perf(nests): dedicated kinds=[10312] limit=1 feed liveness probe

Feed thumbnails were reusing NestRoomFilterAssemblerSubscription to
flip the LIVE/ENDED badge based on the freshest kind-10312 presence.
That assembler subscribes to chat + presence + reactions (kinds 1311,
10312, 7) — so a feed of N rooms paid each popular room's full
chat-history pull per outbox relay just to render a status pill.

Add NestRoomLivenessAssembler, scoped to a single kinds=[10312],
#a=[room], limit=1 filter per relay, and switch the feed thumbnail
to it. The full chat / reaction / admin command REQ stays gated
behind the join flow.

https://claude.ai/code/session_01DMeCvWyBYVVVPez2hwqCs4

amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/reqCommand/RelaySubscriptionsCoordinator.kt

@@ -46,6 +46,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.home.datasource.HomeFilterA
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.livestreams.datasource.LiveStreamsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.longs.datasource.LongsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestRoomFilterAssembler
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestRoomLivenessAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.pictures.datasource.PicturesFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.polls.datasource.PollsFilterAssembler
@@ -109,6 +110,7 @@ class RelaySubscriptionsCoordinator(
     val liveStreams = LiveStreamsFilterAssembler(client)
     val nests = NestsFilterAssembler(client)
     val nestRoom = NestRoomFilterAssembler(client)
+    val nestRoomLiveness = NestRoomLivenessAssembler(client)
     val longs = LongsFilterAssembler(client)
     val articles = ArticlesFilterAssembler(client)
     val badges = BadgesFilterAssembler(client)
@@ -135,6 +137,7 @@ class RelaySubscriptionsCoordinator(
             liveStreams,
             nests,
             nestRoom,
+            nestRoomLiveness,
             longs,
             articles,
             badges,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/nests/NestsFeedLoaded.kt

@@ -78,7 +78,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.nip53L
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.nip53LiveActivities.PrivateFlag
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.nip53LiveActivities.ScheduledFlag
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.discover.nip53LiveActivities.LoadParticipants
-import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestRoomFilterAssemblerSubscription
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestRoomLivenessProbeSubscription
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.room.activity.NestActivity
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.room.activity.NestBridge
 import com.vitorpamplona.amethyst.ui.stringRes
@@ -300,14 +300,14 @@ private fun RenderLiveOrEndedFromPresence(
 
 /**
  * Most recent kind-10312 presence `createdAt` cached for [address],
- * or null until one arrives. Reuses the room's existing assembler
+ * or null until one arrives. Uses the dedicated
- * subscription (`NestRoomFilterAssemblerSubscription`) — same
+ * [NestRoomLivenessProbeSubscription] — `kinds=[10312], #a=[roomA],
- * subscription that warms up when the user actually opens the room
+ * limit=1` per outbox relay — so a feed of N rooms doesn't pay
- * — and reads version notes off the room's [LocalCache] channel,
+ * each popular room's chat-history pull just to render a LIVE /
- * which `LocalCache.consume(MeetingRoomPresenceEvent, …)` attaches
+ * ENDED badge. The assembler reads version notes off the room's
- * by `#a=room`. Trade-off: that REQ also pulls chat + reactions, so
+ * [LocalCache] channel, which `LocalCache.consume(MeetingRoomPresenceEvent, …)`
- * a thumbnail probe pays a popular room's full message history. If
+ * attaches by `#a=room`. The full chat / reaction / admin REQs
- * that load matters, swap to a dedicated limit:1 assembler.
+ * stay gated behind the join flow (see [NestRoomFilterAssemblerSubscription]).
  */
 @OptIn(ExperimentalCoroutinesApi::class)
 @Composable
@@ -315,7 +315,7 @@ private fun observeRoomLatestPresence(
     note: AddressableNote,
     accountViewModel: AccountViewModel,
 ): State<Long?> {
-    NestRoomFilterAssemblerSubscription(note, accountViewModel)
+    NestRoomLivenessProbeSubscription(note, accountViewModel)
 
     val channel = remember(note.idHex) { LocalCache.getOrCreateLiveChannel(note.address) }
     val flow =

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/nests/datasource/NestRoomLivenessProbeAssembler.kt

