diff --git a/.github/scripts/Publish-BootstrapScripts.ps1 b/.github/scripts/Publish-BootstrapScripts.ps1
index 6c1b1a6f..a8c9b624 100644
--- a/.github/scripts/Publish-BootstrapScripts.ps1
+++ b/.github/scripts/Publish-BootstrapScripts.ps1
@@ -16,20 +16,30 @@
     enrolling device, so "current" is a correctness property, not cosmetics.
 
     Steps, in order:
-      1. Parse $ScriptVersion from the bootstrap source.
-      2. Render the -Dev variant by literal substitution of the two URL/manifest
+      1. Parse $ScriptVersion from the loader and the bootstrap source.
+      2. Render the -Dev variants by literal substitution of the URL/manifest
          defaults. A missing anchor is a hard failure -- a silently un-substituted
          dev script would point the dev fleet at the stable agent.
-      3. Version-bump guard: if the published bootstrap differs from the source
-         but carries the same $ScriptVersion, abort. Otherwise the docs badge,
+      3. Version-bump guard: if a published script differs from its source but
+         carries the same $ScriptVersion, abort. Otherwise the docs badge,
          version.json.bootstrapVersion and the portal's "your script is outdated"
          hint would all keep asserting a version that is no longer what ships.
-      4. Upload every script blob with Cache-Control: no-cache (they rotate in
+      4. Build the publish set (loader, bootstrap, both dev renders, the extras).
+      5. Authenticode-sign every script (see -SigningToken). Signing is the LAST
+         transformation: it covers the exact CRLF/UTF-8 bytes that get uploaded,
+         and nothing may touch them afterwards or the signature breaks.
+      6. Upload every script blob with Cache-Control: no-cache (they rotate in
          place), mirrored fail-soft to the legacy account.
-      5. Reconcile the two version oracles: version.json.bootstrapVersion
-         (read-modify-write under If-Match, so a concurrent agent release cannot
-         lose its agent fields) and AdminConfiguration.LatestBootstrapV2ScriptVersion.
-      6. Verify through the alias -- re-download each blob and compare SHA-256.
+      7. Reconcile the version oracles: version.json.bootstrapVersion and
+         .loaderVersion (read-modify-write under If-Match, so a concurrent agent
+         release cannot lose its agent fields) and
+         AdminConfiguration.LatestBootstrapV2ScriptVersion.
+      8. Verify through the alias -- re-download each blob and compare SHA-256.
+
+    Comparisons against a published script always strip its signature block first
+    (Get-ComparableText). A signature carries a timestamp, so signed bytes differ on
+    every run; without stripping, the bump guard and the drift check would report a
+    change for every unchanged script.
 
 .PARAMETER LegacySasToken
     Container SAS for the legacy account. Optional -- a mirror failure warns, never fails.
@@ -40,18 +50,39 @@
     Repository root. Defaults to the parent of .github/scripts.
 
 .PARAMETER DryRun
-    Run every check and render, upload nothing.
+    Run every check and render, upload nothing. A dry run signs when a token is supplied
+    and skips signing when it is not: the PR gate runs this without any Azure login.
+
+.PARAMETER SigningToken
+    Azure Key Vault access token for AzureSignTool. MANDATORY for a real publish -- an
+    unsigned customer script is not something this repo publishes. Together with
+    -KeyVaultUrl and -CertificateName.
+
+.PARAMETER ExpectedPublisher
+    Optional -like pattern the signer subject must match after signing. Pins the publisher
+    instead of accepting any trusted signature; the loader on the device pins the same way.
+
+.PARAMETER SignedOutputDir
+    Optional directory that receives a copy of every published file exactly as uploaded.
+    Used by CI to offer the signed scripts as a build artifact for local inspection.
 
 .EXAMPLE
     ./Publish-BootstrapScripts.ps1 -DryRun
 
 .EXAMPLE
-    ./Publish-BootstrapScripts.ps1 -LegacySasToken $env:LEGACY_SAS
+    ./Publish-BootstrapScripts.ps1 -LegacySasToken $env:LEGACY_SAS -SigningToken $env:AKV_TOKEN `
+        -KeyVaultUrl $env:KV_URL -CertificateName $env:CERT
 #>
 [CmdletBinding()]
 param(
     [string]$LegacySasToken,
     [string]$RepoRoot,
+    [string]$SigningToken,
+    [string]$KeyVaultUrl,
+    [string]$CertificateName,
+    [string]$TimestampUrl = 'http://timestamp.acs.microsoft.com',
+    [string]$ExpectedPublisher,
+    [string]$SignedOutputDir,
     [switch]$DryRun
 )
 
@@ -69,8 +100,23 @@ $TableUrl           = "https://autopilotmonitoreu.table.core.windows.net/AdminCo
 $BootstrapSource   = Join-Path $RepoRoot 'scripts/Bootstrap/Install-AutopilotMonitor.ps1'
 $BootstrapBlob     = 'Install-AutopilotMonitor.ps1'
 $DevBlob           = 'Install-AutopilotMonitor-Dev.ps1'
+# Stage 1. What a customer assigns in Intune once; it downloads the bootstrap above on
+# every device and verifies its publisher before running it.
+$LoaderSource      = Join-Path $RepoRoot 'scripts/Bootstrap/Start-AutopilotMonitor.ps1'
+$LoaderBlob        = 'Start-AutopilotMonitor.ps1'
+$LoaderDevBlob     = 'Start-AutopilotMonitor-Dev.ps1'
 $ScriptContentType = 'text/plain; charset=utf-8'
 
+$SigningEnabled = -not [string]::IsNullOrWhiteSpace($SigningToken)
+if (-not $DryRun -and -not $SigningEnabled) {
+    throw ('Publishing requires -SigningToken (plus -KeyVaultUrl and -CertificateName): the ' +
+           'loader on every device verifies the publisher of what it downloads, so an unsigned ' +
+           'script would be rejected in the field. Only -DryRun may run without signing.')
+}
+if ($SigningEnabled -and ([string]::IsNullOrWhiteSpace($KeyVaultUrl) -or [string]::IsNullOrWhiteSpace($CertificateName))) {
+    throw '-SigningToken needs -KeyVaultUrl and -CertificateName.'
+}
+
 function Get-HttpStatus {
     param($ErrorRecord)
     if ($ErrorRecord.Exception.PSObject.Properties['Response'] -and $ErrorRecord.Exception.Response) {
@@ -116,6 +162,122 @@ function Get-PublishBytes {
     return ,(New-Object System.Text.UTF8Encoding $false).GetBytes($normalised)
 }
 
