diff --git a/Bun/.env b/Bun/.env.example
similarity index 100%
rename from Bun/.env
rename to Bun/.env.example
diff --git a/Bun/test.bat b/Bun/test.bat
index 8ceaa99..b856566 100644
--- a/Bun/test.bat
+++ b/Bun/test.bat
@@ -1,59 +1,182 @@
 @echo off
 setlocal
+set "TEST_BAT_PATH=%~f0"
+powershell -NoProfile -ExecutionPolicy Bypass -Command "$path=$env:TEST_BAT_PATH; $raw=Get-Content -Raw -LiteralPath $path; $marker='# POWERSHELL'; $start=$raw.LastIndexOf($marker); if($start -lt 0){ throw 'PowerShell marker not found' }; $ps=$raw.Substring($start + $marker.Length); Set-Location -LiteralPath (Split-Path -Parent $path); Invoke-Expression $ps"
+exit /b %ERRORLEVEL%
 
-REM FORCE_BUILD=1: rebuild the Bun image with --no-cache before running tests.
-REM FORCE_BUILD=0: reuse the existing Bun image; build only with Docker cache.
-set "FORCE_BUILD=0"
+# POWERSHELL
+$ErrorActionPreference = 'Stop'
+if (Get-Variable -Name PSNativeCommandUseErrorActionPreference -ErrorAction SilentlyContinue) {
+    $PSNativeCommandUseErrorActionPreference = $false
+}
 
-REM VERBOSE=1: print full stdout/stderr logs for every test.
-REM VERBOSE=0: print only [PASS], [NO], and reason lines; full logs stay in logs\.
-set "VERBOSE=0"
+$forceBuild = if ($env:FORCE_BUILD) { $env:FORCE_BUILD } else { '0' }
+$verbose = if ($env:VERBOSE) { $env:VERBOSE } else { '0' }
+$composeBase = @('compose', '--env-file', '.env', '-f', 'compose.yml')
 
-cd /d "%~dp0"
+function Write-TaggedLine {
+    param([string] $Line)
 
-if not exist logs mkdir logs
+    if ($Line.StartsWith('[PASS]')) {
+        Write-Host $Line -ForegroundColor Green
+    } elseif ($Line.StartsWith('[NO]') -or $Line.StartsWith('reason:')) {
+        Write-Host $Line -ForegroundColor Red
+    } elseif ($Line.StartsWith('[RUN]')) {
+        Write-Host $Line -ForegroundColor Cyan
+    } elseif ($Line.StartsWith('[INFO]')) {
+        Write-Host $Line -ForegroundColor DarkCyan
+    }
+}
 
-if "%FORCE_BUILD%"=="1" (
-  docker compose --env-file .env -f compose.yml build --no-cache >logs\build.out 2>logs\build.err
-  if errorlevel 1 (
-    call :build_failed
-    exit /b %errorlevel%
-  )
-) else (
-  docker compose --env-file .env -f compose.yml build >logs\build.out 2>logs\build.err
-  if errorlevel 1 (
-    call :build_failed
-    exit /b %errorlevel%
-  )
+function Invoke-Docker {
+    param([string[]] $Arguments)
+
+    $previousErrorActionPreference = $ErrorActionPreference
+    $ErrorActionPreference = 'Continue'
+    try {
+        $output = & docker @Arguments 2>&1
+        $code = $LASTEXITCODE
+    } finally {
+        $ErrorActionPreference = $previousErrorActionPreference
+    }
+
+    $lines = @(
+        $output | ForEach-Object {
+            if ($_ -is [System.Management.Automation.ErrorRecord]) {
+                $_.Exception.Message
+            } else {
+                $_.ToString()
+            }
+        } | Where-Object {
+            $_ -and $_ -ne 'System.Management.Automation.RemoteException'
+        }
+    )
+
+    [pscustomobject]@{
+        Code = $code
+        Lines = $lines
+    }
+}
+
+function Print-FilteredOutput {
+    param([string[]] $Lines)
+
+    foreach ($line in $Lines) {
+        if ($verbose -eq '1') {
+            Write-Host $line
+        } else {
+            Write-TaggedLine $line
+        }
+    }
+}
+
+function Print-FailureDiagnostics {
+    param([string[]] $Lines)
+
+    $hasNoLine = $Lines | Where-Object { $_.StartsWith('[NO]') } | Select-Object -First 1
+    if (-not $hasNoLine) {
+        Write-Host '--- raw docker output ---' -ForegroundColor Yellow
+        $Lines | Select-Object -Last 80 | ForEach-Object { Write-Host $_ }
+    }
+}
+
+function Build-Image {
+    Write-Host ''
+    Write-TaggedLine '[RUN] Build Bun image'
+
+    $sourceFiles = Get-ChildItem -File Dockerfile, compose.yml, .env, .env.example
+    $env:SOURCE_VERSION = ($sourceFiles | Sort-Object LastWriteTimeUtc -Descending | Select-Object -First 1).LastWriteTimeUtc.Ticks
+
+    $dockerArgs = $composeBase + @('build')
+    if ($forceBuild -eq '1') {
+        $dockerArgs += '--no-cache'
+    }
+
+    $result = Invoke-Docker $dockerArgs
+    if ($result.Code -ne 0) {
+        Write-TaggedLine '[NO] Build Bun image'
+        $result.Lines | ForEach-Object { Write-Host $_ }
+        exit $result.Code
+    }
+
+    Write-TaggedLine '[PASS] Build Bun image'
+    if ($verbose -eq '1') {
+        $result.Lines | ForEach-Object { Write-Host $_ }
+    }
+}
+
+function Run-Case {
+    param(
+        [string] $Title,
+        [string] $Script
+    )
+
+    Write-Host ''
+    Write-TaggedLine "[RUN] $Title"
+
+    $casePath = Join-Path (Get-Location) ('.test-case-{0}.sh' -f ([guid]::NewGuid().ToString('N')))
+    Set-Content -LiteralPath $casePath -Value $Script -NoNewline -Encoding Ascii
+
+    try {
+        $volumeArg = "${casePath}:/tmp/test-case.sh:ro"
+        $dockerArgs = $composeBase + @('run', '--rm', '--no-deps', '-T', '--volume', $volumeArg, 'test', 'bash', '/tmp/test-case.sh')
+        $result = Invoke-Docker $dockerArgs
+    } finally {
+        Remove-Item -LiteralPath $casePath -Force -ErrorAction SilentlyContinue
+    }
+
+    Print-FilteredOutput $result.Lines
+    if ($result.Code -ne 0) {
+        Print-FailureDiagnostics $result.Lines
+    }
+
+    return $result.Code
+}
+
+if (-not (Test-Path -LiteralPath '.env')) {
+    Write-TaggedLine '[NO] .env exists'
+    Write-TaggedLine 'reason: create Bun\.env from Bun\.env.example.'
+    exit 1
+}
+
+$tests = @(
+    @{
+        Title = 'Bun exists'
+        Script = @'
+set -euo pipefail
+bun --version >/tmp/bun-version
+echo "[PASS] bun exists ($(cat /tmp/bun-version))"
+'@
+    }
+    @{
+        Title = 'Bun uses npmmirror registry'
+        Script = @'
+set -euo pipefail
+grep -F 'registry.npmmirror.com' /root/.bunfig.toml >/dev/null
+tmpdir="$(mktemp -d)"
+cd "${tmpdir}"
+printf '%s\n' '{"name":"bun-registry-test","version":"0.0.0","private":true,"dependencies":{"is-number":"7.0.0"}}' > package.json
+bun install --lockfile-only >/tmp/bun-install.out 2>/tmp/bun-install.err
+echo '[PASS] bun install uses npmmirror registry'
+'@
+    }
 )
 
