[BUG] [PowerShell] Reporting $LASTEXITCODE causes unnecessary permission checks

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

I've given instructions to run scripts from the AGENTS.md and use the exit code to determine the response. When Claude calls these scripts it appends "; EXIT=$LASTEXITCODE" as a way to capture the exit code. This unfortunately halts work for a permission check, even when the called script is marked as allowed.

Here is an example tool use that will stop work for a permission check even though the script has been marked as allowed:

{                                                                                                                                                                                                                                                                                                                                                  "type": "tool_use",                                                                                                                                                                                                                                                                                                                                                                                                               "id": "toolu_01Wgvk8JU7LNCZrYp7Gs27b3",                                                                                                                                                                                                                                                                                                 "name": "PowerShell",                                                                                                                                                                                                                                                                                                                                          "input": {                                                                                                                                                                                                                                                                                                                                                                               "command": "./scripts/check-device.ps1; \"EXIT=$LASTEXITCODE\"",                                                                                                                                                                                                                                                                                             "description": "Check device readiness"                                                                                                                                                                                                                                                                                                   }

What Should Happen?

As an example, if a tool call is made for "./scripts/check-device.ps1; \"EXIT=$LASTEXITCODE\"" it should strip/ignore the last part and do the permission check against whats left "./scripts/check-device.ps1"

Error Messages/Logs

Steps to Reproduce

1. Create a script "the-answer.ps1" with contents:

``` PowerShell
exit 42

2. Ask claude to run the script and tell what the exit code was.
3. Observe Claude asks for permissions to run a powershell script: 

────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
PowerShell command

& .\the-answer.ps1; "Exit code: $LASTEXITCODE"
Run script and show exit code

Command contains expandable strings with embedded expressions

Do you want to proceed?
> 1. Yes

1. Yes, and don’t ask again for: & .\exit42.ps1; "Exit code: $LASTEXITCODE"
2. No

Esc to cancel · Tab to amend · ctrl+e to explain

4. Grant the permission and tell claude not to ask again what it suggests: & .\the-answer.ps1; "Exit code: $LASTEXITCODE"
5. Note the script runs and Claude successfully reports it returned 42.
6. Prompt Claude to run the script again, like "Please run the script again and tell me the exit code it returns this time."
7. Grant the permission and tell claude not to ask again for shorter & .\the-answer.ps1
8. Note the script runs and Claude successfully reports it returned 42.
9. Prompt Claude to run the script again, like "Please run the script again and tell me the exit code it returns this time."
10. Observe yet another permission check


For the expected results, there should not have been a second or third permission check. Let me record my settings.local.json after this interaction where it repeatedly asked for permissions: 
```json
{
  "permissions": {
    "allow": [
      "PowerShell(& .\\\\the-answer.ps1; \"Exit code: $LASTEXITCODE\")",
      "PowerShell(& .\\\\the-answer.ps1)"
    ]
  }
}

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.168 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_