fix(chat): preserve midturn steer and session marker ordering (#1241)

app/src/main/java/com/m57/hermescontrol/data/local/ChatMessageDao.kt

@@ -53,7 +53,12 @@ interface ChatMessageDao {
     suspend fun upsert(message: ChatMessageEntity) {
         val existing = getMessage(message.id)
         val restId = message.restId ?: existing?.restId
-        val canonicalOrder = canonicalMessageOrder(restId ?: message.id, message.sessionId)
+        val canonicalOrder =
+            if (message.isSessionStartMarker()) {
+                -1L
+            } else {
+                canonicalMessageOrder(restId ?: message.id, message.sessionId)
+            }
         writeMessage(
             message.copy(
                 restId = restId,

app/src/main/java/com/m57/hermescontrol/data/local/ChatMessageEntity.kt

@@ -56,6 +56,9 @@ data class ChatMessageEntity(
     val sortOrder: Long = 0,
 )
 
+internal fun ChatMessageEntity.isSessionStartMarker(): Boolean =
+    role == "SYSTEM" && (content == "Session created" || content == "Session branched")
+
 /** Only the exact session prefix and a nonnegative decimal suffix identify a canonical row. */
 internal fun canonicalMessageOrder(
     id: String,

app/src/main/java/com/m57/hermescontrol/data/local/ChatMessageMapper.kt

@@ -39,7 +39,7 @@ fun ChatMessageEntity.toUiModel(): ChatMessage =
         tps = tps,
         completionId = completionId,
         restId = restId,
-        localOrder = sortOrder.takeIf { sortGroup == 1 && it > 0 },
+        localOrder = sortOrder.takeIf { sortGroup == 1 && it > 0 && !isSessionStartMarker() },
     )
 
 fun ChatMessage.toEntity(sessionId: String): ChatMessageEntity =