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

app/src/main/java/com/m57/hermescontrol/data/model/MessageReaction.kt

@@ -0,0 +1,33 @@
+package com.m57.hermescontrol.data.model
+
+import kotlinx.serialization.json.JsonArray
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+
+/** One emoji reaction on a message. Tapback semantics: at most one per [author] per message. */
+data class MessageReaction(
+    val emoji: String,
+    val author: String,
+)
+
+/** Reactions carried by a live `message.reaction` event payload (`reactions` list of maps). */
+internal fun parseMessageReactions(raw: Any?): List<MessageReaction> =
+    (raw as? List<*>).orEmpty().mapNotNull { item ->
+        val map = item as? Map<*, *> ?: return@mapNotNull null
+        val emoji = (map["emoji"] as? String)?.takeIf { it.isNotBlank() } ?: return@mapNotNull null
+        MessageReaction(emoji = emoji, author = map["author"] as? String ?: "")
+    }
+
+/** Reactions persisted under `display_metadata.reactions` on a REST transcript row. */
+internal fun parseMessageReactions(displayMetadata: JsonElement?): List<MessageReaction> {
+    val list = (displayMetadata as? JsonObject)?.get("reactions") as? JsonArray ?: return emptyList()
+    return list.mapNotNull { item ->
+        val obj = item as? JsonObject ?: return@mapNotNull null
+        val emoji =
+            (obj["emoji"] as? JsonPrimitive)?.takeIf { it.isString }?.content?.takeIf { it.isNotBlank() }
+                ?: return@mapNotNull null
+        val author = (obj["author"] as? JsonPrimitive)?.takeIf { it.isString }?.content.orEmpty()
+        MessageReaction(emoji = emoji, author = author)
+    }
+}

app/src/main/java/com/m57/hermescontrol/data/model/SessionMessagesResponse.kt

@@ -75,6 +75,10 @@ data class SessionMessage(
     val timestampText: String?
         get() = (timestamp as? JsonPrimitive)?.content
 
+    /** Emoji reactions persisted on this row (`display_metadata.reactions`). */
+    val reactions: List<MessageReaction>
+        get() = parseMessageReactions(display_metadata)
+
     val tokenCount: Int?
         get() {
             val prim = token_count as? JsonPrimitive ?: return null

app/src/main/java/com/m57/hermescontrol/data/ws/EventParser.kt

@@ -1,6 +1,7 @@
 package com.m57.hermescontrol.data.ws
 
 import android.util.Log
+import com.m57.hermescontrol.data.model.parseMessageReactions
 import com.m57.hermescontrol.ui.chat.extractTodosFromMap
 import kotlinx.serialization.json.JsonObject
 
@@ -333,6 +334,20 @@ object EventParser {
                 WsEvent.ReactionEvent(kind)
             }
 
+            "message.reaction" -> {
+                val rowId = (payload?.get("row_id") as? Number)?.toLong()
+                if (rowId == null) {
+                    WsEvent.Unknown(rawJson)
+                } else {
+                    WsEvent.MessageReactionUpdated(
+                        rowId = rowId,
+                        reactions = parseMessageReactions(payload["reactions"]),
+                        role = payload["role"] as? String ?: "",
+                        sessionId = sessionId,
+                    )
+                }
+            }
+
             "approval.request" -> {
                 val command = payload?.get("command") as? String
                 val description = payload?.get("description") as? String

app/src/main/java/com/m57/hermescontrol/data/ws/WsEvent.kt

@@ -445,6 +445,18 @@ sealed class WsEvent {
         val kind: String = "",
     ) : WsEvent()
 
+    /**
+     * `message.reaction`: the agent (or another client) set/cleared a tapback on a stored
+     * message. [reactions] is the row's full list after the write; [rowId] is the gateway
+     * SQLite row id, matched against `ChatMessage.serverRowId`.
+     */
+    data class MessageReactionUpdated(
+        val rowId: Long,
+        val reactions: List<com.m57.hermescontrol.data.model.MessageReaction>,
+        val role: String,
+        val sessionId: String?,
+    ) : WsEvent()
+
     // ── Replay resync (internal) ──────────────────────────────────────────
 
     /** Internal: replay could not cover the reconnect gap (truncated or epoch change) — UI must refetch history. */