feat: render display_kind timeline markers as chips, not user bubbles (#904) (#909)

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

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

@@ -40,4 +40,6 @@ data class ChatMessageEntity(
     val toolStatus: String? = null,
     @ColumnInfo(name = "is_streaming")
     val isStreaming: Boolean = false,
+    @ColumnInfo(name = "display_kind")
+    val displayKind: String? = null,
 )

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

@@ -34,6 +34,7 @@ fun ChatMessageEntity.toUiModel(): ChatMessage =
                 "FAILED" -> ToolStatus.FAILED
                 else -> null
             },
+        displayKind = displayKind,
     )
 
 fun ChatMessage.toEntity(sessionId: String): ChatMessageEntity =
@@ -48,4 +49,5 @@ fun ChatMessage.toEntity(sessionId: String): ChatMessageEntity =
         toolCallId = toolCallId,
         toolStatus = toolStatus?.name,
         isStreaming = isStreaming,
+        displayKind = displayKind,
     )

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

@@ -11,7 +11,7 @@ import java.io.File
 
 @Database(
     entities = [ChatMessageEntity::class],
-    version = 5,
+    version = 6,
     exportSchema = true,
 )
 abstract class HermesDatabase : RoomDatabase() {
@@ -68,13 +68,30 @@ abstract class HermesDatabase : RoomDatabase() {
                         }
                     }
 
+                val migration5to6 =
+                    object : Migration(5, 6) {
+                        override fun migrate(db: SupportSQLiteDatabase) {
+                            // Issue #904: timeline markers (display_kind) keep
+                            // their tag through the Room cache so a cached
+                            // marker never degrades back into a user bubble.
+                            db.execSQL(
+                                "ALTER TABLE `chat_messages` ADD COLUMN `display_kind` TEXT",
+                            )
+                        }
+                    }
+
                 instance ?: Room
                     .databaseBuilder(
                         context.applicationContext,
                         HermesDatabase::class.java,
                         "hermes_control.db",
                     ).openHelperFactory(factory)
-                    .addMigrations(migration2to3, migration3to4, migration4to5)
+                    .addMigrations(
+                        migration2to3,
+                        migration3to4,
+                        migration4to5,
+                        migration5to6,
+                    )
                     .fallbackToDestructiveMigration(false)
                     .build()
                     .also { instance = it }

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

@@ -39,6 +39,15 @@ data class SessionMessage(
     val reasoning: JsonElement? = null,
     val reasoning_text: JsonElement? = null,
     val tool_call_id: String? = null,
+    /**
+     * Timeline-marker tag (backend NS-656 lineage, issue #904): markers like
+     * `model_switch` / `personality_switch` / `auto_continue` ride as
+     * role=user rows so strict providers accept them mid-conversation, but
+     * they are NOT user turns. Nullable/additive — old backends omit it.
+     */
+    val display_kind: String? = null,
+    /** Display-only metadata for the marker (e.g. delegation result counts). */
+    val display_metadata: JsonElement? = null,
 ) {
     val timestampText: String?
         get() = (timestamp as? JsonPrimitive)?.content