fix(ci): improve vswhere MSVC x86 setup to update current process env + better verification

- Use single activation + parse to set both Process env (for current step verification) and GITHUB_ENV (for next steps).
- Verification (where cl + version) now runs in the pwsh process *after* env is applied, so logs show what the step actually sees.
- Added comments referencing the standard vswhere pattern for GitHub + VS2026.
- Kept amd64_x86 (correct for 64-host to 32-target).

This should ensure the 32-bit compiler is visible to the subsequent uv sync step.

Only the x86 CI fix.

Author: AAClause

.github/workflows/build_app.yml

@@ -53,6 +53,7 @@ jobs:
           if (-not (Test-Path $vswhere)) {
             throw "vswhere.exe not found at $vswhere"
           }
+          # Use vswhere (the official/recommended way for GitHub runners, handles VS 2022 and 2026+)
           $installPath = & $vswhere -latest -products * -property installationPath 2>$null | Select-Object -First 1
           if (-not $installPath) {
             throw "vswhere did not return an installation path"
@@ -63,16 +64,23 @@ jobs:
           }
           Write-Host "Using vcvarsall: $vcvarsall"
 
-          # Activate and verify in a child cmd (prints to logs)
-          cmd /c "`"$vcvarsall`" amd64_x86 && echo === Verifying 32-bit MSVC (for uv sdist win32 builds) === && where cl && cl 2>&1 | findstr /C:Version && echo ============================================"
-
-          # Export environment for subsequent steps
+          # Activate, update *current process* env + export to GITHUB_ENV for next steps.
+          # This is the robust pattern used by many CI setups for 32-bit builds.
           cmd /c "`"$vcvarsall`" amd64_x86 && set" | ForEach-Object {
             if ($_ -match '^(.*?)=(.*)$') {
-              Add-Content -Path $env:GITHUB_ENV -Value "$($matches[1])=$($matches[2])" -Encoding utf8
+              $n = $matches[1]
+              $v = $matches[2]
+              [Environment]::SetEnvironmentVariable($n, $v, 'Process')
+              Add-Content -Path $env:GITHUB_ENV -Value "$n=$v" -Encoding utf8
             }
           }
-          Write-Host "MSVC x86 environment exported to GITHUB_ENV"
+
+          # Now verify in the *current* pwsh context (will show in this step's logs)
+          Write-Host "=== Verifying 32-bit MSVC (for uv sdist win32 builds) ==="
+          where.exe cl
+          cl 2>&1 | findstr /C:Version || Write-Host "(cl version not shown)"
+          Write-Host "========================================================"
+          Write-Host "MSVC x86 environment applied to current process and exported to GITHUB_ENV"
       - name: Install dependencies
         working-directory: ${{ github.workspace }}/repo
         run: uv sync --frozen --compile --group build --group test