diff --git a/.github/workflows/package-production.yml b/.github/workflows/package-production.yml
index 0abb8e4a..6aa8d6c8 100644
--- a/.github/workflows/package-production.yml
+++ b/.github/workflows/package-production.yml
@@ -11,8 +11,30 @@ permissions:
   contents: read
 
 jobs:
+  build-rustls-windows:
+    name: Build Rustls package (win-x64)
+    runs-on: windows-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Build and test Rustls win-x64 package
+        shell: pwsh
+        run: ./scripts/package/Build-RustlsTls13ImplementationPackage.ps1 -RuntimeIdentifier win-x64
+
+      - name: Upload Rustls win-x64 package
+        uses: actions/upload-artifact@v4
+        with:
+          name: rustls-tls13-win-x64
+          if-no-files-found: error
+          path: |
+            artifacts/packages/*rustls-tls13*.win-x64.plabpkg
+            artifacts/packages/*rustls-tls13*.win-x64.plabpkg.build-attestation.json
+
   build-packages:
     name: Build package artifacts
+    needs: build-rustls-windows
     runs-on: ubuntu-latest
 
     steps:
@@ -32,9 +54,15 @@ jobs:
             implementations/quic-go-http3/go.sum
             executors/quic-go-raw-load/source/go.sum
 
+      - name: Download Rustls win-x64 package
+        uses: actions/download-artifact@v4
+        with:
+          name: rustls-tls13-win-x64
+          path: artifacts/packages
+
       - name: Build all ProtocolLab component packages
         shell: pwsh
-        run: ./scripts/package/Build-AllProtocolLabComponentPackages.ps1 -Clean
+        run: ./scripts/package/Build-AllProtocolLabComponentPackages.ps1 -ImportedPackageBuildKey 'implementations/rustls-tls13|win-x64'
 
       - name: Upload package production artifacts
         uses: actions/upload-artifact@v4
diff --git a/scripts/package/Build-AllProtocolLabComponentPackages.ps1 b/scripts/package/Build-AllProtocolLabComponentPackages.ps1
index 2a55aa40..09e60a7d 100644
--- a/scripts/package/Build-AllProtocolLabComponentPackages.ps1
+++ b/scripts/package/Build-AllProtocolLabComponentPackages.ps1
@@ -4,7 +4,9 @@ param(
 
     [string]$OutputRoot = (Join-Path $Root 'artifacts/packages'),
 
-    [switch]$Clean
+    [switch]$Clean,
+
+    [string[]]$ImportedPackageBuildKey = @()
 )
 
 $ErrorActionPreference = 'Stop'
@@ -69,6 +71,17 @@ function ConvertTo-StringArray {
     return @($Value | ForEach-Object { [string]$_ })
 }
 
+function Get-PackageBuildKey {
+    param([Parameter(Mandatory)]$Build)
+
+    $arguments = ConvertTo-StringArray -Value $Build.arguments
+    if ($arguments.Count -eq 0) {
+        return [string]$Build.componentPath
+    }
+
+    return '{0}|{1}' -f $Build.componentPath, ($arguments -join ',')
+}
+
 function Get-ProvidedIds {
     param([Parameter(Mandatory)]$Manifest)
 
@@ -257,6 +270,10 @@ $Root = (Resolve-Path $Root).Path
 $OutputRoot = [System.IO.Path]::GetFullPath($OutputRoot)
 Assert-PathIsUnderRoot -CandidatePath $OutputRoot -ExpectedRoot $Root
 
+if ($Clean -and $ImportedPackageBuildKey.Count -gt 0) {
+    throw 'Clean cannot be combined with ImportedPackageBuildKey because cleaning would delete the transferred package artifacts.'
+}
+
 New-Item -ItemType Directory -Force -Path $OutputRoot | Out-Null
 
 if ($Clean) {
@@ -417,10 +434,101 @@ $packageBuilds = @(
     [pscustomobject]@{ componentPath = 'scenarios/masque-connect-udp-performance'; script = 'Build-MasqueConnectUdpScenarioPackage.ps1'; arguments = @() }
 )
 
