feat(audio-rooms): per-room kind-1311 chat subscription

Adds the relay-side wire sub for the live-chat panel — REQs
`kinds=[1311], #a=[roomATag]` against the user's outbox relays
while the room screen is composed.

  RoomChatQueryState / RoomChatFilterSubAssembler /
  RoomChatFilterAssembler — mirror of RoomPresenceFilterAssembler;
  same shape so a future refactor can dedupe.

  RoomChatFilterAssemblerSubscription — Composable lifecycle
  wrapper. Single file (no separate "*Subscription.kt") since
  the assembler + composable are tightly coupled to one event kind.

  RelaySubscriptionsCoordinator.roomChat — registered alongside
  `audioRooms` and `roomPresence` so accountViewModel.dataSources()
  exposes it on the same surface the rest of the screen-scoped
  subs use.

Events arriving in LocalCache are picked up by AudioRoomActivityContent
in the next commit, where they're piped into the VM's chat ledger.

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

@@ -29,6 +29,7 @@ import com.vitorpamplona.amethyst.service.relayClient.reqCommand.user.UserFinder
 import com.vitorpamplona.amethyst.service.relayClient.searchCommand.SearchFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.articles.datasource.ArticlesFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.audiorooms.datasource.AudioRoomsFilterAssembler
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.audiorooms.datasource.RoomChatFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.audiorooms.datasource.RoomPresenceFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.badges.datasource.BadgesFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.badges.profile.datasource.ProfileBadgesFilterAssembler
@@ -109,6 +110,7 @@ class RelaySubscriptionsCoordinator(
     val liveStreams = LiveStreamsFilterAssembler(client)
     val audioRooms = AudioRoomsFilterAssembler(client)
     val roomPresence = RoomPresenceFilterAssembler(client)
+    val roomChat = RoomChatFilterAssembler(client)
     val longs = LongsFilterAssembler(client)
     val articles = ArticlesFilterAssembler(client)
     val badges = BadgesFilterAssembler(client)

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/audiorooms/datasource/RoomChatFilterAssembler.kt

@@ -0,0 +1,114 @@
+/*
+ * 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.audiorooms.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.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.chat.LiveActivitiesChatMessageEvent
+
+/**
+ * Per-screen state for the per-room kind-1311 live-chat
+ * subscription. Mirror of [RoomPresenceQueryState] — the room's
+ * `a`-tag is the address-pointer string (`30312:<host>:<roomId>`).
+ */
+@Stable
+class RoomChatQueryState(
+    val roomATag: String,
+    val account: Account,
+)
+
+/**
+ * REQs `kinds=[1311], #a=[roomATag]` against the user's outbox
+ * relays so the chat panel sees every message tagged for this
+ * room. Events arrive in [com.vitorpamplona.amethyst.model.LocalCache];
+ * the room screen pipes them into `AudioRoomViewModel.onChatEvent`.
+ */
+class RoomChatFilterSubAssembler(
+    client: INostrClient,
+    allKeys: () -> Set<RoomChatQueryState>,
+) : PerUniqueIdEoseManager<RoomChatQueryState, String>(client, allKeys) {
+    override fun updateFilter(
+        key: RoomChatQueryState,
+        since: SincePerRelayMap?,
+    ): List<RelayBasedFilter> {
+        val relays = key.account.outboxRelays.flow.value
+        return relays.map { relay ->
+            RelayBasedFilter(
+                relay = relay,
+                filter =
+                    Filter(
+                        kinds = listOf(LiveActivitiesChatMessageEvent.KIND),
+                        tags = mapOf("a" to listOf(key.roomATag)),
+                        since = since?.get(relay)?.time,
+                    ),
+            )
+        }
+    }
+
+    override fun id(key: RoomChatQueryState): String = key.roomATag
+}
+
+@Stable
+class RoomChatFilterAssembler(
+    client: INostrClient,
+) : ComposeSubscriptionManager<RoomChatQueryState>() {
+    private val sub = RoomChatFilterSubAssembler(client, ::allKeys)
+
+    override fun invalidateKeys() = invalidateFilters()
+
+    override fun invalidateFilters() = sub.invalidateFilters()
+
+    override fun destroy() = sub.destroy()
+}
+
+/**
+ * Lifecycle-aware Composable subscription. Sub stays open while the
+ * Composable is in the tree, then closes on dispose.
+ */
+@Composable
+fun RoomChatFilterAssemblerSubscription(
+    roomATag: String,
+    accountViewModel: AccountViewModel,
+) = RoomChatFilterAssemblerSubscription(
+    roomATag,
+    accountViewModel.account,
+    accountViewModel.dataSources().roomChat,
+)
+
+@Composable
+fun RoomChatFilterAssemblerSubscription(
+    roomATag: String,
+    account: Account,
+    filterAssembler: RoomChatFilterAssembler,
+) {
+    val state = remember(roomATag) { RoomChatQueryState(roomATag, account) }
+    KeyDataSourceSubscription(state, filterAssembler)
+}