test(desktop): move Stop/rewind background tests to their own file

index.test.tsx sits over the file-size ratchet; the interrupt-vs-rewind
suite lives in index.background-interrupt.test.tsx instead.

apps/desktop/src/app/session/hooks/use-prompt-actions/index.background-interrupt.test.tsx

@@ -0,0 +1,141 @@
+import { cleanup } from '@testing-library/react'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { getLatestSessionMessages } from '@/hermes'
+import { textPart } from '@/lib/chat-messages'
+import { $backgroundStatusBySession, reconcileBackgroundProcesses } from '@/store/composer-status'
+import { $gateway } from '@/store/gateway'
+import { clearNotifications } from '@/store/notifications'
+import { $busy, setMessages } from '@/store/session'
+import { $subagentsBySession, upsertSubagent } from '@/store/subagents'
+
+import { actRender, Harness, type HarnessHandle, RUNTIME_SESSION_ID } from './index-test-utils'
+import { clearSingleFlightSessionResumeState } from './single-flight-resume'
+
+beforeEach(() => {
+  clearSingleFlightSessionResumeState()
+  vi.mocked(getLatestSessionMessages).mockReset()
+  vi.mocked(getLatestSessionMessages).mockImplementation(async () => ({ messages: [], session_id: 'session' }))
+})
+
+vi.mock('@/hermes', () => ({
+  getLatestSessionMessages: vi.fn(async () => ({ messages: [], session_id: 'session' })),
+  getProfiles: vi.fn(async () => ({ profiles: [] })),
+  getSession: vi.fn(),
+  PROMPT_SUBMIT_REQUEST_TIMEOUT_MS: 1_800_000,
+  setApiRequestProfile: vi.fn(),
+  transcribeAudio: vi.fn()
+}))
+
+vi.mock('@/store/gateway', async importOriginal => ({
+  ...(await importOriginal<Record<string, unknown>>()),
+  requestGatewayForAgent: vi.fn()
+}))
+
+// Plain interrupts must not kill background work; rewinds must. cancelRun is
+// Stop and "send now" on a queued message while busy — the timeline survives,
+// and the gateway's session.interrupt leaves terminal(background=true) running.
+// reload / restore / edit truncate history, so processes from the discarded
+// turns get reaped.
+describe('usePromptActions background processes: interrupt vs rewind', () => {
+  const seed = [
+    { id: 'u1', parts: [textPart('first')], role: 'user' as const, timestamp: 0 },
+    { id: 'a1', parts: [textPart('reply')], role: 'assistant' as const, timestamp: 1 }
+  ]
+
+  let gatewayCalls: Array<{ method: string; params?: Record<string, unknown> }>
+  // resetSessionBackground remembers dismissed ids per session at module
+  // level, so each test seeds a fresh process id.
+  let procSeq = 0
+  let procId = ''
+
+  beforeEach(() => {
+    procId = `proc_live_${++procSeq}`
+    $busy.set(false)
+    $backgroundStatusBySession.set({})
+    setMessages(seed as never)
+    gatewayCalls = []
+    $gateway.set({
+      request: async (method: string, params?: Record<string, unknown>) => {
+        gatewayCalls.push({ method, params })
+
+        return {} as never
+      }
+    } as never)
+    reconcileBackgroundProcesses(RUNTIME_SESSION_ID, [
+      { command: 'npm run dev', session_id: procId, status: 'running' }
+    ] as never)
+  })
+
+  afterEach(() => {
+    cleanup()
+    clearNotifications()
+    setMessages([])
+    $busy.set(false)
+    $backgroundStatusBySession.set({})
+    $gateway.set(null)
+    vi.restoreAllMocks()
+  })
+
+  const killed = () => gatewayCalls.some(call => call.method === 'process.kill' && call.params?.process_id === procId)
+
+  async function mount(requestGateway: ReturnType<typeof vi.fn>) {
+    let handle: HarnessHandle | null = null
+    await actRender(
+      <Harness
+        onReady={h => (handle = h)}
+        refreshSessions={async () => undefined}
+        requestGateway={requestGateway as never}
+        seedMessages={seed}
+      />
+    )
+
+    return handle!
+  }
+
+  it('cancelRun interrupts the turn but leaves running background processes and subagents alone', async () => {
+    const requestGateway = vi.fn(async () => ({}) as never)
+    const handle = await mount(requestGateway)
+    upsertSubagent(RUNTIME_SESSION_ID, { goal: 'review', status: 'running', subagent_id: 'bg-review', task_index: 0 })
+    upsertSubagent(RUNTIME_SESSION_ID, { goal: 'old', status: 'completed', subagent_id: 'done-1', task_index: 1 })
+
+    await handle.cancelRun()
+
+    expect(($subagentsBySession.get()[RUNTIME_SESSION_ID] ?? []).map(row => [row.id, row.status])).toEqual([
+      ['bg-review', 'running']
+    ])
+
+    expect(requestGateway).toHaveBeenCalledWith('session.interrupt', { session_id: RUNTIME_SESSION_ID })
+    expect(requestGateway).not.toHaveBeenCalledWith('process.kill', expect.anything())
+    expect(killed()).toBe(false)
+
+    const rows = $backgroundStatusBySession.get()[RUNTIME_SESSION_ID] ?? []
+
+    expect(rows.map(row => [row.id, row.state])).toEqual([[procId, 'running']])
+  })
+
+  it('reloadFromMessage (regenerate) kills processes from the truncated turns', async () => {
+    const requestGateway = vi.fn(async () => ({}) as never)
+    const handle = await mount(requestGateway)
+
+    await handle.reloadFromMessage('u1')
+
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      expect.objectContaining({ confirm_truncate: true, truncate_before_message_id: 'u1' }),
+      expect.anything()
+    )
+    expect(killed()).toBe(true)
+    expect($backgroundStatusBySession.get()[RUNTIME_SESSION_ID] ?? []).toEqual([])
+  })
+
+  it('restoreToMessage still kills processes from the discarded turns', async () => {
+    const requestGateway = vi.fn(async () => ({}) as never)
+    const handle = await mount(requestGateway)
+
+    await handle.restoreToMessage('u1')
+
+    expect(killed()).toBe(true)
+    expect($backgroundStatusBySession.get()[RUNTIME_SESSION_ID] ?? []).toEqual([])
+  })
+})

