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

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(
-                                                message = sysMessage,
-                                                onRespondApproval = viewModel::respondToApproval,
-                                            )
+                                            if (sysMessage.displayKind != null) {
+                                                // Timeline marker (issue #904):
+                                                // 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) {
-            MessageRole.USER -> {
+        when {
+            // 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.TOOL -> agentEntries += AgentEntry.ToolRow(message)
-            MessageRole.SYSTEM -> agentEntries += AgentEntry.SystemEvent(message)
+            MessageRole.ASSISTANT == message.role -> agentEntries += AgentEntry.Prose(message)
+            MessageRole.TOOL == message.role -> agentEntries += AgentEntry.ToolRow(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),
+            )
+        }
+    }
+}