Persist selected date across refresh

apps/web/src/store/RawLogStorageSyncMiddleware.ts

@@ -4,7 +4,11 @@ import { createListenerMiddleware, isAnyOf } from '@reduxjs/toolkit';
 import { getLogFromServer, saveLogToServer } from '../services/LogService';
 import { detectConflict } from '../utils/ConflictDetector';
 import { calculateHashSync } from '../utils/HashUtil';
-import { loadFromStorage, saveToStorage } from '../utils/StorageUtil';
+import {
+  loadFromStorage,
+  saveCurrentDateToStorage,
+  saveToStorage,
+} from '../utils/StorageUtil';
 import type { AppDispatch, RootState } from '.';
 import { loginSuccess } from './auth';
 import {
@@ -36,6 +40,14 @@ const startAppListening =
 const shortHash = (value: string | null | undefined): string =>
   typeof value === 'string' ? value.substring(0, 8) : 'null';
 
+startAppListening({
+  matcher: isAnyOf(goToToday, goToPrevDate, goToNextDate),
+  effect: async (_, listenerApi) => {
+    const { currentDate } = listenerApi.getState().logs;
+    saveCurrentDateToStorage(currentDate);
+  },
+});
+
 // localstorage에 저장 & 배업 (Server Sync with Debounce)
 startAppListening({
   actionCreator: updateRawLog,

apps/web/src/store/logs.test.ts

@@ -0,0 +1,48 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+describe('logs initial state', () => {
+  beforeEach(() => {
+    localStorage.clear();
+    vi.resetModules();
+  });
+
+  it('저장된 현재 날짜가 없으면 오늘 날짜로 초기화해야 함', async () => {
+    const { getTodayString } = await import('../utils/DateUtil');
+    const { LogsReducer } = await import('./logs');
+
+    const state = LogsReducer(undefined, { type: '@@INIT' });
+
+    expect(state.currentDate).toBe(getTodayString());
+  });
+
+  it('저장된 현재 날짜가 있으면 그 날짜로 초기화해야 함', async () => {
+    localStorage.setItem('my-commit:current-date', '2026-03-10');
+    localStorage.setItem(
+      '2026-03-10',
+      JSON.stringify({
+        content: 'Persisted log',
+        contentHash: 'hash',
+        parentHash: null,
+        localUpdatedAt: '2026-03-10T10:00:00.000Z',
+      }),
+    );
+
+    const { LogsReducer } = await import('./logs');
+
+    const state = LogsReducer(undefined, { type: '@@INIT' });
+
+    expect(state.currentDate).toBe('2026-03-10');
+    expect(state.rawLogs).toBe('Persisted log');
+  });
+
+  it('저장된 현재 날짜 형식이 잘못되면 오늘 날짜로 폴백해야 함', async () => {
+    localStorage.setItem('my-commit:current-date', 'invalid-date');
+
+    const { getTodayString } = await import('../utils/DateUtil');
+    const { LogsReducer } = await import('./logs');
+
+    const state = LogsReducer(undefined, { type: '@@INIT' });
+
+    expect(state.currentDate).toBe(getTodayString());
+  });
+});

apps/web/src/store/logs.ts

@@ -7,7 +7,10 @@ import {
 } from '../utils/DateUtil';
 import { createLogsFromString } from '../utils/LogConverter';
 import { Log } from '../utils/PaceUtil';
-import { loadFromStorage } from '../utils/StorageUtil';
+import {
+  loadCurrentDateFromStorage,
+  loadFromStorage,
+} from '../utils/StorageUtil';
 
 export type ConflictState = {
   localContent: string;
@@ -28,7 +31,7 @@ export type LogState = {
 };
 
 // reducer 바깥이어서 초기값 설정 구문이 순수하지 않아도 괜찮을 듯
-const initialDate = getTodayString();
+const initialDate = loadCurrentDateFromStorage() ?? getTodayString();
 const initialLocalData = loadFromStorage(initialDate);
 
 const initialState: LogState = {

apps/web/src/utils/DateUtil.ts

@@ -6,6 +6,28 @@ export const getDateString = (date: Date) => {
   )}`;
 };
 
