Merge main into the Web PR (#230)

* Update to RN 71.1.0 (#100)

* Update to RN 71

* Adds missing lint plugin

* Add missing native changes

* Bump @atproto/api@0.0.7 (#112)

* Image not loading on swipe (#114)

* Adds prefetching to images

* Adds image prefetch

* bugfix for images not showing on swipe

* Fixes prefetch bug

* Update src/view/com/util/PostEmbeds.tsx

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

* Fixes to session management (#117)

* Update session-management to solve incorrectly dropped sessions

* Reset the nav on account switch

* Reset the feed on me.load()

* Update tests to reflect new account-switching behavior

* Increase max image resolutions and sizes (#118)

* Slightly increase the hitslop for post controls

* Fix character counter color in dark mode

* Update login to use new session.create api, which enables email login (close #93) (#119)

* Replaces the alert with dropdown for profile image and banner (#123)

* replaces the alert with dropdown for profile image and banner

* lint

* Fix to ordering of images in the embed grid (#121)

* Add explicit link-embed controls to the composer (#120)

* Add explicit link-embed controls

* Update the target rez/size of link embed thumbs

* Remove the alert before publishing without a link card

* [Draft] Fixes image failing on reupload issue (#128)

* Fixes image failing on reupload issue

* Use tmp folder instead of documents

* lint

* Image performance improvements (#126)

* Switch out most images for FastImage

* Add image loading placeholders

* Fix tests

* Collection of fixes to list rendering (#127)

* Fix bug that caused endless spinners in profile feeds

* Bundle fetches of suggested actors into one update

* Fixes to suggested follow rendering

* Fix missing replacement of flex:1 to height:100

* Fixes to navigation swipes (#129)

* Nav swipe: increase the distance traveled in response to gesture movement.

This causes swipes to feel faster and more responsive.

* Fix: fully clamp the swipe against the edge

* Improve the performance of swipes by skipping the interaction manager

* Adds dark mode to the edit screen (#130)

* Adds dark mode to edit screen

* lint

* lint

* lint

* Reduce render cost of post controls and improve perceived responsiveness (#132)

* Move post control animations into conditional render and increase perceived responsiveness

* Remove log

* Adds dark mode to the dropdown (#131)

* Adds dark mode to the bottom sheet

* Make background button lighter (like before)

* lint

* Fix bug in lightbox rendering (#133)

* Fix layout in onboarding to not overflow the footer

* Configure feed FlatList (removeClippedSubviews=true) to improve scroll performance (#136)

* Disable like/repost animations to see if theyre causing #135 (#137)

* Composer: mention tagging now works in middle of text (close #105) (#139)

* Implement account deletion (#141)

* Fix photo & camera permission management (#140)

* Check photo & camera perms and alert the user if not available (close #64)

- Adds perms checks with a prompt to update settings if needed
- Moves initial access of photos in the composer so that the initial prompt
  occurs at an intuitive time.

* Add react-native-permissions test mock

* Fix issue causing multiple access requests

* Use longer var names

* Update podfile.lock

* Lint fix

* Move photo perm request in composer to the gallery btn instead of when the carousel is opened

* Adds more tracking all around the app (#142)

* Adds more tracking all around the app

* more events

* lint

* using better analytics naming

* missed file

* more fixes

* Calculate image aspect ratio on load (#146)

* Calculate image aspect ratio on load

* Move aspect ratio bounds to constants

* Adds detox testing and instructions (#147)

* Adds detox testing and instructions

* lint

* lint

* Error cleanup (close #79) (#148)

* Avoid surfacing errors to the user when it's not critical

* Remove now-unused GetAssertionsView

* Apply cleanError() consistently

* Give a better error message for Upstream Failures (http status 502)

* Hide errors in notifications because they're not useful

* More e2e tests (create account) (#150)

* Adds respots under the 'post' tab under profile (#158)

* Adds dark mode to delete account screen (#159)

* 87 dark mode edit profile (#162)

* Adds dark mode to delete account screen

* Adds one more missed darkmode

* more fixes

* Remove fallback gradient on external links without thumbs (#164)

* Remove fallback gradient on external links without thumbs

* Remove fallback gradient on external links without thumbs in the composer preview

* Fix refresh behavior around a series of models (repost, graph, vote) (#163)

* Fix refresh behavior around a series of models (repost, graph, vote)

* Fix cursor behavior in reposted-by view

* Fixes issue where retrying on image upload fails (#166)

