Issue Description

The conversation metadata (untrusted metadata) is visible to users in the webchat interface, which appears before every message they send.

What's happening

Users see this block before every message they type:

Conversation info (untrusted metadata): {
  message_id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx,
  sender: openclaw-control-ui
}
[Fri 2026-02-20 17:02 GMT-3] user_message_here

Expected Behavior

This metadata should be internal/hidden and only visible to the agent as context, not shown in the user-facing chat interface.

Current Behavior

The metadata is displayed to users, which can be:

• Confusing (what is this JSON block?)
• Unnecessary noise in the conversation flow
• Not user-friendly

Environment

• OpenClaw version: 2026.2.19-2 (45d9b20)
• Interface: webchat
• Channel: webchat

Suggested Fix

Hide the "Conversation info (untrusted metadata)" block from the user-facing chat display. It should only be injected as context for the agent, similar to how system messages are handled.

Notes

The metadata itself is correct and useful for the agent — it just shouldn't be visible to end users in the UI.