Fire impressions on vis change

src/components/Post/Embed/ImageEmbed.tsx

@@ -1,4 +1,4 @@
-import {useEffect, useRef} from 'react'
+import {useRef} from 'react'
 import {InteractionManager, View} from 'react-native'
 import {type AnimatedRef} from 'react-native-reanimated'
 import {Image} from 'expo-image'
@@ -57,20 +57,6 @@ export function ImageEmbed({
     ? {layout, ...postContext}
     : undefined
 
-  // Impression: one per mount of a post photo embed. Covers all three layouts
-  // identically so the opens/impressions CTR is unbiased by layout.
-  useEffect(() => {
-    if (images.length > 0 && postContext) {
-      ax.metric('post:photoEmbed:impression', {
-        layout,
-        totalImages: images.length,
-        ...postContext,
-      })
-    }
-    // Fire once per mount; intentionally not reactive to post context changes.
-    // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [])
-
   // Captured from AutoSizedImage so the peek-commit handler can reuse the same
   // ref + dims that a tap would — keeps the lightbox's return animation intact.
   const singleContainerRef = useRef<AnimatedRef<any> | null>(null)

src/view/com/posts/PostFeed.tsx

@@ -13,6 +13,8 @@ import {
 import {
   type AppBskyActorDefs,
   AppBskyEmbedExternal,
+  AppBskyEmbedGallery,
+  AppBskyEmbedImages,
   AppBskyEmbedVideo,
   type AppBskyFeedDefs,
 } from '@atproto/api'
@@ -907,7 +909,9 @@ let PostFeed = ({
 
   const seenActorWithStatusRef = useRef<Set<string>>(new Set())
   const seenPostUrisRef = useRef<Set<string>>(new Set())
-  const seenStandardSiteUrisRef = useRef<Set<string>>(new Set())
+  // Tracks every post we've seen so we can fire per-post events exactly once,
+  // regardless of the post's position within its slice.
+  const seenPerPostUrisRef = useRef<Set<string>>(new Set())
 
   // Helper to calculate position in feed (count only root posts, not interstitials or thread replies)
   const getPostPosition = useNonReactiveCallback(
@@ -940,6 +944,48 @@ let PostFeed = ({
     (item: FeedRow) => {
       feedFeedback.onItemSeen(item)
 
+      // Events that should fire exactly once for every new post, regardless of
+      // its position within a slice or video grid row.
+      const onPostSeen = (post: AppBskyFeedDefs.PostView) => {
+        if (seenPerPostUrisRef.current.has(post.uri)) return
+        seenPerPostUrisRef.current.add(post.uri)
+
+        // Standard site embed view tracking
+        if (
+          AppBskyEmbedExternal.isView(post.embed) &&
+          isStandardSiteEmbed(post.embed.external)
+        ) {
+          ax.metric('embed:standardSite:view', {url: post.embed.external.uri})
+        }
+
+        // Photo embed impression tracking
+        if (
+          AppBskyEmbedImages.isView(post.embed) ||
+          AppBskyEmbedGallery.isView(post.embed)
+        ) {
+          const totalImages = AppBskyEmbedGallery.isView(post.embed)
+            ? post.embed.items.filter(AppBskyEmbedGallery.isViewImage).length
+            : post.embed.images.length
+          const useExpandedLayout = AppBskyEmbedGallery.isView(post.embed)
+            ? totalImages > 4
+            : ax.features.enabled(ax.features.PostGalleryEmbedEnable)
+          const layout =
+            totalImages === 1
+              ? 'single'
+              : useExpandedLayout
+                ? 'carousel'
+                : 'grid'
+
+          ax.metric('post:photoEmbed:impression', {
+            layout,
+            totalImages,
+            uri: post.uri,
+            authorDid: post.author.did,
+            feedDescriptor: feedFeedback.feedDescriptor || feed,
+          })
+        }
+      }
+
       // Track post:view events
       if (item.type === 'sliceItem') {
         const slice = item.slice
@@ -947,6 +993,8 @@ let PostFeed = ({
         const postItem = slice.items[indexInSlice]
         const post = postItem.post
 
+        onPostSeen(post)
+
         // Only track the root post of each slice (index 0) to avoid double-counting thread items
         if (indexInSlice === 0 && !seenPostUrisRef.current.has(post.uri)) {
           seenPostUrisRef.current.add(post.uri)
@@ -977,16 +1025,6 @@ let PostFeed = ({
             })
           }
         }
-
-        // Standard site embed view tracking
-        if (
-          AppBskyEmbedExternal.isView(post.embed) &&
-          isStandardSiteEmbed(post.embed.external) &&
-          !seenStandardSiteUrisRef.current.has(post.embed.external.uri)
-        ) {
-          seenStandardSiteUrisRef.current.add(post.embed.external.uri)
-          ax.metric('embed:standardSite:view', {url: post.embed.external.uri})
-        }
       } else if (item.type === 'videoGridRow') {
         // Track each video in the grid row
         for (let i = 0; i < item.items.length; i++) {