Fix: Include code snippets with inline file references in chat responses

Fixes #306605

When Copilot CLI provides inline references to code files or locations,
it was only showing links to the files without the actual code snippets.
This made the responses less useful as users had to manually navigate
to the referenced files to see the code.

Changes:
1. **Enhanced IChatContentInlineReference interface** (chatService.ts):
   - Added optional 'snippet' field to store the actual code snippet content
   - Added optional 'languageId' field for syntax highlighting the code

2. **Updated annotation logic** (annotations.ts):
   - Modified annotateSpecialMarkdownContent to include code snippets
   - When an inline reference has a snippet, it's formatted as a code block
   - Added inferLanguageFromLabel helper to determine language for 40+ file types
   - Code snippet is appended right after the reference link

This ensures users see both the file reference and the actual code content
in a single response, improving the overall user experience.

Author: rupeshkumar-555

src/vs/workbench/contrib/chat/common/chatService/chatService.ts

@@ -161,6 +161,16 @@ export interface IChatContentInlineReference {
 	resolveId?: string;
 	inlineReference: URI | Location | IWorkspaceSymbol;
 	name?: string;
+	/**
+	 * Optional code snippet content extracted from the referenced file/location.
+	 * When present, this content should be displayed alongside the reference link.
+	 */
+	snippet?: string;
+	/**
+	 * Optional language identifier for syntax highlighting the code snippet.
+	 * If not provided, will be inferred from the file extension.
+	 */
+	languageId?: string;
 	kind: 'inlineReference';
 }
 

src/vs/workbench/contrib/chat/common/widget/annotations.ts

@@ -12,6 +12,68 @@ import { IChatAgentVulnerabilityDetails } from '../chatService/chatService.js';
 
 export const contentRefUrl = 'http://_vscodecontentref_'; // must be lowercase for URI
 
+/**
+ * Infers the language identifier from a file name or label.
+ * Common language mappings based on file extensions.
+ */
+function inferLanguageFromLabel(label: string): string | undefined {
+	if (!label) {
+		return undefined;
+	}
+
+	const ext = label.substring(label.lastIndexOf('.') + 1).toLowerCase();
+	const languageMap: Record<string, string> = {
+		// Programming languages
+		'js': 'javascript',
+		'jsx': 'javascript',
+		'ts': 'typescript',
+		'tsx': 'typescript',
+		'py': 'python',
+		'java': 'java',
+		'c': 'c',
+		'cpp': 'cpp',
+		'cc': 'cpp',
+		'cxx': 'cpp',
+		'h': 'c',
+		'hpp': 'cpp',
+		'cs': 'csharp',
+		'go': 'go',
+		'rs': 'rust',
+		'rb': 'ruby',
+		'php': 'php',
+		'swift': 'swift',
+		'kt': 'kotlin',
+		'scala': 'scala',
+		'pl': 'perl',
+		'sh': 'bash',
+		'bash': 'bash',
+		'zsh': 'bash',
+		'fish': 'bash',
+		'ps1': 'powershell',
+		'psm1': 'powershell',
+		'lua': 'lua',
+		'r': 'r',
+		'R': 'r',
+		'sql': 'sql',
+		'html': 'html',
+		'htm': 'html',
+		'xml': 'xml',
+		'css': 'css',
+		'scss': 'scss',
+		'sass': 'sass',
+		'less': 'less',
+		'json': 'json',
+		'jsonc': 'jsonc',
+		'yaml': 'yaml',
+		'yml': 'yaml',
+		'toml': 'toml',
+		'md': 'markdown',
+		'markdown': 'markdown',
+	};
+
+	return languageMap[ext];
+}
+
 export function annotateSpecialMarkdownContent(response: Iterable<IChatProgressResponseContent>): IChatProgressRenderableResponseContent[] {
 	let refIdPool = 0;
 
@@ -46,7 +108,13 @@ export function annotateSpecialMarkdownContent(response: Iterable<IChatProgressR
 			} else {
 				const refId = refIdPool++;
 				const printUri = URI.parse(contentRefUrl).with({ path: String(refId) });
-				const markdownText = `[${label}](${printUri.toString()})`;
+				let markdownText = `[${label}](${printUri.toString()})`;
+				
+				// If the inline reference includes a code snippet, append it as a code block
+				if (item.snippet) {
+					const languageId = item.languageId || inferLanguageFromLabel(label) || '';
+					markdownText += `\n\`\`\`${languageId}\n${item.snippet}\n\`\`\``;
+				}
 
 				const annotationMetadata = { [refId]: item };