feat(geohash-chat): map teleport + composer teleport toggle (Phase E)

- LocationPickerMap: an interactive osmdroid map (tap/long-press to pick a
  coordinate) built on the existing display-only map's tile/lifecycle setup.
- GeohashTeleportScreen (Route.GeohashTeleport): tap a spot, pick a precision
  level (region -> building), see the resolved cell + place name, and "Teleport
  here" -> follow the cell (kind 10081) + open its chat with teleported=true.
  Reachable from the builder's new "Teleport to a place on the map" button.
- Route.GeohashChat carries a teleported flag; the chat VM owns the teleport
  state (seeded from the route) and stamps ["t","teleport"] on outgoing messages.
- Composer gains a "Teleport" FilterChip so the user can toggle it per session.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0172JoMccseEKenyWan6txWV

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/AppNavigation.kt

@@ -103,6 +103,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.create.NewCalenda
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.create.NewCalendarEventScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.detail.CalendarEventDetailScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.geohashChat.GeohashChatScreen
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.geohashChat.GeohashTeleportScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.geohashChat.NewGeohashChatScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.marmotGroup.CreateGroupScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.marmotGroup.EditGroupInfoScreen
@@ -631,6 +632,7 @@ fun BuildNavigation(
         composableFromEndArgs<Route.GeohashChat> {
             GeohashChatScreen(
                 geohash = it.geohash,
+                teleported = it.teleported,
                 accountViewModel = accountViewModel,
                 nav = nav,
             )
@@ -638,6 +640,8 @@ fun BuildNavigation(
 
         composableFromBottomArgs<Route.NewGeohashChat> { NewGeohashChatScreen(accountViewModel, nav) }
 
+        composableFromBottomArgs<Route.GeohashTeleport> { GeohashTeleportScreen(accountViewModel, nav) }
+
         composableFromEndArgs<Route.RelayGroup> {
             RelayGroupChatScreen(
                 id = it.id,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/routes/Routes.kt

@@ -643,10 +643,15 @@ sealed class Route {
 
     @Serializable data class GeohashChat(
         val geohash: String,
+        // True when the user is not physically in the cell (jumped in via teleport). Seeds the
+        // composer's teleport toggle so their messages carry the ["t","teleport"] marker.
+        val teleported: Boolean = false,
     ) : Route()
 
     @Serializable object NewGeohashChat : Route()
 
+    @Serializable object GeohashTeleport : Route()
+
     @Serializable data class RelayGroup(
         val id: String,
         val relayUrl: String,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/creators/location/LocationPickerMap.kt

