test(desktop): cover $connection resync on profile switch

Asserts ensureGatewayProfile keeps $connection in lockstep with the active
profile's backend: activating a remote pool profile flips mode to remote,
returning to default resyncs to local, a failed descriptor fetch leaves the
prior connection intact, and a same-profile activation doesn't churn it.
Regression coverage for #46651.

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

@@ -0,0 +1,89 @@
+import { atom } from 'nanostores'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+import type { HermesConnection } from '@/global'
+
+// Keep profile.ts's side-effecting imports inert: the gateway socket layer and
+// the REST query client must not run for real in a unit test.
+const ensureGatewayForProfile = vi.fn(async () => undefined)
+const $gateway = atom<unknown>({ id: 'live-socket' })
+
+vi.mock('@/store/gateway', () => ({ $gateway, ensureGatewayForProfile }))
+vi.mock('@/hermes', () => ({
+  getProfiles: vi.fn(async () => ({ profiles: [] })),
+  setApiRequestProfile: vi.fn()
+}))
+vi.mock('@/lib/query-client', () => ({ queryClient: { invalidateQueries: vi.fn() } }))
+
+const { $activeGatewayProfile, ensureGatewayProfile } = await import('./profile')
+const { $connection } = await import('./session')
+
+const remoteConn = (over: Partial<HermesConnection> = {}): HermesConnection =>
+  ({ baseUrl: 'https://hermes-roy.tail.ts.net', mode: 'remote', profile: 'vps-remote', ...over }) as HermesConnection
+
+const localConn = (over: Partial<HermesConnection> = {}): HermesConnection =>
+  ({ baseUrl: '', mode: 'local', profile: 'default', ...over }) as HermesConnection
+
+const getConnection = vi.fn<(profile?: string | null) => Promise<HermesConnection>>()
+
+beforeEach(() => {
+  getConnection.mockReset()
+  ensureGatewayForProfile.mockClear()
+  $gateway.set({ id: 'live-socket' })
+  $activeGatewayProfile.set('default')
+  $connection.set(localConn())
+  vi.stubGlobal('window', { hermesDesktop: { getConnection } })
+})
+
+afterEach(() => {
+  vi.unstubAllGlobals()
+  $connection.set(null)
+})
+
+describe('ensureGatewayProfile → $connection sync (#46651)', () => {
+  it('refreshes $connection to the remote descriptor when activating a remote pool profile', async () => {
+    // Regression: the primary window backend is local, so $connection.mode is
+    // "local". Activating the remote profile must flip it to "remote" — without
+    // this, image attach uses path-based image.attach against the remote
+    // gateway ("image not found: C:\\…") instead of image.attach_bytes.
+    getConnection.mockResolvedValue(remoteConn())
+
+    await ensureGatewayProfile('vps-remote')
+
+    expect(ensureGatewayForProfile).toHaveBeenCalledWith('vps-remote')
+    expect(getConnection).toHaveBeenCalledWith('vps-remote')
+    expect($connection.get()?.mode).toBe('remote')
+    expect($connection.get()?.profile).toBe('vps-remote')
+  })
+
+  it('resyncs $connection back to local when returning to the default profile', async () => {
+    $activeGatewayProfile.set('vps-remote')
+    $connection.set(remoteConn())
+    getConnection.mockResolvedValue(localConn())
+
+    await ensureGatewayProfile('default')
+
+    expect(getConnection).toHaveBeenCalledWith('default')
+    expect($connection.get()?.mode).toBe('local')
+  })
+
+  it('leaves the prior connection intact when the descriptor fetch fails', async () => {
+    getConnection.mockRejectedValue(new Error('backend unreachable'))
+
+    await ensureGatewayProfile('vps-remote')
+
+    // Best-effort: boot/reconnect resyncs later; we must not null it out here.
+    expect($connection.get()?.mode).toBe('local')
+  })
+
+  it('does not churn $connection when the target is already the active profile', async () => {
+    $activeGatewayProfile.set('vps-remote')
+    $connection.set(remoteConn())
+
+    await ensureGatewayProfile('vps-remote')
+
+    expect(getConnection).not.toHaveBeenCalled()
+    expect(ensureGatewayForProfile).not.toHaveBeenCalled()
+    expect($connection.get()?.mode).toBe('remote')
+  })
+})