fix: keep today habits visible while refreshing

frontend/src/MvpPanel.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { computed, nextTick, onBeforeUnmount, onMounted, ref } from 'vue'
 import { Activity, ArchiveRestore, Check, Download, FileJson, LogOut, RefreshCw, Trash2, Upload, X } from 'lucide-vue-next'
-import { dateKey, habitButtonValue, isHabitComplete, isHabitScheduledToday, mergePage, nextHabitSwipeValue, previousHabitSwipeValue, shouldToggleRowSwipe } from './lib/mvp-utils'
+import { dateKey, habitButtonValue, isHabitComplete, isHabitScheduledToday, mergePage, nextHabitSwipeValue, previousHabitSwipeValue, readHabitGridCache, shouldToggleRowSwipe, writeHabitGridCache } from './lib/mvp-utils'
 import { csrfHeader } from './lib/csrf'
 
 type View = 'habits' | 'today-habits' | 'settings'
@@ -233,10 +233,20 @@ function refreshHabitDay() {
   }
 }
 async function loadHabits() {
-  await safe(async () => {
-    const data = await request(`/habits/grid?week=${dateKey(new Date())}`) as { habits?: Habit[] }
+  const week = dateKey(new Date())
+  const cached = readHabitGridCache<Habit>(week)
+  if (cached) habits.value = cached
+  if (!cached) busy.value = true
+  error.value = ''
+  try {
+    const data = await request(`/habits/grid?week=${week}`) as { habits?: Habit[] }
     habits.value = data.habits ?? []
-  })
+    writeHabitGridCache(week, habits.value)
+  } catch (e) {
+    error.value = e instanceof Error ? e.message : '请求失败'
+  } finally {
+    if (!cached) busy.value = false
+  }
 }
 async function loadSettings() {
   await safe(async () => {
@@ -302,7 +312,7 @@ onBeforeUnmount(() => {
       </header>
 
       <!-- 今日习惯：只展示“今天该做”的习惯，复用正式习惯行样式 -->
-      <div v-if="view === 'today-habits' && !busy" class="habit-list today-habit-list">
+      <div v-if="view === 'today-habits' && (habits.length || !busy)" class="habit-list today-habit-list">
         <div class="habit-toolbar habit-toolbar-today"><label><input v-model="hideCompletedHabits" type="checkbox"> 隐藏已完成</label></div>
         <article v-for="h in visibleTodayHabits" :key="h.id" class="habit-row swipeable" :class="{ done: isDone(h, todayKey), ready: Math.abs(habitSwipeOffsets[h.id] ?? 0) >= 64 }" :style="{ '--swipe-x': `${habitSwipeOffsets[h.id] ?? 0}px` }" @pointerdown="startHabitPointer(h, $event)" @pointermove="moveHabitPointer(h, $event)" @pointerup="finishHabitPointer(h, $event)" @pointercancel="cancelHabitPointer(h)" @touchstart.passive="startHabitSwipe(h, $event)" @touchmove.passive="moveHabitSwipe(h, $event)" @touchend="finishHabitSwipe(h, $event)" @touchcancel="cancelHabitSwipe(h)">
           <button class="task-check habit-check" :aria-label="isDone(h, todayKey) ? `减少${h.name}一次` : `完成${h.name}一次`" :aria-pressed="isDone(h, todayKey)" @click.stop="toggleHabitFromButton(h)"><span class="task-check-mark"><Check v-if="isDone(h, todayKey)" /></span></button>
@@ -310,9 +320,8 @@ onBeforeUnmount(() => {
             <span><span class="habit-name">{{ h.name }}</span><small v-if="habitProgressText(h)">{{ habitProgressText(h) }}</small></span>
           </div>
         </article>
-        <div v-if="!visibleTodayHabits.length" class="empty-panel today-empty-panel"><span>{{ hideCompletedHabits && todayHabits.length ? '已完成的习惯已隐藏。' : '今天没有安排习惯，轻松一下吧。' }}</span><button v-if="!hideCompletedHabits || !todayHabits.length" class="soft-button empty-action" @click="openHabitComposer"><Check/>添加习惯</button></div>
+        <div v-if="!visibleTodayHabits.length && !busy" class="empty-panel today-empty-panel"><span>{{ hideCompletedHabits && todayHabits.length ? '已完成的习惯已隐藏。' : '今天没有安排习惯，轻松一下吧。' }}</span><button v-if="!hideCompletedHabits || !todayHabits.length" class="soft-button empty-action" @click="openHabitComposer"><Check/>添加习惯</button></div>
       </div>
-      <div v-else-if="view === 'today-habits' && busy" class="empty-panel">加载中…</div>
 
