[])
+    expect(withBoardAgain).toEqual(withBoard)
+  })
+
+  it("keeps a denied route as a placeholder in menu-approval mode", () => {
+    const paths = pathsOf(getPrivateRouter([], { menuApprovalMode: true }).routes as RouteNode[])
+
+    expect(paths).toContain("dashboard")
+    expect(paths).toContain("dashboard/:id")
+  })
+})