Bug type

Regression (worked before, now fails)

Summary

After upgrading to 2026.3.13, streaming responses in webchat (Control UI) create multiple duplicate message bubbles with growing text, instead of updating a single message in-place. The complete message only appears after many duplicates.

Steps to reproduce

1. Open webchat (Control UI chat tab)
2. Send any message to the agent
3. Observe streaming response — each chunk creates a new bubble with the full text so far
4. Same content repeats many times, each with 1-2 more sentences added
5. Final complete message appears at the end after many duplicates

Expected behavior

Streaming response updates a single message bubble in-place, showing progressive text without duplication.

Actual behavior

Each streaming chunk creates a new message bubble containing all text so far. The same content repeats many times, each time with slightly more text added. The final complete message appears only after many duplicate bubbles.

OpenClaw version

2026.3.13 (61d171a)

Operating system

Windows 10

Install method

npm global

Model

anthropic/claude-sonnet-4-6

Provider / routing chain

openclaw -> anthropic

Config file / key location

No response

Additional provider/model setup details

No response

Logs, screenshots, and evidence

Impact and severity

Affected: All webchat (Control UI) users
Severity: High (extremely distracting, UI unusable during streaming)
Frequency: 100% repro
Consequence: Every response spams the chat with duplicates

Additional information

Last known good version: pre-2026.3.13. First known bad version: 2026.3.13. This is a regression introduced in this update.