apps/desktop/src/app/session/hooks/use-prompt-actions/index.test.tsx

@@ -11,9 +11,8 @@ import { createClientSessionState } from '@/lib/chat-runtime'
 import { $compactingSessions, setSessionCompacting } from '@/store/compaction'
 import { $composerAttachments, $composerDraft, type ComposerAttachment, setComposerDraft } from '@/store/composer'
 import { $queuedPromptsBySession, getQueuedPrompts } from '@/store/composer-queue'
-import { $backgroundStatusBySession, reconcileBackgroundProcesses } from '@/store/composer-status'
 import { $confirmRequest, settleConfirm } from '@/store/confirm'
-import { $gateway, requestGatewayForAgent } from '@/store/gateway'
+import { requestGatewayForAgent } from '@/store/gateway'
 import { $goalsBySession, setSessionGoal } from '@/store/goals'
 import { $hudMode } from '@/store/hud'
 import { $notifications, clearNotifications } from '@/store/notifications'
@@ -31,7 +30,6 @@ import {
   setSessions
 } from '@/store/session'
 import { dropSessionState, publishSessionState } from '@/store/session-states'
-import { $subagentsBySession, upsertSubagent } from '@/store/subagents'
 import { $wakeWord, resetWakeWordState } from '@/store/wake-word'
 
 import { actRender, Harness, type HarnessHandle, RUNTIME_SESSION_ID, sessionInfo } from './index-test-utils'
@@ -5095,114 +5093,6 @@ describe('usePromptActions cancelRun', () => {
   })
 })
 
