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

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

app/schemas/com.m57.hermescontrol.data.local.HermesDatabase/6.json

@@ -0,0 +1,100 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 6,
+    "identityHash": "aad5a6dec143dc657581201e01029748",
+    "entities": [
+      {
+        "tableName": "chat_messages",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `session_id` TEXT NOT NULL, `role` TEXT NOT NULL, `content` TEXT NOT NULL, `reasoning_text` TEXT NOT NULL, `timestamp` INTEGER NOT NULL, `tool_name` TEXT, `tool_call_id` TEXT NOT NULL, `tool_status` TEXT, `is_streaming` INTEGER NOT NULL, `display_kind` TEXT, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "sessionId",
+            "columnName": "session_id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "role",
+            "columnName": "role",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "content",
+            "columnName": "content",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "reasoningText",
+            "columnName": "reasoning_text",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "timestamp",
+            "columnName": "timestamp",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "toolName",
+            "columnName": "tool_name",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "toolCallId",
+            "columnName": "tool_call_id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "toolStatus",
+            "columnName": "tool_status",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isStreaming",
+            "columnName": "is_streaming",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "displayKind",
+            "columnName": "display_kind",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_chat_messages_session_id_timestamp",
+            "unique": false,
+            "columnNames": [
+              "session_id",
+              "timestamp"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_chat_messages_session_id_timestamp` ON `${TABLE_NAME}` (`session_id`, `timestamp`)"
+          }
+        ]
+      }
+    ],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, 'aad5a6dec143dc657581201e01029748')"
+    ]
+  }
+}

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

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

@@ -59,6 +59,13 @@ data class ChatMessage(
      * Transient — not persisted to SQLite.
      */
     val progressPreview: String? = null,
+    /**
+     * Timeline-marker tag carried from the backend's `display_kind`
+     * (issue #904): `model_switch` / `personality_switch` / `auto_continue`
+     * ride as role=user rows but are NOT user input — the chat list renders
+     * them as centered timeline chips instead of user bubbles.
+     */
+    val displayKind: String? = null,
 )
 
 /**

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

@@ -2919,6 +2919,7 @@ class ChatViewModel(
                     attachments = attachments,
                     timestamp = timestamp,
                     isStreaming = false,
+                    displayKind = msg.display_kind,
                 ),
             )
         }

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

@@ -256,10 +256,17 @@ fun FullBleedChatList(
                                     val sysMessage = entry.message
                                     item(key = "sys-${sysMessage.id}") {
                                         Column(modifier = Modifier.padding(bottom = 6.dp)) {
-                                            FullBleedSystemEvent(
+                                            if (sysMessage.displayKind != null) {
-                                                message = sysMessage,
+                                                // Timeline marker (issue #904):
-                                                onRespondApproval = viewModel::respondToApproval,
+                                                // model/personality switches and
-                                            )
+                                                // auto-continues render as a chip.
+                                                TimelineMarkerChip(message = sysMessage)
+                                            } else {
+                                                FullBleedSystemEvent(
+                                                    message = sysMessage,
+                                                    onRespondApproval = viewModel::respondToApproval,
+                                                )
+                                            }
                                         }
                                     }
                                     entryIndex++

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

@@ -46,15 +46,20 @@ fun groupIntoTurns(messages: List<ChatMessage>): List<ChatTurn> {
     }
 
     messages.forEach { message ->
-        when (message.role) {
+        when {
-            MessageRole.USER -> {
+            // Timeline markers (display_kind) ride as role=user rows but are
+            // NOT user turns — group them as system-style timeline entries so
+            // they render as centered chips, not fake user bubbles (issue #904).
+            message.displayKind != null -> agentEntries += AgentEntry.SystemEvent(message)
+
+            message.role == MessageRole.USER -> {
                 flushAgent()
                 turns += ChatTurn.User(message)
             }
 
