feat(geohash-chat): native Messages rooms via LocalCache (Phase A+B)

Makes geohash location channels first-class in the Messages tab by routing them through the same LocalCache -> feed machinery every other room uses: Phase A (foundation): - commons GeohashChatChannel : Channel, keyed by the bare geohash, with a placeholder-note so a just-joined cell shows before its first message. - LocalCache: geohashChannels map, get/getOrCreateGeohashChannel, a consume(GeohashChatEvent) that routes kind-20000 messages into the cell's channel (presence 20001 stays with the live screen), plus getAnyChannel + the prune loops. - GeohashRelays: a process-wide geohash->relay directory (live CSV once, fallback otherwise). FollowingGeohashChatSubAssembler + filterFollowingGeohashChats subscribe the joined cells (account.geohashList) to each cell's nearest relays, registered in ChatroomListFilterAssembler. Phase B (Messages): - ChatroomListKnownFeedFilter: a geohashChannels family (feed + incremental updateListWith/applyFilter + filterRelevantGeohashChats + geohashRowKey so a placeholder and its later real message resolve to one row). - ChatroomHeaderCompose: a GeohashRoomCompose row (location pin, anonymous — name from the message's n tag) -> Route.GeohashChat. - AccountFeedContentStates: rebuild the list when the joined set changes. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0172JoMccseEKenyWan6txWV
2026-08-12 09:13:23 +00:00 · 2026-07-16 01:07:48 +00:00
parent fba41ecd8e
commit 6657957677
10 changed files with 416 additions and 1 deletions
@@ -32,6 +32,7 @@ import com.vitorpamplona.amethyst.commons.model.cache.ICacheProvider
 import com.vitorpamplona.amethyst.commons.model.cache.LargeSoftCache
 import com.vitorpamplona.amethyst.commons.model.concord.ConcordChannel
 import com.vitorpamplona.amethyst.commons.model.emphChat.EphemeralChatChannel
+import com.vitorpamplona.amethyst.commons.model.geohashChat.GeohashChatChannel
 import com.vitorpamplona.amethyst.commons.model.nip28PublicChats.PublicChatChannel
 import com.vitorpamplona.amethyst.commons.model.nip29RelayGroups.RelayGroupChannel
 import com.vitorpamplona.amethyst.commons.model.nip53LiveActivities.LiveActivitiesChannel
@@ -60,6 +61,7 @@ import com.vitorpamplona.quartz.experimental.audio.header.AudioHeaderEvent
 import com.vitorpamplona.quartz.experimental.audio.track.AudioTrackEvent
 import com.vitorpamplona.quartz.experimental.birdstar.BirdDetectionEvent
 import com.vitorpamplona.quartz.experimental.birdstar.BirdexEvent
+import com.vitorpamplona.quartz.experimental.bitchat.geohash.GeohashChatEvent
 import com.vitorpamplona.quartz.experimental.edits.TextNoteModificationEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.chat.EphemeralChatEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.chat.RoomId
@@ -357,6 +359,7 @@ object LocalCache : ILocalCache, ICacheProvider {
    val publicChatChannels = LargeCache<HexKey, PublicChatChannel>()
    val liveChatChannels = LargeCache<Address, LiveActivitiesChannel>()
    val ephemeralChannels = LargeCache<RoomId, EphemeralChatChannel>()
+    val geohashChannels = LargeCache<String, GeohashChatChannel>()
    val relayGroupChannels = LargeCache<GroupId, RelayGroupChannel>()
    val concordChannels = LargeCache<ConcordChannelId, ConcordChannel>()

@@ -632,6 +635,8 @@ object LocalCache : ILocalCache, ICacheProvider {

    fun getEphemeralChatChannelIfExists(key: RoomId): EphemeralChatChannel? = ephemeralChannels.get(key)

+    fun getGeohashChannelIfExists(geohash: String): GeohashChatChannel? = geohashChannels.get(geohash)
+
    fun getRelayGroupChannelIfExists(key: GroupId): RelayGroupChannel? = relayGroupChannels.get(key)

    /** Every relay group we know of that is hosted on [relay] (its channel directory). */
@@ -725,6 +730,8 @@ object LocalCache : ILocalCache, ICacheProvider {

    fun getOrCreateEphemeralChannel(key: RoomId): EphemeralChatChannel = ephemeralChannels.getOrCreate(key) { EphemeralChatChannel(key) }

