fix(ui): stabilize workplace chat scrolling

opc/plugins/office_ui/frontend_src/workspace/ContextPanel.test.ts

@@ -1,6 +1,10 @@
 import assert from 'node:assert/strict'
 import type { Session } from '../types/kanban'
-import { composerExecModeForSession } from './ContextPanel'
+import {
+  composerExecModeForSession,
+  conversationHasOlderHistory,
+  sessionHasMoreForDetail,
+} from './ContextPanel'
 
 function makeSession(overrides: Partial<Session> = {}): Session {
   return {
@@ -49,4 +53,44 @@ assert.equal(
   'org',
 )
 
+const independentlyPaged = makeSession({
+  hasMore: false,
+  summaryHasMore: false,
+  fullHasMore: true,
+  messageCount: 400,
+})
+assert.equal(sessionHasMoreForDetail(independentlyPaged, 'summary'), false)
+assert.equal(sessionHasMoreForDetail(independentlyPaged, 'full'), true)
+assert.equal(
+  conversationHasOlderHistory([independentlyPaged], 200, 'summary'),
+  false,
+  'a full-detail ACK must not reopen summary history',
+)
+assert.equal(
+  conversationHasOlderHistory([independentlyPaged], 200, 'full'),
+  true,
+  'full history must retain its own cursor state',
+)
+assert.equal(
+  conversationHasOlderHistory([independentlyPaged], 200, 'full', false),
+  true,
+  'a known scoped cursor remains loadable while a company turn is running',
+)
+
+const summaryOnlyState = makeSession({
+  hasMore: false,
+  summaryHasMore: true,
+  messageCount: 400,
+})
+assert.equal(
+  sessionHasMoreForDetail(summaryOnlyState, 'full'),
+  undefined,
+  'generic hasMore is no longer authoritative after a scoped policy is known',
+)
+assert.equal(
+  conversationHasOlderHistory([makeSession({ messageCount: 400 })], 200, 'summary', false),
+  false,
+  'only the racy message-count fallback is suppressed during active generation',
+)
+
 console.log('ContextPanel composer identity checks passed')