diff --git a/src/app/components/ArticleActions.svelte b/src/app/components/ArticleActions.svelte
index e4aa19da..b57d4bee 100644
--- a/src/app/components/ArticleActions.svelte
+++ b/src/app/components/ArticleActions.svelte
@@ -56,7 +56,7 @@
       {createReaction}
       reactionClass="tip-left" />
     {#if showActivity}
-      <EventActivity {url} {path} {event} />
+      <EventActivity {path} {event} {context} />
     {/if}
     <EventActions {url} {event} noun="Article" />
   </ThunkStatusOrDeleted>
diff --git a/src/app/components/CalendarEventActions.svelte b/src/app/components/CalendarEventActions.svelte
index 3f1c4c12..81451175 100644
--- a/src/app/components/CalendarEventActions.svelte
+++ b/src/app/components/CalendarEventActions.svelte
@@ -52,7 +52,7 @@
       {createReaction}
       reactionClass="tip tip-left" />
     {#if showActivity}
-      <EventActivity {url} {path} {event} />
+      <EventActivity {path} {event} {context} />
     {/if}
     <EventActions {url} {event} noun="Event">
       {#snippet customActions()}
diff --git a/src/app/components/ClassifiedActions.svelte b/src/app/components/ClassifiedActions.svelte
index cbff347d..ff8f803c 100644
--- a/src/app/components/ClassifiedActions.svelte
+++ b/src/app/components/ClassifiedActions.svelte
@@ -70,7 +70,7 @@
       {createReaction}
       reactionClass="tip-left" />
     {#if showActivity}
-      <EventActivity {url} {path} {event} />
+      <EventActivity {path} {event} {context} />
     {/if}
     <EventActions {url} {event} noun="Listing">
       {#snippet customActions()}
diff --git a/src/app/components/CommentActions.svelte b/src/app/components/CommentActions.svelte
index 3d614c47..4ad8d368 100644
--- a/src/app/components/CommentActions.svelte
+++ b/src/app/components/CommentActions.svelte
@@ -39,7 +39,7 @@
         {createReaction}
         reactionClass="tip-left" />
       {#if showActivity && path}
-        <EventActivity {url} {path} {event} />
+        <EventActivity {path} {event} {context} />
       {/if}
       <EventActions {url} {event} noun="Comment" />
     </ThunkStatusOrDeleted>
diff --git a/src/app/components/EventActivity.svelte b/src/app/components/EventActivity.svelte
index 1254199f..a47b0b39 100644
--- a/src/app/components/EventActivity.svelte
+++ b/src/app/components/EventActivity.svelte
@@ -1,24 +1,19 @@
 <script lang="ts">
-  import {onMount} from "svelte"
-  import {max, gt, formatTimestampRelative} from "@welshman/lib"
-  import {getCommentFiltersForRoot} from "@welshman/util"
+  import {derived} from "svelte/store"
+  import {filter, max, gt, spec, formatTimestampRelative} from "@welshman/lib"
+  import {COMMENT} from "@welshman/util"
   import type {TrustedEvent} from "@welshman/util"
   import Reply from "@assets/icons/reply-2.svg?dataurl"
   import Icon from "@lib/components/Icon.svelte"
-  import {deriveEvents} from "@app/repository"
-  import {network} from "@app/core"
+  import type {FeedContext} from "@app/feeds"
   import {deriveChecked} from "@app/notifications"
 
-  const {url, path, event}: {url: string; path: string; event: TrustedEvent} = $props()
+  const {path, event, context}: {path: string; event: TrustedEvent; context: FeedContext} = $props()
 
   const checked = deriveChecked(path)
-  const filters = getCommentFiltersForRoot([event])
-  const replies = deriveEvents(filters)
+  const related = context.related(event)
+  const replies = derived(related, $related => filter(spec({kind: COMMENT}), $related))
   const lastActive = $derived(max([...$replies, event].map(e => e.created_at)))
-
-  onMount(() => {
-    $network.load({relays: [url], filters})
-  })
 </script>
 
