diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..f2cc609
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,2 @@
+*.bat text eol=crlf
+*.ps1 text eol=crlf
diff --git a/docs/development-log.md b/docs/development-log.md
index af5c40a..2130e01 100644
--- a/docs/development-log.md
+++ b/docs/development-log.md
@@ -1428,3 +1428,9 @@ This is the append-only implementation and handoff record shared by Codex and Cl
   in the way are stashed, never deleted; `master` is moved to the same commit.
 - Verification: run three times against a throwaway clone (files in the way, already up to
   date, uncommitted change). Not run against the main folder, which is the owner's to run.
+- Correction, same day: the first version failed when the owner ran it. Its Korean text was read
+  by `cmd` as commands, and the files it stashed were still in the folder afterwards, so the
+  merge was refused. Why the stash left them there was not found; it did not happen in a copy.
+  The logic now lives in `tools/sync-main-folder.ps1` (UTF-8 with a byte order mark), moves the
+  files in the way into `.git/sync-backup/` itself, and the batch file is plain ASCII. Run four
+  ways against a throwaway clone, including a Korean file name, from a code page 949 console.
diff --git a/tools/sync-main-folder.bat b/tools/sync-main-folder.bat
index 46f5e99..0f9ae0c 100644
--- a/tools/sync-main-folder.bat
+++ b/tools/sync-main-folder.bat
@@ -3,101 +3,14 @@ rem Brings the main folder up to the branch the work is done on (TASK-062).
 rem
 rem   sync-main-folder.bat [branch] [folder]
 rem
-rem It only ever moves forward (fast-forward). It never discards a change: if files in the main
-rem folder are in the way, they are put in a stash, and the stash is named on screen.
-chcp 65001 >nul
-setlocal EnableExtensions
-
-set "BRANCH=claude/app-features-purpose-c45235"
-set "MAIN=D:\Android\UBGitea"
-if not "%~1"=="" set "BRANCH=%~1"
-if not "%~2"=="" set "MAIN=%~2"
-set "STASHED="
-
-echo.
-echo  메인 폴더 동기화
-echo    폴더   : %MAIN%
-echo    가져올 작업 : %BRANCH%
-echo.
-
-where git >nul 2>nul
-if errorlevel 1 (
-    echo [중단] git 을 찾을 수 없습니다. Git 이 설치되어 있는지 확인해 주세요.
-    goto :fail
-)
-if not exist "%MAIN%\.git" (
-    echo [중단] %MAIN% 은 Git 저장소가 아닙니다.
-    goto :fail
-)
-git -C "%MAIN%" rev-parse --verify --quiet "%BRANCH%" >nul
-if errorlevel 1 (
-    echo [중단] %BRANCH% 브랜치가 없습니다.
-    goto :fail
-)
-
-rem A change to a tracked file is someone's work in progress. It is not touched.
-git -C "%MAIN%" diff --quiet
-if errorlevel 1 goto :dirty
-git -C "%MAIN%" diff --cached --quiet
-if errorlevel 1 goto :dirty
-
-echo [1/3] 최신 작업으로 이동합니다.
-git -C "%MAIN%" merge --ff-only "%BRANCH%" >nul 2>nul
-if not errorlevel 1 goto :merged
-
-rem The usual reason: a file that the branch now tracks already lies in the folder, untracked.
-echo       폴더에 있던 파일이 길을 막고 있어 임시 보관한 뒤 다시 시도합니다.
-set "STASHED=main-folder-before-sync-%DATE%-%TIME%"
-git -C "%MAIN%" stash push -u -m "%STASHED%" >nul
-if errorlevel 1 (
-    echo [중단] 임시 보관에 실패했습니다.
-    set "STASHED="
-    goto :fail
-)
-git -C "%MAIN%" merge --ff-only "%BRANCH%"
-if errorlevel 1 (
-    echo.
-    echo [중단] 앞으로만 이동하는 방식으로는 합칠 수 없습니다.
-    echo        메인 폴더에 이 작업에 없는 커밋이 있는 경우입니다. 아무것도 바뀌지 않았습니다.
-    goto :fail
-)
-
-:merged
-echo [2/3] master 를 같은 위치로 맞춥니다.
-for /f "delims=" %%b in ('git -C "%MAIN%" branch --show-current') do set "CURRENT=%%b"
-if /i "%CURRENT%"=="master" (
-    echo       지금 master 에 있으므로 이미 맞춰졌습니다.
