feat(chat): show agent message reactions (#1422)

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatMessage.kt

@@ -1,6 +1,7 @@
 package com.m57.hermescontrol.ui.chat
 
 import com.m57.hermescontrol.data.model.Attachment
+import com.m57.hermescontrol.data.model.MessageReaction
 import java.util.UUID
 
 /**
@@ -113,6 +114,8 @@ data class ChatMessage(
      * Scoped to the owning profile store; transient.
      */
     val serverRowId: Long? = null,
+    /** Emoji tapbacks on this message (REST `display_metadata` or live `message.reaction`); transient. */
+    val reactions: List<MessageReaction> = emptyList(),
 )
 
 /** Cached REST rows already carry their canonical identity in the persisted primary key. */

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatServerMessageMapper.kt

@@ -274,6 +274,7 @@ internal fun mapServerMessages(
                 tokenCount = tokenCount,
                 completionId = completionId,
                 serverRowId = msg.id?.toLong()?.takeIf { it > 0L },
+                reactions = msg.reactions,
             ),
         )
     }

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatTranscriptMerge.kt

@@ -349,6 +349,7 @@ internal fun dedupeCachedMessages(
             message.copy(
                 restId = it.canonicalRestId,
                 serverRowId = message.serverRowId ?: it.serverRowId,
+                reactions = it.reactions.ifEmpty { message.reactions },
                 completionId = message.completionId ?: it.completionId,
                 displayKind = message.displayKind ?: it.displayKind,
                 isRestoredUnconfirmed = false,
@@ -419,6 +420,7 @@ internal fun mergeCachedTranscriptPage(
                         content = preservedContent ?: rich.content,
                         restId = match.canonicalRestId ?: message.canonicalRestId,
                         serverRowId = match.serverRowId ?: message.serverRowId,
+                        reactions = message.reactions.ifEmpty { match.reactions },
                         completionId = match.completionId ?: message.completionId,
                         displayKind = match.displayKind ?: message.displayKind,
                         isRestoredUnconfirmed =
@@ -457,6 +459,7 @@ internal fun mergeTranscriptWithLive(
                     match.copy(
                         restId = (message.canonicalRestId ?: match.canonicalRestId).takeUnless { it == match.id },
                         serverRowId = message.serverRowId ?: match.serverRowId,
+                        reactions = message.reactions.ifEmpty { match.reactions },
                         displayKind = message.displayKind ?: match.displayKind,
                         isHistoricalCache = false,
                         isRestoredUnconfirmed = false,
@@ -476,6 +479,7 @@ internal fun mergeTranscriptWithLive(
                     match.copy(
                         restId = message.canonicalRestId ?: match.canonicalRestId,
                         serverRowId = message.serverRowId ?: match.serverRowId,
+                        reactions = message.reactions.ifEmpty { match.reactions },
                         content = mergedContent,
                         timestamp = message.timestamp,
                         isStreaming = message.isStreaming,

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatWsEventReducer.kt

@@ -129,6 +129,7 @@ object ChatWsEventReducer {
                 is WsEvent.BtwComplete -> event.sessionId
                 is WsEvent.SessionUsage -> event.sessionId
                 is WsEvent.TranscriptResyncRequired -> event.sessionId
+                is WsEvent.MessageReactionUpdated -> event.sessionId
                 is WsEvent.VaultUnlockRequest -> event.sessionId
                 is WsEvent.VaultUnlockExpire -> event.sessionId
                 is WsEvent.VaultSaveLoginRequest -> event.sessionId
@@ -252,6 +253,8 @@ object ChatWsEventReducer {
             // ReactionEvent is handled by the ViewModel — purely cosmetic animation
             is WsEvent.ReactionEvent -> ReducerResult(state = state, streamingState = streamingState)
 
+            is WsEvent.MessageReactionUpdated -> onMessageReaction(state, streamingState, event)
+
             // Change events (issue #784) are consumed by their screens' ViewModels
             is WsEvent.ChangeEvent -> ReducerResult(state = state, streamingState = streamingState)
 
