fix(desktop): recover the backend update overlay after the remote restarts

The backend Install path set stage:'restart' and stopped — in remote mode no
boot-progress events arrive to carry the overlay to done, so it sat on the
restarting spinner until a manual reload while the backend had already come
back. Poll the backend until it answers again, then clear the overlay and
refresh the backend status. Target-aware applying copy explains the remote
restart + auto-reconnect instead of the local-updater-window wording.

Also switch the apply poll sleeps from window.setTimeout to globalThis.setTimeout
so the flow is exercisable off the renderer.

apps/desktop/src/store/updates.test.ts

@@ -1,4 +1,4 @@
-import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
 import type { DesktopUpdateStatus } from '@/global'
 
@@ -33,7 +33,7 @@ vi.mock('@/hermes', () => ({
   getActionStatus: (...args: unknown[]) => getActionStatusSpy(...args)
 }))
 
-const { maybeNotifyUpdateAvailable, checkBackendUpdates, $backendUpdateStatus } = await import('./updates')
+const { maybeNotifyUpdateAvailable, checkBackendUpdates, $backendUpdateStatus, applyBackendUpdate, $backendUpdateApply } = await import('./updates')
 const { setConnection } = await import('./session')
 
 const status = (over: Partial<DesktopUpdateStatus> = {}): DesktopUpdateStatus => ({
@@ -155,3 +155,32 @@ describe('checkBackendUpdates', () => {
   })
 })
 
+describe('applyBackendUpdate recovery', () => {
+  beforeEach(() => {
+    storage.clear()
+    checkHermesUpdateSpy.mockReset()
+    updateHermesSpy.mockReset()
+    getActionStatusSpy.mockReset()
+    $backendUpdateApply.set({ applying: false, stage: 'idle', message: '', percent: null, error: null, command: null, log: [] })
+    vi.useFakeTimers()
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+  })
+
+  it('waits for the backend to return after the restart drops the connection, then clears the overlay', async () => {
+    updateHermesSpy.mockResolvedValue({ ok: true, name: 'update', pid: 1 })
+    getActionStatusSpy.mockRejectedValue(new Error('ECONNREFUSED'))
+    checkHermesUpdateSpy.mockResolvedValue({ install_method: 'git', current_version: '0.16.0', behind: 0, update_available: false, can_apply: true, update_command: 'hermes update', message: null })
+
+    const promise = applyBackendUpdate()
+    await vi.advanceTimersByTimeAsync(5000)
+    const result = await promise
+
+    expect(result.ok).toBe(true)
+    expect($backendUpdateApply.get().stage).toBe('idle')
+    expect($backendUpdateApply.get().applying).toBe(false)
+  })
+})
+

apps/desktop/src/store/updates.ts

@@ -304,6 +304,22 @@ export async function applyUpdates(opts: DesktopUpdateApplyOptions = {}): Promis
   }
 }
 
+const BACKEND_RETURN_POLL_MS = 1500
+const BACKEND_RETURN_MAX_ATTEMPTS = 40
+
+async function waitForBackendReturn(): Promise<void> {
+  for (let attempt = 0; attempt < BACKEND_RETURN_MAX_ATTEMPTS; attempt += 1) {
+    await new Promise(resolve => globalThis.setTimeout(resolve, BACKEND_RETURN_POLL_MS))
+    try {
+      await checkHermesUpdate()
+
+      return
+    } catch {
+      continue
+    }
+  }
+}
+
 export async function applyBackendUpdate(): Promise<DesktopUpdateApplyResult> {
   dismissNotification(UPDATE_TOAST_ID)
   $backendUpdateApply.set({ ...IDLE, applying: true, stage: 'prepare', message: 'Updating backend…' })
@@ -323,19 +339,22 @@ export async function applyBackendUpdate(): Promise<DesktopUpdateApplyResult> {
 
     let last: Awaited<ReturnType<typeof getActionStatus>> | null = null
     for (let attempt = 0; attempt < 30; attempt += 1) {
-      await new Promise(resolve => window.setTimeout(resolve, 1500))
+      await new Promise(resolve => globalThis.setTimeout(resolve, 1500))
       try {
         last = await getActionStatus(started.name, 200)
       } catch {
         // The dashboard restarts mid-update, dropping this connection — expected, not a failure.
         $backendUpdateApply.set({
           ...$backendUpdateApply.get(),
-          applying: false,
+          applying: true,
           stage: 'restart',
           message: 'Backend restarting to load the update…'
         })
+        await waitForBackendReturn()
+        $backendUpdateApply.set(IDLE)
+        void checkBackendUpdates()
 
-        return { ok: true, message: 'Backend update applied; backend is restarting.' }
+        return { ok: true, message: 'Backend update applied; backend is back online.' }
       }
 
       if (last && !last.running) {
@@ -344,17 +363,24 @@ export async function applyBackendUpdate(): Promise<DesktopUpdateApplyResult> {
     }
 
     const ok = !!last && (last.exit_code ?? 1) === 0
+    if (ok) {
+      $backendUpdateApply.set({ ...$backendUpdateApply.get(), applying: true, stage: 'restart', message: 'Backend restarting to load the update…' })
+      await waitForBackendReturn()
+      $backendUpdateApply.set(IDLE)
+      void checkBackendUpdates()
+
+      return { ok: true, message: 'Backend update applied.' }
+    }
+
     $backendUpdateApply.set({
       ...$backendUpdateApply.get(),
       applying: false,
-      stage: ok ? 'restart' : 'error',
-      error: ok ? null : 'apply-failed',
-      message: ok ? 'Backend updated. Restart it to load the new code.' : 'Backend update failed.'
+      stage: 'error',
+      error: 'apply-failed',
+      message: 'Backend update failed.'
     })
 
-    return ok
-      ? { ok: true, message: 'Backend update applied.' }
-      : { ok: false, error: 'apply-failed', message: 'Backend update failed.' }
+    return { ok: false, error: 'apply-failed', message: 'Backend update failed.' }
   } catch (error) {
     const message = error instanceof Error ? error.message : String(error)
     $backendUpdateApply.set({ ...$backendUpdateApply.get(), applying: false, stage: 'error', error: 'apply-failed', message })