-) else (
-    git -C "%MAIN%" branch -f master "%BRANCH%" >nul 2>nul
-    if errorlevel 1 echo       [주의] master 를 옮기지 못했습니다. 다른 폴더에서 master 를 열어 둔 경우입니다.
-)
-
-echo [3/3] 결과
-git -C "%MAIN%" log --oneline -3
-echo.
-if defined STASHED (
-    echo  임시 보관한 파일이 있습니다: "%STASHED%"
-    echo  최신 버전이 이미 들어 있으므로 보통은 꺼낼 필요가 없습니다.
-    echo  목록 보기: git -C "%MAIN%" stash list
-    echo.
-)
-echo  완료되었습니다.
-echo.
+rem The work is done by sync-main-folder.ps1, next to this file. This file has no text other than
+rem plain ASCII on purpose: cmd reads a batch file in the system's code page, and Korean text in
+rem it was read as commands.
+setlocal
+set "ARGS="
+if not "%~1"=="" set ARGS=-Branch "%~1"
+if not "%~2"=="" set ARGS=%ARGS% -Main "%~2"
+powershell -NoProfile -ExecutionPolicy Bypass -File "%~dp0sync-main-folder.ps1" %ARGS%
+set "RESULT=%ERRORLEVEL%"
 pause
-exit /b 0
-
-:dirty
-echo [중단] 메인 폴더에 저장하지 않은 수정이 있습니다. 아무것도 바꾸지 않았습니다.
-echo        아래 파일을 커밋하거나 되돌린 뒤 다시 실행해 주세요.
-echo.
-git -C "%MAIN%" status --short
-
-:fail
-echo.
-if defined STASHED (
-    echo  임시 보관한 파일이 있습니다: "%STASHED%"
-    echo  되돌리기: git -C "%MAIN%" stash pop
-    echo.
-)
-pause
-exit /b 1
+exit /b %RESULT%
diff --git a/tools/sync-main-folder.ps1 b/tools/sync-main-folder.ps1
new file mode 100644
index 0000000..1563765
--- /dev/null
+++ b/tools/sync-main-folder.ps1
@@ -0,0 +1,123 @@
+# Brings the main folder up to the branch the work is done on (TASK-062).
+# Run it through sync-main-folder.bat.
+#
+# It only ever moves forward (fast-forward), and it never deletes: a file that is in the way is
+# moved into .git\sync-backup\<time>\ and the place is named on screen.
+#
+# This file is saved as UTF-8 with a byte order mark. Windows PowerShell reads a script without
+# one in the system's own code page, and the Korean messages would come out garbled.
+param(
+    [string]$Branch = 'claude/app-features-purpose-c45235',
+    [string]$Main = 'D:\Android\UBGitea'
+)
+
+$ErrorActionPreference = 'Continue'
+# File names come from git as UTF-8; without this a Korean file name is not found again.
+[Console]::OutputEncoding = [System.Text.Encoding]::UTF8
+
+function Stop-Sync([string]$message) {
+    Write-Host ''
+    Write-Host "[중단] $message" -ForegroundColor Yellow
+    Write-Host ''
+    exit 1
+}
+
+function Invoke-Git {
+    # Quietly: what matters to the caller is whether it worked.
+    & git -C $Main -c core.quotepath=false @args 2>$null
+}
+
+Write-Host ''
+Write-Host ' 메인 폴더 동기화'
+Write-Host "   대상 폴더   : $Main"
+Write-Host "   가져올 작업 : $Branch"
+Write-Host ''
+
+if (-not (Get-Command git -ErrorAction SilentlyContinue)) { Stop-Sync 'git 을 찾을 수 없습니다. Git 이 설치되어 있는지 확인해 주세요.' }
+if (-not (Test-Path (Join-Path $Main '.git'))) { Stop-Sync "$Main 은 Git 저장소가 아닙니다." }
+Invoke-Git rev-parse --verify --quiet "$Branch^{commit}" | Out-Null
+if ($LASTEXITCODE -ne 0) { Stop-Sync "$Branch 브랜치가 없습니다." }
+
+# A change to a tracked file is someone's work in progress. It is not touched.