-docker compose --env-file .env -f compose.yml run --rm --no-deps test bun --version >logs\bun-exists.out 2>logs\bun-exists.err
-set "BUN_EXISTS_CODE=%errorlevel%"
-if "%BUN_EXISTS_CODE%"=="0" (
-  call :pass "bun exists"
-) else (
-  call :no "bun exists" logs\bun-exists.err
-)
+Build-Image
 
-docker compose --env-file .env -f compose.yml run --rm --no-deps test bash -lc "grep -F registry.npmmirror.com /root/.bunfig.toml && tmpdir=$(mktemp -d) && cd $tmpdir && printf '{\"name\":\"bun-registry-test\",\"version\":\"0.0.0\",\"private\":true,\"dependencies\":{\"is-number\":\"7.0.0\"}}\n' > package.json && bun install --lockfile-only" >logs\bun-install-registry.out 2>logs\bun-install-registry.err
-set "BUN_INSTALL_REGISTRY_CODE=%errorlevel%"
-if "%BUN_INSTALL_REGISTRY_CODE%"=="0" (
-  call :pass "bun install uses npmmirror registry"
-) else (
-  call :no "bun install uses npmmirror registry" logs\bun-install-registry.err
-)
+$failed = $false
+foreach ($test in $tests) {
+    $code = Run-Case -Title $test.Title -Script $test.Script
+    if ($code -ne 0) {
+        $failed = $true
+    }
+}
 
-if not "%BUN_EXISTS_CODE%"=="0" exit /b %BUN_EXISTS_CODE%
-exit /b %BUN_INSTALL_REGISTRY_CODE%
+Write-Host ''
+if ($failed) {
+    Write-TaggedLine '[NO] one or more tests failed'
+    exit 1
+}
 
-:pass
-powershell -NoProfile -ExecutionPolicy Bypass -Command "Write-Host '[PASS] %~1' -ForegroundColor Green"
-exit /b 0
-
-:no
-powershell -NoProfile -ExecutionPolicy Bypass -Command "Write-Host '[NO] %~1' -ForegroundColor Red; $reason=(Get-Content -LiteralPath '%~2' -ErrorAction SilentlyContinue | Where-Object { $_ } | Select-Object -Last 1); if(!$reason){ $reason='see logs for details' }; Write-Host ('reason: ' + $reason) -ForegroundColor Red"
-exit /b 0
-
-:build_failed
-powershell -NoProfile -ExecutionPolicy Bypass -Command "Write-Host '[NO] build Bun image' -ForegroundColor Red; $reason=(Get-Content -LiteralPath 'logs\build.err' -ErrorAction SilentlyContinue | Where-Object { $_ } | Select-Object -Last 1); if(!$reason){ $reason='docker compose build failed; see Bun\logs\build.err' }; Write-Host ('reason: ' + $reason) -ForegroundColor Red"
-exit /b 0
+Write-TaggedLine '[PASS] all tests passed'
+exit 0