Support browser context attachment

[kycutler]

Closes #312169

[Copilot]

Pull request overview

Adds first-class support for attaching integrated browser tabs/pages as chat context, enabling explicit “attach” flows that can trigger page sharing and show browser attachments consistently alongside other attachment types.

Changes:

• Introduces a new browserView chat variable entry kind and corresponding attachment widgets/rendering paths.
• Adds browser-aware attachment resolution (including prompting to share the page with the agent).
• Extends implicit context rendering to recognize browser resources and show proper labels/icons.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/common/attachments/chatVariableEntries.ts	Adds IBrowserViewVariableEntry and type guard; extends variable entry union.
src/vs/workbench/contrib/chat/browser/widget/media/chat.css	Tweaks text-decoration behavior to support strikethrough inheritance for attachment labels.
src/vs/workbench/contrib/chat/browser/widget/input/chatInputPart.ts	Renders browserView attachments in the input attachment pills via BrowserViewAttachmentWidget.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatAttachmentsContentPart.ts	Renders browserView attachments in the chat transcript attachments area.
src/vs/workbench/contrib/chat/browser/attachments/implicitContextAttachment.ts	Adds browser implicit-context label rendering (globe icon + live label updates).
src/vs/workbench/contrib/chat/browser/attachments/chatImplicitContext.ts	Suggests active browser tab as implicit context and adjusts implicit-entry export behavior.
src/vs/workbench/contrib/chat/browser/attachments/chatAttachmentWidgets.ts	Implements BrowserViewAttachmentWidget for browser attachments (status, hover, open behavior).
src/vs/workbench/contrib/chat/browser/attachments/chatAttachmentResolveService.ts	Resolves browser view attachments and prompts to share when needed.
src/vs/workbench/contrib/chat/browser/attachments/chatAttachmentModel.ts	Routes vscodeBrowser URIs through the attachment resolve service when adding files.
src/vs/workbench/contrib/chat/browser/actions/chatContextActions.ts	Enables attaching browser resources from the “Attach Context” quick pick flow.
src/vs/workbench/contrib/browserView/common/browserEditorInput.ts	Adds onDidResolveModel and isSharingAvailable helpers to support attachment UI behavior.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/browser/attachments/implicitContextAttachment.ts:259

• renderBrowserResource() sets the label text/icon but doesn’t reflect whether the implicit context is disabled (e.g. via label strikethrough). After the CSS change, the disabled state may no longer be obvious for browser implicit context. Consider accepting an enabled (or disabled) parameter and setting strikethrough/title consistently with the file branch.

	private renderBrowserResource(browserUri: URI, label: IResourceLabel, contextNode: HTMLElement): string | undefined {
		const id = BrowserViewUri.getId(browserUri);
		const input = id && this.browserViewService.getKnownBrowserViews().get(id);
		if (!input) {
			return undefined;
		}

		const update = () => {
			label.setLabel(input.getName(), undefined, { iconPath: Codicon.globe });
			contextNode.ariaLabel = localize('chat.implicitBrowserContext', "Suggested browser context, {0}", input.getName());
		};

• Files reviewed: 11/11 changed files
• Comments generated: 8

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@jruales

Matched files:

• src/vs/workbench/contrib/browserView/common/browserEditorInput.ts