fix(ui): stabilize workplace chat scrolling

opc/plugins/office_ui/frontend_src/chat/ChatStore.test.ts

@@ -5,6 +5,58 @@ import { mapBackendMessage } from '../lib/collabSync'
 import { analyzeCheckpointMessages } from './checkpointUtils'
 import { __chatStoreTestUtils } from './ChatStore'
 
+const persistentTimestamps = __chatStoreTestUtils.latestPersistentMessageTimestamps([
+  {
+    id: 'db-assistant-1',
+    channelId: 'session:read-test',
+    sender: 'assistant',
+    senderName: 'OPC',
+    content: 'First persisted reply',
+    timestamp: 10,
+    mentions: [],
+  },
+  {
+    id: 'msg-local-only',
+    channelId: 'session:read-test',
+    sender: 'user',
+    senderName: 'You',
+    content: 'Optimistic message',
+    timestamp: 30,
+    mentions: [],
+    metadata: { ui_message_id: 'ui-local-only' },
+  },
+  {
+    id: 'db-assistant-2',
+    channelId: 'session:read-test',
+    sender: 'assistant',
+    senderName: 'OPC',
+    content: 'Latest persisted reply',
+    timestamp: 20,
+    mentions: [],
+  },
+])
+
+assert.equal(persistentTimestamps['session:read-test'], 20)
+
+const unreadState = { 'session:read-test': 10 }
+const advancedReadState = __chatStoreTestUtils.advanceReadTimestamp(
+  unreadState,
+  'session:read-test',
+  persistentTimestamps['session:read-test'],
+)
+assert.notEqual(advancedReadState, unreadState)
+assert.equal(advancedReadState['session:read-test'], 20)
+assert.equal(
+  __chatStoreTestUtils.advanceReadTimestamp(advancedReadState, 'session:read-test', 20),
+  advancedReadState,
+  'marking an already-read channel must preserve state identity',
+)
+assert.equal(
+  __chatStoreTestUtils.advanceReadTimestamp(advancedReadState, 'session:read-test', 15),
+  advancedReadState,
+  'an older snapshot must not move the read cursor backwards',
+)
+
 const syntheticCheckpoint: ChatMessage = {
   id: 'checkpoint::cp-delivery',
   channelId: 'session:task-1',
@@ -43,6 +95,7 @@ const mergedCheckpoint = __chatStoreTestUtils.dedupeMessages([
 
 assert.equal(mergedCheckpoint.length, 1)
 assert.equal(mergedCheckpoint[0].id, 'db-message-1')
+assert.equal(mergedCheckpoint[0].timestamp, 1, 'checkpoint status updates must keep their original timeline position')
 assert.equal(mergedCheckpoint[0].metadata?.checkpoint_status, 'ignored')
 assert.deepEqual([...analyzeCheckpointMessages(mergedCheckpoint).pendingMessageIds], [])
 assert.deepEqual([...analyzeCheckpointMessages(mergedCheckpoint).respondedMessageIds], ['db-message-1'])
@@ -100,6 +153,42 @@ const mergedUserMessage = __chatStoreTestUtils.dedupeMessages([
 
 assert.equal(mergedUserMessage.length, 1)
 assert.equal(mergedUserMessage[0].metadata?.ui_message_id, 'ui-1')
+assert.equal(mergedUserMessage[0].timestamp, 4, 'backend acknowledgement must replace the optimistic client clock')
+
+const mirroredUserMessages = __chatStoreTestUtils.dedupeMessages([
+  backendUserMessage,
+  { ...backendUserMessage, id: 'db-user-mirror', channelId: 'session:child-task' },
+])
+assert.equal(
+  mirroredUserMessages.length,
+  2,
+  'ui_message_id mirrors in different channels must remain available to each channel projection',
+)
+
+assert.deepEqual(
+  __chatStoreTestUtils.unreadMessageCounts([
+    {
+      id: 'msg-local-system',
+      channelId: 'session:task-1',
+      sender: 'system',
+      senderName: 'System',
+      content: 'Local task assignment notice',
+      timestamp: 100,
+      mentions: [],
+    },
+    {
+      id: 'db-assistant-unread',
+      channelId: 'session:task-1',
+      sender: 'assistant',
+      senderName: 'OPC',
+      content: 'Persisted reply',
+      timestamp: 90,
+      mentions: [],
+    },
+  ], {}),
+  { 'session:task-1': 1 },
+  'local-only system rows must not become unread entries that markRead can never cover',
+)
 
 const nativeCompanyRawTurn: ChatMessage = {
   id: 'native-raw-1',
@@ -137,6 +226,44 @@ const mergedNativeCompanyDuplicate = __chatStoreTestUtils.dedupeMessages([
 assert.equal(mergedNativeCompanyDuplicate.length, 1)
 assert.equal(mergedNativeCompanyDuplicate[0].id, 'role-result-1')
 assert.equal(mergedNativeCompanyDuplicate[0].senderName, 'Chao')
+assert.equal(mergedNativeCompanyDuplicate[0].timestamp, 5, 'semantic result replacement must retain its original timeline position')
+assert.equal(
+  mergedNativeCompanyDuplicate[0].metadata?.ui_timeline_id,
+  'message:native-raw-1',
+  'semantic result replacement must retain the already-mounted row identity',
+)
+const repeatedNativeCompanySync = __chatStoreTestUtils.dedupeMessages([
+  ...mergedNativeCompanyDuplicate,
+  nativeCompanyRawTurn,
+  companyRoleResult,
+])
+assert.equal(repeatedNativeCompanySync.length, 1)
+assert.equal(repeatedNativeCompanySync[0].metadata?.ui_timeline_id, 'message:native-raw-1')
+assert.equal(repeatedNativeCompanySync[0].timestamp, 5)
+
+const mountedHighPriorityResult: ChatMessage = {
+  ...companyRoleResult,
+  id: 'mounted-high-result',
+  timestamp: 10,
+  metadata: { source: 'engine', transcript_kind: 'child_task_result' },
+}
+const olderLowPrioritySurface: ChatMessage = {
+  ...nativeCompanyRawTurn,
+  id: 'older-low-result',
+  timestamp: 4,
+}
+const historyBackfillMerge = __chatStoreTestUtils.mergeMessagesIntoExisting(
+  [mountedHighPriorityResult],
+  [olderLowPrioritySurface],
+)
+assert.equal(historyBackfillMerge.length, 1)
+assert.equal(historyBackfillMerge[0].id, 'mounted-high-result')
+assert.equal(historyBackfillMerge[0].timestamp, 10, 'history backfill must not move an already-mounted result row')
+assert.equal(
+  historyBackfillMerge[0].metadata?.ui_timeline_id,
+  'message:mounted-high-result',
+  'history backfill must retain the mounted high-priority result key',
+)
 
 const mappedTaskGeneralistMessage = mapBackendMessage({
   message_id: 'legacy-task-generalist',
@@ -152,4 +279,4 @@ const mappedTaskGeneralistMessage = mapBackendMessage({
 
 assert.equal(mappedTaskGeneralistMessage.senderName, 'OPC')
 
-console.log('ChatStore.test.ts: OK (optimistic, checkpoint, and company result identity merging)')
+console.log('ChatStore.test.ts: OK (read cursors, optimistic, checkpoint, and company result identity merging)')