-            MessageRole.ASSISTANT -> agentEntries += AgentEntry.Prose(message)
+            MessageRole.ASSISTANT == message.role -> agentEntries += AgentEntry.Prose(message)
-            MessageRole.TOOL -> agentEntries += AgentEntry.ToolRow(message)
+            MessageRole.TOOL == message.role -> agentEntries += AgentEntry.ToolRow(message)
-            MessageRole.SYSTEM -> agentEntries += AgentEntry.SystemEvent(message)
+            MessageRole.SYSTEM == message.role -> agentEntries += AgentEntry.SystemEvent(message)
         }
     }
     flushAgent()

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

@@ -0,0 +1,91 @@
+package com.m57.hermescontrol.ui.chat.fullbleed
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.m57.hermescontrol.R
+import com.m57.hermescontrol.ui.chat.ChatMessage
+
+/**
+ * Friendly label resource for a `display_kind` timeline marker (issue #904).
+ * Returns `null` for kinds we don't have a label for — the caller falls back
+ * to the generic system-event rendering (raw content) instead of inventing
+ * copy for a marker we don't understand.
+ */
+internal fun timelineMarkerLabelRes(kind: String?): Int? =
+    when (kind) {
+        "model_switch" -> R.string.timeline_marker_model_switch
+        "personality_switch" -> R.string.timeline_marker_personality_switch
+        "auto_continue" -> R.string.timeline_marker_auto_continue
+        "async_delegation_complete" -> R.string.timeline_marker_delegation_complete
+        else -> null
+    }
+
+/**
+ * Model name parsed from a model-switch marker's content, e.g.
+ * `[System: The active model for this chat has changed to gpt-5 via provider
+ * openai. ...]` → `gpt-5`. The marker text is model-facing scaffolding — the
+ * chip shows the human-meaningful name instead of the whole block. Interior
+ * dots are kept (`gpt-4.5`); a sentence-ending dot is stripped.
+ */
+internal fun markerModelFromContent(content: String): String? {
+    val raw = MARKER_MODEL_REGEX.find(content)?.groupValues?.getOrNull(1) ?: return null
+    val model = raw.removeSuffix(".").trim()
+    return model.takeIf { it.isNotBlank() }
+}
+
+private val MARKER_MODEL_REGEX = Regex("""changed to ([A-Za-z0-9_.\-]+)""")
+
+/**
+ * Centered timeline chip for a `display_kind` marker (issue #904): model
+ * switches, personality switches and auto-continues render as a small
+ * divider-style chip instead of a fake user bubble. Known kinds get friendly
+ * copy; the model-switch chip names the model when the marker content
+ * carries it.
+ */
+@Composable
+internal fun TimelineMarkerChip(
+    message: ChatMessage,
+    modifier: Modifier = Modifier,
+) {
+    val labelRes = timelineMarkerLabelRes(message.displayKind) ?: return
+    val text =
+        if (message.displayKind == "model_switch") {
+            val model = markerModelFromContent(message.content)
+            if (model != null) {
+                stringResource(R.string.timeline_marker_model_switch_to, model)
+            } else {
+                stringResource(R.string.timeline_marker_model_switch)
+            }
+        } else {
+            stringResource(labelRes)
+        }
+
+    Box(
+        modifier = modifier.fillMaxWidth(),
+        contentAlignment = Alignment.Center,
+    ) {
+        Surface(
+            shape = RoundedCornerShape(50),
+            color = MaterialTheme.colorScheme.surfaceContainerHigh,
+            modifier = Modifier.testTag("timeline_marker"),
+        ) {
+            Text(
+                text = text,
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.padding(horizontal = 10.dp, vertical = 4.dp),
+            )
+        }
+    }
+}

app/src/main/res/values-zh/strings.xml

@@ -968,6 +968,11 @@
     <string name="memory_memories_facts">记忆与事实</string>
     <string name="memory_recent_events">最近的 Agent 自我改进事件</string>
     <string name="message_reasoning_steps">推理 · %1$s 步</string>
+    <string name="timeline_marker_model_switch">模型已切换</string>
+    <string name="timeline_marker_model_switch_to">模型已切换至 %1$s</string>
+    <string name="timeline_marker_personality_switch">人格已切换</string>
+    <string name="timeline_marker_auto_continue">回合已自动继续</string>
+    <string name="timeline_marker_delegation_complete">委派任务已完成</string>
     <string name="message_your_response">你的回复</string>
     <string name="moa_add_preset">添加预设</string>
     <string name="moa_add_reference">添加参考模型</string>

