Fix Windows PATH issue in install.bat

setx reads from the session %PATH% (system + user combined) and silently
truncates at 1024 characters, corrupting the user PATH on install. Use
PowerShell's SetEnvironmentVariable to append only to the user PATH from
the registry, with no length limit.

Also fix the warmup call to use the full installed path instead of relying
on the new PATH entry being active in the current session.

Author: dscpinheiro

.changes/next-release/bugfix-fab9cf64f935850c592eca38cab212cba6579149.json

@@ -0,0 +1,7 @@
+{
+  "type": "bugfix",
+  "description": "Fix Windows user PATH corruption in install.bat caused by setx silently truncating values over 1024 characters",
+  "pull_requests": [
+    "[#3117](https://github.com/smithy-lang/smithy/pull/3117)"
+  ]
+}

smithy-cli/configuration/install.bat

@@ -29,8 +29,13 @@ if exist "%choice_path%" goto upgrade
 
 :: Copy the installation
 xcopy /i /h /e /k "%installer_path%*" "%choice_path%\"
-setx path "%path%;%choice_path%\;"
-call %exe_name% warmup
+set "smithy_install_dir=%choice_path%"
+powershell -Command "& { $installDir = $env:smithy_install_dir; $userPath = [Environment]::GetEnvironmentVariable('PATH','User'); if ([string]::IsNullOrEmpty($userPath)) { [Environment]::SetEnvironmentVariable('PATH', $installDir, 'User') } elseif (-not $userPath.Contains($installDir)) { [Environment]::SetEnvironmentVariable('PATH', $userPath.TrimEnd(';') + ';' + $installDir, 'User') } }"
+if %ERRORLEVEL% neq 0 (
+  echo Failed to update PATH. You may need to add %choice_path% to your PATH manually.
+  goto done
+)
+call "%choice_path%\bin\%exe_name%" warmup
 echo You may now run '%exe_name% --version'
 goto done