+    fun getOrCreateGeohashChannel(geohash: String): GeohashChatChannel = geohashChannels.getOrCreate(geohash) { GeohashChatChannel(geohash) }
+
    fun getOrCreateRelayGroupChannel(key: GroupId): RelayGroupChannel = relayGroupChannels.getOrCreate(key) { RelayGroupChannel(key) }

    fun getConcordChannelIfExists(key: ConcordChannelId): ConcordChannel? = concordChannels.get(key)
@@ -1478,6 +1485,7 @@ object LocalCache : ILocalCache, ICacheProvider {
            is LiveActivitiesChatMessageEvent -> noteEvent.activityAddress()?.let { getLiveActivityChannelIfExists(it) }
            is LiveActivitiesEvent -> getLiveActivityChannelIfExists(noteEvent.address())
            is EphemeralChatEvent -> noteEvent.roomId()?.let { getEphemeralChatChannelIfExists(it) }
+            is GeohashChatEvent -> noteEvent.geohash()?.let { getGeohashChannelIfExists(it) }
            else -> null
        }

@@ -1843,6 +1851,30 @@ object LocalCache : ILocalCache, ICacheProvider {
        return new
    }

+    /**
+     * Public geohash chat message (kind 20000). Routes into the cell's
+     * [GeohashChatChannel]. Presence (kind 20001) is deliberately NOT consumed
+     * here — it is an empty-content heartbeat handled by the live chat screen, so
+     * it never becomes a room's "last message".
+     */
+    fun consume(
+        event: GeohashChatEvent,
+        relay: NormalizedRelayUrl?,
+        wasVerified: Boolean,
+    ): Boolean {
+        val geohash = event.geohash() ?: return false
+
+        val new = consumeRegularEvent(event, relay, wasVerified)
+
+        if (new) {
+            val note = getOrCreateNote(event.id)
+            val channel = getOrCreateGeohashChannel(geohash)
+            channel.addNote(note, relay)
+        }
+
+        return new
+    }
+
    /**
     * NIP-29 relay-signed group metadata (kind 39000). Stored as an addressable
     * note and used to populate the [RelayGroupChannel]'s name/picture/about/
@@ -2881,6 +2913,10 @@ object LocalCache : ILocalCache, ICacheProvider {
            pruneHiddenMessagesChannel(channel, account)
        }

+        geohashChannels.forEach { _, channel ->
+            pruneHiddenMessagesChannel(channel, account)
+        }
+
        liveChatChannels.forEach { _, channel ->
            pruneHiddenMessagesChannel(channel, account)
        }
@@ -2934,6 +2970,10 @@ object LocalCache : ILocalCache, ICacheProvider {
            pruneOldMessagesChannel(channel)
        }

+        geohashChannels.forEach { _, channel ->
+            pruneOldMessagesChannel(channel)
+        }
+
        liveChatChannels.forEach { _, channel ->
            pruneOldMessagesChannel(channel)
        }
@@ -3817,6 +3857,10 @@ object LocalCache : ILocalCache, ICacheProvider {
                    consume(event, relay, wasVerified)
                }

+                is GeohashChatEvent -> {
+                    consume(event, relay, wasVerified)
+                }
+
                is EphemeralChatListEvent -> {
                    consumeBaseReplaceable(event, relay, wasVerified)
                }
@@ -0,0 +1,52 @@
+/*
+ * 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.service.geohash
+
+import com.vitorpamplona.amethyst.Amethyst
+import com.vitorpamplona.amethyst.commons.service.georelay.GeoRelayCsvLoader
+import com.vitorpamplona.amethyst.commons.service.georelay.GeoRelayDirectory
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+
+/**
+ * Process-wide geohash → relay directory, shared by everything that routes
+ * geohash chat traffic (the joined-cell subscription, the chat screen). The live
+ * CSV is fetched once via [ensureLoaded]; until then [closestRelays] falls back
+ * to the small built-in list so routing works offline / on first run.
+ */
+object GeohashRelays {
+    private val directory = GeoRelayDirectory()
+
+    @Volatile private var refreshed = false
+
+    /** Fetches the live directory once. Safe to call repeatedly; subsequent calls are no-ops. */
+    suspend fun ensureLoaded(): Boolean {
+        if (refreshed) return false
+        runCatching {
+            GeoRelayCsvLoader { Amethyst.instance.okHttpClients.getHttpClient(false) }.refresh(directory)
+        }
+        val loaded = directory.size > GeoRelayDirectory.FALLBACK.size
+        refreshed = loaded
+        return loaded
+    }
+
+    /** The relays nearest [geohash]'s center. Synchronous — uses whatever is loaded (fallback if not yet refreshed). */
+    fun closestRelays(geohash: String): List<NormalizedRelayUrl> = directory.closestRelays(geohash)
+}
@@ -179,6 +179,17 @@ class AccountFeedContentStates(
                }
        }