+$packageBuildsByKey = @{}
+foreach ($build in $packageBuilds) {
+    $buildKey = Get-PackageBuildKey -Build $build
+    if ($packageBuildsByKey.ContainsKey($buildKey)) {
+        throw "Duplicate package build key '$buildKey'."
+    }
+
+    $packageBuildsByKey[$buildKey] = $build
+}
+
+$importedBuildKeys = [System.Collections.Generic.HashSet[string]]::new([System.StringComparer]::OrdinalIgnoreCase)
+foreach ($buildKey in $ImportedPackageBuildKey) {
+    if (-not $packageBuildsByKey.ContainsKey($buildKey)) {
+        throw "Imported package build key was not found: '$buildKey'."
+    }
+
+    [void]$importedBuildKeys.Add($buildKey)
+}
+
 $builderResults = [System.Collections.Generic.List[object]]::new()
 $builtArtifacts = [System.Collections.Generic.List[System.IO.FileInfo]]::new()
+$importedArtifactPaths = [System.Collections.Generic.HashSet[string]]::new([System.StringComparer]::OrdinalIgnoreCase)
+
+if ($importedBuildKeys.Count -gt 0) {
+    $currentCommit = (& git -C $Root rev-parse HEAD).Trim()
+    $matchedImportedBuildKeys = [System.Collections.Generic.HashSet[string]]::new([System.StringComparer]::OrdinalIgnoreCase)
+
+    foreach ($artifact in @(Get-ChildItem -LiteralPath $OutputRoot -File -Filter '*.plabpkg' | Sort-Object Name)) {
+        $attestationPath = "$($artifact.FullName).build-attestation.json"
+        if (-not (Test-Path -LiteralPath $attestationPath -PathType Leaf)) {
+            throw "$($artifact.Name): imported package is missing build attestation '$attestationPath'."
+        }
+
+        $attestation = Get-Content -LiteralPath $attestationPath -Raw | ConvertFrom-Json
+        if (-not [string]::Equals([string]$attestation.source.commitSha, $currentCommit, [System.StringComparison]::OrdinalIgnoreCase)) {
+            throw "$($artifact.Name): imported package commit '$($attestation.source.commitSha)' does not match aggregation commit '$currentCommit'."
+        }
+
+        $actualHash = (Get-FileHash -LiteralPath $artifact.FullName -Algorithm SHA256).Hash.ToLowerInvariant()
+        if (-not [string]::Equals([string]$attestation.package.sha256, $actualHash, [System.StringComparison]::OrdinalIgnoreCase)) {
+            throw "$($artifact.Name): imported package hash does not match its build attestation."
+        }
+
+        $candidateBuilds = @(
+            $packageBuilds | Where-Object {
+                [string]::Equals([string]$_.componentPath, [string]$attestation.source.componentPath, [System.StringComparison]::OrdinalIgnoreCase)
+            }
+        )
+        if ($candidateBuilds.Count -gt 1) {
+            $candidateBuilds = @(
+                $candidateBuilds | Where-Object {
+                    (ConvertTo-StringArray -Value $_.arguments) -contains [string]$attestation.build.runtimeIdentifier
+                }
+            )
+        }
+
+        if ($candidateBuilds.Count -ne 1) {
+            throw "$($artifact.Name): imported package could not be associated with exactly one package build."
+        }
+
+        $matchingBuild = $candidateBuilds[0]
+        $matchingBuildKey = Get-PackageBuildKey -Build $matchingBuild
+        if (-not $importedBuildKeys.Contains($matchingBuildKey)) {
+            throw "$($artifact.Name): imported artifact maps to unrequested build '$matchingBuildKey'."
+        }
+
+        $attestation.package.materializationPath = [System.IO.Path]::GetFullPath($artifact.FullName)
+        $attestation.package.buildAttestationPath = [System.IO.Path]::GetFullPath($attestationPath)
+        $attestation | ConvertTo-Json -Depth 8 | Set-Content -LiteralPath $attestationPath -Encoding utf8NoBOM
+
+        [void]$builtArtifacts.Add($artifact)
+        [void]$importedArtifactPaths.Add($artifact.FullName)
+        [void]$matchedImportedBuildKeys.Add($matchingBuildKey)
+        [void]$builderResults.Add([pscustomobject]@{
+            componentPath = $matchingBuild.componentPath
+            script = $matchingBuild.script
+            arguments = ConvertTo-StringArray -Value $matchingBuild.arguments
+            artifacts = @($artifact.Name)
+            status = 'passed'
+        })
+    }
+
+    foreach ($buildKey in $importedBuildKeys) {
+        if (-not $matchedImportedBuildKeys.Contains($buildKey)) {
+            throw "No transferred package artifact matched imported build '$buildKey'."
+        }
+    }
+}
 
 foreach ($build in $packageBuilds) {
+    $buildKey = Get-PackageBuildKey -Build $build
+    if ($importedBuildKeys.Contains($buildKey)) {
+        continue
+    }
+
     $scriptPath = Join-Path $PSScriptRoot $build.script
     if (-not (Test-Path -LiteralPath $scriptPath -PathType Leaf)) {
         throw "Package build script not found: $scriptPath"
@@ -440,7 +548,7 @@ foreach ($build in $packageBuilds) {
 
