feat(cordn): a Cordn Groups entry in the drawer and the tab catalog

The Feeds section listed NavBarItem.MARMOT_GROUPS and had no cordn equivalent,
so the one conversation type whose messages do not come from a relay was the
only one with no way to see it apart from the mixed Messages inbox. Adds
NavBarItem.CORDN_GROUPS, which puts it in the drawer beside the Marmot rooms
and makes it pinnable as a bottom-bar tab like every other entry.

Route.CordnGroupList opens a list of the groups this account is in. It exists
alongside the inbox rather than duplicating it: the inbox mixes every type,
which is right for reading and wrong for finding, and for a cordn group the
question when something stops arriving is always "which coordinator" rather
than "which relay".

It renders from local state alone -- CordnGroupList.all, which CordnRuntime
already holds -- so BottomBarFeedPreloaders has nothing to warm for it, for a
different reason than Marmot's: a cordn message never arrives over a relay REQ
at all, it arrives as a coordinator call the sync loop already makes. Ordered
off the same `revision` signal the inbox ordering uses, because a room's newest
message changes inside the room object and ordering on `all` alone would freeze
after the first message.

Reuses the inbox's own CordnGroupRoomCompose (now internal) rather than a
second rendering of the same row: it already reads the live name, preview,
annotations and unread count off the room, and two of those drifting apart
would be a bug nobody would look for in a list screen.

Icon is Dns, matching every other cordn surface -- a coordinator is a server,
and that is what distinguishes these rows from the Marmot ones above them.

Not exercised on a device.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012BfD4txdnsaPRXmNXbup9n

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

@@ -132,6 +132,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.cordnGroup.CordnCreat
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.cordnGroup.CordnCreateMembersScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.cordnGroup.CordnGroupChatScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.cordnGroup.CordnGroupInfoScreen
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.cordnGroup.CordnGroupListScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.cordnGroup.CordnInvitationsScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.geohashChat.GeohashChatScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.geohashChat.GeohashChatsScreen
@@ -730,6 +731,7 @@ fun BuildNavigation(
         composableFromEndArgs<Route.CordnGroupInfo> {
             CordnGroupInfoScreen(it.coordinatorPubKey, it.gid, accountViewModel, nav)
         }
+        composableFromEnd<Route.CordnGroupList> { CordnGroupListScreen(accountViewModel, nav) }
         composableFromBottom<Route.CordnCreateGroup> { CordnCreateGroupScreen(accountViewModel, nav) }
         composableFromBottom<Route.CordnCreateGroupMembers> { CordnCreateMembersScreen(accountViewModel, nav) }
         composableFromEnd<Route.CordnInvitations> { CordnInvitationsScreen(accountViewModel, nav) }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/bottombars/NavBarItem.kt

@@ -38,6 +38,7 @@ import com.vitorpamplona.amethyst.commons.resources.bottom_bar_category_you
 import com.vitorpamplona.amethyst.commons.resources.browser
 import com.vitorpamplona.amethyst.commons.resources.communities
 import com.vitorpamplona.amethyst.commons.resources.concord_home_title
+import com.vitorpamplona.amethyst.commons.resources.cordn_groups_title
 import com.vitorpamplona.amethyst.commons.resources.discover_marketplace
 import com.vitorpamplona.amethyst.commons.resources.discover_reads
 import com.vitorpamplona.amethyst.commons.resources.drafts
@@ -391,6 +392,16 @@ val NavBarCatalog: Map<NavBarItem, NavBarItemDef> =
                 icon = MaterialSymbols.Lock,
                 resolveRoute = { Route.MarmotGroupList },
             ),
+        NavBarItem.CORDN_GROUPS to
+            NavBarItemDef(
+                id = NavBarItem.CORDN_GROUPS,
+                labelRes = Res.string.cordn_groups_title,
+                // Dns, the symbol every other cordn surface uses: a coordinator
+                // is a server, and that is the one thing that distinguishes
+                // these from the Marmot rooms directly above.
+                icon = MaterialSymbols.Dns,
+                resolveRoute = { Route.CordnGroupList },
+            ),
         NavBarItem.GEOHASH_CHATS to
             NavBarItemDef(
                 id = NavBarItem.GEOHASH_CHATS,
@@ -527,6 +538,7 @@ val BottomBarCategories: List<NavBarCategory> =
                 NavBarItem.RELAY_GROUPS,
                 NavBarItem.CONCORD,
                 NavBarItem.MARMOT_GROUPS,
+                NavBarItem.CORDN_GROUPS,
                 NavBarItem.GEOHASH_CHATS,
             ),
         ),

