diff --git a/skills/scripts/bootstrap-reverse.ps1 b/skills/scripts/bootstrap-reverse.ps1
index 757eaa1..2f176ce 100644
--- a/skills/scripts/bootstrap-reverse.ps1
+++ b/skills/scripts/bootstrap-reverse.ps1
@@ -632,8 +632,31 @@ function Set-CodexMcpServer {
     }
 
     $lines = @()
+    $writeUtf8Bom = $false
+    $newline = [Environment]::NewLine
     if (Test-Path -LiteralPath $path) {
-        $rawLines = @(Get-Content -LiteralPath $path)
+        $bytes = [System.IO.File]::ReadAllBytes($path)
+        $offset = 0
+        if ($bytes.Length -ge 3 -and $bytes[0] -eq 0xEF -and $bytes[1] -eq 0xBB -and $bytes[2] -eq 0xBF) {
+            $writeUtf8Bom = $true
+            $offset = 3
+        }
+
+        # TOML is UTF-8. Decode strictly so an unexpected legacy encoding stops
+        # the update instead of being silently converted into mojibake.
+        $strictUtf8 = [System.Text.UTF8Encoding]::new($false, $true)
+        $text = $strictUtf8.GetString($bytes, $offset, $bytes.Length - $offset)
+        $newlineMatch = [regex]::Match($text, "\r\n|\n|\r")
+        if ($newlineMatch.Success) {
+            $newline = $newlineMatch.Value
+        }
+
+        $rawLines = if ([string]::IsNullOrEmpty($text)) {
+            @()
+        }
+        else {
+            @([regex]::Split($text, "\r\n|\n|\r"))
+        }
         if ($rawLines.Count -eq 1 -and [string]::IsNullOrEmpty($rawLines[0])) {
             $lines = @()
         }
@@ -668,7 +691,12 @@ function Set-CodexMcpServer {
         }
     }
 
-    Set-Content -LiteralPath $path -Value $lines -Encoding utf8
+    $content = $lines -join $newline
+    if ($lines.Count -gt 0) {
+        $content += $newline
+    }
+    $utf8 = [System.Text.UTF8Encoding]::new($writeUtf8Bom)
+    [System.IO.File]::WriteAllText($path, $content, $utf8)
 }
 
