From cf51a64c788250b4eabfe69f5be4009cc584254f Mon Sep 17 00:00:00 2001
From: "kihong.kim" <kihong.kim@yanolja.com>
Date: Sun, 1 Feb 2026 01:45:53 +0900
Subject: [PATCH] =?UTF-8?q?fix:=20=ED=95=A0=EC=9D=BC=20=EB=A7=88=EA=B0=90?=
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- 할일 생성/수정 시 마감일을 KST 기준 정오(12:00)로 정규화
- 클라이언트에서 전송된 날짜가 날짜 경계를 벗어나는 문제 해결
---
 backend/routes/todos.js | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/backend/routes/todos.js b/backend/routes/todos.js
index 8818fa0..79a54a4 100644
--- a/backend/routes/todos.js
+++ b/backend/routes/todos.js
@@ -63,9 +63,22 @@ router.get("/today", async (req, res) => {
   }
 });
 
+// Normalize dueDate to noon KST to avoid timezone boundary issues
+const normalizeDueDate = (dueDate) => {
+  if (!dueDate) return null;
+  // Parse the date and set it to noon KST
+  const date = DateTime.fromISO(dueDate, { zone: KST_TIMEZONE });
+  // Set to noon (12:00) of that day in KST
+  return date.set({ hour: 12, minute: 0, second: 0, millisecond: 0 }).toJSDate();
+};
+
 router.post("/", async (req, res) => {
   try {
-    const todo = await Todo.create(req.body);
+    const todoData = { ...req.body };
+    if (todoData.dueDate) {
+      todoData.dueDate = normalizeDueDate(todoData.dueDate);
+    }
+    const todo = await Todo.create(todoData);
     res.status(201).json(todo);
   } catch (error) {
     res.status(400).json({ message: "Failed to create todo" });
@@ -86,7 +99,11 @@ router.get("/:id", async (req, res) => {
 
 router.put("/:id", async (req, res) => {
   try {
-    const todo = await Todo.findByIdAndUpdate(req.params.id, req.body, { new: true });
+    const updateData = { ...req.body };
+    if (updateData.dueDate) {
+      updateData.dueDate = normalizeDueDate(updateData.dueDate);
+    }
+    const todo = await Todo.findByIdAndUpdate(req.params.id, updateData, { new: true });
     if (!todo) {
       return res.status(404).json({ message: "Todo not found" });
     }