@@ -0,0 +1,126 @@
+/*
+ * 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.note.creators.location
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.viewinterop.AndroidView
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
+import androidx.lifecycle.compose.LocalLifecycleOwner
+import org.osmdroid.config.Configuration
+import org.osmdroid.events.MapEventsReceiver
+import org.osmdroid.tileprovider.tilesource.TileSourceFactory
+import org.osmdroid.util.GeoPoint
+import org.osmdroid.views.CustomZoomButtonsController
+import org.osmdroid.views.MapView
+import org.osmdroid.views.overlay.MapEventsOverlay
+import org.osmdroid.views.overlay.Marker
+
+/**
+ * An interactive OpenStreetMap (osmdroid) picker: tapping the map reports the
+ * tapped coordinate via [onPick], and [pickedLatitude]/[pickedLongitude] (when
+ * set) show a marker there. Used to "teleport" into a remote geohash cell.
+ *
+ * Shares the tile/User-Agent/lifecycle setup with [LocationPreviewMap]; unlike
+ * that display-only map, this one installs a [MapEventsOverlay] for tap picking.
+ */
+@Composable
+fun LocationPickerMap(
+    latitude: Double,
+    longitude: Double,
+    pickedLatitude: Double?,
+    pickedLongitude: Double?,
+    modifier: Modifier = Modifier,
+    zoom: Double = 4.0,
+    onPick: (Double, Double) -> Unit,
+) {
+    val context = LocalContext.current
+    val lifecycleOwner = LocalLifecycleOwner.current
+    val currentOnPick by rememberUpdatedState(onPick)
+
+    val mapView =
+        remember(context) {
+            Configuration.getInstance().userAgentValue = context.packageName
+
+            MapView(context).apply {
+                setTileSource(TileSourceFactory.MAPNIK)
+                setMultiTouchControls(true)
+                zoomController.setVisibility(CustomZoomButtonsController.Visibility.NEVER)
+                controller.setZoom(zoom)
+                controller.setCenter(GeoPoint(latitude, longitude))
+
+                val receiver =
+                    object : MapEventsReceiver {
+                        override fun singleTapConfirmedHelper(p: GeoPoint): Boolean {
+                            currentOnPick(p.latitude, p.longitude)
+                            return true
+                        }
+
+                        override fun longPressHelper(p: GeoPoint): Boolean {
+                            currentOnPick(p.latitude, p.longitude)
+                            return true
+                        }
+                    }
+                overlays.add(0, MapEventsOverlay(receiver))
+            }
+        }
+
+    DisposableEffect(lifecycleOwner, mapView) {
+        val observer =
+            LifecycleEventObserver { _, event ->
+                when (event) {
+                    Lifecycle.Event.ON_RESUME -> mapView.onResume()
+                    Lifecycle.Event.ON_PAUSE -> mapView.onPause()
+                    else -> Unit
+                }
+            }
+        lifecycleOwner.lifecycle.addObserver(observer)
+        onDispose {
+            lifecycleOwner.lifecycle.removeObserver(observer)
+            mapView.onDetach()
+        }
+    }
+
+    AndroidView(
+        modifier = modifier,
+        factory = { mapView },
+        update = { map ->
+            map.overlays.removeAll { it is Marker }
+            if (pickedLatitude != null && pickedLongitude != null) {
+                val point = GeoPoint(pickedLatitude, pickedLongitude)
+                val marker =
+                    Marker(map).apply {
+                        position = point
+                        setAnchor(Marker.ANCHOR_CENTER, Marker.ANCHOR_BOTTOM)
+                        setInfoWindow(null)
+                    }
+                map.overlays.add(marker)
+            }
+            map.invalidate()
+        },
+    )
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/geohashChat/GeohashChatScreen.kt

@@ -31,6 +31,7 @@ import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
+import androidx.compose.material3.FilterChip
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
@@ -75,16 +76,18 @@ import com.vitorpamplona.amethyst.commons.icons.symbols.Icon as SymbolIcon
 @Composable
 fun GeohashChatScreen(
     geohash: String,
+    teleported: Boolean,
     accountViewModel: AccountViewModel,
     nav: INav,
 ) {
     val viewModel: GeohashChatViewModel = viewModel(key = "GeohashChat/$geohash")
-    viewModel.init(geohash, accountViewModel)
+    viewModel.init(geohash, accountViewModel, teleported)
 
     val messages by viewModel.messages.collectAsStateWithLifecycle()
     val participants by viewModel.participants.collectAsStateWithLifecycle()
     val relays by viewModel.relays.collectAsStateWithLifecycle()
     val myPubKey by viewModel.myPubKey.collectAsStateWithLifecycle()
+    val teleporting by viewModel.teleported.collectAsStateWithLifecycle()
 
     var nickname by remember { mutableStateOf("") }
     var draft by remember { mutableStateOf("") }
@@ -117,13 +120,24 @@ fun GeohashChatScreen(
         }
 