* Fixes issue where retrying on image upload fails

* Lint, longer test time

* Longer waitfor time in tests

* even longer timeout

* longer timeout

* missed file

* Update src/view/com/composer/ComposePost.tsx

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

* Update src/view/com/composer/ComposePost.tsx

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

* 154 cached image profile (#167)

* Fixes issue where retrying on image upload fails

* Lint, longer test time

* Longer waitfor time in tests

* even longer timeout

* longer timeout

* missed file

* Fixes image cache error on second try for profile screen

* lint

* lint

* lint

* Refactor session management to use a new "Agent" API (#165)

* Add the atp-agent implementation (temporarily in this repo)

* Rewrite all session & API management to use the new atp-agent

* Update tests for the atp-agent refactor

* Refactor management of session-related state. Includes:
- More careful management of when state is cleared or fetched
- Debug logging to help trace future issues
- Clearer APIs overall

* Bubble session-expiration events to the user and display a toast to explain

* Switch to the new @atproto/api@0.1.0

* Minor aesthetic cleanup in SessionModel

* Wire up ReportAccount and ReportPost (#168)

* Fixes embeds for youtube channels (#169)

* Bump app ios version to 1.1 (needed after app store submission)

* Fix potential issues with promise guards when an error occurs (#170)

* Refactor models to use bundleAsync and lock regions (#171)

* Fix to an edge case with feed re-ordering for threads (#172)

* 151 fix youtube channel embed (#173)

* Fixes embeds for youtube channels

* Tests for youtube extract meta

* lint

* Add 'doesnt use non-exempt encryption' to ios config

* Rework the search UI and add  (#174)

* Add search tab and move icon to footer

* Remove subtitles from view header

* Remove unused code

* Clean up UI of search screen

* Search: give better user feedback to UI state and add a cancel button

* Add WhoToFollow section to search

* Add a temporary SuggestedPosts solution using the patented 'bsky team algo'

* Trigger reload of suggested content in search on open

* Wait five min between reloading discovery content

* Reduce weight of solid search icon in footer

* Fix lint

* Fix tests

* 151 feat youtube embed iframe (#176)

* youtube embed iframe temp commit

* Fixes styling and code cleanup

* lint

* Now clicking between the pause and settings button doesn't trigger the parent

* use modest branding (less yt logos)

* Stop playing the video once there's a navigation event

* Make sure the iframe is unmounted on any navigation event

* fixes tests

* lint

* Add scroll-to-top for all screens (#177)

* Adds hardcoded suggested list (#178)

* Adds hardcoded suggested list

* Update suggested-actors-view to support page sizes smaller than the hardcoded list

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

* more robust centering of the play button (#181)

Co-authored-by: Aryan Goharzad <arrygoo@gmail.com>

* Bundle of UI modifications (#175)

* Adjust visual balance of SuggestedPosts and WhoToFollow

* Fix bug in the discovery load trigger

* Adjust search header aesthetic and have it scroll away

* More visual balance tweaks on the search page

* Even more visual balance tweaks on the search page

* Hide the footer on scroll in search

* Ditch the composer prompt buttons in the home feed

* Center the view header title

* Hide header on scroll on the home feed

* Fix e2e tests

* Fix home feed positioning (closes #189) (#195)

* Fix home feed positioning for floating header

* Fix positioning of errors in home feed

* Fix lint

* Don't show new-content notification for reposts (close #179) (#197)

* Show the splash screen during session resumption (close #186) (#199)

* Fix to suggested follows: chunk the hardcoded fetches to 25 at a time (close #196) (#198)

* UI updates to the floating action button (#201)

* Update FAB to use a plus icon and not drop shadow

* Update FAB positioning to be more consistent in different shell modes

* Animate the FAB's repositioning

* Remove the 'loading' placeholder from images as it degraded feed perf (#202)

* Remove the 'loading' placeholder from images as it degraded feed perf

* Remove references

* Fix RN bug that causes home feed not to load more; also fix home feed load view. (#208)

RN has a bug where rendering a flatlist with an empty array appears to break its
virtual list windowing behaviors. See https://stackoverflow.com/a/67873596

* Only give the loading spinner on the home feed during PTR (#207)

(cherry picked from commit b7a5da12fdfacef74873b5cf6d75f20d259bde0e)

* Implement our own lifecycle tracking to ensure it never fires while the app is backgrounded (close #193) (#211)

* Push notification fixes (#210)

