fix(chat): 保留页面切换后的提供商与模型选择

docs/development/前端壳子与接口层开发说明.md

@@ -227,3 +227,7 @@ Agent 工具列表按 `mcp.<server_id>.<remote_name>` 的远程工具名匹配
 卡片默认显示三行摘要，完整服务原文可展开查看，展开操作不会改变工具选择。服务已提供中文说明时优先保留；未收录的 MCP 工具明确提示暂无中文说明，不将本地摘要当作服务协议或自动翻译结果。原始说明及其中的参数规则完整保留。
 
 验证：前端 84 项测试、类型检查与生产构建通过。新增回归覆盖不同服务器命名空间、未知工具、服务中文说明、原文完整性，以及选择工具时保留原始 ID。
+
+### 聊天模型选择审阅修复
+
+返回聊天页时保留仍启用的提供商与手动模型 ID，仅刷新其模型列表；未选择、已删除或已禁用的提供商才回退到默认值。提供商加载失败时保留当前选择并展示错误。新增页面重新挂载与异常分支回归，前端共 89 项测试通过。

frontend/src/features/chat/ChatView.spec.ts

@@ -0,0 +1,66 @@
+// @vitest-environment happy-dom
+import { beforeEach, expect, it, vi } from 'vitest'
+import { flushPromises, mount } from '@vue/test-utils'
+import { createPinia, setActivePinia } from 'pinia'
+import { useChatStore } from '@/stores/chat'
+import { useProviderStore } from '@/stores/provider'
+import { useSkillStore } from '@/stores/skill'
+import ChatView from './ChatView.vue'
+
+vi.mock('vue-router', () => ({ useRouter: () => ({ push: vi.fn() }) }))
+vi.mock('@/stores/editor', () => ({ useEditorStore: () => ({}) }))
+vi.mock('@/stores/workspace', () => ({ useWorkspaceStore: () => ({}) }))
+vi.mock('@/components/common/MarkdownContent.vue', () => ({ default: { template: '<div />' } }))
+
+beforeEach(() => {
+  setActivePinia(createPinia())
+  const providers = useProviderStore()
+  providers.providers = ['a', 'b'].map(id => ({
+    provider_id: id, provider_type: 'openai_compatible', name: id,
+    default_model: `${id}-default`, enabled: true, capabilities: { chat: true }, has_credential: false,
+  }))
+  providers.defaultProviderId = 'a'
+  vi.spyOn(providers, 'loadProviders').mockResolvedValue(undefined)
+  vi.spyOn(providers, 'loadModels').mockResolvedValue([])
+  vi.spyOn(useSkillStore(), 'loadSkills').mockResolvedValue(undefined)
+})
+
+it('preserves the selected provider and manual model after leaving and returning to chat', async () => {
+  const chat = useChatStore()
+  const first = mount(ChatView)
+  await flushPromises()
+  await first.get('select').setValue('b')
+  await first.get('input[list="chat-models"]').setValue('b-manual')
+  first.unmount()
+  const returned = mount(ChatView)
+  await flushPromises()
+  expect(chat.selectedProviderId).toBe('b')
+  expect(chat.selectedModel).toBe('b-manual')
+  expect(useProviderStore().loadModels).toHaveBeenLastCalledWith('b')
+  returned.unmount()
+})
+
+it.each(['missing', 'disabled', 'unselected'])('uses the default when the selected provider is %s', async state => {
+  const chat = useChatStore()
+  chat.selectedProviderId = state === 'unselected' ? '' : state === 'missing' ? 'deleted' : 'b'
+  chat.selectedModel = 'old-model'
+  if (state === 'disabled') useProviderStore().providers[1]!.enabled = false
+  const wrapper = mount(ChatView)
+  await flushPromises()
+  expect(chat.selectedProviderId).toBe('a')
+  expect(chat.selectedModel).toBe('a-default')
+  wrapper.unmount()
+})
+
+it('preserves the selection when provider discovery fails', async () => {
+  const chat = useChatStore()
+  chat.selectedProviderId = 'b'
+  chat.selectedModel = 'b-manual'
+  useProviderStore().error = 'offline'
+  const wrapper = mount(ChatView)
+  await flushPromises()
+  expect(chat.selectedProviderId).toBe('b')
+  expect(chat.selectedModel).toBe('b-manual')
+  expect(wrapper.get('.error-banner').text()).toBe('offline')
+  wrapper.unmount()
+})

frontend/src/features/chat/ChatView.vue

@@ -22,18 +22,28 @@ const availableModels = computed(() => providerStore.modelsByProvider[chatStore.
 onMounted(async () => {
   try {
     await Promise.all([providerStore.loadProviders(), skillStore.loadSkills()])
-    chatStore.selectedProviderId = providerStore.defaultProviderId
+    if (providerStore.error) return
+    const selected = providerStore.enabledProviders.find(p => p.provider_id === chatStore.selectedProviderId)
+    if (!selected) {
+      chatStore.selectedProviderId = providerStore.defaultProviderId
+    } else {
+      await refreshModels(selected.provider_id)
+    }
   } catch (error) {
     loadError.value = error instanceof Error ? error.message : '无法加载 AI 配置，请检查后端连接。'
   }
 })
 
-watch(() => chatStore.selectedProviderId, async (providerId) => {
-  chatStore.selectedModel = providerStore.providers.find(p => p.provider_id === providerId)?.default_model ?? ''
+async function refreshModels(providerId: string) {
   loadError.value = ''
   if (!providerId) return
   try { await providerStore.loadModels(providerId) }
   catch (error) { if (chatStore.selectedProviderId === providerId) loadError.value = error instanceof Error ? error.message : '模型列表加载失败，请手动填写模型 ID。' }
+}
+
+watch(() => chatStore.selectedProviderId, async (providerId) => {
+  chatStore.selectedModel = providerStore.providers.find(p => p.provider_id === providerId)?.default_model ?? ''
+  await refreshModels(providerId)
 })
 
 function send() { void chatStore.sendMessage(chatStore.inputText) }