 <div class="flex-inline button button-neutral button-xs gap-1 rounded-full">
diff --git a/src/app/components/GoalActions.svelte b/src/app/components/GoalActions.svelte
index 7b39e409..8c94c43c 100644
--- a/src/app/components/GoalActions.svelte
+++ b/src/app/components/GoalActions.svelte
@@ -47,7 +47,7 @@
       {createReaction}
       reactionClass="tip-left" />
     {#if showActivity}
-      <EventActivity {url} {path} {event} />
+      <EventActivity {path} {event} {context} />
     {/if}
     <EventActions {url} {event} hideZap noun="Goal" />
   </ThunkStatusOrDeleted>
diff --git a/src/app/components/PollActions.svelte b/src/app/components/PollActions.svelte
index 2dbe41d4..90d24f39 100644
--- a/src/app/components/PollActions.svelte
+++ b/src/app/components/PollActions.svelte
@@ -44,7 +44,7 @@
       {createReaction}
       reactionClass="tip-left" />
     {#if showActivity}
-      <EventActivity {url} {path} {event} />
+      <EventActivity {path} {event} {context} />
     {/if}
     <EventActions {url} {event} noun="Poll" />
   </ThunkStatusOrDeleted>
diff --git a/src/app/components/ThreadActions.svelte b/src/app/components/ThreadActions.svelte
index 782fd518..56043ebd 100644
--- a/src/app/components/ThreadActions.svelte
+++ b/src/app/components/ThreadActions.svelte
@@ -43,7 +43,7 @@
       {createReaction}
       reactionClass="tip-left" />
     {#if showActivity}
-      <EventActivity {url} {path} {event} />
+      <EventActivity {path} {event} {context} />
     {/if}
     <EventActions {url} {event} noun="Thread" />
   </ThunkStatusOrDeleted>
diff --git a/src/app/components/ThreadBoard.svelte b/src/app/components/ThreadBoard.svelte
index 5bbac8fb..610e88aa 100644
--- a/src/app/components/ThreadBoard.svelte
+++ b/src/app/components/ThreadBoard.svelte
@@ -3,14 +3,16 @@
   import {matchMd} from "@lib/theme"
   import RoomNameWithImage from "@app/components/RoomNameWithImage.svelte"
   import ThreadBoardItem from "@app/components/ThreadBoardItem.svelte"
+  import type {FeedContext} from "@app/feeds"
 
   type Props = {
     url: string
     h: string
     threads: TrustedEvent[]
+    context: FeedContext
   }
 
-  const {url, h, threads}: Props = $props()
+  const {url, h, threads, context}: Props = $props()
 </script>
 
 <section class="card card-flat p-0">
@@ -42,7 +44,7 @@
         </thead>
         <tbody>
           {#each threads as event (event.id)}
-            <ThreadBoardItem {url} {event} />
+            <ThreadBoardItem {url} {event} {context} />
           {/each}
         </tbody>
       </table>
@@ -50,7 +52,7 @@
   {:else}
     <div class="pb-4">
       {#each threads as event (event.id)}
-        <ThreadBoardItem mobile {url} {event} />
+        <ThreadBoardItem mobile {url} {event} {context} />
       {/each}
     </div>
   {/if}
diff --git a/src/app/components/ThreadBoardItem.svelte b/src/app/components/ThreadBoardItem.svelte
index e46bc533..5afbd708 100644
--- a/src/app/components/ThreadBoardItem.svelte
+++ b/src/app/components/ThreadBoardItem.svelte
@@ -1,25 +1,28 @@
 <script lang="ts">
   import {goto} from "$app/navigation"
-  import {formatTimestamp, max} from "@welshman/lib"
+  import {derived} from "svelte/store"
+  import {filter, formatTimestamp, max, spec} from "@welshman/lib"
   import type {TrustedEvent} from "@welshman/util"
-  import {getCommentFiltersForRoot, tagSpec, tagValue} from "@welshman/util"
+  import {COMMENT, tagSpec, tagValue} from "@welshman/util"
   import {fade} from "@lib/transition"
   import Link from "@lib/components/Link.svelte"
   import ProfileCircle from "@app/components/ProfileCircle.svelte"
   import ProfileName from "@app/components/ProfileName.svelte"
-  import {deriveEventsForUrl} from "@app/repository"
+  import type {FeedContext} from "@app/feeds"
   import {notifications} from "@app/notifications"
   import {makeThreadPath} from "@app/routes"
 
   type Props = {
     url: string
     event: TrustedEvent
+    context: FeedContext
     mobile?: boolean
   }
 
-  const {url, event, mobile = false}: Props = $props()
+  const {url, event, context, mobile = false}: Props = $props()
 
-  const replies = deriveEventsForUrl(url, getCommentFiltersForRoot([event]))
+  const related = context.related(event)
+  const replies = derived(related, $related => filter(spec({kind: COMMENT}), $related))
   const replyCount = $derived($replies.length)
   const lastActive = $derived(max([...$replies, event].map(e => e.created_at)))
   const title = tagValue(tagSpec("title"), event.tags)
diff --git a/src/app/content.ts b/src/app/content.ts
index 5c269dc6..dc333a32 100644
--- a/src/app/content.ts
+++ b/src/app/content.ts
@@ -36,7 +36,7 @@ export const makeDeleteFilter = (kinds: number[], extra: Filter = {}) => ({
 
 export const REPOST_KINDS = [REPOST, GENERIC_REPOST]
 