+# A PowerShell signature is appended as a comment block at the end of the file, so the
+# published bytes are "source + signature". Everything that compares a published script to
+# its source has to cut that block off first -- the signature carries a timestamp and is
+# therefore different on every publish, while the script above it is unchanged.
+function Remove-SignatureBlock {
+    param([string]$Text)
+    $marker = '# SIG # Begin signature block'
+    $index = $Text.IndexOf($marker)
+    if ($index -lt 0) { return $Text }
+    return $Text.Substring(0, $index)
+}
+
+# Comparison form: no signature, LF, no trailing blank lines. Used for "is the published
+# copy still this source" -- never for what gets uploaded.
+function Get-ComparableText {
+    param([string]$Text)
+    return (Remove-SignatureBlock $Text).Replace("`r`n", "`n").TrimEnd("`n")
+}
+
+# Signs the publish set in place: each item's bytes are written to a work directory, signed
+# there, verified, and read back as the bytes that will be uploaded. Signing has to be the
+# last transformation -- the signature covers exactly these bytes, so nothing may normalise
+# or re-encode them afterwards.
+function Set-PublishSetSignature {
+    param([object[]]$Items, [string]$WorkDir)
+
+    if (-not (Get-Command azuresigntool -ErrorAction SilentlyContinue)) {
+        throw "azuresigntool is not on PATH. Install it with: dotnet tool install --global AzureSignTool --version 7.0.1"
+    }
+
+    New-Item -ItemType Directory -Force -Path $WorkDir | Out-Null
+
+    $paths = @()
+    foreach ($item in $Items) {
+        $path = Join-Path $WorkDir $item.BlobName
+        [System.IO.File]::WriteAllBytes($path, [byte[]]$item.Bytes)
+        $paths += $path
+    }
+
+    Write-Host "Signing $($paths.Count) script(s) with certificate '$CertificateName'..."
+    & azuresigntool.exe sign --verbose `
+        --azure-key-vault-url $KeyVaultUrl `
+        --azure-key-vault-accesstoken $SigningToken `
+        --azure-key-vault-certificate $CertificateName `
+        --timestamp-rfc3161 $TimestampUrl `
+        --file-digest sha256 `
+        --description 'Autopilot Monitor bootstrap' `
+        --description-url 'https://www.autopilotmonitor.com' `
+        $paths
+
+    # Native tool: PowerShell does not throw on a non-zero exit, and an unnoticed signing
+    # failure would publish unsigned scripts that every loader in the field then rejects.
+    if ($LASTEXITCODE -ne 0) {
+        throw "azuresigntool failed with exit code $LASTEXITCODE -- nothing was uploaded."
+    }
+
+    foreach ($item in $Items) {
+        $path = Join-Path $WorkDir $item.BlobName
+        $sig = Get-AuthenticodeSignature -FilePath $path
+        if ($sig.Status -ne 'Valid') {
+            throw "Signature on $($item.BlobName) is '$($sig.Status)', expected 'Valid'."
+        }
+        # Without a timestamp the signature dies with the certificate, and these scripts sit
+        # on customer devices far longer than a certificate lifetime.
+        if (-not $sig.TimeStamperCertificate) {
+            throw "Signature on $($item.BlobName) carries no timestamp."
+        }
+        if ($ExpectedPublisher -and $sig.SignerCertificate.Subject -notlike $ExpectedPublisher) {
+            throw "$($item.BlobName) was signed by '$($sig.SignerCertificate.Subject)', expected '$ExpectedPublisher'."
+        }
+        $item.Bytes = ,([System.IO.File]::ReadAllBytes($path))
+        Write-Host "  signed $($item.BlobName) ($($item.Bytes.Length) bytes, signer $($sig.SignerCertificate.Subject.Split(',')[0]))"
+    }
+}
+
+# Aborts when a published script changed behaviour without a version bump. Consumers act on
+# the version (docs badge, version.json, the portal's outdated-script hint), so an unchanged
+# version has to mean unchanged behaviour.
+function Assert-VersionBump {
+    param(
+        [string]$BlobName,
+        [string]$SourceContent,
+        [string]$SourceOrigin,
+        [string]$SourceVersion
+    )
+
+    $publishedBytes = Get-PublishedBytes "$AliasUrl/$BlobName"
+    if ($null -eq $publishedBytes) {
+        Write-Host "No published $BlobName yet -- version-bump guard skipped (first publish)"
+        return
+    }
+
+    $publishedText = [System.Text.Encoding]::UTF8.GetString($publishedBytes)
+    if ((Get-ComparableText $publishedText) -eq (Get-ComparableText $SourceContent)) {
+        Write-Host "Published $BlobName is already this source (signature block aside)"
+        return
+    }
+
+    $publishedVersion = Get-BootstrapScriptVersion -Content $publishedText -Origin "$AliasUrl/$BlobName" -Optional
+
+    if ($null -eq $publishedVersion) {
+        Write-Host "::warning::The published $BlobName is not a readable script (no ScriptVersion found). Republishing over it."
+    } elseif ($publishedVersion -ne $SourceVersion) {
+        Write-Host "Version bump: $publishedVersion -> $SourceVersion ($BlobName)"
+    } elseif ((Get-CodeFingerprint -Text (Remove-SignatureBlock $publishedText) -Origin "$AliasUrl/$BlobName") -eq
+              (Get-CodeFingerprint -Text $SourceContent -Origin $SourceOrigin)) {
+        # Comments, typos in comments, reflow -- nothing a consumer of the version can act on.
+        Write-Host "::warning::$BlobName changed in comments or formatting only; publishing under the unchanged version $SourceVersion."
+    } else {
+        throw ("Version-bump guard: $BlobName changed behaviour but ScriptVersion is still $SourceVersion. " +
+               "Bump it in $SourceOrigin -- the docs badge, version.json and the " +
+               'portal outdated-script hint all read that value, and customers decide from it whether ' +
+               'to re-upload their Intune copy. Comment-only and formatting changes do not need a bump.')
+    }
+}
+
 function Get-BootstrapScriptVersion {
     param([string]$Content, [string]$Origin, [switch]$Optional)
     if ($Content -match '\$ScriptVersion\s*=\s*"([\d\.\-a-zA-Z]+)"') { return $Matches[1] }
@@ -143,12 +305,16 @@ function Get-CodeFingerprint {
     return (($tokens | Where-Object { $ignored -notcontains $_.Kind.ToString() } | ForEach-Object { $_.Text }) -join "`n")
 }
 