         HorizontalDivider()
-        OutlinedTextField(
-            value = nickname,
-            onValueChange = { nickname = it },
-            singleLine = true,
-            label = { Text("Nickname (optional)") },
-            modifier = Modifier.fillMaxWidth().padding(horizontal = 12.dp, vertical = 4.dp),
-        )
+        Row(
+            Modifier.fillMaxWidth().padding(horizontal = 12.dp, vertical = 4.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            OutlinedTextField(
+                value = nickname,
+                onValueChange = { nickname = it },
+                singleLine = true,
+                label = { Text("Nickname (optional)") },
+                modifier = Modifier.weight(1f),
+            )
+            FilterChip(
+                selected = teleporting,
+                onClick = { viewModel.setTeleported(!teleporting) },
+                label = { Text("✈ Teleport") },
+                modifier = Modifier.padding(start = 8.dp),
+            )
+        }
         Row(
             Modifier.fillMaxWidth().padding(horizontal = 12.dp, vertical = 4.dp),
             verticalAlignment = Alignment.CenterVertically,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/geohashChat/GeohashChatViewModel.kt

@@ -78,6 +78,10 @@ class GeohashChatViewModel : ViewModel() {
     private val _myPubKey = MutableStateFlow<String?>(null)
     val myPubKey: StateFlow<String?> = _myPubKey.asStateFlow()
 
+    /** Whether our outgoing messages carry the ["t","teleport"] marker (not physically in the cell). */
+    private val _teleported = MutableStateFlow(false)
+    val teleported: StateFlow<Boolean> = _teleported.asStateFlow()
+
     private val seen = HashSet<String>()
     private val present = HashSet<String>()
     private val subId = newSubId()
@@ -87,14 +91,20 @@ class GeohashChatViewModel : ViewModel() {
     fun init(
         geohash: String,
         accountViewModel: AccountViewModel,
+        teleported: Boolean = false,
     ) {
         if (started) return
         started = true
         this.geohash = geohash
         this.accountViewModel = accountViewModel
+        _teleported.value = teleported
         viewModelScope.launch { start() }
     }
 
+    fun setTeleported(value: Boolean) {
+        _teleported.value = value
+    }
+
     private suspend fun start() {
         _myPubKey.value = withContext(Dispatchers.IO) { GeohashChatIdentity.keyPair(accountViewModel.account, geohash).pubKey.toHexKey() }
 
@@ -152,7 +162,6 @@ class GeohashChatViewModel : ViewModel() {
     fun sendMessage(
         text: String,
         nickname: String?,
-        teleported: Boolean = false,
     ) {
         val trimmed = text.trim()
         if (trimmed.isEmpty()) return
@@ -163,7 +172,7 @@ class GeohashChatViewModel : ViewModel() {
             val keyPair = withContext(Dispatchers.IO) { GeohashChatIdentity.keyPair(accountViewModel.account, geohash) }
             val signer = NostrSignerInternal(keyPair)
 
-            var template = GeohashChatEvent.build(trimmed, geohash, nickname = nickname?.ifBlank { null }, teleported = teleported)
+            var template = GeohashChatEvent.build(trimmed, geohash, nickname = nickname?.ifBlank { null }, teleported = _teleported.value)
             template =
                 withContext(Dispatchers.Default) {
                     val deadline = System.nanoTime() + POW_TIMEOUT_NANOS

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/geohashChat/GeohashTeleportScreen.kt