     $artifacts = @(
         Get-ChildItem -LiteralPath $OutputRoot -File -Filter '*.plabpkg' |
-            Where-Object { $_.LastWriteTimeUtc -ge $startTime } |
+            Where-Object { $_.LastWriteTimeUtc -ge $startTime -and -not $importedArtifactPaths.Contains($_.FullName) } |
             Sort-Object FullName
     )
 
diff --git a/scripts/package/Build-RustlsTls13ImplementationPackage.ps1 b/scripts/package/Build-RustlsTls13ImplementationPackage.ps1
index 8415301b..f0bbb1f3 100644
--- a/scripts/package/Build-RustlsTls13ImplementationPackage.ps1
+++ b/scripts/package/Build-RustlsTls13ImplementationPackage.ps1
@@ -3,32 +3,25 @@ param(
     [ValidateSet('win-x64','linux-x64')][string]$RuntimeIdentifier='win-x64',
     [string]$Root=(Resolve-Path (Join-Path $PSScriptRoot '../..')).Path,
     [string]$OutputRoot=(Join-Path $Root 'artifacts/packages'),
-    [string]$Toolchain='stable-x86_64-pc-windows-gnu',
+    [string]$Toolchain='',
     [switch]$AllowDirtySource
 )
 
 $ErrorActionPreference='Stop'
 $Root=[IO.Path]::GetFullPath($Root);$OutputRoot=[IO.Path]::GetFullPath($OutputRoot)
 $componentName='rustls-tls13';$componentRoot=Join-Path $Root "implementations/$componentName";$sourceRoot=Join-Path $componentRoot 'source'
+if($RuntimeIdentifier-eq'win-x64'-and-not$IsWindows){throw 'The win-x64 rustls package must be built and tested on Windows.'}
+if($RuntimeIdentifier-eq'linux-x64'-and-not$IsLinux){throw 'The linux-x64 rustls package must be built and tested on Linux.'}
+if([string]::IsNullOrWhiteSpace($Toolchain)){$Toolchain=if($IsWindows){'stable-x86_64-pc-windows-gnu'}else{'stable'}}
 & cargo "+$Toolchain" test --locked --manifest-path (Join-Path $sourceRoot 'Cargo.toml')
 if($LASTEXITCODE-ne 0){throw 'rustls TLS 1.3 target tests failed.'}
 $rid=switch($RuntimeIdentifier){
     'win-x64'{@{os='windows';arch='x64';target=$null;name='rustls-tls13.exe';source='target/release/protocol-lab-rustls-tls13-target.exe'}}
-    'linux-x64'{@{os='linux';arch='x64';target='x86_64-unknown-linux-musl';name='rustls-tls13';source='target/x86_64-unknown-linux-musl/release/protocol-lab-rustls-tls13-target'}}
+    'linux-x64'{@{os='linux';arch='x64';target=$null;name='rustls-tls13';source='target/release/protocol-lab-rustls-tls13-target'}}
 }
 $buildArgs=@("+$Toolchain",'build','--locked','--release','--manifest-path',(Join-Path $sourceRoot 'Cargo.toml'))
-if($rid.target){$buildArgs+=@('--target',$rid.target)}
-$savedLinker=$env:CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER
-try{
-    if($RuntimeIdentifier-eq'linux-x64'-and$IsWindows){
-        $sysroot=& rustc "+$Toolchain" --print sysroot
-        if($LASTEXITCODE-ne 0){throw 'Unable to resolve the pinned Rust sysroot.'}
-        $env:CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER=Join-Path $sysroot 'lib/rustlib/x86_64-pc-windows-gnu/bin/rust-lld.exe'
-        if(-not(Test-Path $env:CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER)){throw 'rust-lld is unavailable for the Linux musl package build.'}
-    }
-    & cargo @buildArgs
-    if($LASTEXITCODE-ne 0){throw "rustls TLS 1.3 target build failed for $RuntimeIdentifier."}
-}finally{$env:CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER=$savedLinker}
+& cargo @buildArgs
+if($LASTEXITCODE-ne 0){throw "rustls TLS 1.3 target build failed for $RuntimeIdentifier."}
 $staging=Join-Path $OutputRoot "$componentName/$RuntimeIdentifier";$packageRoot=Join-Path $staging 'package'
 Remove-Item -LiteralPath $staging -Recurse -Force -ErrorAction SilentlyContinue
 New-Item -ItemType Directory -Force (Join-Path $packageRoot "bin/$RuntimeIdentifier"),(Join-Path $packageRoot 'implementations'),(Join-Path $packageRoot 'certs')|Out-Null
diff --git a/scripts/package/README.md b/scripts/package/README.md
index c6083c99..1189a64e 100644
--- a/scripts/package/README.md
+++ b/scripts/package/README.md
@@ -36,6 +36,13 @@ Package production fails unless every package has exactly one valid,
 parity-eligible clean-source build attestation. The package index and validation
 summary record each attestation artifact, its SHA-256, and source commit.
 
+The package-production workflow builds and tests the Rustls `win-x64` package
+on Windows, transfers that package and attestation to the Ubuntu aggregation
+job, and builds the Rustls `linux-x64` package natively on Linux. The aggregator
+uses `-ImportedPackageBuildKey` to verify the transferred artifact belongs to
+the same commit, rebase its local attestation paths, and include it in the same
+index, checksum manifest, and validation summary as every other package.
+
 Use the component-specific wrappers when iterating on one package:
 
 ```powershell