fix: rename $Args to $InstallArgs in install.ps1 for Windows

[vaibhavkumar779]

Problem

install.ps1 uses $Args as a param() name, but $Args is a PowerShell automatic variable that cannot be overwritten inside Invoke-Expression. When users run the documented one-liner:

irm https://raw.githubusercontent.com/JuliusBrussee/caveman/main/install.ps1 | iex

PowerShell throws:

Invoke-Expression : Cannot overwrite variable Args because the variable has been optimized.
    + CategoryInfo          : WriteError: (Args:String) [Invoke-Expression], SessionStateUnauthorizedAccessException
    + FullyQualifiedErrorId : VariableNotWritableRare,Microsoft.PowerShell.Commands.InvokeExpressionCommand

This breaks the install on every Windows machine using PowerShell 5.1 (the default shell).

Why it happens

When a script is piped to Invoke-Expression, PowerShell compiles the script block in the caller's scope. The automatic $Args variable is marked as an optimized/read-only variable in that context, so param([string[]]$Args) fails because it tries to reassign it.

Running the script as a file (& .\install.ps1) works fine because it gets its own scope — but that defeats the purpose of the one-liner install.

Environment

• OS: Windows 11
• PowerShell: 5.1.26100.4061
• Editor: VS Code with GitHub Copilot agent
• Node: v22.x

Fix

1. install.ps1 — Rename parameter (3 occurrences)

Before	After
[string[]]$Args	[string[]]$InstallArgs
@Args (splat in local path)	@InstallArgs
@Args (splat in npx path)	@InstallArgs

Also updated the header comment to use the download-then-run pattern and added a NOTE block explaining why $Args cannot be used.

2. README.md — Updated Windows install command

-# Windows (PowerShell 5.1+)
-irm https://raw.githubusercontent.com/JuliusBrussee/caveman/main/install.ps1 | iex
+# Windows (PowerShell 5.1+)
+$f = "$env:TEMP\caveman-install.ps1"; irm https://raw.githubusercontent.com/JuliusBrussee/caveman/main/install.ps1 -OutFile $f; & $f; Remove-Item $f

3. INSTALL.md — Updated install command + troubleshooting

• Updated the Windows install command to match README
• Replaced the irm | iex troubleshooting bullet with an explicit warning and the correct command

Testing

1. Before fix: irm ... | iex → crashes with VariableNotWritableRare
2. After fix (download-then-run): Downloads to %TEMP%, runs in own scope, installs successfully, cleans up temp file
3. After fix (local clone): & .\install.ps1 still works (no regression)
4. Verified: All 7 skills installed successfully for GitHub Copilot on Windows 11

Checklist

• $Args → $InstallArgs in install.ps1 (all 3 occurrences)
• README.md Windows command updated
• INSTALL.md Windows command updated
• INSTALL.md troubleshooting section updated
• No breaking changes for macOS/Linux (install.sh untouched)
• No breaking changes for local clone usage (& .\install.ps1 still works)