* Fix to when screen analytics events are firing

* Fix: dont trigger update state when backgrounded

* Small fix to notifee API usage

* Fix: properly load notification info for push card

* Add feedback link to main menu (close #191) (#212)

* Add "follows you" information and sync follow state between views (#215)

* Bump @atproto/api@0.1.2 and update API usage

* Add 'follows you' pill to profile header (close #110)

* Add 'follows you' to followers and follows (close #103)

* Update reposted-by and liked-by views to use the same components as followers and following

* Create a local follows cache MyFollowsModel to keep views in sync (close #205)

* Add incremental hydration to the MyFollows model

* Fix tests

* Update deps

* Fix lint

* Fix to paginated fetches

* Fix reference

* Fix potential state-desync issue

* Fixes to notifications (#216)

* Improve push-notification for follows

* Refresh notifications on screen open (close #214)

* Avoid showing loader more than needed in post threads

* Refactor notification polling to handle view-state more effectively

* Delete a bunch of tests taht werent adding value

* Remove the accounts integration test; we'll use the e2e test instead

* Load latest in notifications when the screen is open rather than full refresh

* Randomize hard-coded suggested follows (#226)

* Ensure follows are loaded before filtering hardcoded suggestions

* Randomize hard-coded suggested profiles (close #219)

* Sanitizes posts on publish and render (#217)

* Sanatizes posts on publish and render

* lint

* lint and added sanitize to thread view as well

* adjusts indices based on replaced text

* Woops, fixes a bug

* bugfix + cleanup

* comment

* lint

* move sanitize text to later in the flow

* undo changes to compose post

* Add RichText library building upon the sanitizePost library method

* Add lodash.clonedeep dep

* Switch to RichText processing on record load & render

* Fix lint

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

* A group of notifications fixes (#227)

* Fix: don't group together notifications that can't visually be grouped (close #221)

* Mark all notifications read on PTR

* Small optimization: useCallback and useMemo in posts feed

* Add loading spinner to footer of notifications (close #222)

* Fix to scrolling to posts within a thread (#228)

* Fix: render the entire thread at start so that scrollToIndex works always (close #270)

* Visual fixes to thread 'load more'

* A few small perf improvements to thread rendering

* Fix lint

* 1.2

* Remove unused logger lib

* Remove state-mock

* Type fixes

* Reorganize the folder structure for lib and switch to typescript path aliases

* Move build-flags into lib

* Move to the state path alias

* Add view path alias

* Fix lint

* iOS build fixes

* Wrap analytics in native/web splitter and re-enable in all view code

* Add web version of react-native-webview

* Add web split for version number

* Fix BlurView import for web

* Add web split for fastimage

* Create web split for permissions lib

* Fix for web high priority images

---------

Co-authored-by: Aryan Goharzad <arrygoo@gmail.com>

1 files changed, 178 insertions, 165 deletions

diff --git a/src/state/models/feed-view.ts b/src/state/models/feed-view.ts
index 621059822..f80c5f2c0 100644
--- a/src/state/models/feed-view.ts
+++ b/src/state/models/feed-view.ts
@@ -5,13 +5,16 @@ import {
   AppBskyFeedPost,
   AppBskyFeedGetAuthorFeed as GetAuthorFeed,
 } from '@atproto/api'
+import AwaitLock from 'await-lock'
+import {bundleAsync} from 'lib/async/bundle'
 type FeedViewPost = AppBskyFeedFeedViewPost.Main
 type ReasonRepost = AppBskyFeedFeedViewPost.ReasonRepost
 type PostView = AppBskyFeedPost.View
 import {AtUri} from '../../third-party/uri'
 import {RootStoreModel} from './root-store'
-import * as apilib from '../lib/api'
-import {cleanError} from '../../lib/strings'
+import * as apilib from 'lib/api/index'
+import {cleanError} from 'lib/strings/errors'
+import {RichText} from 'lib/strings/rich-text'
 
 const PAGE_SIZE = 30
 
@@ -37,6 +40,7 @@ export class FeedItemModel {
   reply?: FeedViewPost['reply']
   replyParent?: FeedItemModel
   reason?: FeedViewPost['reason']
+  richText?: RichText
 