-# ------------------------------------------------------------------ 1. source
+# ------------------------------------------------------------------ 1. sources
 $sourceContent = Get-Content $BootstrapSource -Raw
 $sourceBytes   = Get-PublishBytes $sourceContent
 $scriptVersion = Get-BootstrapScriptVersion -Content $sourceContent -Origin $BootstrapSource
 Write-Host "Bootstrap script version: $scriptVersion"
 
+$loaderContent = Get-Content $LoaderSource -Raw
+$loaderVersion = Get-BootstrapScriptVersion -Content $loaderContent -Origin $LoaderSource
+Write-Host "Loader script version: $loaderVersion"
+
 # ------------------------------------------------------------------ 2. dev render
 $stableUrlLiteral = '$AgentDownloadUrl = "https://download.autopilotmonitor.com/agent/AutopilotMonitor-Agent.zip"'
 $devUrlLiteral    = '$AgentDownloadUrl = "https://download.autopilotmonitor.com/agent/AutopilotMonitor-Agent-dev.zip"'
@@ -161,33 +327,21 @@ if ($sourceContent.IndexOf($stableUrlLiteral) -lt 0 -or $sourceContent.IndexOf($
 $devContent = $sourceContent.Replace($stableUrlLiteral, $devUrlLiteral).Replace($stableManLiteral, $devManLiteral)
 Write-Host "Rendered $DevBlob (dev agent URL + version-dev.json)"
 
-# ------------------------------------------------------------------ 3. bump guard
-$publishedBytes = Get-PublishedBytes "$AliasUrl/$BootstrapBlob"
-if ($null -eq $publishedBytes) {
-    Write-Host 'No published bootstrap yet -- version-bump guard skipped (first publish)'
-} elseif ((Get-Sha256 $publishedBytes) -eq (Get-Sha256 $sourceBytes)) {
-    Write-Host 'Published bootstrap is already byte-identical to the source'
-} else {
-    $publishedText    = [System.Text.Encoding]::UTF8.GetString($publishedBytes)
-    $publishedVersion = Get-BootstrapScriptVersion -Content $publishedText -Origin "$AliasUrl/$BootstrapBlob" -Optional
+# The dev loader must fetch the dev bootstrap, or a dev device would run the stable chain.
+$stableLoaderLiteral = '$BootstrapUrl = "https://download.autopilotmonitor.com/agent/Install-AutopilotMonitor.ps1"'
+$devLoaderLiteral    = '$BootstrapUrl = "https://download.autopilotmonitor.com/agent/Install-AutopilotMonitor-Dev.ps1"'
 
-    if ($null -eq $publishedVersion) {
-        Write-Host "::warning::The published $BootstrapBlob is not a readable bootstrap script (no ScriptVersion found). Republishing over it."
-    } elseif ($publishedVersion -ne $scriptVersion) {
-        Write-Host "Version bump: $publishedVersion -> $scriptVersion"
-    } elseif ((Get-CodeFingerprint -Text $publishedText -Origin "$AliasUrl/$BootstrapBlob") -eq
-              (Get-CodeFingerprint -Text $sourceContent -Origin $BootstrapSource)) {
-        # Comments, typos in comments, reflow -- nothing a consumer of the version can act on.
-        Write-Host "::warning::$BootstrapBlob changed in comments or formatting only; publishing under the unchanged version $scriptVersion."
-    } else {
-        throw ("Version-bump guard: $BootstrapBlob changed behaviour but ScriptVersion is still $scriptVersion. " +
-               "Bump it in $BootstrapSource -- the docs badge, version.json.bootstrapVersion and the " +
-               'portal outdated-script hint all read that value, and customers decide from it whether ' +
-               'to re-upload their Intune copy. Comment-only and formatting changes do not need a bump.')
-    }
+if ($loaderContent.IndexOf($stableLoaderLiteral) -lt 0) {
+    throw "Loader dev-render: anchor literal missing in $LoaderSource"
 }
+$devLoaderContent = $loaderContent.Replace($stableLoaderLiteral, $devLoaderLiteral)
+Write-Host "Rendered $LoaderDevBlob (points at $DevBlob)"
 
-# ------------------------------------------------------------------ 4. upload
+# ------------------------------------------------------------------ 3. bump guards
+Assert-VersionBump -BlobName $BootstrapBlob -SourceContent $sourceContent -SourceOrigin $BootstrapSource -SourceVersion $scriptVersion
+Assert-VersionBump -BlobName $LoaderBlob    -SourceContent $loaderContent -SourceOrigin $LoaderSource    -SourceVersion $loaderVersion
+
+# ------------------------------------------------------------------ 4. publish set
 # Sources beyond the bootstrap pair, read straight from the repo.
 $extraSources = @(
     @{ Path = 'scripts/Bootstrap/Test-ShouldBootstrapAgent.ps1';       BlobName = 'Test-ShouldBootstrapAgent.ps1' }
@@ -197,15 +351,29 @@ $extraSources = @(
 # Uninstall-AutopilotMonitor.ps1 is deliberately NOT published: nothing links it, and
 # an unauthenticated uninstall script on the public download host is not a feature.
 