 function Ensure-McpServer {
diff --git a/skills/scripts/smoke.ps1 b/skills/scripts/smoke.ps1
index e6aa2df..fc7fc66 100644
--- a/skills/scripts/smoke.ps1
+++ b/skills/scripts/smoke.ps1
@@ -71,7 +71,8 @@ $scripts = @(
     'append-evidence.ps1',
     'case-guard.ps1',
     'test-routing.ps1',
-    'extract-summaries.ps1'
+    'extract-summaries.ps1',
+    'test-bootstrap-codex-encoding.ps1'
 )
 $parseOk = 0
 $parseFail = 0
diff --git a/skills/scripts/test-bootstrap-codex-encoding.ps1 b/skills/scripts/test-bootstrap-codex-encoding.ps1
new file mode 100644
index 0000000..3e06173
--- /dev/null
+++ b/skills/scripts/test-bootstrap-codex-encoding.ps1
@@ -0,0 +1,111 @@
+#Requires -Version 5.1
+param(
+    [string]$ScratchDir = ''
+)
+
+$ErrorActionPreference = 'Stop'
+$scriptDir = $PSScriptRoot
+if ([string]::IsNullOrWhiteSpace($ScratchDir)) {
+    $ScratchDir = Join-Path ([System.IO.Path]::GetTempPath()) ('reverse-skill-codex-encoding-' + [guid]::NewGuid().ToString('N'))
+}
+New-Item -ItemType Directory -Path $ScratchDir -Force | Out-Null
+
+. (Join-Path $scriptDir 'lib\ToolDiscovery.ps1')
+
+# Load only the functions under test; do not execute bootstrap installation code.
+$bootstrapPath = Join-Path $scriptDir 'bootstrap-reverse.ps1'
+$tokens = $null
+$errors = $null
+$ast = [System.Management.Automation.Language.Parser]::ParseFile($bootstrapPath, [ref]$tokens, [ref]$errors)
+if ($errors.Count -gt 0) {
+    throw "bootstrap-reverse.ps1 parse failed: $($errors[0].Message)"
+}
+foreach ($name in @('ConvertTo-TomlLiteral', 'Remove-CodexMcpServerBlocks', 'Set-CodexMcpServer')) {
+    $functionAst = $ast.Find({
+        param($node)
+        $node -is [System.Management.Automation.Language.FunctionDefinitionAst] -and $node.Name -eq $name
+    }, $true)
+    if ($null -eq $functionAst) {
+        throw "Function not found: $name"
+    }
+    Invoke-Expression $functionAst.Extent.Text
+}
+
+function Assert-True {
+    param([bool]$Condition, [string]$Message)
+    if (-not $Condition) {
+        throw "ASSERTION FAILED: $Message"
+    }
+    Write-Host "[OK] $Message" -ForegroundColor Green
+}
+
+function Test-CodexConfigRoundTrip {
+    param(
+        [string]$Name,
+        [bool]$WithBom,
+        [string]$Newline
+    )
+
+    $path = Join-Path $ScratchDir "$Name.toml"
+    $original = @(
+        "[projects.'e:\codex目录\blender脚本管理器']",
+        'trust_level = "trusted"',
+        '',
+        '[mcp_servers.existing]',
+        'command = "existing"'
+    ) -join $Newline
+    $original += $Newline
+    [System.IO.File]::WriteAllText($path, $original, [System.Text.UTF8Encoding]::new($WithBom))
+
+    $oldConfigPath = $env:CODEX_CONFIG_PATH
+    try {
+        $env:CODEX_CONFIG_PATH = $path
+        Set-CodexMcpServer -ServerName 'encoding-test' -ServerDefinition @{
+            type = 'stdio'
+            command = 'cmd'
+            args = @('/c', 'echo', '中文参数')
+        }
+    }
+    finally {
+        $env:CODEX_CONFIG_PATH = $oldConfigPath
+    }
+
+    $bytes = [System.IO.File]::ReadAllBytes($path)
+    $hasBom = $bytes.Length -ge 3 -and $bytes[0] -eq 0xEF -and $bytes[1] -eq 0xBB -and $bytes[2] -eq 0xBF
+    Assert-True ($hasBom -eq $WithBom) "$Name preserves UTF-8 BOM state"
+
+    $text = [System.Text.Encoding]::UTF8.GetString($bytes)
+    if ($text.Length -gt 0 -and $text[0] -eq [char]0xFEFF) {
+        $text = $text.Substring(1)
+    }
+    Assert-True ($text.Contains("[projects.'e:\codex目录\blender脚本管理器']")) "$Name preserves Chinese TOML path and closing quote"
+    Assert-True ($text.Contains('[mcp_servers.encoding-test]')) "$Name adds MCP server"
+    Assert-True ($text.Contains('中文参数')) "$Name preserves new Chinese values"
+    if ($Newline -eq "`r`n") {
+        Assert-True (-not ($text -replace "`r`n", '').Contains("`n")) "$Name preserves CRLF newlines"
+    }
+}
+
+Test-CodexConfigRoundTrip -Name 'utf8-no-bom-crlf' -WithBom $false -Newline "`r`n"
+Test-CodexConfigRoundTrip -Name 'utf8-bom-lf' -WithBom $true -Newline "`n"
+
+$invalidPath = Join-Path $ScratchDir 'invalid-utf8.toml'
+[System.IO.File]::WriteAllBytes($invalidPath, [byte[]](0x5B, 0x80, 0x5D))
+$oldConfigPath = $env:CODEX_CONFIG_PATH
+$threw = $false
+try {
+    $env:CODEX_CONFIG_PATH = $invalidPath
+    Set-CodexMcpServer -ServerName 'must-not-write' -ServerDefinition @{ command = 'x' }
+}
+catch [System.Text.DecoderFallbackException] {
+    $threw = $true
+}
+finally {
+    $env:CODEX_CONFIG_PATH = $oldConfigPath
+}
+Assert-True $threw 'invalid UTF-8 fails closed instead of rewriting the file'
+$invalidBytes = [System.IO.File]::ReadAllBytes($invalidPath)
+Assert-True ($invalidBytes.Length -eq 3 -and $invalidBytes[1] -eq 0x80) 'invalid UTF-8 file remains unchanged'
+
+Write-Host 'OVERALL: ALL PASS' -ForegroundColor Green
+