Shell command runner does not inherit environment variables from PowerShell #5281

Describe the bug

Environment variables available in the PowerShell process that launches Copilot are not visible to Copilot's shell command runner. This prevents commands and integrations launched by the runner from using user-configured environment variables such as GITHUB_PERSONAL_ACCESS_TOKEN.

Affected version

Copilot CLI 1.0.105

Steps to reproduce the behavior

1. On Windows, store GITHUB_PERSONAL_ACCESS_TOKEN in the User environment-variable scope.

2. Open a new PowerShell 7 prompt.

3. Load the User-scope value into the current process and verify it without printing the secret:

   $env:GITHUB_PERSONAL_ACCESS_TOKEN = [Environment]::GetEnvironmentVariable('GITHUB_PERSONAL_ACCESS_TOKEN', 'User')
   $env:GITHUB_PERSONAL_ACCESS_TOKEN -ne $null

   This returns True.

4. Launch Copilot CLI from that same PowerShell prompt.

5. In the Copilot session, run:

   ! $env:GITHUB_PERSONAL_ACCESS_TOKEN -ne $null
   

   This returns False.

6. The runner reports the following scope state without exposing the secret value:

   Process: False
   User:    True
   Machine: False
   

The behavior reproduces in a newly opened PowerShell prompt and a newly launched Copilot session. No token value was printed or included in this report.

Expected behavior

The shell command runner should inherit the environment of the Copilot process that was launched from PowerShell, or the behavior should be clearly documented if credential variables are intentionally filtered.

Additional context

• Operating system: Windows
• Shell: PowerShell 7
• The runner and launcher are running under the same Windows account; account/domain details are intentionally omitted.
• The issue appears specific to the Copilot command-runner process boundary. It may be intentional credential sanitization, but this is not documented and prevents expected environment-based authentication for child commands.