+        // Joining/leaving a geohash location channel (kind 10081 list) changes the Messages list but
+        // no event flows through LocalCache, so force a rebuild — otherwise a just-joined cell (whose
+        // ephemeral messages haven't arrived yet) wouldn't show its placeholder row until later.
+        scope.launch(Dispatchers.IO) {
+            account.geohashList.flow
+                .drop(1)
+                .collect {
+                    dmKnown.invalidateData()
+                }
+        }
+
        // Flipping the NIP-29 view mode (inline groups vs one row per relay) changes what the
        // Messages feed emits for joined groups, but no event flows through LocalCache — force a
        // full rebuild so the list switches shape immediately.
@@ -54,6 +54,7 @@ import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbol
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
 import com.vitorpamplona.amethyst.commons.model.concord.ConcordChannel
 import com.vitorpamplona.amethyst.commons.model.emphChat.EphemeralChatChannel
+import com.vitorpamplona.amethyst.commons.model.geohashChat.GeohashChatChannel
 import com.vitorpamplona.amethyst.commons.model.marmotGroups.MarmotGroupChatroom
 import com.vitorpamplona.amethyst.commons.model.nip28PublicChats.PublicChatChannel
 import com.vitorpamplona.amethyst.commons.model.nip29RelayGroups.RelayGroupChannel
@@ -99,6 +100,7 @@ import com.vitorpamplona.amethyst.ui.theme.StdHorzSpacer
 import com.vitorpamplona.amethyst.ui.theme.grayText
 import com.vitorpamplona.amethyst.ui.theme.newItemBubbleModifier
 import com.vitorpamplona.amethyst.ui.theme.placeholderText
+import com.vitorpamplona.quartz.experimental.bitchat.geohash.GeohashChatEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.chat.EphemeralChatEvent
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.displayUrl
 import com.vitorpamplona.quartz.nip17Dm.base.ChatroomKey
@@ -193,6 +195,12 @@ private fun ChatroomEntry(
        return
    }

+    val geohashChannel = lastMessage.inGatherers?.firstNotNullOfOrNull { it as? GeohashChatChannel }
+    if (geohashChannel != null) {
+        GeohashRoomCompose(lastMessage, geohashChannel, accountViewModel, nav)
+        return
+    }
+
    // A NIP-29 group message whose channel gatherer didn't attach (e.g. loaded before its channel
    // existed, or via a path that skips attach) has no case in the when() below and would blank out.
    // Resolve the group from its `h` tag + provenance relay and render the group row anyway.
@@ -332,6 +340,41 @@ private fun ChannelRoomCompose(
    )
 }

+@Composable
+private fun GeohashRoomCompose(
+    lastMessage: Note,
+    channel: GeohashChatChannel,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    val channelState by observeChannel(channel, accountViewModel)
+    val geohashChannel = channelState?.channel as? GeohashChatChannel ?: channel
+
+    // Anonymous cells have no author profile; the sender's display name lives in the message's `n` tag.
+    val noteEvent = lastMessage.event as? GeohashChatEvent
+    val nick = noteEvent?.nickname()?.takeIf { it.isNotBlank() } ?: lastMessage.author?.pubkeyHex?.take(8)
+    val description = noteEvent?.content?.take(200)
+    val lastContent = if (noteEvent != null) "$nick: $description" else ""
+
+    val lastReadTime by accountViewModel.account.loadLastReadFlow("Geohash/${geohashChannel.geohash}").collectAsStateWithLifecycle()
+
+    ChannelName(
+        channelIdHex = "Geohash/${geohashChannel.geohash}",
+        channelPicture = null,
+        channelTitle = { modifier -> ChannelTitleWithLabelInfo(geohashChannel.toBestDisplayName(), MaterialSymbols.LocationOn, R.string.geohash_chat, modifier) },
+        channelLastTime = lastMessage.createdAt(),
+        channelLastContent = lastContent,
+        hasNewMessages = (noteEvent?.createdAt ?: Long.MIN_VALUE) > lastReadTime,
+        loadProfilePicture = accountViewModel.settings.showProfilePictures(),
+        loadRobohash = accountViewModel.settings.isNotPerformanceMode(),
+        autoPlayGif =
+            accountViewModel.settings.autoPlayVideosFlow
+                .collectAsStateWithLifecycle()
+                .value,
+        onClick = { nav.nav(Route.GeohashChat(geohashChannel.geohash)) },
+    )
+}
+
@Composable
 private fun MarmotGroupRoomCompose(
    lastMessage: Note,
@@ -22,6 +22,7 @@ package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.dal