-export const REACTION_DISPLAY_KINDS = [REPORT, REACTION, ZAP_RECEIPT]
+export const EVENT_CONTEXT_KINDS = [REPORT, REACTION, ZAP_RECEIPT, COMMENT]
 
 export const REACTION_KINDS = [REPORT, DELETE, REACTION]
 
diff --git a/src/app/feeds.ts b/src/app/feeds.ts
index f43f13fe..783b55bd 100644
--- a/src/app/feeds.ts
+++ b/src/app/feeds.ts
@@ -1,12 +1,16 @@
-import {readable, writable} from "svelte/store"
+import {derived, readable, writable} from "svelte/store"
 import type {Readable} from "svelte/store"
 import {batch, between, call, int, now, on, sortBy, uniqBy, MONTH, YEAR} from "@welshman/lib"
 import {
+  COMMENT,
   DELETE,
   EVENT_TIME,
+  addressTags,
   getAddress,
+  getCommentFiltersForRoot,
   getReplyFilters,
   hexTags,
+  isReplaceableKind,
   matchFilters,
   tagSpec,
   tagValue,
@@ -17,12 +21,24 @@ import {mergeRepositoryUpdates} from "@welshman/net"
 import type {RepositoryUpdate} from "@welshman/net"
 import {createScroller} from "@lib/html"
 import {daysBetween} from "@lib/util"
-import {REACTION_DISPLAY_KINDS, REACTION_KINDS} from "@app/content"
+import {EVENT_CONTEXT_KINDS, REACTION_KINDS} from "@app/content"
 import {app, network} from "@app/core"
 import {getEventsForUrl} from "@app/repository"
 
 const noEvents: TrustedEvent[] = []
 
+// Reactions, zaps and reports point at their subject with `e`/`a`. A NIP-22 comment instead
+// points at its thread *root* with `E`/`A`, so filing it by those tags puts a whole thread in
+// the root's bucket — which is the scope a reply count wants.
+const getTargets = ({kind, tags}: TrustedEvent) =>
+  kind === COMMENT
+    ? [...tagValues(hexTags("E"), tags), ...tagValues(addressTags("A"), tags)]
+    : [...tagValues(hexTags("e"), tags), ...tagValues(addressTags("a"), tags)]
+
+// A related event may point at a replaceable one by either id or address, so both are keys
+const getKeys = (event: TrustedEvent) =>
+  isReplaceableKind(event.kind) ? [event.id, getAddress(event)] : [event.id]
+
 export const makeFeedContext = ({relays}: {relays: string[] | Promise<string[]>}) => {
   const {repository} = app.get()
   const controller = new AbortController()
@@ -35,7 +51,7 @@ export const makeFeedContext = ({relays}: {relays: string[] | Promise<string[]>}
     // An event seen before its target was tracked stays unfiled, so that adding the target
     // later can pick it up out of the repository
     if (!targetsByEventId.has(event.id)) {
-      const eventTargets = tagValues(hexTags("e"), event.tags).filter(target => targets.has(target))
+      const eventTargets = getTargets(event).filter(target => targets.has(target))
 
       if (eventTargets.length > 0) {
         targetsByEventId.set(event.id, eventTargets)
@@ -81,9 +97,10 @@ export const makeFeedContext = ({relays}: {relays: string[] | Promise<string[]>}
 
     // What's already local — an earlier page, our own optimistic reactions — never comes
     // through the update listener, so file it before asking the network for the rest
-    for (const event of repository.query(
-      getReplyFilters(events, {kinds: REACTION_DISPLAY_KINDS}),
-    )) {
+    for (const event of repository.query([
+      ...getReplyFilters(events, {kinds: EVENT_CONTEXT_KINDS}),
+      ...getCommentFiltersForRoot(events),
+    ])) {
       addEvent(event, touched)
     }
 