+# Text is the unsigned publish form and stays the reference for every comparison against a
+# published copy; Bytes is what goes on the wire and carries the signature after step 4.
 $publishSet = [System.Collections.Generic.List[object]]::new()
-$publishSet.Add([pscustomobject]@{ BlobName = $BootstrapBlob; Bytes = $sourceBytes })
-$publishSet.Add([pscustomobject]@{ BlobName = $DevBlob;       Bytes = (Get-PublishBytes $devContent) })
+$publishSet.Add([pscustomobject]@{ BlobName = $LoaderBlob;    Text = $loaderContent;    Bytes = (Get-PublishBytes $loaderContent) })
+$publishSet.Add([pscustomobject]@{ BlobName = $LoaderDevBlob; Text = $devLoaderContent; Bytes = (Get-PublishBytes $devLoaderContent) })
+$publishSet.Add([pscustomobject]@{ BlobName = $BootstrapBlob; Text = $sourceContent;    Bytes = $sourceBytes })
+$publishSet.Add([pscustomobject]@{ BlobName = $DevBlob;       Text = $devContent;       Bytes = (Get-PublishBytes $devContent) })
 foreach ($extra in $extraSources) {
     $extraPath = Join-Path $RepoRoot $extra.Path
     if (-not (Test-Path $extraPath)) {
         throw "Publish source missing: $extraPath"
     }
-    $publishSet.Add([pscustomobject]@{ BlobName = $extra.BlobName; Bytes = (Get-PublishBytes (Get-Content $extraPath -Raw)) })
+    $extraText = Get-Content $extraPath -Raw
+    $publishSet.Add([pscustomobject]@{ BlobName = $extra.BlobName; Text = $extraText; Bytes = (Get-PublishBytes $extraText) })
+}
+
+# ------------------------------------------------------------------ 5. sign
+# After this point the bytes are final. Normalising, re-encoding or rewriting a line ending
+# would invalidate the signature, and the device-side loader would refuse the script.
+if ($SigningEnabled) {
+    Set-PublishSetSignature -Items $publishSet -WorkDir (Join-Path ([System.IO.Path]::GetTempPath()) "apm-publish-$PID")
+} else {
+    Write-Host '::warning::No signing token supplied -- dry run continues with unsigned scripts.'
 }
 
 $legacySas = if ($LegacySasToken) { $LegacySasToken.TrimStart('?') } else { '' }
@@ -214,6 +382,7 @@ $legacySas = if ($LegacySasToken) { $LegacySasToken.TrimStart('?') } else { '' }
 # (bootstrap-script-gates.yml) executes this script with -DryRun and never logs in.
 $authHeaders = if ($DryRun) { $null } else { & (Join-Path $PSScriptRoot 'Get-StorageAuthHeaders.ps1') }
 
+# ------------------------------------------------------------------ 6. upload
 foreach ($item in $publishSet) {
     # Explicit type, not a convenience: an Object[] body is uploaded as space-separated
     # decimals rather than raw bytes, and every hash check still passes because [byte[]]
@@ -221,11 +390,21 @@ foreach ($item in $publishSet) {
     [byte[]]$bytes = $item.Bytes
     $item | Add-Member -NotePropertyName Sha256 -NotePropertyValue (Get-Sha256 $bytes) -Force
 
+    # Exactly the bytes that go on the wire, for the CI artifact. Written in a dry run too:
+    # that is the run an operator uses to inspect a signed script before it is published.
+    if ($SignedOutputDir) {
+        New-Item -ItemType Directory -Force -Path $SignedOutputDir | Out-Null
+        [System.IO.File]::WriteAllBytes((Join-Path $SignedOutputDir $item.BlobName), $bytes)
+    }
+
     if ($DryRun) {
-        # Doubles as a drift check: says per blob whether the alias already serves this source.
+        # Doubles as a drift check: says per blob whether the alias already serves this
+        # source. Compared as text without the signature block -- signed bytes differ on
+        # every run, so a byte comparison would report drift for every unchanged script.
         $served = Get-PublishedBytes "$AliasUrl/$($item.BlobName)"
         $state = if ($null -eq $served) { 'MISSING on the alias' }
-                 elseif ((Get-Sha256 $served) -eq $item.Sha256) { 'already current' }
+                 elseif ((Get-ComparableText ([System.Text.Encoding]::UTF8.GetString($served))) -eq
+                         (Get-ComparableText $item.Text)) { 'already current' }
                  else { 'STALE on the alias' }
         Write-Host "  [dry-run] $($item.BlobName) ($($bytes.Length) bytes, sha256 $($item.Sha256)) -- $state"
         continue
@@ -260,7 +439,7 @@ foreach ($item in $publishSet) {
     }
 }
 
-# ------------------------------------------------------------------ 5. version oracles
+# ------------------------------------------------------------------ 7. version oracles
 # version.json is the agent manifest; only bootstrapVersion belongs to us. Read from the
 # blob (not the alias) for an authoritative ETag, write back under If-Match so a concurrent
 # agent release cannot lose its version/sha256 fields.
@@ -272,11 +451,15 @@ if (-not $DryRun) {
         } else { [string]$manifestResp.Content }
         $manifest = $manifestRaw | ConvertFrom-Json
 
-        if ($manifest.bootstrapVersion -eq $scriptVersion) {
-            Write-Host "version.json already reports bootstrapVersion $scriptVersion"
+        if ($manifest.bootstrapVersion -eq $scriptVersion -and $manifest.loaderVersion -eq $loaderVersion) {
+            Write-Host "version.json already reports bootstrapVersion $scriptVersion and loaderVersion $loaderVersion"
         } else {
             $etag = '"' + ([string]($manifestResp.Headers['ETag'] | Select-Object -First 1)).Trim('"') + '"'
             $manifest | Add-Member -NotePropertyName 'bootstrapVersion' -NotePropertyValue $scriptVersion -Force
+            # Additive: no consumer reads loaderVersion yet. It exists so support can tell
+            # which stage-1 file a device was assigned -- stage 2 is always current by
+            # construction, so its version says nothing about the customer's Intune copy.
+            $manifest | Add-Member -NotePropertyName 'loaderVersion' -NotePropertyValue $loaderVersion -Force
             $body = [System.Text.Encoding]::UTF8.GetBytes(($manifest | ConvertTo-Json -Compress))
             $manifestHeaders = @{
                 'x-ms-blob-type'          = 'BlockBlob'
@@ -285,7 +468,7 @@ if (-not $DryRun) {
                 'If-Match'                = $etag
             }
             Invoke-RestMethod -Uri "$ContainerUrl/version.json" -Method Put -Headers ($authHeaders + $manifestHeaders) -Body $body | Out-Null
-            Write-Host "version.json bootstrapVersion -> $scriptVersion (agent fields untouched)"
+            Write-Host "version.json bootstrapVersion -> $scriptVersion, loaderVersion -> $loaderVersion (agent fields untouched)"
 
             if ($legacySas) {
                 try {
@@ -317,7 +500,7 @@ if ($DryRun) {
     Write-Host "AdminConfiguration.LatestBootstrapV2ScriptVersion = $scriptVersion"
 }
 
