feat(10-01): harden the admin cookie session and prefix boot guards

- refresh and logout read the Bearer header first, then the summer_admin
  cookie; a cookie refresh rotates the cookie without a token in the body and
  logout always expires the cookie
- backend.cookie_secure (default true) may drop Secure outside production only
- activation rejects controller vendor segments api, assets, login, settings
- BuildRouter rejects non-cabana routes at or under the admin prefix
- SPA single-flights refresh on 401, replays once, and refreshes proactively
  at 80 percent of expires_in; dist rebuilt
- scripts/check-admin-dist.sh rebuilds the SPA and fails on dist drift
- tests: TestPhase10CookieAuth, TestPhase10CSRF, TestPhase10Prefix,
  TestPhase10AdminPrefixCollision, boardwalk serving and header tests

admin/src/api/client.ts

@@ -2,6 +2,11 @@
 // paths (D-15). Every request carries X-Requested-With (the CSRF header the
 // admin API requires on state-changing cookie requests, D-19) and same-origin
 // credentials; the JWT lives in an HttpOnly cookie the SPA never reads.
+//
+// A 401 on any call other than login and refresh starts one shared refresh
+// (concurrent 401s wait for the same one); on success the original request is
+// replayed once from a clone taken before it was sent. A failed refresh or a
+// second 401 reports the session as gone.
 import createClient, { type Middleware } from 'openapi-fetch'
 import type { paths } from './schema'
 import { runtime } from '../app/runtime'
@@ -9,28 +14,81 @@ import { runtime } from '../app/runtime'
 export const REQUESTED_WITH = 'XMLHttpRequest'
 
 type UnauthorizedHandler = () => void
+type RefreshedHandler = (expiresIn: number | null) => void
 
 let unauthorizedHandler: UnauthorizedHandler | null = null
+let refreshedHandler: RefreshedHandler | null = null
+let inflight: Promise<boolean> | null = null
+const replays = new WeakMap<Request, Request>()
 
-/** Registers what happens when an API call other than login returns 401. */
+/** Registers what happens when the session cannot be recovered after a 401. */
 export function onUnauthorized(handler: UnauthorizedHandler | null): void {
   unauthorizedHandler = handler
 }
 
-function isLoginRequest(request: Request): boolean {
-  return new URL(request.url, 'http://local').pathname.endsWith('/auth/login')
+/** Registers a listener for successful refreshes (the new access lifetime). */
+export function onRefreshed(handler: RefreshedHandler | null): void {
+  refreshedHandler = handler
+}
+
+function pathOf(request: Request): string {
+  return new URL(request.url, 'http://local').pathname
+}
+
+function isAuthEndpoint(request: Request): boolean {
+  const path = pathOf(request)
+  return path.endsWith('/auth/login') || path.endsWith('/auth/refresh')
+}
+
+/**
+ * Refreshes the cookie session. Concurrent callers share one request; the
+ * promise resolves to whether the server issued a new session.
+ */
+export function refreshSession(): Promise<boolean> {
+  if (inflight) {
+    return inflight
+  }
+  inflight = (async () => {
+    try {
+      const { data, response } = await api.POST('/auth/refresh')
+      if (!response.ok || !data) {
+        return false
+      }
+      const expiresIn = data.data.expires_in
+      refreshedHandler?.(typeof expiresIn === 'number' ? expiresIn : null)
+      return true
+    } catch {
+      return false
+    } finally {
+      inflight = null
+    }
+  })()
+  return inflight
 }
 
 export const transport: Middleware = {
   onRequest({ request }) {
     request.headers.set('X-Requested-With', REQUESTED_WITH)
+    if (!isAuthEndpoint(request)) {
+      replays.set(request, request.clone())
+    }
     return request
   },
-  onResponse({ request, response }) {
-    if (response.status === 401 && !isLoginRequest(request)) {
+  async onResponse({ request, response }) {
+    if (response.status !== 401 || isAuthEndpoint(request)) {
+      return response
+    }
+    const replay = replays.get(request)
+    replays.delete(request)
+    if (!replay || !(await refreshSession())) {
+      unauthorizedHandler?.()
+      return response
+    }
+    const retried = await globalThis.fetch(replay)
+    if (retried.status === 401) {
       unauthorizedHandler?.()
     }
-    return response
+    return retried
   },
 }