   constructor(
     public rootStore: RootStoreModel,
@@ -49,6 +53,11 @@ export class FeedItemModel {
       const valid = AppBskyFeedPost.validateRecord(this.post.record)
       if (valid.success) {
         this.postRecord = this.post.record
+        this.richText = new RichText(
+          this.postRecord.text,
+          this.postRecord.entities,
+          {cleanNewlines: true},
+        )
       } else {
         rootStore.log.warn(
           'Received an invalid app.bsky.feed.post record',
@@ -187,10 +196,9 @@ export class FeedModel {
   hasMore = true
   loadMoreCursor: string | undefined
   pollCursor: string | undefined
-  _loadPromise: Promise<void> | undefined
-  _loadMorePromise: Promise<void> | undefined
-  _loadLatestPromise: Promise<void> | undefined
-  _updatePromise: Promise<void> | undefined
+
+  // used to linearize async modifications to state
+  private lock = new AwaitLock()
 
   // data
   feed: FeedItemModel[] = []
@@ -206,10 +214,6 @@ export class FeedModel {
         rootStore: false,
         params: false,
         loadMoreCursor: false,
-        _loadPromise: false,
-        _loadMorePromise: false,
-        _loadLatestPromise: false,
-        _updatePromise: false,
       },
       {autoBind: true},
     )
@@ -229,13 +233,22 @@ export class FeedModel {
   }
 
   get nonReplyFeed() {
-    return this.feed.filter(
-      item =>
+    const nonReplyFeed = this.feed.filter(item => {
+      const params = this.params as GetAuthorFeed.QueryParams
+      const isRepost =
+        item.reply &&
+        (item?.reasonRepost?.by?.handle === params.author ||
+          item?.reasonRepost?.by?.did === params.author)
+
+      return (
         !item.reply || // not a reply
+        isRepost ||
         ((item._isThreadParent || // but allow if it's a thread by the user
           item._isThreadChild) &&
-          item.reply?.root.author.did === item.post.author.did),
-    )
+          item.reply?.root.author.did === item.post.author.did)
+      )
+    })
+    return nonReplyFeed
   }
 
   setHasNewLatest(v: boolean) {
@@ -246,21 +259,44 @@ export class FeedModel {
   // =
 
   /**
+   * Nuke all data
+   */
+  clear() {
+    this.rootStore.log.debug('FeedModel:clear')
+    this.isLoading = false
+    this.isRefreshing = false
+    this.hasNewLatest = false
+    this.hasLoaded = false
+    this.error = ''
+    this.hasMore = true
+    this.loadMoreCursor = undefined
+    this.pollCursor = undefined
+    this.feed = []
+  }
+
+  /**
    * Load for first render
    */
-  async setup(isRefreshing = false) {
+  setup = bundleAsync(async (isRefreshing: boolean = false) => {
+    this.rootStore.log.debug('FeedModel:setup', {isRefreshing})
     if (isRefreshing) {
       this.isRefreshing = true // set optimistically for UI
     }
-    if (this._loadPromise) {
-      return this._loadPromise
+    await this.lock.acquireAsync()
+    try {
+      this.setHasNewLatest(false)
+      this._xLoading(isRefreshing)
+      try {
+        const res = await this._getFeed({limit: PAGE_SIZE})
+        await this._replaceAll(res)
+        this._xIdle()
+      } catch (e: any) {
+        this._xIdle(e)
+      }
+    } finally {
+      this.lock.release()
     }
-    await this._pendingWork()
-    this.setHasNewLatest(false)
-    this._loadPromise = this._initialLoad(isRefreshing)
-    await this._loadPromise
-    this._loadPromise = undefined
-  }
+  })
 
   /**
    * Register any event listeners. Returns a cleanup function.
@@ -280,42 +316,93 @@ export class FeedModel {
   /**
    * Load more posts to the end of the feed
    */
-  async loadMore() {
-    if (this._loadMorePromise) {
-      return this._loadMorePromise
+  loadMore = bundleAsync(async () => {
+    await this.lock.acquireAsync()
+    try {
+      if (!this.hasMore || this.hasError) {
+        return
+      }
+      this._xLoading()
+      try {
+        const res = await this._getFeed({
+          before: this.loadMoreCursor,
+          limit: PAGE_SIZE,
+        })
+        await this._appendAll(res)
+        this._xIdle()
+      } catch (e: any) {
+        this._xIdle() // don't bubble the error to the user
+        this.rootStore.log.error('FeedView: Failed to load more', {
+          params: this.params,
+          e,
+        })
+      }
+    } finally {
+      this.lock.release()
     }
-    await this._pendingWork()
-    this._loadMorePromise = this._loadMore()
-    await this._loadMorePromise
-    this._loadMorePromise = undefined
-  }
+  })
 