-// Plain interrupts must not kill background work; rewinds must. cancelRun is
-// Stop and "send now" on a queued message while busy — the timeline survives,
-// and the gateway's session.interrupt leaves terminal(background=true) running.
-// reload / restore / edit truncate history, so processes from the discarded
-// turns get reaped.
-describe('usePromptActions background processes: interrupt vs rewind', () => {
-  const seed = [
-    { id: 'u1', parts: [textPart('first')], role: 'user' as const, timestamp: 0 },
-    { id: 'a1', parts: [textPart('reply')], role: 'assistant' as const, timestamp: 1 }
-  ]
-
-  let gatewayCalls: Array<{ method: string; params?: Record<string, unknown> }>
-  // resetSessionBackground remembers dismissed ids per session at module
-  // level, so each test seeds a fresh process id.
-  let procSeq = 0
-  let procId = ''
-
-  beforeEach(() => {
-    procId = `proc_live_${++procSeq}`
-    $busy.set(false)
-    $backgroundStatusBySession.set({})
-    setMessages(seed as never)
-    gatewayCalls = []
-    $gateway.set({
-      request: async (method: string, params?: Record<string, unknown>) => {
-        gatewayCalls.push({ method, params })
-
-        return {} as never
-      }
-    } as never)
-    reconcileBackgroundProcesses(RUNTIME_SESSION_ID, [
-      { command: 'npm run dev', session_id: procId, status: 'running' }
-    ] as never)
-  })
-
-  afterEach(() => {
-    cleanup()
-    clearNotifications()
-    setMessages([])
-    $busy.set(false)
-    $backgroundStatusBySession.set({})
-    $gateway.set(null)
-    vi.restoreAllMocks()
-  })
-
-  const killed = () => gatewayCalls.some(call => call.method === 'process.kill' && call.params?.process_id === procId)
-
-  async function mount(requestGateway: ReturnType<typeof vi.fn>) {
-    let handle: HarnessHandle | null = null
-    await actRender(
-      <Harness
-        onReady={h => (handle = h)}
-        refreshSessions={async () => undefined}
-        requestGateway={requestGateway as never}
-        seedMessages={seed}
-      />
-    )
-
-    return handle!
-  }
-
-  it('cancelRun interrupts the turn but leaves running background processes and subagents alone', async () => {
-    const requestGateway = vi.fn(async () => ({}) as never)
-    const handle = await mount(requestGateway)
-    upsertSubagent(RUNTIME_SESSION_ID, { goal: 'review', status: 'running', subagent_id: 'bg-review', task_index: 0 })
-    upsertSubagent(RUNTIME_SESSION_ID, { goal: 'old', status: 'completed', subagent_id: 'done-1', task_index: 1 })
-
-    await handle.cancelRun()
-
-    expect(($subagentsBySession.get()[RUNTIME_SESSION_ID] ?? []).map(row => [row.id, row.status])).toEqual([
-      ['bg-review', 'running']
-    ])
-
-    expect(requestGateway).toHaveBeenCalledWith('session.interrupt', { session_id: RUNTIME_SESSION_ID })
-    expect(requestGateway).not.toHaveBeenCalledWith('process.kill', expect.anything())
-    expect(killed()).toBe(false)
-
-    const rows = $backgroundStatusBySession.get()[RUNTIME_SESSION_ID] ?? []
-
-    expect(rows.map(row => [row.id, row.state])).toEqual([[procId, 'running']])
-  })
-
-  it('reloadFromMessage (regenerate) kills processes from the truncated turns', async () => {
-    const requestGateway = vi.fn(async () => ({}) as never)
-    const handle = await mount(requestGateway)
-
-    await handle.reloadFromMessage('u1')
-
-    expect(requestGateway).toHaveBeenCalledWith(
-      'prompt.submit',
-      expect.objectContaining({ confirm_truncate: true, truncate_before_message_id: 'u1' }),
-      expect.anything()
-    )
-    expect(killed()).toBe(true)
-    expect($backgroundStatusBySession.get()[RUNTIME_SESSION_ID] ?? []).toEqual([])
-  })
-
-  it('restoreToMessage still kills processes from the discarded turns', async () => {
-    const requestGateway = vi.fn(async () => ({}) as never)
-    const handle = await mount(requestGateway)
-
-    await handle.restoreToMessage('u1')
-
-    expect(killed()).toBe(true)
-    expect($backgroundStatusBySession.get()[RUNTIME_SESSION_ID] ?? []).toEqual([])
-  })
-})
-
 describe('usePromptActions eager attachment upload (drop-time)', () => {
   afterEach(() => {
     cleanup()