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

@@ -1089,6 +1089,13 @@
     <string name="memory_memories_facts">Memories &amp; Facts</string>
     <string name="memory_recent_events">Recent Agent Self-Improvement Events</string>
     <string name="message_reasoning_steps">Reasoning · %1$s steps</string>
+
+    <!-- Timeline markers (issue #904) -->
+    <string name="timeline_marker_model_switch">Model switched</string>
+    <string name="timeline_marker_model_switch_to">Model switched to %1$s</string>
+    <string name="timeline_marker_personality_switch">Personality switched</string>
+    <string name="timeline_marker_auto_continue">Turn auto-continued</string>
+    <string name="timeline_marker_delegation_complete">Delegated task completed</string>
     <string name="message_your_response">Your response</string>
     <string name="moa_add_preset">Add preset</string>
     <string name="moa_add_reference">Add reference model</string>

app/src/test/java/com/m57/hermescontrol/data/local/ChatMessageMapperTest.kt

@@ -161,4 +161,36 @@ class ChatMessageMapperTest {
 
         assertEquals("r", roundTripped.reasoningText)
     }
+
+    @Test
+    fun roundTripPreservesDisplayKind() {
+        val ui =
+            ChatMessage(
+                id = "msg-4",
+                role = MessageRole.USER,
+                content = "[System: ...changed to gpt-5...]",
+                displayKind = "model_switch",
+                timestamp = 4000L,
+            )
+
+        val roundTripped = ui.toEntity("s").toUiModel()
+
+        assertEquals("model_switch", roundTripped.displayKind)
+        assertEquals(MessageRole.USER, roundTripped.role)
+    }
+
+    @Test
+    fun roundTripWithoutDisplayKindStaysNull() {
+        val ui =
+            ChatMessage(
+                id = "msg-5",
+                role = MessageRole.USER,
+                content = "plain user text",
+                timestamp = 5000L,
+            )
+
+        val roundTripped = ui.toEntity("s").toUiModel()
+
+        assertNull(roundTripped.displayKind)
+    }
 }

app/src/test/java/com/m57/hermescontrol/data/model/ModelSerializationTest.kt

@@ -4,6 +4,7 @@ import com.m57.hermescontrol.data.remote.OkHttpProvider
 import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonObject
 import kotlinx.serialization.json.JsonPrimitive
 import kotlinx.serialization.json.booleanOrNull
 import org.junit.Assert.assertEquals
@@ -420,6 +421,49 @@ class ModelSerializationTest {
         assertNull(response.disk?.free_mb)
     }
 
+    @Test
+    fun testSessionMessageDeserialization_displayKindMarker() {
+        val jsonStr =
+            """
+            {
+                "id": 42,
+                "role": "user",
+                "content": "[System: The active model for this chat has changed to gpt-5 via provider openai. From this point forward, use this runtime metadata when answering questions about what model/provider is active.]",
+                "timestamp": 1755260000000,
+                "display_kind": "model_switch",
+                "display_metadata": {
+                    "delegation_id": "dlg-1",
+                    "task_count": 3
+                }
+            }
+            """.trimIndent()
+        val message = json.decodeFromString<SessionMessage>(jsonStr)
+        assertEquals(42, message.id)
+        assertEquals("user", message.role)
+        assertEquals("model_switch", message.display_kind)
+        val metadata = message.display_metadata
+        assertNotNull(metadata)
+        val delegationId =
+            (metadata as? JsonObject)?.get("delegation_id") as? JsonPrimitive
+        assertEquals("dlg-1", delegationId?.content)
+    }
+
+    @Test
+    fun testSessionMessageDeserialization_missingDisplayKind() {
+        val jsonStr =
+            """
+            {
+                "id": 7,
+                "role": "assistant",
+                "content": "hi"
+            }
+            """.trimIndent()
+        val message = json.decodeFromString<SessionMessage>(jsonStr)
+        assertEquals(7, message.id)
+        assertNull(message.display_kind)
+        assertNull(message.display_metadata)
+    }
+
     @Test
     fun testStatusResponseDeserialization_typeMismatchInGatewayPlatforms() {
         val jsonStr =

app/src/test/java/com/m57/hermescontrol/ui/chat/FullBleedTurnsTest.kt

@@ -81,6 +81,45 @@ class FullBleedTurnsTest {
         assertEquals(listOf(entries(AgentEntry.SystemEvent(s))), result)
     }
 
