move more progress parts to shimmer

[justschen]

fix #318585

[Copilot]

Pull request overview

This PR updates how chat tool-invocation progress is visually represented, shifting shimmer styling behavior (including a new “partial shimmer” for askQuestions) and adjusting shimmer eligibility logic across several tool progress parts.

Changes:

• Refines shimmer eligibility via shouldShimmerForTool(...), focusing shimmer on askQuestions invocation text (and adding partial shimmer styling for the prefix before " (").
• Updates chat progress rendering/CSS to support partial shimmer via a dedicated span (.chat-progress-shimmer-text) and selector changes.
• Expands/updates unit tests to cover the new shimmer rules and plaintext rendering in the markdown renderer mock.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/test/browser/widget/chatContentParts/chatToolProgressPart.test.ts	Updates tests for new shimmer rules and adds coverage for partial shimmer output.
src/vs/workbench/contrib/chat/browser/widget/media/chat.css	Adjusts shimmer selectors to support partial shimmer spans.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/toolInvocationParts/chatToolProgressPart.ts	Computes shimmer per tool/content and wires shimmer + icon behavior into ChatProgressContentPart.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/toolInvocationParts/chatToolPartUtilities.ts	Adds isAskQuestionsToolInvocation and changes shimmer decision logic to depend on displayed content.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/toolInvocationParts/chatSimpleToolProgressPart.ts	Passes displayed message into shimmer decision helper.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/toolInvocationParts/chatInputOutputMarkdownProgressPart.ts	Passes displayed message into shimmer decision helper.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatProgressContentPart.ts	Implements partial shimmer DOM wrapping for askQuestions progress text.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/browser/widget/media/chat.css:3085

• The new shimmer animation runs unconditionally. To respect users’ reduced-motion preferences, disable the shimmer animation under @media (prefers-reduced-motion: reduce) (similar to other chat animations in this stylesheet).

	&.shimmer-progress .rendered-markdown.progress-step:not(.chat-progress-partial-shimmer) > p,
	&.shimmer-progress .rendered-markdown.progress-step.chat-progress-partial-shimmer .chat-progress-shimmer-text {
		background: linear-gradient(90deg,
				var(--vscode-descriptionForeground) 0%,
				var(--vscode-descriptionForeground) 30%,
				var(--vscode-chat-thinkingShimmer) 50%,
				var(--vscode-descriptionForeground) 70%,
				var(--vscode-descriptionForeground) 100%);
		background-size: 400% 100%;
		background-clip: text;
		-webkit-background-clip: text;
		-webkit-text-fill-color: transparent;
		animation: chat-thinking-shimmer 2s linear infinite;
		will-change: background-position;

• Files reviewed: 7/7 changed files
• Comments generated: 1