Description

When using the exec tool to run PowerShell commands on Windows, if the command output contains binary content (e.g., Python stdout with a UTF-8 BOM), the Gateway renders the response as "see in attachment" instead of showing the actual output text.

This breaks the agent's ability to read and process command output directly in context.

Steps to Reproduce

1. Run OpenClaw Gateway on Windows (Node 24.x)
2. Execute any PowerShell command via the exec tool that produces output containing a binary BOM
3. The tool response shows "see in attachment" rather than the plain text

Example:

python -c "print('hello')"

Current Workaround

Appending | ForEach-Object ToString to every PowerShell command:

python -c "print('hello')" | ForEach-Object ToString

But this is fragile, easy to forget, and must be applied to every exec call.

Expected Behavior

The exec tool should handle binary content or BOM-prefixed text output gracefully -- either stripping the BOM and rendering as text, or providing a configuration option to control the text vs. attachment threshold.

Environment

• OS: Windows 10/11 (64-bit)
• OpenClaw: latest (2026.7.x)
• Node: v24.x
• Shell: PowerShell
• Python: 3.13+

Additional Context

Only occurs on Windows with PowerShell. Linux/macOS shells do not exhibit this behavior since they do not emit BOM bytes before stdout text output.