Avoidincluding customizations variables into CLI prompt as context (#4392)

* Avoidincluding customizations variables into CLI prompt as context

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: DonJayamanne

src/extension/chatSessions/copilotcli/node/copilotcliPromptResolver.ts

@@ -18,7 +18,7 @@ import { extUriBiasedIgnorePathCase, relativePath } from '../../../../util/vs/ba
 import { URI } from '../../../../util/vs/base/common/uri';
 import { IInstantiationService } from '../../../../util/vs/platform/instantiation/common/instantiation';
 import { ChatReferenceBinaryData, ChatReferenceDiagnostic, FileType, Location } from '../../../../vscodeTypes';
-import { ChatVariablesCollection, isPromptInstruction, isInstructionFile, PromptVariable } from '../../../prompt/common/chatVariablesCollection';
+import { ChatVariablesCollection, isCustomizationsIndex, isInstructionFile, isPromptInstruction, PromptVariable } from '../../../prompt/common/chatVariablesCollection';
 import { generateUserPrompt } from '../../../prompts/node/agent/copilotCLIPrompt';
 import { getWorkingDirectory, isIsolationEnabled, IWorkspaceInfo } from '../../common/workspaceInfo';
 import { ICopilotCLIImageSupport, isImageMimeType } from './copilotCLIImageSupport';
@@ -76,8 +76,8 @@ export class CopilotCLIPromptResolver {
 		const folderToWorktreeMap = this.buildFolderToWorktreeMap(workspaceInfo, additionalWorkspaces);
 		const hasAnyWorkingDirectory = getWorkingDirectory(workspaceInfo) || additionalWorkspaces.some(ws => getWorkingDirectory(ws));
 		await Promise.all(Array.from(variables).map(async variable => {
-			// Unsupported references.
-			if (isPromptInstruction(variable) || isInstructionFile(variable)) {
+			// Unsupported references: prompt instructions, instruction files, and the customizations index.
+			if (isPromptInstruction(variable) || isInstructionFile(variable) || isCustomizationsIndex(variable)) {
 				return;
 			}
 			// If isolation is enabled, and we have workspace repo information, skip it.

src/extension/prompt/common/chatVariablesCollection.ts

@@ -134,3 +134,12 @@ export function isInstructionFile(variable: PromptVariable): variable is PromptV
 }
 
 export const InstructionFileIdPrefix = 'vscode.instructions.file';
+
+/**
+ * Check if provided variable is the workspace "customizations index" file.
+ */
+export function isCustomizationsIndex(variable: PromptVariable): variable is PromptVariable & { value: vscode.Uri } {
+	return variable.reference.id === CustomizationsIndexId;
+}
+
+export const CustomizationsIndexId = 'vscode.customizations.index';

src/extension/prompts/node/agent/test/parseAttachments.spec.ts

@@ -465,6 +465,38 @@ suite('CopilotCLI Generate & parse prompts', () => {
 				expect(instructionAttachment).toBeUndefined();
 			});
 
+			test('excludes customizations index from references and attachments', async () => {
+				const customizationsIndex = {
+					id: 'vscode.customizations.index',
+					name: 'customizations',
+					value: URI.file('/workspace/.github/copilot-instructions.md')
+				};
+				const regularFileRef = {
+					id: 'regular-file',
+					name: 'regular.ts',
+					value: URI.file('/workspace/regular.ts')
+				};
+				createMockFile(customizationsIndex.value, `# Customizations\nSome instructions.`);
+				createMockFile(regularFileRef.value, `const x = 1;`);
+
+				const req = new TestChatRequest('Process these files', [
+					customizationsIndex,
+					regularFileRef
+				]);
+
+				const resolved = await resolver.resolvePrompt(req, undefined, [], workspaceInfo, [], CancellationToken.None);
+
+				// Customizations index should be excluded from references and attachments
+				const customizationsRef = resolved.references.find(r => URI.isUri(r.value) && (r.value as URI).fsPath.includes('copilot-instructions.md'));
+				expect(customizationsRef).toBeUndefined();
+				// Regular file reference should still be included
+				const regularRef = resolved.references.find(r => URI.isUri(r.value) && (r.value as URI).fsPath.includes('regular.ts'));
+				expect(regularRef).toBeDefined();
+				// Attachment for customizations index should not be present
+				const customizationsAttachment = resolved.attachments.find(a => a.type === 'file' && a.path.includes('copilot-instructions.md'));
+				expect(customizationsAttachment).toBeUndefined();
+			});
+
 			test('extract GitHub PR/Issues', async () => {
 				const result = extractChatPromptReferences(getPromptTextWithGithubIssuePR());
 				expect(result).toMatchSnapshot();