 import com.vitorpamplona.amethyst.commons.model.concord.ConcordChannel
 import com.vitorpamplona.amethyst.commons.model.concord.ConcordViewMode
+import com.vitorpamplona.amethyst.commons.model.geohashChat.GeohashChatChannel
 import com.vitorpamplona.amethyst.commons.model.nip29RelayGroups.RelayGroupChannel
 import com.vitorpamplona.amethyst.commons.model.nip29RelayGroups.RelayGroupViewMode
 import com.vitorpamplona.amethyst.commons.util.replace
@@ -31,6 +32,7 @@ import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.ui.dal.AdditiveFeedFilter
 import com.vitorpamplona.amethyst.ui.dal.sortedByDefaultFeedOrder
 import com.vitorpamplona.quartz.concord.cord03Channels.ConcordChannelId
+import com.vitorpamplona.quartz.experimental.bitchat.geohash.GeohashChatEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.chat.EphemeralChatEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.chat.RoomId
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
@@ -91,6 +93,18 @@ class ChatroomListKnownFeedFilter(
                        .firstOrNull()
                }

+        // Joined geohash location channels (kind 10081 list). Ephemeral, so a quiet
+        // cell has no stored message — show a placeholder row until one arrives, the
+        // same way just-joined NIP-29/Marmot groups do.
+        val geohashChannels =
+            account.geohashList.flow.value.map { geohash ->
+                val channel = LocalCache.getOrCreateGeohashChannel(geohash)
+                channel.notes
+                    .filter { _, it -> account.isAcceptable(it) && it.event != null }
+                    .sortedByDefaultFeedOrder()
+                    .firstOrNull() ?: channel.placeholderNote()
+            }
+
        val marmotGroups =
            account.marmotGroupList.rooms.mapNotNull { _, chatroom ->
                if (chatroom.isKnown(followingKeySet)) {
@@ -160,7 +174,7 @@ class ChatroomListKnownFeedFilter(
                    }
            }

-        return sort((privateMessages + publicChannels + ephemeralChats + marmotGroups + relayGroups + concordChannels).toSet())
+        return sort((privateMessages + publicChannels + ephemeralChats + geohashChannels + marmotGroups + relayGroups + concordChannels).toSet())
    }

    override fun updateListWith(
@@ -172,6 +186,7 @@ class ChatroomListKnownFeedFilter(
        // Gets the latest message by channel from the new items.
        val newRelevantPublicMessages = filterRelevantPublicMessages(newItems, account)
        val newRelevantEphemeralChats = filterRelevantEphemeralChats(newItems, account)
+        val newRelevantGeohashChats = filterRelevantGeohashChats(newItems, account)

        // Gets the latest message by room from the new items.
        val newRelevantPrivateMessages = filterRelevantPrivateMessages(newItems, account)
@@ -181,6 +196,7 @@ class ChatroomListKnownFeedFilter(
        if (newRelevantPrivateMessages.isEmpty() &&
            newRelevantPublicMessages.isEmpty() &&
            newRelevantEphemeralChats.isEmpty() &&
+            newRelevantGeohashChats.isEmpty() &&
            newRelevantRelayGroups.isEmpty() &&
            newRelevantConcord.isEmpty()
        ) {
@@ -221,6 +237,21 @@ class ChatroomListKnownFeedFilter(
            }
        }

+        newRelevantGeohashChats.forEach { newNotePair ->
+            var hasUpdated = false
+            oldList.forEach { oldNote ->
+                if (newNotePair.key == oldNote.geohashRowKey()) {
+                    hasUpdated = true
+                    if ((newNotePair.value.createdAt() ?: 0L) > (oldNote.createdAt() ?: 0L)) {
+                        myNewList = myNewList.replace(oldNote, newNotePair.value)
+                    }
+                }
+            }
+            if (!hasUpdated) {
+                myNewList = myNewList.plus(newNotePair.value)
+            }
+        }
+
        newRelevantPrivateMessages.forEach { newNotePair ->
            var hasUpdated = false
            oldList.forEach { oldNote ->
@@ -275,6 +306,7 @@ class ChatroomListKnownFeedFilter(
        // Gets the latest message by channel from the new items.
        val newRelevantPublicMessages = filterRelevantPublicMessages(newItems, account)
        val newRelevantEphemeralChats = filterRelevantEphemeralChats(newItems, account)
+        val newRelevantGeohashChats = filterRelevantGeohashChats(newItems, account)

