Description

When sending a message to another contact via the message tool, the session's displayName incorrectly updates to the recipient's number instead of staying as the session owner's number.

Steps to Reproduce

1. Have a session with user A (e.g., +26269300000)
2. Send a message to user B (e.g., +3378000000) using the message tool
3. Check sessions_list output

Expected Behavior

displayName should remain as user A's number (+ 26269300000)

Actual Behavior

displayName changes to user B's number (+ 3378000000)

Evidence

{
  "key": "agent:main:main",
  "displayName": "+ 3378000000",  // ❌ Wrong - this is the message recipient
  "deliveryContext": {
    "to": "+ 26269300000"  // ✅ Correct session owner
  },
  "lastTo": "+ 26269300000"  // ✅ Correct
}

Impact

• Display/UI confusion only
• Functionality is not affected (messages route correctly)

Environment

• OpenClaw version: 2026.1.29
• Channel: webchat + whatsapp
• OS: macOS (Darwin 25.1.0)