-# ------------------------------------------------------------------ 6. verify via alias
+# ------------------------------------------------------------------ 8. verify via alias
 if (-not $DryRun) {
     $pending = [System.Collections.ArrayList]::new()
     $publishSet | ForEach-Object { [void]$pending.Add($_) }
@@ -349,7 +532,8 @@ if ($env:GITHUB_STEP_SUMMARY) {
     $summary = @(
         "### Bootstrap scripts: $mode",
         '',
-        "Bootstrap script version: **$scriptVersion**",
+        "Loader script version: **$loaderVersion** | Bootstrap script version: **$scriptVersion**",
+        "Signed: **$(if ($SigningEnabled) { "yes, certificate '$CertificateName'" } else { 'NO (unsigned dry run)' })**",
         ''
     ) + ($publishSet | ForEach-Object { "- $($_.BlobName) -- sha256 $($_.Sha256)" })
     ($summary -join [Environment]::NewLine) | Out-File -FilePath $env:GITHUB_STEP_SUMMARY -Append -Encoding utf8
diff --git a/.github/workflows/build-agent.yml b/.github/workflows/build-agent.yml
index d515a725..3d3b775e 100644
--- a/.github/workflows/build-agent.yml
+++ b/.github/workflows/build-agent.yml
@@ -434,8 +434,16 @@ jobs:
             # to main, so a release lands a set that is consistent with what is already live
             # (dev render, version-bump guard, bootstrapVersion oracles, alias verification).
             # Runs AFTER version.json so its bootstrapVersion read sees this build's manifest.
+            # Same signing identity as the binaries above: the loader on every device
+            # verifies the publisher of the script it downloads, so the publisher refuses
+            # to upload unsigned scripts.
             ./.github/scripts/Publish-BootstrapScripts.ps1 `
-              -LegacySasToken '${{ secrets.AZURE_BLOB_AGENT_LEGACY_SAS_TOKEN }}'
+              -LegacySasToken '${{ secrets.AZURE_BLOB_AGENT_LEGACY_SAS_TOKEN }}' `
+              -SigningToken $env:CODE_SIGN_AKV_ACCESS_TOKEN `
+              -KeyVaultUrl $env:CODE_SIGN_KEY_VAULT_URL `
+              -CertificateName $env:CODE_SIGN_CERTIFICATE_NAME `
+              -TimestampUrl $env:CODE_SIGN_TIMESTAMP_URL `
+              -ExpectedPublisher $env:CODE_SIGN_EXPECTED_SUBJECT
           }
 
           # Update AdminConfiguration LatestAgentV2* -- ONLY on stable cutover. The hash-oracle
diff --git a/.github/workflows/publish-scripts.yml b/.github/workflows/publish-scripts.yml
index 789b841e..f964764e 100644
--- a/.github/workflows/publish-scripts.yml
+++ b/.github/workflows/publish-scripts.yml
@@ -35,6 +35,16 @@ concurrency:
   group: agent-blob-publish
   cancel-in-progress: false
 
+# Authenticode for the customer scripts. Same identity and same repository variables as
+# build-agent.yml -- the loader on every device pins this publisher, so the two must not
+# drift apart.
+env:
+  CODE_SIGN_CLIENT_ID: ${{ vars.CODE_SIGN_CLIENT_ID }}
+  CODE_SIGN_CERTIFICATE_NAME: ${{ vars.CODE_SIGN_CERTIFICATE_NAME }}
+  CODE_SIGN_KEY_VAULT_URL: ${{ vars.CODE_SIGN_KEY_VAULT_URL }}
+  CODE_SIGN_EXPECTED_SUBJECT: ${{ vars.CODE_SIGN_EXPECTED_SUBJECT }}
+  CODE_SIGN_TIMESTAMP_URL: http://timestamp.acs.microsoft.com
+
 jobs:
   gates:
     uses: ./.github/workflows/bootstrap-script-gates.yml
@@ -46,6 +56,37 @@ jobs:
     steps:
       - uses: actions/checkout@v7
 
+      - name: Check code-signing configuration
+        shell: pwsh
+        run: |
+          foreach ($name in 'CODE_SIGN_CLIENT_ID', 'CODE_SIGN_CERTIFICATE_NAME', 'CODE_SIGN_KEY_VAULT_URL') {
+            if ([string]::IsNullOrWhiteSpace([Environment]::GetEnvironmentVariable($name))) {
+              throw "Repository variable $name is not set. Published customer scripts must be signed."
+            }
+          }
+
+      # First, and only to fetch the Key Vault token: azure/login sets the default az
+      # account and the storage login below has to be the one that stays. See D-223 --
+      # both federated credentials are bound to the ref, so this job must never carry a
+      # GitHub `environment:`.
+      - name: Login to Azure (code-signing identity)
+        uses: azure/login@7ddb5af1ef8758cf1353cf3b42f940aee27ba21c # v3
+        with:
+          client-id: ${{ env.CODE_SIGN_CLIENT_ID }}
+          tenant-id: ${{ secrets.AZURE_TENANT_ID }}
+          allow-no-subscriptions: true
+
+      - name: Acquire Key Vault token for signing
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = 'Stop'
+          $token = az account get-access-token --scope https://vault.azure.net/.default --query accessToken --output tsv
+          if ($LASTEXITCODE -ne 0 -or [string]::IsNullOrWhiteSpace($token)) {
+            throw "Could not acquire a Key Vault token for the code-signing identity."
+          }
+          Write-Host "::add-mask::$token"
+          "CODE_SIGN_AKV_ACCESS_TOKEN=$token" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+
       # Authorizes the eu blob writes and the AdminConfiguration merge. The gates job above
       # runs the same publisher with -DryRun and deliberately without a login -- a dry run
       # must never need Azure credentials.
@@ -56,10 +97,38 @@ jobs:
           tenant-id: ${{ secrets.AZURE_TENANT_ID }}
           subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}
 