+    @Test
+    fun `display_kind marker is a SystemEvent entry not a user turn`() {
+        val marker =
+            msg("m1", MessageRole.USER, content = "[System: The active model has changed to gpt-5]")
+                .copy(displayKind = "model_switch")
+        val result = groupIntoTurns(listOf(marker))
+        assertEquals(listOf<ChatTurn>(entries(AgentEntry.SystemEvent(marker))), result)
+    }
+
+    @Test
+    fun `marker between assistant and user does not close the agent turn`() {
+        val a = msg("a1", MessageRole.ASSISTANT)
+        val marker =
+            msg("m1", MessageRole.USER, content = "marker")
+                .copy(displayKind = "personality_switch")
+        val u = msg("u1", MessageRole.USER)
+        val result = groupIntoTurns(listOf(a, marker, u))
+        assertEquals(
+            listOf(
+                entries(AgentEntry.Prose(a), AgentEntry.SystemEvent(marker)),
+                ChatTurn.User(u),
+            ),
+            result,
+        )
+    }
+
+    @Test
+    fun `marker only closes nothing and trailing marker lands in agent turn`() {
+        val u = msg("u1", MessageRole.USER)
+        val marker =
+            msg("m1", MessageRole.USER, content = "marker")
+                .copy(displayKind = "auto_continue")
+        val result = groupIntoTurns(listOf(u, marker))
+        assertEquals(
+            listOf(ChatTurn.User(u), entries(AgentEntry.SystemEvent(marker))),
+            result,
+        )
+    }
+
     @Test
     fun `user message closes the current agent turn`() {
         val a1 = msg("a1", MessageRole.ASSISTANT)

app/src/test/java/com/m57/hermescontrol/ui/chat/fullbleed/TimelineMarkerTest.kt

@@ -0,0 +1,59 @@
+package com.m57.hermescontrol.ui.chat.fullbleed
+
+import com.m57.hermescontrol.R
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class TimelineMarkerTest {
+    @Test
+    fun knownKindsMapToLabels() {
+        assertEquals(R.string.timeline_marker_model_switch, timelineMarkerLabelRes("model_switch"))
+        assertEquals(
+            R.string.timeline_marker_personality_switch,
+            timelineMarkerLabelRes("personality_switch"),
+        )
+        assertEquals(R.string.timeline_marker_auto_continue, timelineMarkerLabelRes("auto_continue"))
+        assertEquals(
+            R.string.timeline_marker_delegation_complete,
+            timelineMarkerLabelRes("async_delegation_complete"),
+        )
+    }
+
+    @Test
+    fun unknownAndNullKindsHaveNoLabel() {
+        assertNull(timelineMarkerLabelRes("hidden"))
+        assertNull(timelineMarkerLabelRes("some_future_kind"))
+        assertNull(timelineMarkerLabelRes(null))
+        assertNull(timelineMarkerLabelRes(""))
+    }
+
+    @Test
+    fun modelParsedFromMarkerContent() {
+        assertEquals(
+            "gpt-5",
+            markerModelFromContent(
+                "[System: The active model for this chat has changed to gpt-5 via provider openai. ...]",
+            ),
+        )
+        assertEquals(
+            "deepseek-v4",
+            markerModelFromContent(
+                "The active model for this chat has changed to deepseek-v4. From this point forward...",
+            ),
+        )
+        assertEquals(
+            "gpt-4.5",
+            markerModelFromContent(
+                "The active model for this chat has changed to gpt-4.5 via provider openai.",
+            ),
+        )
+    }
+
+    @Test
+    fun modelParseHandlesMissingOrOddContent() {
+        assertNull(markerModelFromContent(""))
+        assertNull(markerModelFromContent("[System: personality switched]"))
+        assertNull(markerModelFromContent("changed to"))
+    }
+}