Add salt

package.json

@@ -114,6 +114,7 @@
     "base64-js": "^1.5.1",
     "bcp-47": "^2.1.0",
     "bcp-47-match": "^2.0.3",
+    "bloomfilter": "^0.0.19",
     "date-fns": "^2.30.0",
     "deprecated-react-native-prop-types": "^5.0.0",
     "email-validator": "^2.0.4",

src/lib/api/feed/custom.ts

@@ -5,6 +5,8 @@ import {
   jsonStringToLex,
 } from '@atproto/api'
 
+import {DISCOVER_FEED_URI} from '#/lib/constants'
+import {isLikelyGloballySeenPost} from '#/state/feed-feedback'
 import {
   getAppLanguageAsContentLanguage,
   getContentLanguages,
@@ -72,6 +74,35 @@ export class CustomFeedAPI implements FeedAPI {
         )
       : await loggedOutFetch({...this.params, cursor, limit})
     if (res.success) {
+      if (this.params.feed === DISCOVER_FEED_URI) {
+        // Try not to show a post in Discover if you've seen it elsewhere in the app.
+        // A proper way to do this might be to let a feed declare it wants client-side filtering.
+        // I'm hacking this in here because it needs to be consistent for re-renders so
+        // the decision on what got included or not for this page needs to happen once.
+        const candidateFeed = res.data.feed.filter(post => {
+          if (isLikelyGloballySeenPost(post.post.uri)) {
+            return false
+          }
+          if (post.reply) {
+            if (
+              AppBskyFeedDefs.isPostView(post.reply.parent) &&
+              isLikelyGloballySeenPost(post.reply.parent.uri)
+            ) {
+              return false
+            }
+            if (
+              AppBskyFeedDefs.isPostView(post.reply.root) &&
+              isLikelyGloballySeenPost(post.reply.root.uri)
+            ) {
+              return false
+            }
+          }
+          return true
+        })
+        if (candidateFeed.length >= res.data.feed.length / 2) {
+          res.data.feed = candidateFeed
+        }
+      }
       // NOTE
       // some custom feeds fail to enforce the pagination limit
       // so we manually truncate here

src/state/feed-feedback.tsx

@@ -1,6 +1,8 @@
 import React from 'react'
 import {AppState, AppStateStatus} from 'react-native'
 import {AppBskyFeedDefs} from '@atproto/api'
+// @ts-ignore
+import {BloomFilter} from 'bloomfilter'
 import throttle from 'lodash.throttle'
 
 import {PROD_DEFAULT_FEED} from '#/lib/constants'
@@ -18,7 +20,15 @@ type StateContext = {
 
 const stateContext = React.createContext<StateContext>({
   enabled: false,
-  onItemSeen: (_item: any) => {},
+  onItemSeen: (feedItem: any) => {
+    const slice = getFeedPostSlice(feedItem)
+    if (slice === null) {
+      return
+    }
+    for (const postItem of slice.items) {
+      markGloballySeenPost(postItem.uri)
+    }
+  },
   sendInteraction: (_interaction: AppBskyFeedDefs.Interaction) => {},
 })
 
@@ -93,24 +103,25 @@ export function useFeedFeedback(feed: FeedDescriptor, hasSession: boolean) {
 
