[Bug] Windows 11 + PowerShell 7.6.3: Mouse wheel scroll up jumps to top of session view during task execution

Bug Description

During task execution in a Kimi Code session, scrolling up with the mouse wheel to review earlier conversation content causes the session view to jump unexpectedly to the very top of the session window (the "Welcome to Kimi Code!" page). This happens with high probability, making it very difficult to review previous messages while a task is running.

Environment

• OS: Windows 11
• Shell: PowerShell 7.6.3
• Kimi Code Version: Latest (as of 2026-07-13)
• Terminal: Windows Terminal (default)

Steps to Reproduce

1. Start a Kimi Code session (kimi in PowerShell 7.6.3)
2. Initiate any task that produces multiple turns of output (e.g., ask the agent to write or modify code)
3. While the task is executing and generating output, use the mouse wheel to scroll up to review earlier conversation content
4. Observe: The view jumps to the top of the session (the "Welcome to Kimi Code!" welcome page) instead of scrolling smoothly through previous messages

Expected Behavior

Mouse wheel scroll should move smoothly through the conversation history, allowing the user to review earlier messages while the task continues executing in the background.

Actual Behavior

Scrolling up with the mouse wheel causes the session view to jump directly to the top of the session window (the welcome page). This makes it impossible to review intermediate messages during task execution.

Frequency

• High probability: Occurs in roughly 70-80% of scroll-up attempts during active task execution
• Does not seem to occur (or occurs less frequently) when no task is actively running

Additional Context

• This appears to be a TUI rendering/scroll buffer issue, possibly triggered by concurrent background task output updates while the user is attempting to scroll
• The jump seems to happen specifically when the session is actively receiving new messages (the scroll position is being reset/forced to bottom by new output, and then the user's scroll-up action interacts badly with this behavior)
• No keyboard shortcuts (PageUp, Up arrow) seem to trigger this same behavior consistently -- it is primarily reproducible with the mouse wheel

Start by reproducing the issue in the Kimi Code CLI using Windows 11, PowerShell 7.6.3, and Windows Terminal while a task is producing output. Inspect the TUI scroll handling and concurrent rendering updates; done means mouse-wheel scrolling remains at the requested conversation position instead of jumping to the welcome page.