feat(buzz): use the full chat composer for forum replies

The forum thread's reply field was a bare OutlinedTextField. Replace it with the
same rich composer chats use (EditFieldRow): emoji + @mention suggestions, media
attach, drafts, and the typing indicator, with the standard send button styling.

Reuse works by making ChannelNewMessageViewModel.createTemplate() protected/open
and adding ForumReplyNewMessageViewModel, which overrides only the built event so
a send publishes a kind-45003 ForumCommentEvent scoped to the open thread.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -26,38 +26,32 @@ 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.layout.size
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.material3.HorizontalDivider
-import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateListOf
-import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.amethyst.R
-import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
-import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.topbars.TopBarWithBackButton
 import com.vitorpamplona.amethyst.ui.note.UserPicture
 import com.vitorpamplona.amethyst.ui.note.UsernameDisplay
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.send.EditFieldRow
 import com.vitorpamplona.amethyst.ui.stringRes
 import com.vitorpamplona.amethyst.ui.theme.Size35dp
 import com.vitorpamplona.quartz.buzz.forum.ForumCommentEvent
@@ -67,16 +61,15 @@ import com.vitorpamplona.quartz.nip01Core.relay.client.reqs.subscribeAsFlow
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer
 import com.vitorpamplona.quartz.nip29RelayGroups.GroupId
-import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 
 /**
  * The detail view of a Buzz **forum thread**: the root post (kind 45001) and its comment
- * replies (kind 45003), with an inline composer. Kept apart from the generic note thread
- * screen because Buzz forum comments use NIP-10 `e` tags (not the kind-1111 NIP-22 shape),
- * so they need their own root-scoped fetch + reply build ([ForumCommentEvent.build]).
+ * replies (kind 45003). Replies compose through the same rich chat composer everything else
+ * uses ([EditFieldRow] + [ForumReplyNewMessageViewModel]), which just swaps the built event for
+ * a kind-45003 [ForumCommentEvent]. Kept apart from the generic note thread screen because Buzz
+ * forum comments use NIP-10 `e` tags (not the kind-1111 NIP-22 shape), so they need their own
+ * root-scoped fetch.
  */
 @Composable
 fun BuzzForumThreadScreen(
@@ -88,6 +81,7 @@ fun BuzzForumThreadScreen(
 ) {
     val relay = remember(relayUrl) { RelayUrlNormalizer.normalizeOrNull(relayUrl) } ?: return
     val rootNote = remember(rootId) { LocalCache.getOrCreateNote(rootId) }
+    val channel = remember(channelId, relay) { LocalCache.getOrCreateRelayGroupChannel(GroupId(channelId, relay)) }
 
     // The replies to this root. Seed from cache (the forum-list REQ already pulls 45003 for the
     // channel), then live-subscribe by the root `e` tag so replies arrive while the thread is open.
@@ -105,32 +99,31 @@ fun BuzzForumThreadScreen(
         if (at < 0) replies.add(event) else replies.add(at, event)
     }
 
-    fun seedFromCache() = LocalCache.filter(replyFilter).forEach { (it.event as? ForumCommentEvent)?.let(::accept) }
-
     // Bumped after we post a reply. The relay stores our reply but doesn't re-deliver it on our already-open
     // subscription, so a bump restarts the REQ — a fresh fetch returns every reply, including the new one.
     var refreshKey by remember(rootId) { mutableIntStateOf(0) }
 
     LaunchedEffect(rootId, refreshKey) {
         if (refreshKey > 0) delay(600) // let our just-sent reply persist on the relay before re-fetching
-        seedFromCache()
+        LocalCache.filter(replyFilter).forEach { (it.event as? ForumCommentEvent)?.let(::accept) }
         accountViewModel.account.client.subscribeAsFlow(relay, replyFilter).collect { events ->
             events.filterIsInstance<ForumCommentEvent>().forEach(::accept)
         }
     }
 
-    val canPost =
-        remember(rootId) {
-            LocalCache.getOrCreateRelayGroupChannel(GroupId(channelId, relay))
-        }.canPost(accountViewModel.userProfile().pubkeyHex)
+    val canPost = channel.canPost(accountViewModel.userProfile().pubkeyHex)
+
+    val replyModel: ForumReplyNewMessageViewModel = viewModel(key = "forum-reply-$rootId")
+    replyModel.init(accountViewModel)
+    replyModel.loadForumThread(channel, rootId)
 
