vscode/src/vs/workbench/api/common/extHostLanguageModelTools.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import { raceCancellation } from '../../../base/common/async.js';
import { CancellationToken } from '../../../base/common/cancellation.js';
import { CancellationError } from '../../../base/common/errors.js';
import { IDisposable, toDisposable } from '../../../base/common/lifecycle.js';
import { revive } from '../../../base/common/marshalling.js';
import { generateUuid } from '../../../base/common/uuid.js';
import { IExtensionDescription } from '../../../platform/extensions/common/extensions.js';
import { ExtHostLanguageModelToolsShape, IMainContext, IToolDataDto, MainContext, MainThreadLanguageModelToolsShape } from './extHost.protocol.js';
import * as typeConvert from './extHostTypeConverters.js';
import { IToolInvocation, IToolInvocationContext, IToolResult } from '../../contrib/chat/common/languageModelToolsService.js';
import type * as vscode from 'vscode';

export class ExtHostLanguageModelTools implements ExtHostLanguageModelToolsShape {
	/** A map of tools that were registered in this EH */
	private readonly _registeredTools = new Map<string, { extension: IExtensionDescription; tool: vscode.LanguageModelTool }>();
	private readonly _proxy: MainThreadLanguageModelToolsShape;
	private readonly _tokenCountFuncs = new Map</* call ID */string, (text: string, token?: vscode.CancellationToken) => Thenable<number>>();

	/** A map of all known tools, from other EHs or registered in vscode core */
	private readonly _allTools = new Map<string, IToolDataDto>();

	constructor(mainContext: IMainContext) {
		this._proxy = mainContext.getProxy(MainContext.MainThreadLanguageModelTools);

		this._proxy.$getTools().then(tools => {
			for (const tool of tools) {
				this._allTools.set(tool.id, revive(tool));
			}
		});
	}

	async $countTokensForInvocation(callId: string, input: string, token: CancellationToken): Promise<number> {
		const fn = this._tokenCountFuncs.get(callId);
		if (!fn) {
			throw new Error(`Tool invocation call ${callId} not found`);
		}

		return await fn(input, token);
	}

	async invokeTool(toolId: string, options: vscode.LanguageModelToolInvocationOptions, token: CancellationToken): Promise<vscode.LanguageModelToolResult> {
		const callId = generateUuid();
		if (options.tokenOptions) {
			this._tokenCountFuncs.set(callId, options.tokenOptions.countTokens);
		}
		try {
			// Making the round trip here because not all tools were necessarily registered in this EH
			const result = await this._proxy.$invokeTool({
				toolId,
				callId,
				parameters: options.parameters,
				tokenBudget: options.tokenOptions?.tokenBudget,
				context: options.toolInvocationToken as IToolInvocationContext | undefined,
			}, token);
			return typeConvert.LanguageModelToolResult.to(result);
		} finally {
			this._tokenCountFuncs.delete(callId);
		}
	}

	$onDidChangeTools(tools: IToolDataDto[]): void {
		this._allTools.clear();
		for (const tool of tools) {
			this._allTools.set(tool.id, tool);
		}
	}

	get tools(): vscode.LanguageModelToolDescription[] {
		return Array.from(this._allTools.values())
			.map(tool => typeConvert.LanguageModelToolDescription.to(tool));
	}

	async $invokeTool(dto: IToolInvocation, token: CancellationToken): Promise<IToolResult> {
		const item = this._registeredTools.get(dto.toolId);
		if (!item) {
			throw new Error(`Unknown tool ${dto.toolId}`);
		}

		const options: vscode.LanguageModelToolInvocationOptions = { parameters: dto.parameters, toolInvocationToken: dto.context };
		if (dto.tokenBudget !== undefined) {
			options.tokenOptions = {
				tokenBudget: dto.tokenBudget,
				countTokens: this._tokenCountFuncs.get(dto.callId) || ((value, token = CancellationToken.None) =>
					this._proxy.$countTokensForInvocation(dto.callId, value, token))
			};
		}

		// Some participant in extHostChatAgents calls invokeTool, goes to extHostLMTools
		// mainThreadLMTools invokes the tool, which calls back to extHostLMTools
		// The tool requests permission
		// The tool in extHostLMTools calls for permission back to mainThreadLMTools
		// And back to extHostLMTools, and back to the participant in extHostChatAgents
		// Is there a tool call ID to identify the call?
		const extensionResult = await raceCancellation(Promise.resolve(item.tool.invoke(options, token)), token);
		if (!extensionResult) {
			throw new CancellationError();
		}

		for (const key of Object.keys(extensionResult)) {
			const value = extensionResult[key];
			if (value instanceof Promise) {
				throw new Error(`Tool result for '${key}' cannot be a Promise`);
			}
		}

		return typeConvert.LanguageModelToolResult.from(extensionResult);
	}

	registerTool(extension: IExtensionDescription, name: string, tool: vscode.LanguageModelTool): IDisposable {
		this._registeredTools.set(name, { extension, tool });
		this._proxy.$registerTool(name);

		return toDisposable(() => {
			this._registeredTools.delete(name);
			this._proxy.$unregisterTool(name);
		});
	}
}