@@ -1079,6 +1082,22 @@ object ChatWsEventReducer {
         }
     }
 
+    /** Paints a live tapback on the row whose gateway id matches; unmatched rows arrive with the next REST load. */
+    private fun onMessageReaction(
+        state: ChatUiState,
+        streamingState: StreamingState,
+        event: WsEvent.MessageReactionUpdated,
+    ): ReducerResult {
+        if (state.messages.none { it.serverRowId == event.rowId }) {
+            return ReducerResult(state = state, streamingState = streamingState)
+        }
+        val messages =
+            state.messages.map {
+                if (it.serverRowId == event.rowId) it.copy(reactions = event.reactions) else it
+            }
+        return ReducerResult(state = state.copy(messages = messages), streamingState = streamingState)
+    }
+
     private fun onUnknown(
         state: ChatUiState,
         streamingState: StreamingState,

app/src/main/java/com/m57/hermescontrol/ui/chat/components/MessageReactionChips.kt

@@ -0,0 +1,44 @@
+package com.m57.hermescontrol.ui.chat.components
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.unit.dp
+import com.m57.hermescontrol.data.model.MessageReaction
+
+/**
+ * Tapback chips shown under a message. One reaction per author, so a short row is enough;
+ * renders nothing when [reactions] is empty.
+ */
+@Composable
+fun MessageReactionChips(
+    reactions: List<MessageReaction>,
+    modifier: Modifier = Modifier,
+) {
+    if (reactions.isEmpty()) return
+    Row(
+        modifier = modifier.testTag("message_reactions"),
+        horizontalArrangement = Arrangement.spacedBy(4.dp),
+    ) {
+        reactions.forEach { reaction ->
+            Surface(
+                shape = CircleShape,
+                color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                tonalElevation = 0.dp,
+            ) {
+                Text(
+                    text = reaction.emoji,
+                    style = MaterialTheme.typography.bodySmall,
+                    modifier = Modifier.padding(horizontal = 6.dp, vertical = 2.dp),
+                )
+            }
+        }
+    }
+}

app/src/main/java/com/m57/hermescontrol/ui/chat/fullbleed/FullBleedAgentMessage.kt

@@ -41,6 +41,7 @@ import com.m57.hermescontrol.ui.chat.InlineAttachment
 import com.m57.hermescontrol.ui.chat.MarkdownText
 import com.m57.hermescontrol.ui.chat.MessageSegment
 import com.m57.hermescontrol.ui.chat.TokenEstimator
+import com.m57.hermescontrol.ui.chat.components.MessageReactionChips
 import com.m57.hermescontrol.ui.chat.components.ReasoningCard
 import com.m57.hermescontrol.ui.chat.components.rememberCopyFeedback
 import com.m57.hermescontrol.ui.chat.splitByMedia
@@ -143,6 +144,10 @@ internal fun FullBleedAgentMessage(
             }
         }
 
+        if (!message.isStreaming) {
+            MessageReactionChips(message.reactions, Modifier.padding(top = 2.dp))
+        }
+
         if (!message.isStreaming && message.content.isNotBlank()) {
             val showTokenStat =
                 messageStatsEnabled && showAssistantMessageTokens &&

app/src/main/java/com/m57/hermescontrol/ui/chat/fullbleed/FullBleedChatList.kt

@@ -41,6 +41,7 @@ import com.m57.hermescontrol.ui.chat.UserBubble
 import com.m57.hermescontrol.ui.chat.components.ChatHistoryPrefetch
 import com.m57.hermescontrol.ui.chat.components.ChatScrollController
 import com.m57.hermescontrol.ui.chat.components.ClarifyBubble
+import com.m57.hermescontrol.ui.chat.components.MessageReactionChips
 import com.m57.hermescontrol.ui.chat.components.ReasoningCard
 import com.m57.hermescontrol.ui.chat.components.VaultCodeCard
 import com.m57.hermescontrol.ui.chat.components.VaultSaveLoginCard
@@ -311,6 +312,15 @@ fun FullBleedChatList(
                                             messageStatsEnabled = messageStatsEnabled,
                                             showUserMessageTokens = showUserMessageTokens,
                                         )
+                                        if (userMessage.reactions.isNotEmpty()) {
+                                            MessageReactionChips(
+                                                reactions = userMessage.reactions,
+                                                modifier =
+                                                    Modifier
+                                                        .align(Alignment.End)
+                                                        .padding(horizontal = 12.dp),
+                                            )
+                                        }
                                     }
                                 }
                             }