Environment

• OpenClaw Version: 2026.2.19-2
• OS: Windows_NT 10.0.26100 (x64)
• Node Version: v22.13.1
• Channel: Telegram

Describe the bug

When using the message tool with the file parameter to send a local file (e.g., .png or .txt) on Windows, the tool returns { "ok": true }, but the message/file is never received on the Telegram side. This is a silent failure as the agent logic assumes success.

Reproduction steps

1. Run OpenClaw on a Windows host.
2. Attempt to send a local file via the message tool to a Telegram user/group.
3. Observe that the tool result is ok: true.
4. Check Telegram and see that no message or file has arrived.

Workaround / Comparison

Directly calling the Telegram API via curl on the same Windows host works perfectly:

C:\Windows\System32\curl.exe -F chat_id=CHAT_ID -F photo=@C:\path\to\file.png https://api.telegram.org/bot<TOKEN>/sendPhoto

This suggests the issue lies in how the message tool handles local file paths or multipart streams on Windows.

Suspected cause

Likely an issue with Windows path normalization (backslash vs forward slash) or the underlying file streaming implementation in the Telegram channel provider when running in a Windows environment.