   const onItemSeen = React.useCallback(
     (feedItem: any) => {
-      if (!enabled) {
-        return
-      }
       const slice = getFeedPostSlice(feedItem)
       if (slice === null) {
         return
       }
       for (const postItem of slice.items) {
-        if (!history.current.has(postItem)) {
-          history.current.add(postItem)
-          queue.current.add(
-            toString({
-              item: postItem.uri,
-              event: 'app.bsky.feed.defs#interactionSeen',
-              feedContext: slice.feedContext,
-            }),
-          )
-          sendToFeed()
+        markGloballySeenPost(postItem.uri)
+
+        if (enabled) {
+          if (!history.current.has(postItem)) {
+            history.current.add(postItem)
+            queue.current.add(
+              toString({
+                item: postItem.uri,
+                event: 'app.bsky.feed.defs#interactionSeen',
+                feedContext: slice.feedContext,
+              }),
+            )
+            sendToFeed()
+          }
         }
       }
     },
@@ -254,3 +265,26 @@ function flushToStatsig(stats: AggregatedStats | null) {
     stats.seenCount = 0
   }
 }
+
+// https://hur.st/bloomfilter/?n=50k&p=0.001&m=&k=
+const p = 0.001 // 0.1% probability of collisions...
+const n = 50_000 // ...while we stay below 50k expected items
+const m = Math.ceil((n * Math.log(p)) / Math.log(1 / Math.pow(2, Math.log(2))))
+const k = Math.round((m / n) * Math.log(2))
+let globalBloomFilter = new BloomFilter(m, k)
+
+const salt = Math.random().toString(36).slice(2)
+
+export function markGloballySeenPost(uri: string) {
+  if (globalBloomFilter.size() >= n) {
+    // If we ever get here, just restart to avoid saturation.
+    globalBloomFilter = new BloomFilter(m, k)
+  }
+  const key = uri + salt
+  globalBloomFilter.add(key)
+}
+
+export function isLikelyGloballySeenPost(uri: string) {
+  const key = uri + salt
+  return globalBloomFilter.test(key)
+}

src/view/com/post-thread/PostThread.tsx

@@ -1,4 +1,4 @@
-import React, {memo, useRef, useState} from 'react'
+import React, {memo, useEffect, useRef, useState} from 'react'
 import {StyleSheet, useWindowDimensions, View} from 'react-native'
 import {runOnJS} from 'react-native-reanimated'
 import Animated from 'react-native-reanimated'
@@ -18,6 +18,7 @@ import {ScrollProvider} from '#/lib/ScrollContext'
 import {sanitizeDisplayName} from '#/lib/strings/display-names'
 import {cleanError} from '#/lib/strings/errors'
 import {isAndroid, isNative, isWeb} from '#/platform/detection'
+import {markGloballySeenPost} from '#/state/feed-feedback'
 import {useModerationOpts} from '#/state/preferences/moderation-opts'
 import {
   fillThreadModerationCache,
@@ -391,6 +392,22 @@ export function PostThread({uri}: {uri: string | undefined}) {
     [refetch],
   )
 
+  useEffect(() => {
+    if (skeleton) {
+      // We're not tracking linger time here so conservatively mark
+      // just the highlighted post and the parents. Presumably,
+      // if you're already midthread, you know what was above.
+      const {parents, highlightedPost} = skeleton
+      markGloballySeenPost(highlightedPost.uri)
+      for (let i = 0; i < parents.length; i++) {
+        const parent = parents[i]
+        if (isThreadPost(parent)) {
+          markGloballySeenPost(parent.uri)
+        }
+      }
+    }
+  }, [skeleton])
+
   const {openComposer} = useComposerControls()
   const onPressReply = React.useCallback(() => {
     if (thread?.type !== 'post') {

yarn.lock

@@ -3261,7 +3261,7 @@
     "@babel/parser" "^7.25.9"
     "@babel/types" "^7.25.9"
 
-"@babel/traverse--for-generate-function-map@npm:@babel/traverse@^7.25.3", "@babel/traverse@^7.25.3", "@babel/traverse@^7.25.9":
+"@babel/traverse--for-generate-function-map@npm:@babel/traverse@^7.25.3":
   version "7.25.9"
   resolved "https://registry.yarnpkg.com/@babel/traverse/-/traverse-7.25.9.tgz#a50f8fe49e7f69f53de5bea7e413cd35c5e13c84"
   integrity sha512-ZCuvfwOwlz/bawvAuvcj8rrithP2/N55Tzz342AkTvq4qaWbGfmCk/tKhNaV2cthijKrPAA8SRJV5WWe7IBMJw==
@@ -3322,6 +3322,19 @@
     debug "^4.3.1"
     globals "^11.1.0"
 
