fix: preserve code block toolbar visibility during chat streaming#307978
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roblourens merged 1 commit intomicrosoft:mainfrom Apr 7, 2026
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…crosoft#255290) Add JavaScript-based hover tracking to CodeBlockPart so the toolbar remains clickable through DOM detach/reattach cycles during streaming.
vijayupadya
approved these changes
Apr 7, 2026
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Fixes #255290
https://github.com/microsoft/vscode/wiki/How-to-Contribute#pull-requests
Summary
Bug: The copy button on code snippets in chat responses was unclickable while the AI was still streaming, because the toolbar would flicker and lose interactivity.
Root Cause: During streaming, code block DOM elements are briefly detached and reattached as markdown is re-rendered. This causes the browser to lose CSS
:hoverstate, which in turn hides the toolbar (due to apointer-events: nonerule on the non-hovered state). The toolbar becomes invisible and unclickable mid-stream.Fix: Added JavaScript-based hover tracking (
mouseenter/mouseleavelisteners) toCodeBlockPartthat toggles aforce-visibilityclass on the toolbar element. This class persists across DOM detach/reattach cycles, keeping the toolbar visible and clickable even while streaming. The hover state is also restored in the render path so that re-renders during streaming preserve toolbar visibility.Changes
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/codeBlockPart.ts: Added_isHoveredboolean andmouseenter/mouseleaveevent listeners that toggleforce-visibilityon the toolbar. Added post-render restore of toolbar visibility when hovered. Integrated with existing dropdown visibility tracking.src/vs/workbench/contrib/chat/test/browser/widget/chatContentParts/chatMarkdownContentPart.test.ts: Added three regression tests verifying that code block content is correctly set during streaming, that re-renders update content properly, and that the code block pool produces correct data across multiple renders.Testing
chatMarkdownContentPart.test.tsthat verify code block text is correctly rendered during streaming and across re-renders