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.Stable
+import androidx.compose.runtime.remember
+import com.vitorpamplona.amethyst.commons.relayClient.composeSubscriptionManagers.ComposeSubscriptionManager
+import com.vitorpamplona.amethyst.commons.relayClient.subscriptions.KeyDataSourceSubscription
+import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.amethyst.model.AddressableNote
+import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.PerUniqueIdEoseManager
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+import com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.MeetingSpaceEvent
+import com.vitorpamplona.quartz.nip53LiveActivities.presence.MeetingRoomPresenceEvent
+
+/**
+ * Per-room state for the lightweight liveness probe — used by feed
+ * thumbnail cards to flip the LIVE / ENDED badge based on whether
+ * any speaker has published a fresh kind-10312 presence.
+ *
+ * Distinct from [NestRoomQueryState] (which fans out to chat,
+ * presence, reactions, and admin commands for an actively-joined
+ * room) — the feed should not pay a popular room's full chat
+ * history just to render a status pill.
+ */
+@Stable
+class NestRoomLivenessQueryState(
+    val note: AddressableNote,
+    val account: Account,
+)
+
+/**
+ * Single per-room sub-assembler for the feed thumbnail liveness
+ * probe. Issues ONE narrow [Filter] per outbox relay:
+ *
+ *   `kinds=[10312]`, `#a=[roomATag]`, `limit=1`
+ *
+ * Net wire change: the previous code reused [NestRoomFilterSubAssembler]
+ * for the badge probe, which subscribes to chat + presence + reactions
+ * (kinds 1311, 10312, 7) — so a feed of N rooms cost N popular-room
+ * chat-history pulls per relay. This probe asks for the single
+ * latest presence per room and nothing else.
+ */
+class NestRoomLivenessSubAssembler(
+    client: INostrClient,
+    allKeys: () -> Set<NestRoomLivenessQueryState>,
+) : PerUniqueIdEoseManager<NestRoomLivenessQueryState, String>(client, allKeys) {
+    override fun updateFilter(
+        key: NestRoomLivenessQueryState,
+        since: SincePerRelayMap?,
+    ): List<RelayBasedFilter> {
+        val relays =
+            key.account.outboxRelays.flow.value +
+                key.note.relays +
+                ((key.note.event as? MeetingSpaceEvent)?.relays()?.toSet() ?: emptySet())
+
+        return relays.map { relay ->
+            RelayBasedFilter(
+                relay = relay,
+                filter =
+                    Filter(
+                        kinds = listOf(MeetingRoomPresenceEvent.KIND),
+                        tags = mapOf("a" to listOf(key.note.idHex)),
+                        // limit=1: the badge only needs the freshest
+                        // heartbeat — older ones don't change the
+                        // verdict. since is still threaded so the
+                        // EOSE manager can resume after a reconnect.
+                        limit = 1,
+                        since = since?.get(relay)?.time,
+                    ),
+            )
+        }
+    }
+
+    override fun id(key: NestRoomLivenessQueryState): String = key.note.idHex
+}
+
+@Stable
+class NestRoomLivenessAssembler(
+    client: INostrClient,
+) : ComposeSubscriptionManager<NestRoomLivenessQueryState>() {
+    private val sub = NestRoomLivenessSubAssembler(client, ::allKeys)
+
+    override fun invalidateKeys() = invalidateFilters()
+
+    override fun invalidateFilters() = sub.invalidateFilters()
+
+    override fun destroy() = sub.destroy()
+}
+
+/**
+ * Lifecycle-aware subscription. Stays open while the feed card is in
+ * the tree (LazyColumn auto-disposes off-screen cards); closes on
+ * dispose. Use this from feed thumbnails — the join flow uses
+ * [NestRoomFilterAssemblerSubscription] which is heavier.
+ */
+@Composable
+fun NestRoomLivenessProbeSubscription(
+    note: AddressableNote,
+    accountViewModel: AccountViewModel,
+) = NestRoomLivenessProbeSubscription(
+    note,
+    accountViewModel.account,
+    accountViewModel.dataSources().nestRoomLiveness,
+)
+
+@Composable
+fun NestRoomLivenessProbeSubscription(
+    note: AddressableNote,
+    account: Account,
+    filterAssembler: NestRoomLivenessAssembler,
+) {
+    val state =
+        remember(note, account.pubKey) {
+            NestRoomLivenessQueryState(note, account)
+        }
+    KeyDataSourceSubscription(state, filterAssembler)
+}