+const DATE_STRING_REGEX = /^\d{4}-\d{2}-\d{2}$/;
+
+export const isValidDateString = (dateString: string) => {
+  if (!DATE_STRING_REGEX.test(dateString)) {
+    return false;
+  }
+
+  const [yearString, monthString, dayString] = dateString.split('-');
+  const year = Number(yearString);
+  const month = Number(monthString);
+  const day = Number(dayString);
+
+  const parsedDate = new Date(year, month - 1, day);
+
+  return (
+    Number.isFinite(parsedDate.getTime()) &&
+    parsedDate.getFullYear() === year &&
+    parsedDate.getMonth() === month - 1 &&
+    parsedDate.getDate() === day
+  );
+};
+
 // TODO: validation하기
 export const justOneDayAwayAtMost = (
   dateAString: string,

apps/web/src/utils/StorageUtil.test.ts

@@ -1,14 +1,57 @@
 import { beforeEach, describe, expect, it } from 'vitest';
 
 import { calculateHashSync } from './HashUtil';
-import { loadFromStorage, saveToStorage } from './StorageUtil';
+import {
+  CURRENT_DATE_STORAGE_KEY,
+  loadCurrentDateFromStorage,
+  loadFromStorage,
+  saveCurrentDateToStorage,
+  saveToStorage,
+} from './StorageUtil';
 
 describe('StorageUtil', () => {
   beforeEach(() => {
     // localStorage 초기화
     localStorage.clear();
   });
 
+  describe('current date persistence', () => {
+    it('현재 날짜를 저장하고 로드해야 함', () => {
+      saveCurrentDateToStorage('2026-03-15');
+
+      expect(localStorage.getItem(CURRENT_DATE_STORAGE_KEY)).toBe('2026-03-15');
+      expect(loadCurrentDateFromStorage()).toBe('2026-03-15');
+    });
+
+    it('잘못된 형식의 현재 날짜는 무시해야 함', () => {
+      localStorage.setItem(CURRENT_DATE_STORAGE_KEY, '2026/03/15');
+
+      expect(loadCurrentDateFromStorage()).toBeNull();
+    });
+
+    it('형식은 맞지만 실제 달력이 아닌 날짜는 무시해야 함', () => {
+      localStorage.setItem(CURRENT_DATE_STORAGE_KEY, '2026-13-40');
+
+      expect(loadCurrentDateFromStorage()).toBeNull();
+    });
+
+    it('잘못된 현재 날짜를 저장하려 하면 키를 제거해야 함', () => {
+      localStorage.setItem(CURRENT_DATE_STORAGE_KEY, '2026-03-15');
+
+      saveCurrentDateToStorage('invalid-date');
+
+      expect(localStorage.getItem(CURRENT_DATE_STORAGE_KEY)).toBeNull();
+    });
+
+    it('형식은 맞지만 실제 달력이 아닌 날짜를 저장하려 하면 키를 제거해야 함', () => {
+      localStorage.setItem(CURRENT_DATE_STORAGE_KEY, '2026-03-15');
+
+      saveCurrentDateToStorage('2026-02-30');
+
+      expect(localStorage.getItem(CURRENT_DATE_STORAGE_KEY)).toBeNull();
+    });
+  });
+
   describe('loadFromStorage', () => {
     it('빈 키로 로드 시 빈 데이터를 반환해야 함', () => {
       const data = loadFromStorage('2026-01-12');

apps/web/src/utils/StorageUtil.ts

@@ -1,3 +1,4 @@
+import { isValidDateString } from './DateUtil';
 import { calculateHashSync } from './HashUtil';
 
 export interface LocalLogData {
@@ -7,6 +8,27 @@ export interface LocalLogData {
   localUpdatedAt: string; // 로컬에서 마지막 수정 시간
 }
 
+export const CURRENT_DATE_STORAGE_KEY = 'my-commit:current-date';
+
+export const loadCurrentDateFromStorage = (): string | null => {
+  const storedDate = localStorage.getItem(CURRENT_DATE_STORAGE_KEY);
+
+  if (!storedDate || !isValidDateString(storedDate)) {
+    return null;
+  }
+
+  return storedDate;
+};
+
+export const saveCurrentDateToStorage = (date: string): void => {
+  if (!isValidDateString(date)) {
+    localStorage.removeItem(CURRENT_DATE_STORAGE_KEY);
+    return;
+  }
+
+  localStorage.setItem(CURRENT_DATE_STORAGE_KEY, date);
+};
+
 export const loadFromStorage = (key: string): LocalLogData => {
   const stored = localStorage.getItem(key);
   if (!stored) {
@@ -99,8 +121,6 @@ export const saveToStorage = (
 // Re-export LocalStorageManager from its new location
 export { LocalStorageManager } from './LocalStorageManager';
 
-const LOG_DATE_REGEX = /^\d{4}-\d{2}-\d{2}$/;
-
 /**
  * localStorage에서 모든 로그 데이터(날짜 키)를 삭제합니다.
  * 설정 및 기타 데이터는 유지됩니다.
@@ -110,7 +130,7 @@ export const clearAllLogData = (): void => {
 
   for (let i = 0; i < localStorage.length; i++) {
     const key = localStorage.key(i);
-    if (key && LOG_DATE_REGEX.test(key)) {
+    if (key && isValidDateString(key)) {
       keysToDelete.push(key);
     }
   }