+      # Version pinned so a new or compromised NuGet release cannot flow into signing
+      # unreviewed; roll-forward because the tool targets an older runtime than the SDK
+      # preinstalled on the runner.
+      - name: Install AzureSignTool
+        env:
+          DOTNET_ROLL_FORWARD: LatestMajor
+        run: dotnet tool install --no-cache --global AzureSignTool --version 7.0.1
+
       - name: Publish bootstrap + customer scripts
         shell: pwsh
+        env:
+          DOTNET_ROLL_FORWARD: LatestMajor
         run: |
           $dryRun = '${{ inputs.dry_run }}' -eq 'true'
           ./.github/scripts/Publish-BootstrapScripts.ps1 `
             -LegacySasToken '${{ secrets.AZURE_BLOB_AGENT_LEGACY_SAS_TOKEN }}' `
+            -SigningToken $env:CODE_SIGN_AKV_ACCESS_TOKEN `
+            -KeyVaultUrl $env:CODE_SIGN_KEY_VAULT_URL `
+            -CertificateName $env:CODE_SIGN_CERTIFICATE_NAME `
+            -TimestampUrl $env:CODE_SIGN_TIMESTAMP_URL `
+            -ExpectedPublisher $env:CODE_SIGN_EXPECTED_SUBJECT `
+            -SignedOutputDir "$env:RUNNER_TEMP/signed-scripts" `
             -DryRun:$dryRun
+
+      # The exact bytes that were (or, on a dry run, would have been) uploaded. A dry-run
+      # dispatch is therefore the way to inspect a signed script locally before it reaches
+      # a single customer. Kept on failure too: a failed alias verification is precisely
+      # when someone wants to look at the file.
+      - name: Upload signed scripts
+        if: always()
+        uses: actions/upload-artifact@v7
+        with:
+          name: signed-scripts
+          path: ${{ runner.temp }}/signed-scripts
+          if-no-files-found: ignore
diff --git a/internal b/internal
index 702dbb53..473df395 160000
--- a/internal
+++ b/internal
@@ -1 +1 @@
-Subproject commit 702dbb53dca97d5f3e80f0a8dbd8619f273a8de5
+Subproject commit 473df39529dca56a33382c7fda905d02302e4d37
diff --git a/scripts/Bootstrap/Start-AutopilotMonitor.Tests.ps1 b/scripts/Bootstrap/Start-AutopilotMonitor.Tests.ps1
new file mode 100644
index 00000000..0c5fe59f
--- /dev/null
+++ b/scripts/Bootstrap/Start-AutopilotMonitor.Tests.ps1
@@ -0,0 +1,127 @@
+# Pester tests (Pester 5+) for the stage-1 loader Start-AutopilotMonitor.ps1.
+#
+# The script under test is dot-sourced; its entry guard prevents the loader from
+# executing, so loading it here is side-effect free. Network and signature checks
+# are mocked -- what is verified is the DECISION: what does the loader accept, what
+# does it refuse, and how often does it retry.
+#
+# Run under Windows PowerShell 5.1 to match the IME runtime:
+#   powershell.exe -NoProfile -Command "& { $c = New-PesterConfiguration; $c.Run.Path = 'scripts\Bootstrap'; $c.Output.Verbosity = 'Detailed'; Invoke-Pester -Configuration $c }"
+#
+# This file MUST remain pure ASCII (PS 5.1 reads BOM-less files as ANSI).
+
+BeforeAll {
+    . (Join-Path $PSScriptRoot 'Start-AutopilotMonitor.ps1')
+
+    function New-FakeSignature {
+        param([string]$Status, [string]$Subject)
+        $cert = if ($Subject) {
+            [pscustomobject]@{ Subject = $Subject; Thumbprint = '0123456789ABCDEF' }
+        } else { $null }
+        return [pscustomobject]@{ Status = $Status; SignerCertificate = $cert }
+    }
+}
+
+Describe 'Test-BootstrapSignature' {
+    BeforeEach {
+        Mock Write-Log { }
+    }
+
+    It 'accepts a valid signature from the expected publisher' {
+        Mock Get-AuthenticodeSignature { New-FakeSignature -Status 'Valid' -Subject 'CN=glueckkanja AG, O=glueckkanja AG, C=DE' }
+        Test-BootstrapSignature -Path 'TestDrive:\x.ps1' | Should -BeTrue
+    }
+
+    It 'refuses an unsigned script' {
+        Mock Get-AuthenticodeSignature { New-FakeSignature -Status 'NotSigned' -Subject $null }
+        Test-BootstrapSignature -Path 'TestDrive:\x.ps1' | Should -BeFalse
+    }
+
+    It 'refuses a tampered script (hash mismatch)' {
+        Mock Get-AuthenticodeSignature { New-FakeSignature -Status 'HashMismatch' -Subject 'CN=glueckkanja AG, O=glueckkanja AG, C=DE' }
+        Test-BootstrapSignature -Path 'TestDrive:\x.ps1' | Should -BeFalse
+    }
+
+    It 'refuses a signature whose chain does not validate' {
+        Mock Get-AuthenticodeSignature { New-FakeSignature -Status 'UnknownError' -Subject 'CN=glueckkanja AG, O=glueckkanja AG, C=DE' }
+        Test-BootstrapSignature -Path 'TestDrive:\x.ps1' | Should -BeFalse
+    }
+
+    # The whole point of the pinned publisher: a validly signed script from someone else
+    # is exactly what an attacker with any code-signing certificate can produce.
+    It 'refuses a valid signature from a different publisher' {
+        Mock Get-AuthenticodeSignature { New-FakeSignature -Status 'Valid' -Subject 'CN=Somebody Else, O=Somebody Else Ltd, C=US' }
+        Test-BootstrapSignature -Path 'TestDrive:\x.ps1' | Should -BeFalse
+    }
+
+    It 'refuses when the signature check itself fails' {
+        Mock Get-AuthenticodeSignature { throw 'file not found' }
+        Test-BootstrapSignature -Path 'TestDrive:\x.ps1' | Should -BeFalse
+    }
+}
+
+Describe 'Get-VerifiedBootstrapScript' {
+    BeforeEach {
+        Mock Write-Log { }
+        Mock Start-Sleep { }
+        Mock Invoke-WebRequest { }
+    }
+
+    It 'returns after the first attempt when the download verifies' {
+        Mock Test-BootstrapSignature { $true }
