Add IPC contract tests for SMB connection commands

Covers connect_to_server, list_shares_on_host, mount_network_share. The
mount_network_share signature has 6 positional args and AGENTS.md specifically
calls out positional-soup as fragile — pinning the wire order here catches
the kind of drift that would otherwise surface as a runtime 'not allowed'.

Each command tests both the happy path and a typed error variant
(ShareListError::auth_required, MountError::auth_failed, string error for
connect_to_server).

Author: vdavid

apps/desktop/src/lib/ipc/network-smb.test.ts

@@ -0,0 +1,141 @@
+/**
+ * IPC contract tests for the network/SMB connection surface: `connect_to_server`,
+ * `list_shares_on_host`, `mount_network_share`.
+ *
+ * MTP and SMB stood out in the coverage report as nearly-zero IPC coverage. The
+ * underlying smb2 / mDNS logic is tested in its own crate; what this group catches
+ * is the **wire format**, especially the many-positional-arg shapes that AGENTS.md
+ * specifically calls out as fragile (the `mountNetworkShare(server, share, username,
+ * password, port, timeoutMs)` signature has 6 positional args; getting the order
+ * wrong silently breaks at runtime).
+ */
+
+import { afterEach, describe, expect, it } from 'vitest'
+
+import { commands } from '$lib/ipc/bindings'
+import type { ManualConnectResult, MountResult, ShareListResult } from '$lib/ipc/bindings'
+import { clearIpcMocks, installIpcMock } from '$lib/ipc/test-helpers'
+
+afterEach(() => {
+  clearIpcMocks()
+})
+
+describe('commands.connectToServer', () => {
+  it('forwards address as a single payload key', async () => {
+    const ipc = installIpcMock()
+    const result: ManualConnectResult = {
+      host: {
+        id: 'manual-1',
+        name: 'storage.local',
+        hostname: 'storage.local',
+        ipAddress: '192.168.1.42',
+        port: 445,
+      },
+      sharePath: null,
+    }
+    ipc.mock('connect_to_server', () => result)
+
+    const out = await commands.connectToServer('smb://storage.local/share')
+
+    expect(out).toEqual({ status: 'ok', data: result })
+    expect(ipc.lastCall('connect_to_server')?.payload).toEqual({
+      address: 'smb://storage.local/share',
+    })
+  })
+
+  it('surfaces a string error on unreachable hosts', async () => {
+    const ipc = installIpcMock()
+    ipc.mock('connect_to_server', () => {
+      throw 'host unreachable'
+    })
+
+    const out = await commands.connectToServer('smb://nonexistent.invalid')
+
+    expect(out.status).toBe('error')
+    if (out.status === 'error') expect(out.error).toBe('host unreachable')
+  })
+})
+
+describe('commands.listSharesOnHost', () => {
+  it('sends all six positional args as camelCase payload keys', async () => {
+    const ipc = installIpcMock()
+    const result: ShareListResult = {
+      shares: [{ name: 'Public', isDisk: true, comment: null }],
+      authMode: 'guest_allowed',
+      fromCache: false,
+    }
+    ipc.mock('list_shares_on_host', () => result)
+
+    const hostId = 'host-1'
+    const hostname = 'TEST_SERVER.local'
+    const ipAddress: string | null = '192.168.1.42'
+    const port = 4450
+    const timeoutMs: number | null = 15000
+    const cacheTtlMs: number | null = 30000
+
+    await commands.listSharesOnHost(hostId, hostname, ipAddress, port, timeoutMs, cacheTtlMs)
+
+    expect(ipc.lastCall('list_shares_on_host')?.payload).toEqual({
+      hostId,
+      hostname,
+      ipAddress,
+      port,
+      timeoutMs,
+      cacheTtlMs,
+    })
+  })
+
+  it('surfaces the typed ShareListError discriminator (e.g. auth_required)', async () => {
+    const ipc = installIpcMock()
+    ipc.mock('list_shares_on_host', () => {
+      throw { type: 'auth_required', message: 'Server requires credentials' }
+    })
+
+    const out = await commands.listSharesOnHost('h', 'x.local', null, 445, null, null)
+
+    expect(out.status).toBe('error')
+    if (out.status === 'error') {
+      expect(out.error).toEqual({ type: 'auth_required', message: 'Server requires credentials' })
+    }
+  })
+})
+
+describe('commands.mountNetworkShare', () => {
+  it('sends the 6 positional args in declared order (server, share, username, password, port, timeoutMs)', async () => {
+    const ipc = installIpcMock()
+    const result: MountResult = { mountPath: '/Volumes/Public', alreadyMounted: false }
+    ipc.mock('mount_network_share', () => result)
+
+    const server = 'storage.local'
+    const share = 'Public'
+    const username: string | null = 'dave'
+    const password: string | null = 'hunter2'
+    const port: number | null = 445
+    const timeoutMs: number | null = 20000
+
+    await commands.mountNetworkShare(server, share, username, password, port, timeoutMs)
+
+    expect(ipc.lastCall('mount_network_share')?.payload).toEqual({
+      server,
+      share,
+      username,
+      password,
+      port,
+      timeoutMs,
+    })
+  })
+
+  it('surfaces typed MountError variants (auth_failed) on the error branch', async () => {
+    const ipc = installIpcMock()
+    ipc.mock('mount_network_share', () => {
+      throw { type: 'auth_failed', message: 'bad credentials' }
+    })
+
+    const out = await commands.mountNetworkShare('s', 'sh', 'u', 'p', null, null)
+
+    expect(out.status).toBe('error')
+    if (out.status === 'error') {
+      expect(out.error).toEqual({ type: 'auth_failed', message: 'bad credentials' })
+    }
+  })
+})