[Statsig] Typecheck gates (#3467)

* Typecheck gates

* Lint against untyped useGate()

* Alphabetic

.eslintrc.js

···
         },
       },
     ],
+    'bsky-internal/use-typed-gates': 'error',
     'simple-import-sort/imports': [
       'warn',
       {

eslint/index.js

···
 module.exports = {
   rules: {
     'avoid-unwrapped-text': require('./avoid-unwrapped-text'),
+    'use-typed-gates': require('./use-typed-gates'),
   },
 }

eslint/use-typed-gates.js

···
+'use strict'
+
+exports.create = function create(context) {
+  return {
+    ImportSpecifier(node) {
+      if (
+        !node.local ||
+        node.local.type !== 'Identifier' ||
+        node.local.name !== 'useGate'
+      ) {
+        return
+      }
+      if (
+        node.parent.type !== 'ImportDeclaration' ||
+        !node.parent.source ||
+        node.parent.source.type !== 'Literal'
+      ) {
+        return
+      }
+      const source = node.parent.source.value
+      if (source.startsWith('.') || source.startsWith('#')) {
+        return
+      }
+      context.report({
+        node,
+        message:
+          "Use useGate() from '#/lib/statsig/statsig' instead of the one on npm.",
+      })
+    },
+  }
+}

src/lib/statsig/gates.ts

···
-import {useGate} from './statsig'
-
-export const useNewSearchGate = () => useGate('new_search')
+export type Gate =
+  // Keep this alphabetic please.
+  | 'autoexpand_suggestions_on_profile_follow'
+  | 'disable_min_shell_on_foregrounding'
+  | 'disable_poll_on_discover'
+  | 'new_search'
+  | 'show_follow_back_label'
+  | 'start_session_with_following'

src/lib/statsig/statsig.tsx

···
 import {logger} from '#/logger'
 import {useSession} from '../../state/session'
 import {LogEvents} from './events'
+import {Gate} from './gates'
 
 export type {LogEvents}
 
···
   }
 }
 
-export function useGate(gateName: string) {
+export function useGate(gateName: Gate): boolean {
   const {isLoading, value} = useStatsigGate(gateName)
   if (isLoading) {
     // This should not happen because of waitForInitialization={true}.

src/view/screens/Search/Search.tsx

···
 import {usePalette} from '#/lib/hooks/usePalette'
 import {MagnifyingGlassIcon} from '#/lib/icons'
 import {NavigationProp} from '#/lib/routes/types'
-import {useNewSearchGate} from '#/lib/statsig/gates'
+import {useGate} from '#/lib/statsig/statsig'
 import {augmentSearchQuery} from '#/lib/strings/helpers'
 import {s} from '#/lib/styles'
 import {logger} from '#/logger'
···
   const {isDesktop} = useWebMediaQueries()
   const {_} = useLingui()
 
-  const isNewSearch = useNewSearchGate()
+  const isNewSearch = useGate('new_search')
 
   const onPageSelected = React.useCallback(
     (index: number) => {