Update guide presentation and route preview gating

src/domain/guideReadiness.ts

@@ -4,7 +4,7 @@ import type {
 
 export const NAV_ROUTE_GRAPH_READY = false
 
-export const NAV_ROUTE_UNAVAILABLE_MESSAGE = '当前支持位置预览、三维位置预览与室外入口参考'
+export const NAV_ROUTE_UNAVAILABLE_MESSAGE = '当前暂不支持正式导航，可查看位置预览、路线示意和室外参考'
 
 export const NAV_ROUTE_READINESS: GuideRouteReadiness = {
   ready: NAV_ROUTE_GRAPH_READY,
@@ -12,4 +12,34 @@ export const NAV_ROUTE_READINESS: GuideRouteReadiness = {
   requiredData: ['route_graph', 'nav_data']
 }
 
+export const applyRouteReadinessGate = (
+  readiness: GuideRouteReadiness | null | undefined
+): GuideRouteReadiness => {
+  const fallback = readiness || NAV_ROUTE_READINESS
+  const requiredData = fallback.requiredData?.length
+    ? fallback.requiredData
+    : NAV_ROUTE_READINESS.requiredData
+
+  if (!NAV_ROUTE_GRAPH_READY) {
+    return {
+      ...NAV_ROUTE_READINESS,
+      requiredData
+    }
+  }
+
+  if (!fallback.ready) {
+    return {
+      ...fallback,
+      ready: false,
+      message: fallback.message || NAV_ROUTE_UNAVAILABLE_MESSAGE,
+      requiredData
+    }
+  }
+
+  return {
+    ...fallback,
+    requiredData
+  }
+}
+
 export const NAV_ASSET_BASE_URL = '/static/nav-assets/codex_nav_20260621_175310_museum_default_centerline_finalxy'