     Scaffold(
         topBar = { TopBarWithBackButton(stringRes(R.string.buzz_forum_thread_title), nav) },
         bottomBar = {
             if (canPost) {
-                // The relay doesn't re-deliver our reply on the open subscription, so restart the REQ after
-                // a send (see [refreshKey]) to re-fetch the thread including it.
-                ForumReplyComposer(channelId, rootId, relay.url, accountViewModel, onSent = { refreshKey++ })
+                // Reuse the full chat composer; a send publishes the kind-45003 reply and then bumps
+                // refreshKey to re-fetch (the relay doesn't echo our reply on the open subscription).
+                EditFieldRow(replyModel, accountViewModel, onSendNewMessage = { refreshKey++ }, nav)
             }
         },
     ) { padding ->
@@ -182,62 +175,3 @@ private fun ForumReplyRow(
         }
     }
 }
-
-@Composable
-private fun ForumReplyComposer(
-    channelId: String,
-    rootId: HexKey,
-    relayUrl: String,
-    accountViewModel: AccountViewModel,
-    onSent: () -> Unit,
-) {
-    var body by remember { mutableStateOf("") }
-    var isPosting by remember { mutableStateOf(false) }
-    val scope = rememberCoroutineScope()
-
-    Surface(tonalElevation = 2.dp) {
-        Row(
-            modifier = Modifier.fillMaxWidth().padding(horizontal = 12.dp, vertical = 8.dp),
-            verticalAlignment = Alignment.CenterVertically,
-            horizontalArrangement = Arrangement.spacedBy(8.dp),
-        ) {
-            OutlinedTextField(
-                value = body,
-                onValueChange = { body = it },
-                placeholder = { Text(stringRes(R.string.buzz_forum_reply_hint)) },
-                modifier = Modifier.weight(1f),
-                enabled = !isPosting,
-                maxLines = 4,
-            )
-            IconButton(
-                enabled = body.isNotBlank() && !isPosting,
-                onClick = {
-                    val relay = RelayUrlNormalizer.normalizeOrNull(relayUrl) ?: return@IconButton
-                    val text = body.trim()
-                    isPosting = true
-                    scope.launch {
-                        try {
-                            withContext(Dispatchers.IO) {
-                                accountViewModel.account.signAndSendPrivatelyOrBroadcast(
-                                    // Direct reply to the root: rootEventId == parentEventId.
-                                    ForumCommentEvent.build(channelId, text, rootEventId = rootId, parentEventId = rootId),
-                                ) { listOf(relay) }
-                            }
-                            body = ""
-                            onSent()
-                        } finally {
-                            isPosting = false
-                        }
-                    }
-                },
-            ) {
-                Icon(
-                    symbol = MaterialSymbols.AutoMirrored.Send,
-                    contentDescription = stringRes(R.string.buzz_forum_reply_action),
-                    tint = MaterialTheme.colorScheme.primary,
-                    modifier = Modifier.size(22.dp),
-                )
-            }
-        }
-    }
-}

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

@@ -0,0 +1,58 @@
+/*
+ * 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.buzz
+
+import com.vitorpamplona.amethyst.commons.model.nip29RelayGroups.RelayGroupChannel
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.send.ChannelNewMessageViewModel
+import com.vitorpamplona.quartz.buzz.forum.ForumCommentEvent
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.signers.EventTemplate
+
+/**
+ * The Buzz forum-reply composer. Reuses the whole rich chat composer ([ChannelNewMessageViewModel] +
+ * `EditFieldRow`: emoji, mentions, media, drafts, typing) but overrides only the built event so a send
+ * publishes a kind-45003 [ForumCommentEvent] scoped to the open thread instead of a chat message.
+ */
+class ForumReplyNewMessageViewModel : ChannelNewMessageViewModel() {
+    private var forumRootId: HexKey? = null
+
+    /** Bind to the forum [channel] and the thread [rootId] this composer replies into. */
+    fun loadForumThread(
+        channel: RelayGroupChannel,
+        rootId: HexKey,
+    ) {
+        load(channel)
+        forumRootId = rootId
+    }
+
+    override suspend fun createTemplate(): EventTemplate<out Event>? {
+        val forumChannel = channel as? RelayGroupChannel ?: return super.createTemplate()
+        val root = forumRootId ?: return super.createTemplate()
+        val text = message.text.toString().trim()
+        if (text.isEmpty()) return null
+        // A reply to another comment nests under it (parent = that comment); a top-level reply targets
+        // the root (parent == root), per ForumCommentEvent.build's root/parent contract.
+        val parent = replyTo.value?.idHex ?: root
+        val mentions = listOfNotNull(replyTo.value?.author?.pubkeyHex)
+        return ForumCommentEvent.build(forumChannel.groupId.id, text, rootEventId = root, parentEventId = parent, mentions = mentions)
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/send/ChannelNewMessageViewModel.kt

@@ -530,7 +530,9 @@ open class ChannelNewMessageViewModel :
         }
     }
 
-    private suspend fun createTemplate(): EventTemplate<out Event>? {
+    // `protected open` so a specialized composer (e.g. the Buzz forum reply) can reuse this whole
+    // rich EditFieldRow but swap only the event it builds for the composed text.
+    protected open suspend fun createTemplate(): EventTemplate<out Event>? {
         val channel = channel ?: return null
 
         val messageText = message.text.toString()

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

@@ -3323,8 +3323,6 @@
     <string name="buzz_forum_body_label">What do you want to discuss?</string>
     <string name="buzz_forum_post_action">Post topic</string>
     <string name="buzz_forum_thread_title">Forum thread</string>
-    <string name="buzz_forum_reply_hint">Write a reply…</string>
-    <string name="buzz_forum_reply_action">Send reply</string>
     <string name="buzz_dm_title">Direct Messages</string>
     <string name="buzz_dm_nav_label">Buzz DMs</string>
     <string name="buzz_dm_card_subtitle">Private conversations on your workspaces</string>