Cowork UI: messages render out-of-order / require scroll to find — regression on 1.569.0

Description

Cowork mode messages intermittently render out of position or fail to appear until the user scrolls or sends another message. User messages appear to 'pulse' — flickering in and out of view — requiring manual scrolling to piece together the conversation flow. Started approximately late March / early April 2026.

Environment

• Claude Desktop version: 1.569.0 (49894a) 2026-04-02T20:01:42.000Z
• Platform: macOS

Steps to Reproduce

1. Open Cowork mode in Claude Desktop
2. Have a multi-turn conversation with tool calls (Bash, Read, WebSearch, etc.)
3. After several exchanges, Claude's responses and/or user messages render out of order or require scrolling to locate

Expected Behavior

Messages render in chronological order and remain visible without manual scrolling.

Actual Behavior

• Messages appear to 'pulse' or flicker in/out of view
• User must scroll up/down to find messages that should be inline
• Problem worsens over the course of a session
• Backend processing is correct — only UI rendering is affected

Workaround

Adding a trivial Bash tool call (e.g. echo done) after each response forces the render cycle to flush, partially mitigating the issue.

Related Issues (regression)

Previously reported and closed against earlier builds:

• #26881 (canonical: messages not rendering until user sends next prompt)
• #26876, #26878, #26888 (duplicates)
• #26805 (responses not rendering; 'working through complex response' hang)

Those were filed against builds 1.1.3541 / 2.1.45. The behavior has returned on 1.569.0.