        // Gets the latest message by room from the new items.
        val newRelevantPrivateMessages = filterRelevantPrivateMessages(newItems, account)
@@ -284,6 +316,7 @@ class ChatroomListKnownFeedFilter(
        return if (newRelevantPrivateMessages.isEmpty() &&
            newRelevantPublicMessages.isEmpty() &&
            newRelevantEphemeralChats.isEmpty() &&
+            newRelevantGeohashChats.isEmpty() &&
            newRelevantRelayGroups.isEmpty() &&
            newRelevantConcord.isEmpty()
        ) {
@@ -293,12 +326,36 @@ class ChatroomListKnownFeedFilter(
                newRelevantPrivateMessages.values +
                    newRelevantPublicMessages.values +
                    newRelevantEphemeralChats.values +
+                    newRelevantGeohashChats.values +
                    newRelevantRelayGroups.values +
                    newRelevantConcord.values
            ).toSet()
        }
    }

+    /** The geohash a Messages row belongs to — from a real kind-20000 note or a placeholder's channel gatherer. */
+    private fun Note.geohashRowKey(): String? =
+        (event as? GeohashChatEvent)?.geohash()
+            ?: inGatherers?.firstNotNullOfOrNull { (it as? GeohashChatChannel)?.geohash }
+
+    private fun filterRelevantGeohashChats(
+        newItems: Set<Note>,
+        account: Account,
+    ): MutableMap<String, Note> {
+        val joined = account.geohashList.flow.value
+        val newRelevant = mutableMapOf<String, Note>()
+        newItems.forEach { newNote ->
+            val geohash = (newNote.event as? GeohashChatEvent)?.geohash()
+            if (geohash != null && geohash in joined && account.isAcceptable(newNote)) {
+                val lastNote = newRelevant[geohash]
+                if (lastNote == null || (newNote.createdAt() ?: 0L) > (lastNote.createdAt() ?: 0L)) {
+                    newRelevant[geohash] = newNote
+                }
+            }
+        }
+        return newRelevant
+    }
+
    /**
     * The row a Concord note belongs to, so [updateListWith] can find and replace it: a per-community
     * [ConcordServerRoomNote] (GROUPED), else the note's ConcordChannel gatherer keyed by channel
@@ -47,6 +47,7 @@ class ChatroomListFilterAssembler(
            nip04History,
            FollowingPublicChatSubAssembler(client, ::allKeys),
            FollowingEphemeralChatSubAssembler(client, ::allKeys),
+            FollowingGeohashChatSubAssembler(client, ::allKeys),
        )