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/drawer/DrawerSections.kt

@@ -153,6 +153,7 @@ private val DrawerFeedsItems: List<NavBarItem> =
         NavBarItem.RELAY_GROUPS,
         NavBarItem.CONCORD,
         NavBarItem.MARMOT_GROUPS,
+        NavBarItem.CORDN_GROUPS,
         NavBarItem.GEOHASH_CHATS,
         NavBarItem.CALENDARS,
         NavBarItem.CALENDAR_COLLECTIONS,

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

@@ -160,6 +160,13 @@ private fun PreloadFor(
         // to warm up, and adding one would duplicate those.
         NavBarItem.MARMOT_GROUPS -> Unit
 
+        // Same as Marmot, for a different reason: a cordn group's messages never
+        // arrive over a relay REQ at all. They are coordinator calls made by
+        // CordnRuntime's sync loop, which is already running for every
+        // coordinator this account holds -- there is no relay subscription a
+        // list could warm up.
+        NavBarItem.CORDN_GROUPS -> Unit
+
         NavBarItem.FOLLOW_PACKS -> FollowPacksFilterAssemblerSubscription(accountViewModel)
 
         NavBarItem.LIVE_STREAMS -> LiveStreamsFilterAssemblerSubscription(accountViewModel)

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/cordnGroup/CordnGroupListScreen.kt

@@ -0,0 +1,144 @@
+/*
+ * 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.cordnGroup
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
+import androidx.compose.material3.Button
+import androidx.compose.material3.HorizontalDivider
+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.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import com.vitorpamplona.amethyst.R
+import com.vitorpamplona.amethyst.commons.model.navigation.Route
+import com.vitorpamplona.amethyst.commons.resources.Res
+import com.vitorpamplona.amethyst.commons.resources.cordn_groups_title
+import com.vitorpamplona.amethyst.commons.ui.components.EmptyState
+import com.vitorpamplona.amethyst.commons.ui.navigation.navs.INav
+import com.vitorpamplona.amethyst.commons.ui.navigation.topbars.TopBarWithBackButton
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.CordnGroupRoomCompose
+import com.vitorpamplona.amethyst.ui.stringRes
+
+/**
+ * Every cordn group this account is in.
+ *
+ * ## Why this exists when Messages already lists them
+ *
+ * Messages mixes every conversation type into one inbox, which is right for
+ * reading and wrong for finding: a cordn group is the one kind whose messages
+ * do not come from a relay, so when something is not arriving the question is
+ * always "which coordinator" rather than "which relay". A list of just these,
+ * reachable from the drawer like the Marmot rooms beside it, is where that
+ * question can be answered. Tapping a row opens the same chat the inbox opens.
+ *
+ * ## It renders from local state alone
+ *
+ * `CordnGroupList.all` is the rooms `CordnRuntime` already holds, and its sync
+ * loop already subscribes per coordinator. There is no relay REQ behind this
+ * screen and no list-level fetch to make -- which is why
+ * `BottomBarFeedPreloaders` has nothing to warm for it. Ordered by the newest
+ * message, off the same `revision` signal the inbox ordering uses, so a group
+ * that has just received something rises here too.
+ */
+@Composable
+fun CordnGroupListScreen(
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    val runtime = accountViewModel.account.cordnRuntime
+
+    Scaffold(
+        topBar = { TopBarWithBackButton(stringRes(Res.string.cordn_groups_title), nav) },
+    ) { padding ->
+        if (runtime == null) {
+            EmptyState(
+                title = stringRes(R.string.cordn_group_unavailable),
+                description = stringRes(R.string.cordn_group_unavailable_detail),
+                modifier = Modifier.padding(padding),
+            )
+            return@Scaffold
+        }
+
+        // `revision` rather than `all`: a room's newest message changes inside
+        // the room object, which `all` cannot see, so ordering on `all` alone
+        // would freeze after the first message. See CordnGroupList.revision.
+        val revision by runtime.groups.revision.collectAsStateWithLifecycle()
+        val rooms =
+            remember(revision) {
+                runtime.groups.all.value
+                    .sortedByDescending {
+                        it.newest.value
+                            ?.envelope
+                            ?.createdAt ?: 0L
+                    }
+            }
+
+        if (rooms.isEmpty()) {
+            Column(
+                modifier = Modifier.padding(padding).fillMaxSize().padding(horizontal = 24.dp),
+                verticalArrangement = Arrangement.spacedBy(16.dp, Alignment.CenterVertically),
+                horizontalAlignment = Alignment.CenterHorizontally,
+            ) {
+                Text(
+                    text = stringRes(R.string.cordn_groups_none),
+                    style = MaterialTheme.typography.titleMedium,
+                )
+                Text(
+                    text = stringRes(R.string.cordn_groups_none_detail),
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+                Button(onClick = { nav.nav(Route.CordnCreateGroup) }) {
+                    Text(stringRes(R.string.cordn_groups_start))
+                }
+            }
+            return@Scaffold
+        }
+
+        LazyColumn(
+            modifier = Modifier.padding(padding).fillMaxSize(),
+            state = rememberLazyListState(),
+        ) {
+            items(rooms, key = { it.coordinatorPubKey + it.gid }) { room ->
+                // The inbox's own row, not a second rendering of it: it already
+                // reads the live name, preview, annotations and unread count off
+                // the room, and two of those going out of step would be a bug
+                // nobody would look for here.
+                CordnGroupRoomCompose(room, accountViewModel, nav)
+                HorizontalDivider(Modifier.fillMaxWidth())
+            }
+        }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/rooms/ChatroomHeaderCompose.kt