+        Get-VerifiedBootstrapScript -Url 'https://example.invalid/s.ps1' -Destination 'TestDrive:\s.ps1' | Should -BeTrue
+        Should -Invoke Invoke-WebRequest -Times 1 -Exactly
+    }
+
+    It 'gives up after three attempts when verification keeps failing' {
+        Mock Test-BootstrapSignature { $false }
+        Get-VerifiedBootstrapScript -Url 'https://example.invalid/s.ps1' -Destination 'TestDrive:\s.ps1' | Should -BeFalse
+        Should -Invoke Invoke-WebRequest -Times 3 -Exactly
+    }
+
+    # A truncated or proxy-mangled body fails verification, so the retry has to cover the
+    # download AND the check, not just the transport.
+    It 'retries a failed verification and accepts a later attempt' {
+        $script:calls = 0
+        Mock Test-BootstrapSignature { $script:calls++; return ($script:calls -ge 2) }
+        Get-VerifiedBootstrapScript -Url 'https://example.invalid/s.ps1' -Destination 'TestDrive:\s.ps1' | Should -BeTrue
+        Should -Invoke Invoke-WebRequest -Times 2 -Exactly
+    }
+
+    It 'retries a transport failure' {
+        $script:downloads = 0
+        Mock Invoke-WebRequest { $script:downloads++; if ($script:downloads -eq 1) { throw 'connection reset' } }
+        Mock Test-BootstrapSignature { $true }
+        Get-VerifiedBootstrapScript -Url 'https://example.invalid/s.ps1' -Destination 'TestDrive:\s.ps1' | Should -BeTrue
+        Should -Invoke Invoke-WebRequest -Times 2 -Exactly
+    }
+
+    It 'never executes anything when no attempt verifies' {
+        Mock Test-BootstrapSignature { $false }
+        Get-VerifiedBootstrapScript -Url 'https://example.invalid/s.ps1' -Destination 'TestDrive:\s.ps1' | Should -BeFalse
+    }
+}
+
+Describe 'publish contract' {
+    BeforeAll {
+        $script:loaderText = Get-Content (Join-Path $PSScriptRoot 'Start-AutopilotMonitor.ps1') -Raw
+    }
+
+    # Publish-BootstrapScripts.ps1 renders the -Dev loader by substituting this exact
+    # literal and fails the publish when it is gone. Catching that here means the PR fails
+    # instead of the publish.
+    It 'carries the dev-render anchor the publisher substitutes' {
+        $anchor = '$BootstrapUrl = "https://download.autopilotmonitor.com/agent/Install-AutopilotMonitor.ps1"'
+        $script:loaderText.Contains($anchor) | Should -BeTrue
+    }
+
+    # The publisher parses this to write version.json.loaderVersion and to run the
+    # version-bump guard.
+    It 'declares a parsable ScriptVersion' {
+        $script:loaderText -match '\$ScriptVersion\s*=\s*"([\d\.\-a-zA-Z]+)"' | Should -BeTrue
+    }
+
+    It 'pins the expected publisher by subject, not by thumbprint' {
+        $script:loaderText -match '\$ExpectedPublisher\s*=\s*"\*O=' | Should -BeTrue
+    }
+}
diff --git a/scripts/Bootstrap/Start-AutopilotMonitor.ps1 b/scripts/Bootstrap/Start-AutopilotMonitor.ps1
new file mode 100644
index 00000000..fb4df167
--- /dev/null
+++ b/scripts/Bootstrap/Start-AutopilotMonitor.ps1
@@ -0,0 +1,197 @@
+<#
+.SYNOPSIS
+    Stage 1 of the Autopilot Monitor bootstrap: fetches the current installer and runs it.
+
+.DESCRIPTION
+    This is the file an administrator assigns in Intune. It carries no enrollment logic at
+    all: it downloads the published Install-AutopilotMonitor.ps1, proves that it was signed
+    by Autopilot Monitor, and runs it in this process.
+
+    Why two stages: the installer holds every guard, relax rule and download path, and those
+    change. Whoever assigns the installer directly has to replace their Intune copy each
+    time; whoever assigns this loader never does, because the part that changes lives on the
+    server. Assigning the installer directly stays supported and unchanged.
+
+    This file is deliberately boring. It is the one piece that cannot be fixed remotely, so
+    it does the least it can: download, verify, invoke, log.
+
+    Verification is by Authenticode publisher, not by hash. A hash oracle would have to be
+    fetched from the same host as the script itself, so it could not survive a compromise of
+    that host, while the expected publisher below travels with this file. It pins the
+    certificate SUBJECT and not a thumbprint, so a certificate renewal does not brick a
+    loader that is already deployed on devices.
+
+    Fail-soft: the loader always exits 0 and never throws into the caller. A device that
+    cannot reach the download endpoint is a device without monitoring, never a failed
+    enrollment step. Verification failures are the same: nothing runs, and the reason is in
+    the log. Refusing to execute unverified code as SYSTEM is the point of this file.
+
+    This file MUST remain pure ASCII (PS 5.1 reads BOM-less files as ANSI).
+
+.PARAMETER BootstrapUrl
+    Installer URL. Defaults to the published stable installer; the -Dev variant of this
+    loader is rendered from that default at publish time.
+
+.PARAMETER BootstrapArguments
+    Everything else is passed through to the installer unchanged, so any parameter the
+    installer accepts can be set here without this file knowing about it.
+
+.EXAMPLE
+    .\Start-AutopilotMonitor.ps1
+
+.EXAMPLE
+    .\Start-AutopilotMonitor.ps1 -MaxBootstrapWindowHours 24
+
+.NOTES
+    Author  : Oliver Kieselbach (autopilotmonitor.com)
+    Runtime : Windows PowerShell 5.1, SYSTEM context, during Autopilot enrollment
+
+.CHANGELOG
+    2026-09-08  v1.0  Initial version: two-stage bootstrap, publisher-pinned verification.
