Description

When uploading images via the Control UI (webchat) attachment button, the images disappear and are not received by the agent.

Steps to Reproduce

1. Open Control UI at http://127.0.0.1:18789/
2. Click the attachment button (📎) in the chat input area
3. Select an image file
4. The image disappears from the input field and is never sent to the agent

Expected Behavior

Images should be uploaded and sent to the agent along with the message, or at least show an error if upload fails.

Environment

• OpenClaw version: 2026.3.13
• macOS: 26.3.1
• Platform: Control UI (browser-based webchat)
• Gateway: running on localhost

Additional Notes

• Text messages work fine
• This issue prevents users from sending images through the webchat interface
• Telegram channel works correctly for image uploads