+Invoke-Git diff --quiet
+$changed = $LASTEXITCODE -ne 0
+Invoke-Git diff --cached --quiet
+if ($changed -or $LASTEXITCODE -ne 0) {
+    Write-Host '[중단] 메인 폴더에 저장하지 않은 수정이 있습니다. 아무것도 바꾸지 않았습니다.' -ForegroundColor Yellow
+    Write-Host '       아래 파일을 커밋하거나 되돌린 뒤 다시 실행해 주세요.'
+    Write-Host ''
+    Invoke-Git status --short --untracked-files=no
+    Write-Host ''
+    exit 1
+}
+
+# Moving forward is only possible from a commit the branch already contains.
+Invoke-Git merge-base --is-ancestor HEAD $Branch
+if ($LASTEXITCODE -ne 0) {
+    Stop-Sync '메인 폴더에 이 작업에 없는 커밋이 있어, 앞으로만 이동하는 방식으로는 합칠 수 없습니다. 아무것도 바뀌지 않았습니다.'
+}
+
+# A file lying in the folder, unknown to git, that the branch has a file of its own for. Git will
+# not write over it, rightly; so it is moved aside first.
+$blocking = @(Invoke-Git ls-files --others --exclude-standard | Where-Object {
+    Invoke-Git cat-file -e "${Branch}:$_"
+    $LASTEXITCODE -eq 0
+})
+$backup = $null
+if ($blocking.Count -gt 0) {
+    $backup = Join-Path $Main (Join-Path '.git\sync-backup' (Get-Date -Format 'yyyyMMdd-HHmmss'))
+    Write-Host "[1/3] 길을 막는 파일 $($blocking.Count)개를 옮겨 둡니다."
+    $moved = @()
+    foreach ($path in $blocking) {
+        $from = Join-Path $Main $path
+        $to = Join-Path $backup $path
+        try {
+            New-Item -ItemType Directory -Force -Path (Split-Path $to) -ErrorAction Stop | Out-Null
+            Move-Item -LiteralPath $from -Destination $to -ErrorAction Stop
+            $moved += $path
+            Write-Host "        $path"
+        } catch {
+            # All or nothing: put back what was already moved.
+            foreach ($done in $moved) {
+                Move-Item -LiteralPath (Join-Path $backup $done) -Destination (Join-Path $Main $done) -ErrorAction SilentlyContinue
+            }
+            Stop-Sync "$path 을(를) 옮길 수 없습니다. 이 파일을 연 프로그램(PowerPoint, Android Studio 등)을 닫고 다시 실행해 주세요. 아무것도 바뀌지 않았습니다."
+        }
+    }
+} else {
+    Write-Host '[1/3] 길을 막는 파일이 없습니다.'
+}
+
+Write-Host '[2/3] 최신 작업으로 이동합니다.'
+$output = & git -C $Main merge --ff-only $Branch 2>&1
+if ($LASTEXITCODE -ne 0) {
+    foreach ($done in $blocking) {
+        Move-Item -LiteralPath (Join-Path $backup $done) -Destination (Join-Path $Main $done) -ErrorAction SilentlyContinue
+    }
+    $output | ForEach-Object { Write-Host "        $_" }
+    Stop-Sync '이동하지 못했습니다. 옮겨 둔 파일은 제자리로 돌려놓았습니다.'
+}
+
+$current = Invoke-Git branch --show-current
+if ($current -eq 'master') {
+    Write-Host '      지금 master 에 있으므로 master 도 함께 이동했습니다.'
+} else {
+    Invoke-Git branch -f master $Branch | Out-Null
+    if ($LASTEXITCODE -ne 0) {
+        Write-Host '      [주의] master 를 옮기지 못했습니다. 다른 폴더에서 master 를 열어 둔 경우입니다.' -ForegroundColor Yellow
+    } else {
+        Write-Host '      master 도 같은 위치로 맞췄습니다.'
+    }
+}
+
+Write-Host '[3/3] 결과'
+Invoke-Git log --oneline -3 | ForEach-Object { Write-Host "        $_" }
+Write-Host ''
+if ($backup) {
+    Write-Host " 옮겨 둔 예전 파일: $backup"
+    Write-Host ' 같은 파일의 최신 버전이 들어왔으므로 보통은 필요 없습니다.'
+    Write-Host ''
+}
+Write-Host ' 완료되었습니다.' -ForegroundColor Green
+Write-Host ''
+exit 0