Missing prompt contribution should not break chat (#281451)

src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts

@@ -16,7 +16,7 @@ import { IModelService } from '../../../../../../editor/common/services/model.js
 import { localize } from '../../../../../../nls.js';
 import { IConfigurationService } from '../../../../../../platform/configuration/common/configuration.js';
 import { IExtensionDescription } from '../../../../../../platform/extensions/common/extensions.js';
-import { IFileService } from '../../../../../../platform/files/common/files.js';
+import { FileOperationError, FileOperationResult, IFileService } from '../../../../../../platform/files/common/files.js';
 import { IExtensionService } from '../../../../../services/extensions/common/extensions.js';
 import { IInstantiationService } from '../../../../../../platform/instantiation/common/instantiation.js';
 import { ILabelService } from '../../../../../../platform/label/common/label.js';
@@ -387,7 +387,7 @@ export class PromptsService extends Disposable implements IPromptsService {
 		let agentFiles = await this.listPromptFiles(PromptsType.agent, token);
 		const disabledAgents = this.getDisabledPromptFiles(PromptsType.agent);
 		agentFiles = agentFiles.filter(promptPath => !disabledAgents.has(promptPath.uri));
-		const customAgents = await Promise.all(
+		const customAgentsResults = await Promise.allSettled(
 			agentFiles.map(async (promptPath): Promise<ICustomAgent> => {
 				const uri = promptPath.uri;
 				const ast = await this.parseNew(uri, token);
@@ -432,6 +432,23 @@ export class PromptsService extends Disposable implements IPromptsService {
 				return { uri, name, description, model, tools, handOffs, argumentHint, target, infer, agentInstructions, source };
 			})
 		);
+
+		const customAgents: ICustomAgent[] = [];
+		for (let i = 0; i < customAgentsResults.length; i++) {
+			const result = customAgentsResults[i];
+			if (result.status === 'fulfilled') {
+				customAgents.push(result.value);
+			} else {
+				const uri = agentFiles[i].uri;
+				const error = result.reason;
+				if (error instanceof FileOperationError && error.fileOperationResult === FileOperationResult.FILE_NOT_FOUND) {
+					this.logger.warn(`[computeCustomAgents] Skipping agent file that does not exist: ${uri}`, error.message);
+				} else {
+					this.logger.error(`[computeCustomAgents] Failed to parse agent file: ${uri}`, error);
+				}
+			}
+		}
+
 		return customAgents;
 	}
 

src/vs/workbench/contrib/chat/test/common/promptSyntax/service/promptsService.test.ts

@@ -1202,6 +1202,57 @@ suite('PromptsService', () => {
 
 			registered.dispose();
 		});
+
+		test('Contributed agent file that does not exist should not crash', async () => {
+			const nonExistentUri = URI.parse('file://extensions/my-extension/nonexistent.agent.md');
+			const existingUri = URI.parse('file://extensions/my-extension/existing.agent.md');
+			const extension = {
+				identifier: { value: 'test.my-extension' }
+			} as unknown as IExtensionDescription;
+
+			// Only create the existing file
+			await mockFiles(fileService, [
+				{
+					path: existingUri.path,
+					contents: [
+						'---',
+						'name: \'Existing Agent\'',
+						'description: \'An agent that exists\'',
+						'---',
+						'I am an existing agent.',
+					]
+				}
+			]);
+
+			// Register both agents (one exists, one doesn't)
+			const registered1 = service.registerContributedFile(
+				PromptsType.agent,
+				'NonExistent Agent',
+				'An agent that does not exist',
+				nonExistentUri,
+				extension
+			);
+
+			const registered2 = service.registerContributedFile(
+				PromptsType.agent,
+				'Existing Agent',
+				'An agent that exists',
+				existingUri,
+				extension
+			);
+
+			// Verify that getCustomAgents doesn't crash and returns only the valid agent
+			const agents = await service.getCustomAgents(CancellationToken.None);
+
+			// Should only get the existing agent, not the non-existent one
+			assert.strictEqual(agents.length, 1, 'Should only return the agent that exists');
+			assert.strictEqual(agents[0].name, 'Existing Agent');
+			assert.strictEqual(agents[0].description, 'An agent that exists');
+			assert.strictEqual(agents[0].uri.toString(), existingUri.toString());
+
+			registered1.dispose();
+			registered2.dispose();
+		});
 	});
 
 	suite('findClaudeSkills', () => {