    override fun invalidateKeys() = invalidateFilters()
@@ -0,0 +1,56 @@
+/*
+ * 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.chats.rooms.datasource
+
+import com.vitorpamplona.amethyst.service.geohash.GeohashRelays
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.experimental.bitchat.geohash.GeohashChatEvent
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+
+/**
+ * REQ for the user's joined geohash location channels: for each cell, subscribe
+ * to its kind-20000 messages on the relays nearest that cell
+ * ([GeohashRelays.closestRelays]) — the same rendezvous set Bitchat uses. One
+ * [RelayBasedFilter] per (cell, relay). Presence (kind 20001) is left to the live
+ * chat screen so it never becomes a room's last message.
+ */
+fun filterFollowingGeohashChats(
+    geohashes: Set<String>,
+    since: SincePerRelayMap?,
+): List<RelayBasedFilter>? {
+    if (geohashes.isEmpty()) return null
+
+    return geohashes.flatMap { geohash ->
+        GeohashRelays.closestRelays(geohash).map { relay ->
+            RelayBasedFilter(
+                relay = relay,
+                filter =
+                    Filter(
+                        kinds = listOf(GeohashChatEvent.KIND),
+                        tags = mapOf("g" to listOf(geohash)),
+                        limit = 100,
+                        since = since?.get(relay)?.time,
+                    ),
+            )
+        }
+    }
+}
@@ -0,0 +1,87 @@
+/*
+ * 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.chats.rooms.datasource
+
+import com.vitorpamplona.amethyst.model.User
+import com.vitorpamplona.amethyst.service.geohash.GeohashRelays
+import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.PerUserEoseManager
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.client.subscriptions.Subscription
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.sample
+import kotlinx.coroutines.launch
+
+/**
+ * Keeps the user's joined geohash location channels ([account.geohashList]) live
+ * in [com.vitorpamplona.amethyst.model.LocalCache] so they surface in the rooms
+ * list and Home, mirroring [FollowingEphemeralChatSubAssembler]. Because the
+ * events are ephemeral, this is a live tail — quiet cells simply have no last
+ * message until one arrives.
+ */
+class FollowingGeohashChatSubAssembler(
+    client: INostrClient,
+    allKeys: () -> Set<ChatroomListState>,
+) : PerUserEoseManager<ChatroomListState>(client, allKeys) {
+    override fun updateFilter(
+        key: ChatroomListState,
+        since: SincePerRelayMap?,
+    ): List<RelayBasedFilter> =
+        listOfNotNull(
+            filterFollowingGeohashChats(key.account.geohashList.flow.value, since),
+        ).flatten()
+
+    override fun user(key: ChatroomListState) = key.account.userProfile()
+
+    val userJobMap = mutableMapOf<User, List<Job>>()
+
+    @OptIn(FlowPreview::class)
+    override fun newSub(key: ChatroomListState): Subscription {
+        userJobMap[key.account.userProfile()]?.forEach { it.cancel() }
+        userJobMap[key.account.userProfile()] =
+            listOf(
+                // Rebuild when the joined set changes.
+                key.account.scope.launch(Dispatchers.IO) {
+                    key.account.geohashList.flow.sample(500).collectLatest {
+                        invalidateFilters()
+                    }
+                },
+                // Once the live relay directory loads, re-route to the proper nearest relays.
+                key.account.scope.launch(Dispatchers.IO) {
+                    if (GeohashRelays.ensureLoaded()) invalidateFilters()
+                },
+            )
+
+        return super.newSub(key)
+    }
+
+    override fun endSub(
+        key: User,
+        subId: String,
+    ) {
+        super.endSub(key, subId)
+        userJobMap[key]?.forEach { it.cancel() }
+    }
+}
@@ -4293,6 +4293,7 @@
    <string name="app_name_debug" translatable="false">Amy Debug</string>
    <string name="app_name_benchmark" translatable="false">Amy Benchmark</string>
    <string name="geohash_chat_open">Open location chat</string>
+    <string name="geohash_chat">Location chat</string>
    <string name="new_conversation_location_title">Location channel</string>
    <string name="new_conversation_location_tagline">Chat with whoever\'s near a place, by geohash.</string>
    <string name="new_conversation_location_chip">Local</string>
@@ -0,0 +1,63 @@
+/*
+ * 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.commons.model.geohashChat
+
+import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.commons.model.Channel
+import com.vitorpamplona.amethyst.commons.model.Note
+import com.vitorpamplona.amethyst.commons.util.KmpLock
+import com.vitorpamplona.amethyst.commons.util.withLock
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+
+/**
+ * A public geohash location chat channel (Bitchat-interoperable), keyed by the
+ * bare geohash cell. Unlike an ephemeral relay chat — which lives on one relay —
+ * a cell is served by the relays geographically nearest its center, so this
+ * channel does not carry a relay in its key; the subscription layer derives the
+ * relay set from the geohash.
+ */
+@Stable
+class GeohashChatChannel(
+    val geohash: String,
+) : Channel() {
+    override fun toBestDisplayName() = "#$geohash"
+
+    fun anyNameStartsWith(prefix: String): Boolean = geohash.contains(prefix, true)
+
+    private val placeholderLock = KmpLock()
+    private var cachedPlaceholder: Note? = null
+
+    /**
+     * A stable empty-row Note so a just-joined cell shows in Messages before its
+     * first (ephemeral) message arrives — mirrors the NIP-29 / Marmot group rows.
+     */
+    fun placeholderNote(): Note =
+        placeholderLock.withLock {
+            cachedPlaceholder ?: Note(placeholderIdHex(geohash)).apply {
+                addGatherer(this@GeohashChatChannel)
+                cachedPlaceholder = this
+            }
+        }
+
+    companion object {
+        fun placeholderIdHex(geohash: String): HexKey = "geohash-empty-$geohash"
+    }
+}