   /**
    * Load more posts to the start of the feed
    */
-  async loadLatest() {
-    if (this._loadLatestPromise) {
-      return this._loadLatestPromise
+  loadLatest = bundleAsync(async () => {
+    await this.lock.acquireAsync()
+    try {
+      this.setHasNewLatest(false)
+      this._xLoading()
+      try {
+        const res = await this._getFeed({limit: PAGE_SIZE})
+        await this._prependAll(res)
+        this._xIdle()
+      } catch (e: any) {
+        this._xIdle() // don't bubble the error to the user
+        this.rootStore.log.error('FeedView: Failed to load latest', {
+          params: this.params,
+          e,
+        })
+      }
+    } finally {
+      this.lock.release()
     }
-    await this._pendingWork()
-    this.setHasNewLatest(false)
-    this._loadLatestPromise = this._loadLatest()
-    await this._loadLatestPromise
-    this._loadLatestPromise = undefined
-  }
+  })
 
   /**
    * Update content in-place
    */
-  async update() {
-    if (this._updatePromise) {
-      return this._updatePromise
+  update = bundleAsync(async () => {
+    await this.lock.acquireAsync()
+    try {
+      if (!this.feed.length) {
+        return
+      }
+      this._xLoading()
+      let numToFetch = this.feed.length
+      let cursor
+      try {
+        do {
+          const res: GetTimeline.Response = await this._getFeed({
+            before: cursor,
+            limit: Math.min(numToFetch, 100),
+          })
+          if (res.data.feed.length === 0) {
+            break // sanity check
+          }
+          this._updateAll(res)
+          numToFetch -= res.data.feed.length
+          cursor = res.data.cursor
+        } while (cursor && numToFetch > 0)
+        this._xIdle()
+      } catch (e: any) {
+        this._xIdle() // don't bubble the error to the user
+        this.rootStore.log.error('FeedView: Failed to update', {
+          params: this.params,
+          e,
+        })
+      }
+    } finally {
+      this.lock.release()
     }
-    await this._pendingWork()
-    this._updatePromise = this._update()
-    await this._updatePromise
-    this._updatePromise = undefined
-  }
+  })
 
   /**
    * Check if new posts are available
@@ -324,17 +411,18 @@ export class FeedModel {
     if (this.hasNewLatest) {
       return
     }
-    await this._pendingWork()
     const res = await this._getFeed({limit: 1})
     const currentLatestUri = this.pollCursor
-    const receivedLatestUri = res.data.feed[0]
-      ? res.data.feed[0].post.uri
-      : undefined
-    const hasNewLatest = Boolean(
-      receivedLatestUri &&
-        (this.feed.length === 0 || receivedLatestUri !== currentLatestUri),
-    )
-    this.setHasNewLatest(hasNewLatest)
+    const item = res.data.feed[0]
+    if (!item) {
+      return
+    }
+    if (AppBskyFeedFeedViewPost.isReasonRepost(item.reason)) {
+      if (item.reason.by.did === this.rootStore.me.did) {
+        return // ignore reposts by the user
+      }
+    }
+    this.setHasNewLatest(item.post.uri !== currentLatestUri)
   }
 
   /**
@@ -363,95 +451,15 @@ export class FeedModel {
     this.isLoading = false
     this.isRefreshing = false
     this.hasLoaded = true
-    this.error = err ? cleanError(err.toString()) : ''
+    this.error = cleanError(err)
     if (err) {
       this.rootStore.log.error('Posts feed request failed', err)
     }
   }
 
