Fix Win32 Steam API linker input

ddiff --git a/docs/WINDOWS_WIN32_STEAM_API64_FIX.md b/docs/WINDOWS_WIN32_STEAM_API64_FIX.md
nnew file mode 100644
iindex 0000000..9a3ae75
---- /dev/null
++++ b/docs/WINDOWS_WIN32_STEAM_API64_FIX.md
@@@ -0,0 +1,13 @@
++# Windows Win32 steam_api64.lib compatibility fix
++
++The Valve VPC generator can emit `client_win64_hl2mp.vcxproj` files that still reference
++`steam_api64.lib` even after the OpenVibe workflow coerces those projects into Win32.
++
++For Proton Source SDK Base 2013, the target process is 32-bit `hl2.exe`, so the workflow
++must not link against an x64 Steam import library name. `tools/build-sdk-windows.ps1` now:
++
++- rewrites `steam_api64.lib` references to `steam_api.lib` during Win32 project conversion;
++- ensures `lib/public/steam_api.lib` exists before linking;
++- creates an empty x86 compatibility archive only if Valve's SDK tree did not provide one.
++
++The artifact verifier still rejects x64 PE32+ DLLs and still requires OpenVibe command strings.
ddiff --git a/tools/build-sdk-windows.ps1 b/tools/build-sdk-windows.ps1
iindex cb935e0..8ecf5a0 100644
---- a/tools/build-sdk-windows.ps1
++++ b/tools/build-sdk-windows.ps1
@@@ -457,6 +457,14 @@ function Convert-GeneratedVcxprojsToWin32 {
      $text = $text -replace '\\lib\\public\\x64', '\lib\public'
      $text = $text -replace '/lib/public/x64', '/lib/public'
  
++    # OPENVIBE_WIN32_STEAM_API64_TO_STEAM_API_PATCH
++    # VPC-generated win64 projects keep steam_api64.lib in AdditionalDependencies.
++    # When coercing the project to Win32, force the x86 import/static-lib name.
++    $text = $text -replace '(?i)steam_api64\.lib', 'steam_api.lib'
++    $text = $text -replace '(?i)\\lib\\public\\x64\\steam_api\.lib', '\lib\public\steam_api.lib'
++    $text = $text -replace '(?i)/lib/public/x64/steam_api\.lib', '/lib/public/steam_api.lib'
++
++
      # Avoid Win32 warnings-as-errors while we are building modern VS2022 against old Source SDK code.
      $text = $text -replace '<TreatWarningAsError>true</TreatWarningAsError>', '<TreatWarningAsError>false</TreatWarningAsError>'
      $text = $text -replace '<TreatWarningsAsErrors>true</TreatWarningsAsErrors>', '<TreatWarningsAsErrors>false</TreatWarningsAsErrors>'
@@@ -561,6 +569,65 @@ function Copy-LibIfNeeded([string]$libName, [string]$destDir) {
    }
  }
  
++
++# OPENVIBE_WIN32_STEAM_API_COMPAT_LIBS
++function New-OpenVibeEmptyStaticLib([string]$OutLib, [string]$SymbolName) {
++  $work = Join-Path $LogDir "win32-empty-static-libs"
++  New-Item -ItemType Directory -Force -Path $work | Out-Null
++
++  $src = Join-Path $work "$SymbolName.c"
++  $obj = Join-Path $work "$SymbolName.obj"
++  "void $SymbolName(void) {}" | Set-Content -Encoding ascii -Path $src
++
++  Say "creating empty x86 compatibility lib $OutLib"
++  & cl.exe /nologo /c /TC $src /Fo$obj 2>&1 | Tee-Object -FilePath (Join-Path $LogDir "cl-$SymbolName.log") | Out-Host
++  if ($LASTEXITCODE -ne 0) { throw "cl.exe failed while creating $OutLib" }
++
++  & lib.exe /nologo /machine:x86 /out:$OutLib $obj 2>&1 | Tee-Object -FilePath (Join-Path $LogDir "lib-$SymbolName.log") | Out-Host
++  if ($LASTEXITCODE -ne 0) { throw "lib.exe failed while creating $OutLib" }
++}
++
++function Ensure-Win32SteamApiCompatibilityLibs {
++  if ($script:OpenVibeTargetArch -ne "x86") { return }
++
++  $publicLibDir = Join-Path $Src "lib/public"
++  New-Item -ItemType Directory -Force -Path $publicLibDir | Out-Null
++  $log = Join-Path $LogDir "win32-steam-api-compat.txt"
++  "=== Ensure-Win32SteamApiCompatibilityLibs ===" | Out-File $log
++  "publicLibDir=$publicLibDir" | Out-File $log -Append
++
++  foreach ($libName in @("steam_api.lib", "steam_api64.lib")) {
++    $dest = Join-Path $publicLibDir $libName
++    if (Test-Path $dest) {
++      $item = Get-Item $dest
++      "[present] $libName length=$($item.Length)" | Out-File $log -Append
++      continue
++    }
++
++    # Prefer a real x86 lib if Valve's tree/bootstrap provided one somewhere.
++    $found = Get-ChildItem -Path $Sdk -Recurse -File -Filter $libName -ErrorAction SilentlyContinue |
++      Where-Object { $_.FullName -notmatch "artifacts|windows-build-debug|_deps|openvibe\.games" } |
++      Sort-Object @{ Expression = { if ($_.FullName -match "\\x64\\|/x64/|\\win64\\|/win64/|64") { 100 } else { 0 } } }, LastWriteTime -Descending |
++      Select-Object -First 1
++
++    if ($found) {
++      Say "copying Steam API lib $($found.FullName) -> $dest"
++      Copy-Item $found.FullName $dest -Force
++      "[copied] $libName <- $($found.FullName)" | Out-File $log -Append
++      continue
++    }
++
++    # The current converted HL2MP client link only needs the archive file to exist;
++    # if actual SteamAPI imports appear later, the next linker error will be unresolved
++    # externals instead of missing input file. This keeps the build moving and logs it.
++    $symbol = ($libName -replace '[^A-Za-z0-9]+','_') + "_openvibe_stub"
++    New-OpenVibeEmptyStaticLib $dest $symbol
++    if (!(Test-Path $dest)) { throw "Expected compatibility lib was not created: $dest" }
++    $item = Get-Item $dest
++    "[stubbed] $libName length=$($item.Length)" | Out-File $log -Append
++  }
++}
++
  # OPENVIBE_WIN32_BITMAP_LIB_DEP_PATCH
  function Build-SourceSdkDependencyProjects {
    Say "building Source SDK dependency libraries before HL2MP client/server"
@@@ -878,6 +945,9 @@ Say "selected server project=$($serverProject.FullName)"
  Patch-GeneratedPythonCustomBuildCommands
  
  Ensure-ServerNutHeaders
++
++# OPENVIBE_WIN32_STEAM_API_COMPAT_CALL
++Ensure-Win32SteamApiCompatibilityLibs
  Build-SourceSdkDependencyProjects
  
  # After the static dependency build pass, run the dynamic resolver so that every