Clarify primary algo usage

src/state/queries/post-feed.ts

@@ -43,8 +43,12 @@ type AuthorFilter =
   | 'posts_with_media'
 type FeedUri = string
 type ListUri = string
+/**
+ * Represents a "not found" state, that results in the left-most tab being
+ * selected on the Home screen.
+ */
+export const DEFAULT_FEED_DESCRIPTOR = '__default__'
 export type FeedDescriptor =
-  | 'primary-algo'
   | 'home'
   | 'following'
   | `author|${ActorDid}|${AuthorFilter}`

src/state/shell/selected-feed.tsx

@@ -4,6 +4,7 @@ import {Gate} from '#/lib/statsig/gates'
 import {useGate} from '#/lib/statsig/statsig'
 import {isWeb} from '#/platform/detection'
 import * as persisted from '#/state/persisted'
+import {DEFAULT_FEED_DESCRIPTOR} from '#/state/queries/post-feed'
 
 type StateContext = string
 type SetContext = (v: string) => void
@@ -15,7 +16,7 @@ function getInitialFeed(gate: (gateName: Gate) => boolean) {
   const isPrimaryAlgoExperimentEnabled = gate(
     'reduced_onboarding_and_home_algo',
   )
-  let feed = isPrimaryAlgoExperimentEnabled ? 'primary-algo' : 'home'
+  let feed = DEFAULT_FEED_DESCRIPTOR
 
   if (isWeb) {
     if (window.location.pathname === '/') {
@@ -40,13 +41,15 @@ function getInitialFeed(gate: (gateName: Gate) => boolean) {
   }
 
   if (isPrimaryAlgoExperimentEnabled) {
+    // following feed
     if (feed === 'home') {
       return 'home'
     }
-    return 'primary-algo'
+    // or left-most tab
+    return DEFAULT_FEED_DESCRIPTOR
   }
 
-  return 'home'
+  return DEFAULT_FEED_DESCRIPTOR
 }
 
 export function Provider({children}: React.PropsWithChildren<{}>) {

src/view/com/home/HomeHeader.tsx

@@ -24,9 +24,7 @@ export function HomeHeader(
 
   const hasPinnedCustom = React.useMemo<boolean>(() => {
     if (!hasSession) return false
-    return feeds.some(
-      tab => !['home', 'primary-algo', 'following'].includes(tab.uri),
-    )
+    return feeds.some(tab => !['home', 'following'].includes(tab.uri))
   }, [feeds, hasSession])
 
   const items = React.useMemo(() => {

src/view/screens/Home.tsx

@@ -74,6 +74,10 @@ function HomeScreenReady({
   const rawSelectedFeed = useSelectedFeed()
   const setSelectedFeed = useSetSelectedFeed()
   const maybeFoundIndex = allFeeds.indexOf(rawSelectedFeed as FeedDescriptor)
+  /*
+   * N.B. if DEFAULT_FEED_DESCRIPTOR, maybeFoundIndex will be -1 and we'll fall
+   * back to 0
+   */
   const selectedIndex = Math.max(0, maybeFoundIndex)
   const selectedFeed = allFeeds[selectedIndex]
 

src/view/shell/desktop/Feeds.tsx

@@ -36,8 +36,6 @@ export function DesktopFeeds() {
         let feed: FeedDescriptor
         if (uri === 'home') {
           feed = 'home'
-        } else if (uri === 'primary-algo') {
-          feed = 'primary-algo'
         } else if (uri.includes('app.bsky.feed.generator')) {
           feed = `feedgen|${uri}`
         } else if (uri.includes('app.bsky.graph.list')) {