Add support for custom file link rendering metadata

[pwang347]

Sample usage: microsoft/vscode-copilot-chat#2756

[Copilot]

Pull request overview

This PR adds support for custom file link rendering metadata in the chat widget. The feature allows markdown links to specify custom display names for file references through JSON metadata in the link text.

Key changes:

• Added support for parsing JSON metadata from link text to enable custom file name rendering
• Updated InlineAnchorWidget constructor to accept optional metadata parameter
• Modified file widget rendering logic to support both empty link text (existing behavior) and JSON metadata format

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
chatInlineAnchorWidget.ts	Adds InlineAnchorWidgetMetadata type, implements JSON metadata parsing in renderFileWidgets(), updates InlineAnchorWidget constructor to accept metadata parameter, and uses metadata.fileName for custom display names
chatMarkdownDecorationsRenderer.ts	Updates InlineAnchorWidget instantiation to pass undefined as the third parameter (metadata), maintaining backward compatibility

Comments suppressed due to low confidence (2)

src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatInlineAnchorWidget.ts:66

• The comment on line 66 states "Also support metadata format: {"vscodeLinkType": "file", ...}" but doesn't clarify that the fileName field is optional. The comment should be more explicit about the expected metadata structure, such as: '{"vscodeLinkType": "file", "fileName": "optional-display-name"}'. This will help developers understand the complete API and avoid confusion about whether fileName is required.

		// Also support metadata format: [{"vscodeLinkType": "file", ...}](uri)

src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatInlineAnchorWidget.ts:77

• The metadata validation lacks a type guard to ensure the parsed JSON is an object. While the condition checks metadata && metadata.vscodeLinkType === 'file', if JSON.parse returns a primitive value (string, number, boolean) or an array, accessing metadata.vscodeLinkType won't throw an error but will return undefined, and the condition will silently fail. Add an explicit check that the parsed value is a plain object: metadata && typeof metadata === 'object' && !Array.isArray(metadata) before accessing its properties.

				metadata = JSON.parse(linkText);
				if (metadata && metadata.vscodeLinkType === 'file' && typeof metadata.fileName === 'string') {