fix: discover AGENTS.md and CLAUDE.md at workspace roots (#4989)

The provider only found copilot-instructions.md (via
customInstructionsService.getAgentInstructions()). AGENTS.md and
CLAUDE.md live at the workspace root and are also agent instructions
but weren't discovered. Now stats workspace roots for these files
and includes them as agent-instructions items.

Author: joshspicer

src/extension/chatSessions/vscode-node/copilotCLICustomizationProvider.ts

@@ -7,13 +7,16 @@ import * as l10n from '@vscode/l10n';
 import * as vscode from 'vscode';
 import { ICustomInstructionsService } from '../../../platform/customInstructions/common/customInstructionsService';
 import { INSTRUCTION_FILE_EXTENSION, SKILL_FILENAME } from '../../../platform/customInstructions/common/promptTypes';
+import { IFileSystemService } from '../../../platform/filesystem/common/fileSystemService';
 import { ILogService } from '../../../platform/log/common/logService';
 import { IPromptsService } from '../../../platform/promptFiles/common/promptsService';
+import { IWorkspaceService } from '../../../platform/workspace/common/workspaceService';
 import { CancellationToken } from '../../../util/vs/base/common/cancellation';
 import { isCancellationError } from '../../../util/vs/base/common/errors';
 import { Emitter } from '../../../util/vs/base/common/event';
 import { Disposable } from '../../../util/vs/base/common/lifecycle';
 import { basename } from '../../../util/vs/base/common/resources';
+import { URI } from '../../../util/vs/base/common/uri';
 import { IChatPromptFileService } from '../common/chatPromptFileService';
 import { ICopilotCLIAgents } from '../copilotcli/node/copilotCli';
 
@@ -42,6 +45,8 @@ export class CopilotCLICustomizationProvider extends Disposable implements vscod
 		@ICustomInstructionsService private readonly customInstructionsService: ICustomInstructionsService,
 		@IPromptsService private readonly promptsService: IPromptsService,
 		@ILogService private readonly logService: ILogService,
+		@IWorkspaceService private readonly workspaceService: IWorkspaceService,
+		@IFileSystemService private readonly fileSystemService: IFileSystemService,
 	) {
 		super();
 
@@ -90,12 +95,26 @@ export class CopilotCLICustomizationProvider extends Disposable implements vscod
 	 * Collects all instruction items from the prompt file service,
 	 * categorizing them with groupKeys and badges matching the core
 	 * implementation:
-	 * - agent-instructions: copilot-instructions.md files
+	 * - agent-instructions: AGENTS.md, CLAUDE.md, copilot-instructions.md
 	 * - context-instructions: files with an applyTo pattern (badge = pattern)
 	 * - on-demand-instructions: files without an applyTo pattern
 	 */
 	private async getInstructionItems(token: CancellationToken): Promise<vscode.ChatSessionCustomizationItem[]> {
+		// Collect agent instruction URIs from customInstructionsService
+		// (copilot-instructions.md) plus workspace-root AGENTS.md and CLAUDE.md
 		const agentInstructionUriList = await this.customInstructionsService.getAgentInstructions();
+		const rootFileNames = ['AGENTS.md', 'CLAUDE.md'];
+		for (const folder of this.workspaceService.getWorkspaceFolders()) {
+			for (const fileName of rootFileNames) {
+				const uri = URI.joinPath(folder, fileName);
+				try {
+					await this.fileSystemService.stat(uri);
+					agentInstructionUriList.push(uri);
+				} catch {
+					// file doesn't exist
+				}
+			}
+		}
 
 		const items: vscode.ChatSessionCustomizationItem[] = [];
 		const seenUris = new Set<string>();

src/extension/chatSessions/vscode-node/test/copilotCLICustomizationProvider.spec.ts

@@ -160,6 +160,8 @@ describe('CopilotCLICustomizationProvider', () => {
 			mockCustomInstructionsService,
 			mockPromptsService,
 			new TestLogService(),
+			{ getWorkspaceFolders: () => [] } as any,
+			{ stat: () => Promise.reject(new Error('not found')) } as any,
 		));
 	});
 
@@ -364,6 +366,36 @@ describe('CopilotCLICustomizationProvider', () => {
 			expect(instrItems.map(i => i.name)).toEqual(['AGENTS.md', 'CLAUDE.md', 'copilot-instructions.md']);
 		});
 
+		it('discovers AGENTS.md and CLAUDE.md from workspace roots via filesystem', async () => {
+			const workspaceRoot = URI.file('/workspace');
+			const agentsUri = URI.file('/workspace/AGENTS.md');
+			const claudeUri = URI.file('/workspace/CLAUDE.md');
+			const existingUris = new Set([agentsUri.toString(), claudeUri.toString()]);
+
+			const testProvider = disposables.add(new CopilotCLICustomizationProvider(
+				mockPromptFileService,
+				mockCopilotCLIAgents,
+				mockCustomInstructionsService,
+				mockPromptsService,
+				new TestLogService(),
+				{ getWorkspaceFolders: () => [workspaceRoot] } as any,
+				{
+					stat: (uri: URI) => existingUris.has(uri.toString())
+						? Promise.resolve({ type: 1, ctime: 0, mtime: 0, size: 0 })
+						: Promise.reject(new Error('not found')),
+				} as any,
+			));
+
+			mockPromptFileService.setInstructions([]);
+			mockCustomInstructionsService.setAgentInstructionUris([]);
+
+			const items = await testProvider.provideChatSessionCustomizations(undefined!);
+			const instrItems = items.filter(i => i.type === FakeChatSessionCustomizationType.Instructions);
+			expect(instrItems).toHaveLength(2);
+			expect(instrItems.every(i => i.groupKey === 'agent-instructions')).toBe(true);
+			expect(instrItems.map(i => i.name)).toEqual(['AGENTS.md', 'CLAUDE.md']);
+		});
+
 		it('uses context-instructions groupKey with badge for instructions with applyTo pattern', async () => {
 			const uri = URI.file('/workspace/.github/style.instructions.md');
 			mockPromptFileService.setInstructions([{ uri }]);