{Packaging} Optimize MSI upgrade performance with REINSTALLMODE=amus

Author: wangzelin007

build_scripts/windows/Product.wxs

@@ -49,7 +49,10 @@
       <UpgradeVersion Property="WIX_DOWNGRADE_DETECTED" Minimum="$(var.ProductVersion)" IncludeMinimum="no" OnlyDetect="yes" />
     </Upgrade>
     <InstallExecuteSequence>
-      <RemoveExistingProducts After="InstallExecute" />
+      <!-- RemoveExistingProducts runs BEFORE InstallInitialize to completely remove old version first.
+           This prevents DLL conflicts when upgrading across Python versions (e.g., 3.12 to 3.13).
+           See: https://github.com/Azure/azure-cli/issues/32045 -->
+      <RemoveExistingProducts Before="InstallInitialize" />
     </InstallExecuteSequence>
 
     <!-- New product architectures should upgrade the original x86 product - even of the same version. -->
@@ -74,6 +77,13 @@
     <Property Id="MSIFASTINSTALL" Value="7" />
     <Property Id="ApplicationFolderName" Value="Microsoft SDKs\Azure" />
     <Property Id="WixAppFolder" Value="WixPerMachineFolder" />
+    
+    <!-- Force reinstall of all files during upgrade to handle cross-Python-version upgrades.
+         'a' = Force reinstall of all files regardless of version
+         This is necessary because pywin32's .pyd files have version numbers like 3.11.xxx or 3.13.xxx,
+         and MSI's version comparison may incorrectly determine that older Python version files are "newer".
+         See: https://github.com/Azure/azure-cli/issues/32045 -->
+    <SetProperty Id="REINSTALLMODE" Value="amus" Before="CostFinalize" Sequence="both">WIX_UPGRADE_DETECTED</SetProperty>
 
     <Feature Id="ProductFeature"
              Title="Microsoft Azure CLI"