Add feature gate

src/lib/statsig/gates.ts

@@ -3,3 +3,4 @@ export type Gate =
   | 'debug_show_feedcontext' // DISABLED DUE TO EME
   | 'post_feed_lang_window' // DISABLED DUE TO EME
   | 'remove_show_latest_button'
+  | 'trending_topics_beta'

src/state/trending-config.tsx

@@ -1,5 +1,6 @@
 import React from 'react'
 
+import {useGate} from '#/lib/statsig/statsig'
 import {useServiceConfigQuery} from '#/state/queries/service-config'
 import {device} from '#/storage'
 
@@ -12,19 +13,40 @@ const Context = React.createContext<Context>({
 })
 
 export function Provider({children}: React.PropsWithChildren<{}>) {
+  const gate = useGate()
   // refetches at most every minute
   const {data: config, isLoading: isInitialLoad} = useServiceConfigQuery()
   const ctx = React.useMemo<Context>(() => {
-    // previously cached value
+    /*
+     * While loading, use cached value
+     */
     const cachedEnabled = device.get(['trendingBetaEnabled'])
     if (isInitialLoad) {
       return {enabled: Boolean(cachedEnabled)}
     }
+
+    /*
+     * Doing an extra check here to reduce hits to statsig. If it's disabled on
+     * the server, we can exit early.
+     */
     const enabled = Boolean(config?.topicsEnabled)
+    if (!enabled) {
+      // cache for next reload
+      device.set(['trendingBetaEnabled'], enabled)
+      return {enabled: false}
+    }
+
+    /*
+     * Service is enabled, but also check statsig in case we're rolling back.
+     */
+    const gateEnabled = gate('trending_topics_beta')
+    const _enabled = enabled && gateEnabled
+
     // update cache
-    device.set(['trendingBetaEnabled'], enabled)
-    return {enabled}
-  }, [isInitialLoad, config])
+    device.set(['trendingBetaEnabled'], _enabled)
+
+    return {enabled: _enabled}
+  }, [isInitialLoad, config, gate])
   return <Context.Provider value={ctx}>{children}</Context.Provider>
 }