Show replies in context of their threads (#4871)

* Don't reconstruct threads from separate posts

* Remove post-level dedupe for now

* Change repost dedupe condition to look just at length

* Delete unused isThread

* Delete another isThread field

It is now meaningless because there's nothing special about author threads.

* Narrow down slice item shape so it does not need reply

* Consolidate slice validation criteria in one place

* Show replies in context

* Make fallback marker work

* Remove misleading and now-unused property

It was called rootUri but it was actually the leaf URI. Regardless, it's not used anymore.

* Add by-thread dedupe to non-author feeds

* Add post-level dedupe

* Always count from the start

This is easier to think about.

* Only tuner state need to be untouched on dry run

* Account for threads in reply filtering

* Remove repost deduping

This is already being taken care of by item-level deduping. It's also now wrong and removing too much (since it wasn't filtering for reposts directly).

* Calculate rootUri correctly

* Apply Following settings to all lists

* Don't dedupe intentional reposts by thread

* Show reply parent when ambiguous

* Explicitly remove orphaned replies from following/lists

* Fix thread dedupe to work across pages

* Mark grandparent-blocked as orphaned

* Guard tuner state change by dryRun

* Remove dead code

* Don't dedupe feedgen threads

* Revert "Apply Following settings to all lists"

This reverts commit aff86be6d37b60cc5d0ac38f22c31a4808342cf4.

Let's not do this yet and have a bit more discussion. This is a chunky change already.

* Reason belongs to a slice, not item

* Logically feedContext belongs to the slice

* Update comment to reflect latest behavior

src/view/com/posts/Feed.tsx

@@ -14,7 +14,6 @@ import {msg} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
 import {useQueryClient} from '@tanstack/react-query'
 
-import {FALLBACK_MARKER_POST} from '#/lib/api/feed/home'
 import {DISCOVER_FEED_URI, KNOWN_SHUTDOWN_FEEDS} from '#/lib/constants'
 import {logEvent, useGate} from '#/lib/statsig/statsig'
 import {logger} from '#/logger'
@@ -472,7 +471,7 @@ let Feed = ({
       } else if (item.type === progressGuideInterstitialType) {
         return <ProgressGuide />
       } else if (item.type === 'slice') {
-        if (item.slice.rootUri === FALLBACK_MARKER_POST.post.uri) {
+        if (item.slice.isFallbackMarker) {
           // HACK
           // tell the user we fell back to discover
           // see home.ts (feed api) for more info

src/view/com/posts/FeedItem.tsx

@@ -345,11 +345,9 @@ let FeedItemInner = ({
             postHref={href}
             onOpenAuthor={onOpenAuthor}
           />
-          {!isThreadChild &&
-            showReplyTo &&
-            (parentAuthor || isParentBlocked) && (
-              <ReplyToLabel blocked={isParentBlocked} profile={parentAuthor} />
-            )}
+          {showReplyTo && (parentAuthor || isParentBlocked) && (
+            <ReplyToLabel blocked={isParentBlocked} profile={parentAuthor} />
+          )}
           <LabelsOnMyPost post={post} />
           <PostContent
             moderation={moderation}

src/view/com/posts/FeedSlice.tsx

@@ -18,7 +18,7 @@ let FeedSlice = ({
   slice: FeedPostSlice
   hideTopBorder?: boolean
 }): React.ReactNode => {
-  if (slice.isThread && slice.items.length > 3) {
+  if (slice.isIncompleteThread && slice.items.length >= 3) {
     const beforeLast = slice.items.length - 2
     const last = slice.items.length - 1
     return (
@@ -27,25 +27,28 @@ let FeedSlice = ({
           key={slice.items[0]._reactKey}
           post={slice.items[0].post}
           record={slice.items[0].record}
-          reason={slice.items[0].reason}
-          feedContext={slice.items[0].feedContext}
+          reason={slice.reason}
+          feedContext={slice.feedContext}
           parentAuthor={slice.items[0].parentAuthor}
-          showReplyTo={true}
+          showReplyTo={false}
           moderation={slice.items[0].moderation}
           isThreadParent={isThreadParentAt(slice.items, 0)}
           isThreadChild={isThreadChildAt(slice.items, 0)}
           hideTopBorder={hideTopBorder}
           isParentBlocked={slice.items[0].isParentBlocked}
         />
-        <ViewFullThread slice={slice} />
+        <ViewFullThread uri={slice.items[0].uri} />
         <FeedItem
           key={slice.items[beforeLast]._reactKey}
           post={slice.items[beforeLast].post}
           record={slice.items[beforeLast].record}
-          reason={slice.items[beforeLast].reason}
-          feedContext={slice.items[beforeLast].feedContext}
+          reason={undefined}
+          feedContext={slice.feedContext}
           parentAuthor={slice.items[beforeLast].parentAuthor}
-          showReplyTo={false}
+          showReplyTo={
+            slice.items[beforeLast].parentAuthor?.did !==
+            slice.items[beforeLast].post.author.did
+          }
           moderation={slice.items[beforeLast].moderation}
           isThreadParent={isThreadParentAt(slice.items, beforeLast)}
           isThreadChild={isThreadChildAt(slice.items, beforeLast)}
@@ -55,8 +58,8 @@ let FeedSlice = ({
           key={slice.items[last]._reactKey}
           post={slice.items[last].post}
           record={slice.items[last].record}
-          reason={slice.items[last].reason}
-          feedContext={slice.items[last].feedContext}
+          reason={undefined}
+          feedContext={slice.feedContext}
           parentAuthor={slice.items[last].parentAuthor}
           showReplyTo={false}
           moderation={slice.items[last].moderation}
@@ -76,8 +79,8 @@ let FeedSlice = ({
           key={item._reactKey}
           post={slice.items[i].post}
           record={slice.items[i].record}
-          reason={slice.items[i].reason}
-          feedContext={slice.items[i].feedContext}
+          reason={i === 0 ? slice.reason : undefined}
+          feedContext={slice.feedContext}
           moderation={slice.items[i].moderation}
           parentAuthor={slice.items[i].parentAuthor}
           showReplyTo={i === 0}
@@ -96,12 +99,12 @@ let FeedSlice = ({
 FeedSlice = memo(FeedSlice)
 export {FeedSlice}
 
-function ViewFullThread({slice}: {slice: FeedPostSlice}) {
+function ViewFullThread({uri}: {uri: string}) {
   const pal = usePalette('default')
   const itemHref = React.useMemo(() => {
-    const urip = new AtUri(slice.rootUri)
+    const urip = new AtUri(uri)
     return makeProfileLink({did: urip.hostname, handle: ''}, 'post', urip.rkey)
-  }, [slice.rootUri])
+  }, [uri])
 
   return (
     <Link style={[styles.viewFullThread]} href={itemHref} asAnchor noFeedback>