-  // loader functions
+  // helper functions
   // =
 
-  private async _pendingWork() {
-    if (this._loadPromise) {
-      await this._loadPromise
-    }
-    if (this._loadMorePromise) {
-      await this._loadMorePromise
-    }
-    if (this._loadLatestPromise) {
-      await this._loadLatestPromise
-    }
-    if (this._updatePromise) {
-      await this._updatePromise
-    }
-  }
-
-  private async _initialLoad(isRefreshing = false) {
-    this._xLoading(isRefreshing)
-    try {
-      const res = await this._getFeed({limit: PAGE_SIZE})
-      await this._replaceAll(res)
-      this._xIdle()
-    } catch (e: any) {
-      this._xIdle(e)
-    }
-  }
-
-  private async _loadLatest() {
-    this._xLoading()
-    try {
-      const res = await this._getFeed({limit: PAGE_SIZE})
-      await this._prependAll(res)
-      this._xIdle()
-    } catch (e: any) {
-      this._xIdle(e)
-    }
-  }
-
-  private async _loadMore() {
-    if (!this.hasMore || this.hasError) {
-      return
-    }
-    this._xLoading()
-    try {
-      const res = await this._getFeed({
-        before: this.loadMoreCursor,
-        limit: PAGE_SIZE,
-      })
-      await this._appendAll(res)
-      this._xIdle()
-    } catch (e: any) {
-      this._xIdle(e)
-    }
-  }
-
-  private async _update() {
-    if (!this.feed.length) {
-      return
-    }
-    this._xLoading()
-    let numToFetch = this.feed.length
-    let cursor
-    try {
-      do {
-        const res: GetTimeline.Response = await this._getFeed({
-          before: cursor,
-          limit: Math.min(numToFetch, 100),
-        })
-        if (res.data.feed.length === 0) {
-          break // sanity check
-        }
-        this._updateAll(res)
-        numToFetch -= res.data.feed.length
-        cursor = res.data.cursor
-      } while (cursor && numToFetch > 0)
-      this._xIdle()
-    } catch (e: any) {
-      this._xIdle(e)
-    }
-  }
-
   private async _replaceAll(
     res: GetTimeline.Response | GetAuthorFeed.Response,
   ) {
@@ -570,32 +578,9 @@ function preprocessFeed(feed: FeedViewPost[]): FeedViewPostWithThreadMeta[] {
     reorg.unshift(item)
   }
 
-  // phase two: identify the positions of the threads
-  let activeSlice = -1
-  let threadSlices: Slice[] = []
-  for (let i = 0; i < reorg.length; i++) {
-    const item = reorg[i] as FeedViewPostWithThreadMeta
-    if (activeSlice === -1) {
-      if (item._isThreadParent) {
-        activeSlice = i
-      }
-    } else {
-      if (!item._isThreadChild) {
-        threadSlices.push({index: activeSlice, length: i - activeSlice})
-        if (item._isThreadParent) {
-          activeSlice = i
-        } else {
-          activeSlice = -1
-        }
-      }
-    }
-  }
-  if (activeSlice !== -1) {
-    threadSlices.push({index: activeSlice, length: reorg.length - activeSlice})
-  }
-
-  // phase three: reorder the feed so that the timestamp of the
+  // phase two: reorder the feed so that the timestamp of the
   // last post in a thread establishes its ordering
+  let threadSlices: Slice[] = identifyThreadSlices(reorg)
   for (const slice of threadSlices) {
     const removed: FeedViewPostWithThreadMeta[] = reorg.splice(
       slice.index,
@@ -610,8 +595,10 @@ function preprocessFeed(feed: FeedViewPost[]): FeedViewPostWithThreadMeta[] {
     slice.index = newIndex
   }
 
-  // phase four: compress any threads that are longer than 3 posts
+  // phase three: compress any threads that are longer than 3 posts
   let removedCount = 0
+  // phase 2 moved posts around, so we need to re-identify the slice indices
+  threadSlices = identifyThreadSlices(reorg)
   for (const slice of threadSlices) {
     if (slice.length > 3) {
       reorg.splice(slice.index - removedCount + 1, slice.length - 3)
@@ -626,6 +613,32 @@ function preprocessFeed(feed: FeedViewPost[]): FeedViewPostWithThreadMeta[] {
   return reorg
 }
 
+function identifyThreadSlices(feed: FeedViewPost[]): Slice[] {
+  let activeSlice = -1
+  let threadSlices: Slice[] = []
+  for (let i = 0; i < feed.length; i++) {
+    const item = feed[i] as FeedViewPostWithThreadMeta
+    if (activeSlice === -1) {
+      if (item._isThreadParent) {
+        activeSlice = i
+      }
+    } else {
+      if (!item._isThreadChild) {
+        threadSlices.push({index: activeSlice, length: i - activeSlice})
+        if (item._isThreadParent) {
+          activeSlice = i
+        } else {
+          activeSlice = -1
+        }
+      }
+    }
+  }
+  if (activeSlice !== -1) {
+    threadSlices.push({index: activeSlice, length: feed.length - activeSlice})
+  }
+  return threadSlices
+}
+
 // WARNING: mutates `feed`
 function dedupReposts(feed: FeedItemModel[]) {
   // remove duplicates caused by reposts