@@ -0,0 +1,145 @@
+/*
+ * 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.geohashChat
+
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.material3.Button
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FilterChip
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.ui.navigation.navs.INav
+import com.vitorpamplona.amethyst.ui.navigation.routes.Route
+import com.vitorpamplona.amethyst.ui.navigation.topbars.TopBarExtensibleWithBackButton
+import com.vitorpamplona.amethyst.ui.note.creators.location.LoadCityName
+import com.vitorpamplona.amethyst.ui.note.creators.location.LocationPickerMap
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.quartz.experimental.bitchat.geohash.GeohashChannelLevel
+import com.vitorpamplona.quartz.nip01Core.tags.geohash.GeoHash
+
+/**
+ * Teleport: tap a point on the map to join a remote geohash cell (at a chosen
+ * precision level) you are not physically in. Joining follows the cell (kind
+ * 10081) and opens the chat with the teleport flag set, so outgoing messages
+ * carry the ["t","teleport"] marker.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun GeohashTeleportScreen(
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    var pickedLat by remember { mutableStateOf<Double?>(null) }
+    var pickedLon by remember { mutableStateOf<Double?>(null) }
+    var level by remember { mutableStateOf(GeohashChannelLevel.CITY) }
+
+    val cell =
+        remember(pickedLat, pickedLon, level) {
+            val lat = pickedLat
+            val lon = pickedLon
+            if (lat != null && lon != null) GeoHash.encode(lat, lon, level.chars).toString() else null
+        }
+
+    Scaffold(
+        topBar = {
+            TopBarExtensibleWithBackButton(
+                title = { Text("Teleport", fontWeight = FontWeight.Bold) },
+                popBack = nav::popBack,
+            )
+        },
+    ) { pad ->
+        Column(
+            Modifier
+                .fillMaxSize()
+                .padding(top = pad.calculateTopPadding(), bottom = pad.calculateBottomPadding()),
+        ) {
+            LocationPickerMap(
+                latitude = 20.0,
+                longitude = 0.0,
+                pickedLatitude = pickedLat,
+                pickedLongitude = pickedLon,
+                modifier = Modifier.weight(1f).fillMaxWidth(),
+                onPick = { lat, lon ->
+                    pickedLat = lat
+                    pickedLon = lon
+                },
+            )
+
+            Column(Modifier.fillMaxWidth().padding(16.dp)) {
+                Text(
+                    if (cell == null) "Tap the map to pick a spot." else "Precision",
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+
+                Row(
+                    Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()).padding(vertical = 8.dp),
+                    horizontalArrangement = Arrangement.spacedBy(8.dp),
+                ) {
+                    GeohashChannelLevel.ordered.forEach { lvl ->
+                        FilterChip(
+                            selected = lvl == level,
+                            onClick = { level = lvl },
+                            label = { Text(lvl.label()) },
+                        )
+                    }
+                }
+
+                if (cell != null) {
+                    LoadCityName(geohashStr = cell) { cityName ->
+                        Text(
+                            "$cityName · #$cell",
+                            style = MaterialTheme.typography.bodyLarge,
+                            fontWeight = FontWeight.Medium,
+                            modifier = Modifier.padding(top = 4.dp, bottom = 8.dp),
+                        )
+                    }
+                    Button(
+                        onClick = {
+                            accountViewModel.followGeohash(cell)
+                            nav.popBack()
+                            nav.nav(Route.GeohashChat(cell, teleported = true))
+                        },
+                        modifier = Modifier.fillMaxWidth(),
+                    ) {
+                        Text("Teleport here")
+                    }
+                }
+            }
+        }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/geohashChat/NewGeohashChatScreen.kt

@@ -105,6 +105,14 @@ fun NewGeohashChatScreen(
             ManualEntrySection(onOpen = ::joinAndOpen)
             HorizontalDivider(Modifier.padding(vertical = 16.dp))
             NearMeSection(onOpen = ::joinAndOpen)
+            HorizontalDivider(Modifier.padding(vertical = 16.dp))
+            OutlinedButton(
+                onClick = { nav.nav(Route.GeohashTeleport) },
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                SymbolIcon(symbol = MaterialSymbols.LocationOn, contentDescription = null)
+                Text("  Teleport to a place on the map")
+            }
         }
     }
 }
@@ -259,7 +267,7 @@ private fun LevelRow(
     }
 }
 
-private fun GeohashChannelLevel.label(): String =
+internal fun GeohashChannelLevel.label(): String =
     when (this) {
         GeohashChannelLevel.REGION -> "Region"
         GeohashChannelLevel.PROVINCE -> "Province"