@@ -94,7 +111,10 @@ export const makeFeedContext = ({relays}: {relays: string[] | Promise<string[]>}
     const context = await network.get().load({
       relays: urls,
       signal: controller.signal,
-      filters: getReplyFilters(events, {kinds: REACTION_KINDS}),
+      filters: [
+        ...getReplyFilters(events, {kinds: REACTION_KINDS}),
+        ...getCommentFiltersForRoot(events),
+      ],
     })
 
     if (context.length > 0) {
@@ -114,7 +134,7 @@ export const makeFeedContext = ({relays}: {relays: string[] | Promise<string[]>}
       const touched = new Set<string>()
 
       for (const event of added) {
-        if (REACTION_DISPLAY_KINDS.includes(event.kind)) {
+        if (EVENT_CONTEXT_KINDS.includes(event.kind)) {
           addEvent(event, touched)
         }
       }
@@ -130,35 +150,49 @@ export const makeFeedContext = ({relays}: {relays: string[] | Promise<string[]>}
   // Track an event so its context gets requested with the rest of the batch
   const add = (event: TrustedEvent) => {
     if (!targets.has(event.id)) {
-      targets.add(event.id)
+      for (const key of getKeys(event)) {
+        targets.add(key)
+      }
+
       loadContext(event)
     }
   }
 
+  const relatedForKey = (key: string) =>
+    readable(eventsByTarget.get(key) || noEvents, set => {
+      let subscribers = subscribersByTarget.get(key)
+
+      if (!subscribers) {
+        subscribers = new Set()
+        subscribersByTarget.set(key, subscribers)
+      }
+
+      subscribers.add(set)
+      set(eventsByTarget.get(key) || noEvents)
+
+      return () => {
+        subscribers.delete(set)
+
+        if (subscribers.size === 0) {
+          subscribersByTarget.delete(key)
+        }
+      }
+    })
+
   return {
     add,
     related: (event: TrustedEvent): Readable<TrustedEvent[]> => {
       add(event)
 
-      return readable(eventsByTarget.get(event.id) || noEvents, set => {
-        let subscribers = subscribersByTarget.get(event.id)
+      const [key, ...rest] = getKeys(event)
 
-        if (!subscribers) {
-          subscribers = new Set()
-          subscribersByTarget.set(event.id, subscribers)
-        }
-
-        subscribers.add(set)
-        set(eventsByTarget.get(event.id) || noEvents)
-
-        return () => {
-          subscribers.delete(set)
-
-          if (subscribers.size === 0) {
-            subscribersByTarget.delete(event.id)
-          }
-        }
-      })
+      // A replaceable event collects both its buckets, and something tagging it by id and
+      // address at once lands in both
+      return rest.length > 0
+        ? derived([relatedForKey(key), ...rest.map(relatedForKey)], buckets =>
+            uniqBy(event => event.id, buckets.flat()),
+          )
+        : relatedForKey(key)
     },
     cleanup: () => {
       controller.abort()
diff --git a/src/routes/spaces/[relay]/threads/+page.svelte b/src/routes/spaces/[relay]/threads/+page.svelte
index cf935291..f16e5710 100644
--- a/src/routes/spaces/[relay]/threads/+page.svelte
+++ b/src/routes/spaces/[relay]/threads/+page.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import {onMount} from "svelte"
+  import {onDestroy, onMount} from "svelte"
   import {readable} from "svelte/store"
   import type {Readable} from "svelte/store"
   import {page} from "$app/stores"
@@ -18,10 +18,13 @@
   import {decodeRelay} from "@app/relays"
   import {displayRoom} from "@app/rooms"
   import {makeCommentFilter} from "@app/content"
-  import {makeFeed} from "@app/feeds"
+  import {makeFeed, makeFeedContext} from "@app/feeds"
   import {pushModal} from "@app/modal"
 
   const url = decodeRelay($page.params.relay!)
+  const context = makeFeedContext({relays: [url]})
+
+  onDestroy(context.cleanup)
 
   let loading = $state(true)
   let element: HTMLElement | undefined = $state()
@@ -54,6 +57,7 @@
     const feed = makeFeed({
       relays: [url],
       element: element!,
+      onEvent: context.add,
       filters: [{kinds: [THREAD]}, makeCommentFilter([THREAD])],
       onBackwardExhausted: () => {
         loading = false
@@ -62,9 +66,7 @@
 
     events = feed.events
 
-    return () => {
-      feed.cleanup()
-    }
+    return () => feed.cleanup()
   })
 </script>
 
@@ -85,7 +87,7 @@
 
 <PageContent bind:element class="flex flex-col gap-2 p-2 sm:gap-4 sm:p-4">
   {#each threadFeed.boards as [h, threads] (h || "general")}
-    <ThreadBoard {url} {h} {threads} />
+    <ThreadBoard {url} {h} {threads} {context} />
   {/each}
   <p class="flex h-10 items-center justify-center py-20">
     <Spinner {loading}>