+"@babel/traverse@^7.25.3", "@babel/traverse@^7.25.9":
+  version "7.25.9"
+  resolved "https://registry.yarnpkg.com/@babel/traverse/-/traverse-7.25.9.tgz#a50f8fe49e7f69f53de5bea7e413cd35c5e13c84"
+  integrity sha512-ZCuvfwOwlz/bawvAuvcj8rrithP2/N55Tzz342AkTvq4qaWbGfmCk/tKhNaV2cthijKrPAA8SRJV5WWe7IBMJw==
+  dependencies:
+    "@babel/code-frame" "^7.25.9"
+    "@babel/generator" "^7.25.9"
+    "@babel/parser" "^7.25.9"
+    "@babel/template" "^7.25.9"
+    "@babel/types" "^7.25.9"
+    debug "^4.3.1"
+    globals "^11.1.0"
+
 "@babel/types@^7.0.0", "@babel/types@^7.20.0", "@babel/types@^7.20.7", "@babel/types@^7.22.10", "@babel/types@^7.22.5", "@babel/types@^7.3.3", "@babel/types@^7.4.4":
   version "7.22.10"
   resolved "https://registry.yarnpkg.com/@babel/types/-/types-7.22.10.tgz#4a9e76446048f2c66982d1a989dd12b8a2d2dc03"
@@ -8200,6 +8213,11 @@ bl@^4.0.3, bl@^4.1.0:
     inherits "^2.0.4"
     readable-stream "^3.4.0"
 
+bloomfilter@^0.0.19:
+  version "0.0.19"
+  resolved "https://registry.yarnpkg.com/bloomfilter/-/bloomfilter-0.0.19.tgz#3d0e62ce41fc8fe402533902cd27e09e6a738d43"
+  integrity sha512-WPhd8qNG79Gnz3i3Uk/wx/Dm6ghYV5sUsTmWGbiQNV7WvnsC8OTGZSe0WNXfPPsKDdxV2g6Q7JiO6af1BOGmXA==
+
 bn.js@^4.0.0, bn.js@^4.11.8, bn.js@^4.11.9:
   version "4.12.0"
   resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.12.0.tgz#775b3f278efbb9718eec7361f483fb36fbbfea88"
@@ -17457,7 +17475,16 @@ string-natural-compare@^3.0.1:
   resolved "https://registry.yarnpkg.com/string-natural-compare/-/string-natural-compare-3.0.1.tgz#7a42d58474454963759e8e8b7ae63d71c1e7fdf4"
   integrity sha512-n3sPwynL1nwKi3WJ6AIsClwBMa0zTi54fn2oLU6ndfTSIO05xaznjSf15PcBZU6FNWbmN5Q6cxT4V5hGvB4taw==
 
-"string-width-cjs@npm:string-width@^4.2.0", string-width@^4.1.0, string-width@^4.2.0, string-width@^4.2.3:
+"string-width-cjs@npm:string-width@^4.2.0":
+  version "4.2.3"
+  resolved "https://registry.yarnpkg.com/string-width/-/string-width-4.2.3.tgz#269c7117d27b05ad2e536830a8ec895ef9c6d010"
+  integrity sha512-wKyQRQpjJ0sIp62ErSZdGsjMJWsap5oRNihHhu6G7JVO/9jIB6UyevL+tXuOqrng8j/cxKTWyWUwvSTriiZz/g==
+  dependencies:
+    emoji-regex "^8.0.0"
+    is-fullwidth-code-point "^3.0.0"
+    strip-ansi "^6.0.1"
+
+string-width@^4.1.0, string-width@^4.2.0, string-width@^4.2.3:
   version "4.2.3"
   resolved "https://registry.yarnpkg.com/string-width/-/string-width-4.2.3.tgz#269c7117d27b05ad2e536830a8ec895ef9c6d010"
   integrity sha512-wKyQRQpjJ0sIp62ErSZdGsjMJWsap5oRNihHhu6G7JVO/9jIB6UyevL+tXuOqrng8j/cxKTWyWUwvSTriiZz/g==
@@ -17557,7 +17584,7 @@ string_decoder@~1.1.1:
   dependencies:
     safe-buffer "~5.1.0"
 