@@ -582,7 +582,7 @@ private fun attachmentLabelFor(tags: TagArray): StringResource {
  * is on the room. Reading the Note would render an empty row forever.
  */
 @Composable
-private fun CordnGroupRoomCompose(
+internal fun CordnGroupRoomCompose(
     chatroom: CordnGroupChatroom,
     accountViewModel: AccountViewModel,
     nav: INav,

amethyst/src/main/res/values/strings.xml

@@ -305,6 +305,9 @@
 
 
 
+    <string name="cordn_groups_none">No cordn groups yet</string>
+    <string name="cordn_groups_none_detail">A cordn group lives on one coordinator that holds its membership and passes messages along, without ever seeing what anyone writes.</string>
+    <string name="cordn_groups_start">Start one</string>
     <string name="cordn_group_unavailable">This group is not available. Its coordinator may have been removed.</string>
     <string name="cordn_group_info">Group info</string>
     <string name="cordn_message_deleted">Message deleted</string>

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/navigation/NavBarItem.kt

@@ -68,6 +68,7 @@ enum class NavBarItem {
     RELAY_GROUPS,
     CONCORD,
     MARMOT_GROUPS,
+    CORDN_GROUPS,
     GEOHASH_CHATS,
     FOLLOW_PACKS,
     LIVE_STREAMS,

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/navigation/Routes.kt

@@ -653,6 +653,8 @@ sealed class Route {
         val gid: String,
     ) : Route()
 
+    @Serializable object CordnGroupList : Route()
+
     @Serializable object CordnCreateGroup : Route()
 
     @Serializable object CordnCreateGroupMembers : Route()

commonsUI/src/commonMain/composeResources/values/strings.xml

@@ -2911,6 +2911,7 @@
     <string name="community_rules_violation_wot_gate_failed">You don't pass this community's web-of-trust requirements.</string>
     <string name="community_rules_violation_stale_rules">The latest community rules document was rejected as stale.</string>
     <string name="marmot_groups_title">Marmot Groups</string>
+    <string name="cordn_groups_title">Cordn Groups</string>
     <string name="marmot_create_group">Create Group</string>
     <string name="marmot_create_group_title">Create Marmot Group</string>
     <string name="marmot_create_group_footer">A new MLS group will be created. You can add members after.</string>