function Use-FallbackDrive {

param([string]$Reason)

Write-Warning "$Reason Falling back to C:"

return "C:"

}

function Invoke-BestEffort {

param([scriptblock]$Script, [string]$Description)

try {

& $Script

} catch {

Write-Warning "$Description failed: $($_.Exception.Message)"

}

}

if (Test-Path "D:\") {

Write-Output "Using existing drive at D:"

$Drive = "D:"

} else {

try {

$VhdPath = Join-Path $env:RUNNER_TEMP "codex-dev-drive.vhdx"

$SizeBytes = 64GB

if (Test-Path $VhdPath) {

Remove-Item -Path $VhdPath -Force

}

New-VHD -Path $VhdPath -SizeBytes $SizeBytes -Dynamic -ErrorAction Stop | Out-Null

$Mounted = Mount-VHD -Path $VhdPath -Passthru -ErrorAction Stop

$Disk = $Mounted | Get-Disk -ErrorAction Stop

$Disk | Initialize-Disk -PartitionStyle GPT -ErrorAction Stop

$Partition = $Disk | New-Partition -AssignDriveLetter -UseMaximumSize -ErrorAction Stop

$Volume = $Partition | Format-Volume -FileSystem ReFS -NewFileSystemLabel "CodexDevDrive" -DevDrive -Confirm:$false -Force -ErrorAction Stop

$Drive = "$($Volume.DriveLetter):"

Invoke-BestEffort { fsutil devdrv trust $Drive } "Trusting Dev Drive $Drive"

Invoke-BestEffort { fsutil devdrv enable /disallowAv } "Disabling AV filter attachment for Dev Drives"

Invoke-BestEffort { fsutil devdrv query $Drive } "Querying Dev Drive $Drive"

Write-Output "Using Dev Drive at $Drive"

} catch {

$Drive = Use-FallbackDrive "Failed to create Dev Drive: $($_.Exception.Message)"

}

}

$Tmp = "$Drive\codex-tmp"

New-Item -Path $Tmp -ItemType Directory -Force | Out-Null

@(

"DEV_DRIVE=$Drive"

"TMP=$Tmp"

"TEMP=$Tmp"

) | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append