[WebUI] Workspace files sidebar: action buttons hidden when filenames are too long

Bug Description

In the WebUI's "Workspace files" sidebar, long filenames push the action buttons (expand arrow > / download button) outside the visible viewport, making them unclickable. The sidebar width is fixed and cannot be resized.

Environment

• Kimi Code CLI Version: v1.41.0
• Browser: Chrome, Firefox, Edge (all affected)
• OS: Linux (Docker container)
• WebUI Access: kimi web command (port 5494)

Steps to Reproduce

1. Start Kimi Code CLI WebUI: kimi web
2. Open WebUI in browser
3. Click the right "Workspace files" panel
4. Navigate to a directory with long filenames, e.g., ./projects/ or ./projects/vcp-mate/bak/
5. Observe the right side of file list items

Expected Behavior

Action buttons on the right side of each file list item should always remain visible. Long filenames should be truncated with ... ellipsis.

Actual Behavior

• Root directory (/workspace): short directory names, buttons visible ✅
• ./projects/: names like aivmate-webui-gitea, buttons pushed out of viewport ❌
• ./projects/vcp-mate/bak/: long names like vcp-mate-bak-p0-batch1-20260508_..., download button completely invisible ❌

Root Cause Analysis

1. Radix UI ScrollArea: The content container inside the ScrollArea viewport uses display: table with minWidth: "100%". This causes the container width to expand based on the longest content rather than being constrained by the viewport. The viewport has overflow-x: hidden, which clips the right side, including the action buttons.
2. Missing overflow control: The file list item uses flex layout with truncate on the filename, but the parent text container lacks overflow: hidden, preventing flex shrink from working correctly.

Proposed Fix

See linked PR. The fix involves:

• Adding CSS override for Radix UI ScrollArea display: table → display: block
• Adding overflow-hidden to file list items and text containers
• Adding w-full to filename divs

Screenshots

The issue identifies the WebUI Workspace files sidebar and kimi web as the entry point; reproduce it with a directory containing long filenames and inspect the linked PR. Done means the expand and download controls remain visible while long names truncate within the fixed sidebar across the described browsers.