       <!-- 完整习惯列表 -->
       <Transition name="task-compose">

frontend/src/lib/mvp-utils.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { calendarModeLabel, clampFabPosition, countdownDayText, countdownKindLabel, dateKey, defaultView, habitButtonValue, habitWeek, isFabDrag, isHabitComplete, isHabitScheduledToday, isTaskView, nextHabitSwipeValue, numericHabitInputValue, previousHabitSwipeValue, quickTaskFields, shouldToggleRowSwipe } from './mvp-utils'
+import { calendarModeLabel, clampFabPosition, countdownDayText, countdownKindLabel, dateKey, defaultView, habitButtonValue, habitWeek, isFabDrag, isHabitComplete, isHabitScheduledToday, isTaskView, nextHabitSwipeValue, nextTotalAfterLocalTaskAdd, numericHabitInputValue, previousHabitSwipeValue, quickTaskFields, readHabitGridCache, shouldToggleRowSwipe, writeHabitGridCache } from './mvp-utils'
 
 describe('MVP view utilities', () => {
   it('formats a local date as YYYY-MM-DD', () => {
@@ -70,6 +70,13 @@ describe('MVP view utilities', () => {
     expect(habitButtonValue('boolean', 1, 1)).toBe(0)
   })
 
+  it('reuses the current week habit grid while refreshing in the background', () => {
+    const habits = [{ id: 'habit-1', name: '喝水' }]
+    writeHabitGridCache('2026-09-07', habits)
+    expect(readHabitGridCache('2026-09-07')).toEqual(habits)
+    expect(readHabitGridCache('2026-09-14')).toBeNull()
+  })
+
   it('renders countdown labels from date-only day values', () => {
     expect(countdownDayText(8)).toBe('还有 8 天')
     expect(countdownDayText(0)).toBe('就是今天')

frontend/src/lib/mvp-utils.ts

@@ -114,6 +114,16 @@ export function isFabDrag(deltaX: number, deltaY: number, threshold = 8) {
   return Math.hypot(deltaX, deltaY) >= threshold
 }
 
+let habitGridCache: { week: string; habits: unknown[] } | null = null
+
+export function readHabitGridCache<T>(week: string): T[] | null {
+  return habitGridCache?.week === week ? habitGridCache.habits as T[] : null
+}
+
+export function writeHabitGridCache<T>(week: string, habits: T[]) {
+  habitGridCache = { week, habits }
+}
+
 export function formatApiErrorDetail(detail: unknown): string {
   if (typeof detail === 'string') return detail
   if (Array.isArray(detail)) {

frontend/src/style.test.ts

@@ -110,6 +110,13 @@ describe('task and habit row decoration', () => {
     expect(css).toContain('.empty-action{')
   })
 
+  it('keeps cached today habits visible during background refresh', () => {
+    expect(mvpPanel).toContain('readHabitGridCache<Habit>(week)')
+    expect(mvpPanel).toContain('writeHabitGridCache(week, habits.value)')
+    expect(mvpPanel).toContain("view === 'today-habits' && (habits.length || !busy)")
+    expect(mvpPanel).not.toContain("view === 'today-habits' && busy\" class=\"empty-panel\">加载中…")
+  })
+
   it('keeps habit cards borderless so the rounded left edge has no visual gap', () => {
     expect(css).toMatch(/\.habit-row\{border:0;/)
     expect(css).not.toMatch(/\.habit-row\{[^}]*border-top:/)