Fix the CI failures the merge left behind

- A merged import list named the same module twice, which the native code
  quality plugin fails on.
- A running turn is now reported by the host with no duration, so the settled
  map carries an explicit null for it; the hook test still expected the entry
  to be absent.
- main gave the older-page action a cursor with a head-trim guard, so the
  retention test's epoch-only action no longer typechecks; it now passes an
  unbounded sequence, which is what the old shape meant.
- The roster comparator moved into the extracted module, leaving its import
  unused in the reducer.

src/renderer/src/components/native-chat/use-structured-agent-session.test.tsx

@@ -49,13 +49,15 @@ vi.mock('./use-structured-agent-session-outbox', () => ({
   })
 }))
 
-import type { AgentJournalSubmission } from '../../../../shared/agent-session-journal-types'
+import type {
+  AgentJournalRenderItem,
+  AgentJournalSubmission
+} from '../../../../shared/agent-session-journal-types'
 import {
   applyNativeChatSessionOptionSettingsMutation,
   resolveStructuredLaunchSeedOptions
 } from '../../../../shared/native-chat-session-option-defaults'
 import type { PersistedNativeChatSessionOptions } from '../../../../shared/native-chat-session-options'
-import type { AgentJournalRenderItem } from '../../../../shared/agent-session-journal-types'
 import { useStructuredAgentSession } from './use-structured-agent-session'
 
 /** Replay every host mutation in order, exactly as the runtime does. */
@@ -598,8 +600,11 @@ describe('turn timing', () => {
       )
       expect(result.current.isWorking).toBe(true)
       expect(result.current.workingStartedAt).toBe(50_000 - 300)
+      // t2 is still running, so the host has no duration for it: an explicit null
+      // that outranks whatever this client clocked locally.
       expect([...result.current.settledTurns]).toEqual([
-        ['u1', { startedAt: 9_000_000, workedSeconds: 4 }]
+        ['u1', { startedAt: 9_000_000, workedSeconds: 4 }],
+        ['u2', null]
       ])
       vi.setSystemTime(80_000)
       rerender()

src/shared/structured-agent-session-reducer.ts

@@ -3,14 +3,13 @@ import type {
   AgentJournalRenderItem,
   AgentJournalSubmission
 } from './agent-session-journal-types'
-import {
-  agentSessionBackgroundTasksEqual,
-  type AgentSessionBackgroundTaskState,
-  type AgentSessionSlashCommand,
-  type AgentSessionHandoffStatus,
-  type AgentSessionHistoryPage,
-  type AgentSessionSubscribeEvent,
-  type AgentSessionTurnActivity
+import type {
+  AgentSessionBackgroundTaskState,
+  AgentSessionSlashCommand,
+  AgentSessionHandoffStatus,
+  AgentSessionHistoryPage,
+  AgentSessionSubscribeEvent,
+  AgentSessionTurnActivity
 } from './agent-session-wire'
 import { backgroundTaskStatesEqual } from './agent-session-background-task-state-equality'
 import { agentJournalSubmissionKey } from './agent-session-journal-item-key'

src/shared/structured-agent-session-turn-timing-retention.test.ts

@@ -73,7 +73,7 @@ function loadedHistory() {
   for (const first of [129, 65, 1]) {
     state = reduceStructuredAgentSession(state, {
       type: 'older-page',
-      requestedEpoch: 'epoch',
+      requestedCursor: { epoch: 'epoch', sequence: Number.MAX_SAFE_INTEGER },
       page: page(Array.from({ length: 64 }, (_, index) => index + first))
     })
   }
@@ -84,7 +84,7 @@ describe('durable turn attribution across paginated history', () => {
   it('keeps an older page duration after the recent submission budget fills', () => {
     const state = reduceStructuredAgentSession(loadedHistory(), {
       type: 'older-page',
-      requestedEpoch: 'epoch',
+      requestedCursor: { epoch: 'epoch', sequence: Number.MAX_SAFE_INTEGER },
       page: page([0])
     })
     expect(
@@ -125,7 +125,7 @@ describe('durable turn attribution across paginated history', () => {
   it('drops an old alias once rewind removes its user item', () => {
     const loaded = reduceStructuredAgentSession(loadedHistory(), {
       type: 'older-page',
-      requestedEpoch: 'epoch',
+      requestedCursor: { epoch: 'epoch', sequence: Number.MAX_SAFE_INTEGER },
       page: page([0])
     })
     const removed = reduceStructuredAgentSession(loaded, {