Description

After updating to OpenClaw 2026.4.24, the webchat Control UI renders duplicate assistant messages on every reply. Each assistant response appears twice in the chat history.

Environment

• OpenClaw version: 2026.4.24 (cbcfdf6)
• OS: Windows 11
• Channel: webchat (Control UI)
• Session: agent:main:main

Steps to Reproduce

1. Update OpenClaw to 2026.4.24
2. Open webchat Control UI
3. Send any message
4. Observe assistant reply

Expected Behavior

Assistant message should appear once in chat history.

Actual Behavior

Assistant message appears twice (duplicate rendering).

Additional Context

• Backend transcript is NOT duplicated — only UI rendering issue
• Page reload does NOT fix the issue
• Similar to closed issue Control UI webchat: duplicate assistant messages rendered on every reply #5964 (Feb 2026), but this is a regression in 2026.4.24
• Verified by OpenClaw itself during troubleshooting session

Related Issues

• Control UI webchat: duplicate assistant messages rendered on every reply #5964 (closed as not planned, Feb 1 2026)

Verification

This issue was identified, verified, and reported by OpenClaw during a live troubleshooting session with the user.