fix: .bat files had Unix-style /dev/null; add CI lint

The previous .bat rewrite accidentally contained '>/dev/null' which
cmd.exe treats as a literal file path ('dev\null'), so start.bat
would create bogus files instead of suppressing output — it was still
broken on Windows.

- Rewrite start.bat/stop.bat with '1>/dev/null 2>&1' + CRLF line endings.
- Add a Windows CI lint step that rejects any .bat containing
  non-ASCII bytes, LF-only line endings, or '/dev/null'.
- Add an end-to-end 'Run start.bat' CI step so future bat regressions
  fail in CI instead of on a real Windows box.

Author: ouyyyyang

.github/workflows/windows-smoke.yml

@@ -26,6 +26,63 @@ jobs:
         shell: pwsh
         run: npm ci
 
+      - name: Lint .bat launchers
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = "Stop"
+          $bats = @("start.bat", "stop.bat")
+          $failed = $false
+          foreach ($bat in $bats) {
+            $bytes = [System.IO.File]::ReadAllBytes($bat)
+            $text  = [System.Text.Encoding]::ASCII.GetString($bytes)
+
+            # 1. Pure ASCII (no UTF-8 multi-byte sequences that would
+            #    be misread under Chinese Windows code page 936).
+            foreach ($b in $bytes) {
+              if ($b -gt 0x7f) {
+                Write-Error "$bat contains non-ASCII byte 0x$("{0:X2}" -f $b) — cmd.exe on zh-CN will fail to parse it"
+                $failed = $true
+                break
+              }
+            }
+
+            # 2. CRLF line endings — LF-only .bat files misbehave on some
+            #    cmd.exe versions.
+            if ($text -notmatch "`r`n") {
+              Write-Error "$bat has no CRLF line endings"
+              $failed = $true
+            }
+
+            # 3. No Unix-style /dev/null redirection — cmd.exe would create
+            #    an actual file named 'null' under a 'dev' directory.
+            if ($text -match "/dev/null") {
+              Write-Error "$bat contains Unix-style '/dev/null' — use 'NUL' instead"
+              $failed = $true
+            }
+          }
+          if ($failed) { exit 1 }
+          Write-Host "All .bat files passed ASCII / CRLF / NUL lint."
+
+      - name: Run start.bat end-to-end
+        shell: cmd
+        run: |
+          start.bat
+
+      - name: Stop agent started by start.bat
+        shell: pwsh
+        run: |
+          $pidFile = "runtime/agent/agent.pid"
+          if (Test-Path $pidFile) {
+            $agentPid = (Get-Content $pidFile -Raw).Trim()
+            try {
+              Stop-Process -Id $agentPid -Force -ErrorAction Stop
+              Write-Host "Stopped start.bat agent PID $agentPid"
+            } catch {
+              Write-Host "start.bat agent PID $agentPid already gone"
+            }
+            Remove-Item -Force -ErrorAction SilentlyContinue $pidFile, "runtime/agent/agent.port"
+          }
+
       - name: Start agent via start-local-agent.ps1 (foreground)
         shell: pwsh
         run: |

start.bat

@@ -4,7 +4,7 @@
 
 cd /d "%~dp0"
 
-where pwsh >/dev/null 2>&1
+where pwsh 1>NUL 2>&1
 if %errorlevel% equ 0 (
     pwsh -NoProfile -ExecutionPolicy Bypass -File "%~dp0scripts\dev\start-local-agent.ps1"
 ) else (
@@ -14,5 +14,5 @@ if %errorlevel% equ 0 (
 if %errorlevel% neq 0 (
     echo.
     echo Something went wrong. Press any key to close...
-    pause >/dev/null
+    pause 1>NUL
 )

stop.bat

@@ -3,7 +3,7 @@
 
 cd /d "%~dp0"
 
-where pwsh >/dev/null 2>&1
+where pwsh 1>NUL 2>&1
 if %errorlevel% equ 0 (
     pwsh -NoProfile -ExecutionPolicy Bypass -File "%~dp0scripts\dev\stop-local-agent.ps1"
 ) else (
@@ -13,5 +13,5 @@ if %errorlevel% equ 0 (
 if %errorlevel% neq 0 (
     echo.
     echo Press any key to close...
-    pause >/dev/null
+    pause 1>NUL
 )