-"strip-ansi-cjs@npm:strip-ansi@^6.0.1", strip-ansi@^6.0.0, strip-ansi@^6.0.1:
+"strip-ansi-cjs@npm:strip-ansi@^6.0.1":
   version "6.0.1"
   resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-6.0.1.tgz#9e26c63d30f53443e9489495b2105d37b67a85d9"
   integrity sha512-Y38VPSHcqkFrCpFnQ9vuSXmquuv5oXOKpGeT6aGrr3o3Gc9AlVa6JBfUSOCnbxGGZF+/0ooI7KrPuUSztUdU5A==
@@ -17571,6 +17598,13 @@ strip-ansi@^5.2.0:
   dependencies:
     ansi-regex "^4.1.0"
 
+strip-ansi@^6.0.0, strip-ansi@^6.0.1:
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-6.0.1.tgz#9e26c63d30f53443e9489495b2105d37b67a85d9"
+  integrity sha512-Y38VPSHcqkFrCpFnQ9vuSXmquuv5oXOKpGeT6aGrr3o3Gc9AlVa6JBfUSOCnbxGGZF+/0ooI7KrPuUSztUdU5A==
+  dependencies:
+    ansi-regex "^5.0.1"
+
 strip-ansi@^7.0.1:
   version "7.1.0"
   resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-7.1.0.tgz#d5b6568ca689d8561370b0707685d22434faff45"
@@ -18845,7 +18879,7 @@ wordwrap@^1.0.0:
   resolved "https://registry.yarnpkg.com/wordwrap/-/wordwrap-1.0.0.tgz#27584810891456a4171c8d0226441ade90cbcaeb"
   integrity sha512-gvVzJFlPycKc5dZN4yPkP8w7Dc37BtP1yczEneOb4uq34pXZcvrtRTmWV8W+Ume+XCxKgbjM+nevkyFPMybd4Q==
 
-"wrap-ansi-cjs@npm:wrap-ansi@^7.0.0", wrap-ansi@^7.0.0:
+"wrap-ansi-cjs@npm:wrap-ansi@^7.0.0":
   version "7.0.0"
   resolved "https://registry.yarnpkg.com/wrap-ansi/-/wrap-ansi-7.0.0.tgz#67e145cff510a6a6984bdf1152911d69d2eb9e43"
   integrity sha512-YVGIj2kamLSTxw6NsZjoBxfSwsn0ycdesmc4p+Q21c5zPuZ1pl+NfxVdxPtdHvmNVOQ6XSYG4AUtyt/Fi7D16Q==
@@ -18863,6 +18897,15 @@ wrap-ansi@^6.2.0:
     string-width "^4.1.0"
     strip-ansi "^6.0.0"
 
+wrap-ansi@^7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/wrap-ansi/-/wrap-ansi-7.0.0.tgz#67e145cff510a6a6984bdf1152911d69d2eb9e43"
+  integrity sha512-YVGIj2kamLSTxw6NsZjoBxfSwsn0ycdesmc4p+Q21c5zPuZ1pl+NfxVdxPtdHvmNVOQ6XSYG4AUtyt/Fi7D16Q==
+  dependencies:
+    ansi-styles "^4.0.0"
+    string-width "^4.1.0"
+    strip-ansi "^6.0.0"
+
 wrap-ansi@^8.0.1, wrap-ansi@^8.1.0:
   version "8.1.0"
   resolved "https://registry.yarnpkg.com/wrap-ansi/-/wrap-ansi-8.1.0.tgz#56dc22368ee570face1b49819975d9b9a5ead214"