Replace the FAB with a compose prompt at the top of the feed

src/view/com/posts/Feed.tsx

@@ -6,23 +6,34 @@ import {EmptyState} from '../util/EmptyState'
 import {ErrorMessage} from '../util/ErrorMessage'
 import {FeedModel, FeedItemModel} from '../../../state/models/feed-view'
 import {FeedItem} from './FeedItem'
+import {ComposePrompt} from '../composer/Prompt'
+
+const COMPOSE_PROMPT_ITEM = {_reactKey: '__prompt__'}
 
 export const Feed = observer(function Feed({
   feed,
   style,
   scrollElRef,
+  onPressCompose,
   onPressTryAgain,
 }: {
   feed: FeedModel
   style?: StyleProp<ViewStyle>
   scrollElRef?: MutableRefObject<FlatList<any> | null>
+  onPressCompose?: () => void
   onPressTryAgain?: () => void
 }) {
   // TODO optimize renderItem or FeedItem, we're getting this notice from RN: -prf
   //   VirtualizedList: You have a large list that is slow to update - make sure your
   //   renderItem function renders components that follow React performance best practices
   //   like PureComponent, shouldComponentUpdate, etc
-  const renderItem = ({item}: {item: FeedItemModel}) => <FeedItem item={item} />
+  const renderItem = ({item}: {item: FeedItemModel}) => {
+    if (item === COMPOSE_PROMPT_ITEM) {
+      return <ComposePrompt onPressCompose={onPressCompose} />
+    } else {
+      return <FeedItem item={item} />
+    }
+  }
   const onRefresh = () => {
     feed.refresh().catch(err => console.error('Failed to refresh', err))
   }
@@ -45,7 +56,7 @@ export const Feed = observer(function Feed({
       {feed.hasContent && (
         <FlatList
           ref={scrollElRef}
-          data={feed.feed.slice()}
+          data={[COMPOSE_PROMPT_ITEM].concat(feed.feed.slice())}
           keyExtractor={item => item._reactKey}
           renderItem={renderItem}
           refreshing={feed.isRefreshing}