fix(profile): preserve username edits made during save

frontend/src/components/user/profile/ProfileEditForm.vue

@@ -58,10 +58,12 @@ const authStore = useAuthStore()
 const appStore = useAppStore()
 
 const username = ref(props.initialUsername)
+let savedUsername = props.initialUsername
 const loading = ref(false)
 
 watch(() => props.initialUsername, (val) => {
-  username.value = val
+  if (username.value === savedUsername) username.value = val
+  savedUsername = val
 })
 
 const handleUpdateProfile = async () => {
@@ -71,10 +73,13 @@ const handleUpdateProfile = async () => {
   }
 
   loading.value = true
+  const submittedUsername = username.value
   try {
     const updatedUser = await userAPI.updateProfile({
-      username: username.value
+      username: submittedUsername
     })
+    if (username.value === submittedUsername) username.value = updatedUser.username
+    savedUsername = updatedUser.username
     authStore.user = updatedUser
     appStore.showSuccess(t('profile.updateSuccess'))
   } catch (error: unknown) {

frontend/src/components/user/profile/__tests__/ProfileEditForm.draft.spec.ts

@@ -0,0 +1,53 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { enableAutoUnmount, flushPromises, mount } from '@vue/test-utils'
+import { defineComponent, reactive } from 'vue'
+import ProfileEditForm from '../ProfileEditForm.vue'
+
+const mocks = vi.hoisted(() => ({ updateProfile: vi.fn(), state: { user: { username: 'alice' } } }))
+vi.mock('@/api', () => ({ userAPI: { updateProfile: mocks.updateProfile } }))
+vi.mock('@/stores/auth', () => ({ useAuthStore: () => reactive(mocks.state) }))
+vi.mock('@/stores/app', () => ({ useAppStore: () => ({ showError: vi.fn(), showSuccess: vi.fn() }) }))
+vi.mock('vue-i18n', () => ({ useI18n: () => ({ t: (key: string) => key }) }))
+enableAutoUnmount(afterEach)
+beforeEach(() => {
+  vi.resetAllMocks()
+  mocks.state.user = { username: 'alice' }
+})
+
+const Harness = defineComponent({
+  components: { ProfileEditForm },
+  setup: () => ({ auth: reactive(mocks.state) }),
+  template: '<ProfileEditForm :initial-username="auth.user.username" />'
+})
+
+describe('profile username draft', () => {
+  it.each(['next-draft', 'alice'])('preserves %s typed while the previous username is being saved', async (draft) => {
+    let finish!: (value: unknown) => void
+    mocks.updateProfile.mockReturnValue(new Promise(resolve => { finish = resolve }))
+    const wrapper = mount(Harness)
+    await wrapper.get('#username').setValue('submitted')
+    await wrapper.get('form').trigger('submit')
+    expect(mocks.updateProfile).toHaveBeenCalledWith({ username: 'submitted' })
+    await wrapper.get('#username').setValue(draft)
+    finish({ username: 'submitted' })
+    await flushPromises()
+    expect(mocks.state.user.username).toBe('submitted')
+    expect((wrapper.get('#username').element as HTMLInputElement).value).toBe(draft)
+  })
+
+  it('still synchronizes a pristine input with profile updates', async () => {
+    const wrapper = mount(Harness)
+    reactive(mocks.state).user = { username: 'updated' }
+    await flushPromises()
+    expect((wrapper.get('#username').element as HTMLInputElement).value).toBe('updated')
+  })
+
+  it('shows the server username after saving without further edits', async () => {
+    mocks.updateProfile.mockResolvedValue({ username: 'saved-name' })
+    const wrapper = mount(Harness)
+    await wrapper.get('#username').setValue(' saved-name ')
+    await wrapper.get('form').trigger('submit')
+    await flushPromises()
+    expect((wrapper.get('#username').element as HTMLInputElement).value).toBe('saved-name')
+  })
+})