+#>
+
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory = $false)]
+    [string]$BootstrapUrl = "https://download.autopilotmonitor.com/agent/Install-AutopilotMonitor.ps1",
+
+    [Parameter(Mandatory = $false, ValueFromRemainingArguments = $true)]
+    [string[]]$BootstrapArguments
+)
+
+# Script version (bump on meaningful changes; see .CHANGELOG above)
+$ScriptVersion = "1.0"
+
+# The publisher every downloaded stage-2 script must carry. A -like pattern on the subject,
+# NOT a thumbprint: certificates are renewed, deployed loaders are not.
+$ExpectedPublisher = "*O=glueckkanja AG*"
+
+$LoaderBasePath = "$env:ProgramData\AutopilotMonitor"
+$LoaderLogPath  = "$LoaderBasePath\Logs"
+$LogFile        = "$LoaderLogPath\bootstrap-loader.log"
+$BootstrapPath  = "$LoaderBasePath\Install-AutopilotMonitor.ps1"
+
+$DownloadAttempts = 3
+$RetryDelaySeconds = 10
+
+# Write-Host as well as the file: the Intune script output is what an administrator sees in
+# the portal, the file is what a support case reads.
+function Write-Log {
+    param([string]$Message)
+    $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
+    $logMessage = "[$timestamp] $Message"
+    Write-Host $logMessage
+    Add-Content -Path $LogFile -Value $logMessage -ErrorAction SilentlyContinue
+}
+
+# True only when the file is signed, the signature validates against the machine's trust
+# chain, and the signer is us. Any error is a false -- an unreadable signature is an
+# unverified script.
+function Test-BootstrapSignature {
+    param([string]$Path)
+
+    try {
+        $sig = Get-AuthenticodeSignature -FilePath $Path -ErrorAction Stop
+    }
+    catch {
+        Write-Log "Signature check failed to run: $($_.Exception.Message)"
+        return $false
+    }
+
+    if ($null -eq $sig) {
+        Write-Log "Signature check returned nothing."
+        return $false
+    }
+
+    $subject = if ($sig.SignerCertificate) { $sig.SignerCertificate.Subject } else { "<unsigned>" }
+    Write-Log "Signature status: $($sig.Status). Signer: $subject"
+
+    if ($sig.Status -ne 'Valid') {
+        Write-Log "REJECTED: expected signature status 'Valid'."
+        return $false
+    }
+    if ($subject -notlike $ExpectedPublisher) {
+        Write-Log "REJECTED: signer does not match the expected publisher."
+        return $false
+    }
+
+    Write-Log "Signature accepted (thumbprint $($sig.SignerCertificate.Thumbprint))."
+    return $true
+}
+
+# Downloads the installer and returns $true once a downloaded copy passes verification.
+# Verification lives inside the retry loop on purpose: a truncated or proxy-mangled body
+# fails the signature check, and that is worth another attempt.
+function Get-VerifiedBootstrapScript {
+    param([string]$Url, [string]$Destination)
+
+    for ($attempt = 1; $attempt -le $DownloadAttempts; $attempt++) {
+        try {
+            Write-Log "Download attempt $attempt/$DownloadAttempts from $Url"
+            Invoke-WebRequest -Uri $Url -OutFile $Destination -UseBasicParsing -TimeoutSec 60 -ErrorAction Stop
+
+            if (Test-BootstrapSignature -Path $Destination) {
+                return $true
+            }
+        }
+        catch {
+            Write-Log "Download attempt $attempt failed: $($_.Exception.Message)"
+        }
+
+        if ($attempt -lt $DownloadAttempts) {
+            Start-Sleep -Seconds $RetryDelaySeconds
+        }
+    }
+
+    return $false
+}
+
+# Main flow. Only invoked when the script is run directly (see entry guard at the bottom),
+# so the Pester suite can dot-source this file without bootstrapping anything.
+function Start-BootstrapLoader {
+    New-Item -ItemType Directory -Force -Path $LoaderLogPath -ErrorAction SilentlyContinue | Out-Null
+
+    Write-Log "=== Autopilot Monitor bootstrap loader v$ScriptVersion started (user=$env:USERNAME, pid=$PID) ==="
+
+    # PS 5.1 on an OOBE device still defaults to TLS 1.0 for this process.
+    try {
+        [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12
+    }
+    catch {
+        Write-Log "INFO: could not raise the TLS protocol: $($_.Exception.Message)"
+    }
+
+    if (-not (Get-VerifiedBootstrapScript -Url $BootstrapUrl -Destination $BootstrapPath)) {
+        Write-Log "No verified installer available after $DownloadAttempts attempt(s). Nothing was executed."
+        return
+    }
+
+    Write-Log "Executing $BootstrapPath"
+
+    # Same process, so the execution policy this loader runs under applies to stage 2 as
+    # well and no second policy decision can strand the installer. Splatting an array of
+    # remaining arguments keeps this file free of any knowledge about the installer's
+    # parameters.
+    $arguments = @()
+    if ($BootstrapArguments) { $arguments = $BootstrapArguments }
+
+    try {
+        & $BootstrapPath @arguments
+        Write-Log "Installer finished (exit code $LASTEXITCODE)."
+    }
+    catch {
+        Write-Log "Installer threw: $($_.Exception.Message)"
+    }
+}
+
+# Entry guard: dot-sourcing (Pester) loads the functions without running the loader.
+if ($MyInvocation.InvocationName -ne '.') {
+    try {
+        Start-BootstrapLoader
+    }
+    catch {
+        # Nothing above should throw; if it does, it must not become a failed Intune script.
+        Write-Log "Loader failed: $($_.Exception.Message)"
+    }
+    exit 0
+}