AI Customizations: Extension Tools list is clipped and hides tools

[copilot-swe-agent]

Type of issue

Bug

Description

The Extension Tools section in the AI Customizations view does not show all available tool sets. The list is clipped at the bottom, leaving one or more tools inaccessible even though the section count indicates additional entries.

Steps to reproduce

1. Open the Agents window.
2. Open AI Customizations.
3. Expand Extension Tools.
4. Attempt to view all listed extension tool sets.

Expected behavior

All extension tool sets are visible or can be reached by scrolling.

Actual behavior

The bottom of the list is clipped, so not all tools can be seen.

[vs-code-engineering]

Sharing media and context from merged PR #335355 for verification:

Summary

• move the customizations list, migration page, and Tools section scrollbars to the outer pane edge
• make each panel own vertical spacing while its header, controls, and content own their horizontal inset
• give virtualized pages dedicated native scroll containers around their content roots
• preserve the existing centered maximum width without negative margins or synthetic width expansion
• fix the clipped Extension Tools section so every tool set remains reachable
• strengthen narrow fixtures with independently scrollable outer and nested lists

Verification

• npm run stylelint -- src/vs/workbench/contrib/chat/browser/aiCustomization/media/aiCustomizationManagement.css
• npm run eslint -- src/vs/workbench/contrib/chat/browser/aiCustomization/{aiCustomizationManagementEditor,toolsListWidget}.ts
• npm run eslint -- src/vs/workbench/test/browser/componentFixtures/sessions/aiCustomizationManagementEditor.fixture.ts
• 69 focused customization editor/list/Tools unit tests
• all migration fixtures, plus Agents standard/narrow, Skills, Tools standard/narrow/light/empty/browse, and MCP regression fixtures
• customization and migration nested-scroll assertions: Workspace items, outer sections, and User items scroll independently
• Extension Tools assertion: outer sections reach Extension Tools, its nested list reaches exact end, and Tool Set 8 is visible

After

Customization list — outer and nested scrollbars

customizations-scrollbar-after-final.mp4

Migrations dashboard and workspace review scrollbars

merged-migration-scrollbars-final.mp4

Extension Tools — #335508

extension-tools-overflow-final.mp4

Source PR: #335355